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Sample records for acyl chain order

  1. Insertion of apoLp-III into a lipid monolayer is more favorable for saturated, more ordered, acyl-chains

    SciTech Connect

    Rathnayake, Sewwandi S.; Mirheydari, Mona; Schulte, Adam; Gillahan, James E.; Gentit, Taylor; Phillips, Ashley N.; Okonkwo, Rose K.; Burger, Koert N.J.; Mann, Elizabeth K.; Vaknin, David; Bu, Wei; Agra-Kooijman, Dena Mae; Kooijman, Edgar E.

    2013-10-04

    Neutral lipid transport in mammals is complicated involving many types of apolipoprotein. The exchangeable apolipoproteins mediate the transfer of hydrophobic lipids between tissues and particles, and bind to cell surface receptors. Amphipathic a-helices form a common structural motif that facilitates their lipid binding and exchangeability. ApoLp-III, the only exchangeable apolipoprotein found in insects, is a model amphipathic a:helix bundle protein and its three dimensional structure and function mimics that of the mammalian proteins apoE and apoAI. Even the intracellular exchangeable lipid droplet protein TIP47/perilipin 3 contains an a-helix bundle domain with high structural similarity to that of apoE and apoLp-III. Here, we investigated the interaction of apoLp-III from Locusta migratoria with lipid monolayers. Consistent with earlier work we find that insertion of apoLp-III into fluid lipid monolayers is highest for diacylglycerol. We observe a preference for saturated and more highly ordered lipids, suggesting a new mode of interaction for amphipathic a-helix bundles. X-ray reflectivity shows that apoLp-III unfolds at a hydrophobic interface and flexible loops connecting the amphipathic cc-helices stay in solution. X-ray diffraction indicates that apoLp-III insertion into diacylglycerol monolayers induces additional ordering of saturated acyl-chains. These results thus shed important new insight into the protein-lipid interactions of a model exchangeable apolipoprotein with significant implications for its mammalian counterparts. (C) 2013 Elsevier B.V. All rights reserved.

  2. Lipid Acyl Chain Remodeling in Yeast

    PubMed Central

    Renne, Mike F.; Bao, Xue; De Smet, Cedric H.; de Kroon, Anton I. P. M.

    2015-01-01

    Membrane lipid homeostasis is maintained by de novo synthesis, intracellular transport, remodeling, and degradation of lipid molecules. Glycerophospholipids, the most abundant structural component of eukaryotic membranes, are subject to acyl chain remodeling, which is defined as the post-synthetic process in which one or both acyl chains are exchanged. Here, we review studies addressing acyl chain remodeling of membrane glycerophospholipids in Saccharomyces cerevisiae, a model organism that has been successfully used to investigate lipid synthesis and its regulation. Experimental evidence for the occurrence of phospholipid acyl chain exchange in cardiolipin, phosphatidylcholine, phosphatidylinositol, and phosphatidylethanolamine is summarized, including methods and tools that have been used for detecting remodeling. Progress in the identification of the enzymes involved is reported, and putative functions of acyl chain remodeling in yeast are discussed. PMID:26819558

  3. Effect of a bovine lung surfactant protein isolate (SP-B/C) on egg phosphatidylglycerol acyl chain order in a lipid mixture with dipalmitoylphosphatidylcholine and palmitic acid.

    PubMed

    Krill, S L; Gupta, S L

    1994-04-01

    Dynamic surface tension measurements of films of a d62 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine:L-alpha-phosphatidyl-DL - glycerol:d31 palmitic acid (d62-DPPC:EggPG:d31-PA) lipid matrix in the presence of a bovine pulmonary surfactant protein isolate (SP-B/C) demonstrate the improved surface activity over that of the lipids alone. Thus, significant interaction of the proteins with the lipid matrix is demonstrated. The effect of SP-B/C on the acyl chain order of the negatively charged EggPG within a d62-DPPC:EggPG:d31-PA lipid matrix in D2O saline was investigated in thermal perturbation Fourier transform IR spectroscopic studies. The EggPG thermotropic phase behavior was determined independently of the other lipid components with perdeuterated lipids and D2O. The data demonstrate the high degree of EggPG acyl chain disorder in the absence of the protein isolate. A broad transition occurs between 30 and 40 degrees C. The addition of the protein isolate did not alter the acyl chain order at 0.281 and 1.46 mg/mL of protein. However, alterations in the lipid carbonyl vibrational mode were observed. PMID:8046609

  4. Pulmonary lung surfactant synthetic peptide concentration-dependent modulation of DPPC and POPG acyl chain order in a DPPC:POPG:palmitic acid lipid mixture.

    PubMed

    Krill, S L; Gupta, S L; Smith, T

    1994-05-01

    Lung surfactant-associated protein interaction with lipid matrices and the effects on lipid thermotropic phase behavior are areas of active research. Many studies limit the lipids to a single or two-component system. The current investigation utilizes a three-lipid component matrix (DPPC:POPG:palmitic acid) to investigate the impact of a synthetic surfactant protein B fragment (SP-B 53-78 DiACM) on the dynamic surface activity of the lipid admixture as measured by a Wilhelmy surface balance. Also, the modulation of the individual lipid acyl chain order by the peptide within the lipid matrix is studied through the use of thermal perturbation FTIR spectroscopy. The data clearly demonstrate a concentration-dependent effect of the peptide on the surface activity with an improvement in the dynamic surface tension diagram characteristics (decreased surface tension and increased collapse plateau) especially at low, 0.36 M%, peptide concentrations. These effects are diminished upon further addition of the peptide. FTIR spectral data demonstrate that the peptide addition results in a significant increase in the acyl chain order of the DPPC and POPG components as measured by the position of the methylene stretching vibrational bands. DPPC is most sensitive to the peptide presence, while the palmitic acid is least affected. The transition temperatures of the individual lipids are also increased with the addition of the peptide. The presence of POPG in the matrix achieves the surface activity similarly seen with natural lung surfactant relative to a DPPC/palmitic acid lipid matrix alone. Its presence increases the sensitivity of the DPPC acyl chains to the presence of the peptide. These effects on the chain order are most probably related to the increased acyl chain fluidity which POPG imparts to the lipid matrix because of the presence of the cis double bond. The phosphatidylglycerol headgroup also adds a negative charge to the lipid matrix which enhances the peptide

  5. The membrane interaction of amphiphilic model peptides affects phosphatidylserine headgroup and acyl chain order and dynamics. Application of the phospholipid headgroup electrometer concept to phosphatidylserine

    SciTech Connect

    de Kroon, A.I.P.M.; Killian, J.A.; de Gier, J.; de Kruijff, B. )

    1991-01-29

    Deuterium nuclear magnetic resonance ({sup 2}H NMR) was used to study the interaction of amphiphilic model peptides with model membranes consisting of 1,2-dioleoyl-sn-glycero-3-phospho-L-serine deuterated either at the {beta}-position of the serine moiety ((2-{sup 2}H)DOPS) or at the 11-position of the acyl chains ((11,11-{sup 2}H{sub 2})DOPS). The peptides are derived from the sequences H-Ala-Met-Leu-Trp-Ala-OH and H-Arg-Met-Leu-Trp-Ala-OH and contain a positive charge of +1 or +2 at the amino terminus or one positive charge at each end of the molecule. Upon titration of dispersions of DOPS with the peptides, the divalent peptides show a similar extent of binding to the DOPS bilyers, which is larger than that of the single charged peptide. Under these conditions the values of the quadrupolar splitting of both (2-{sup 2}H)DOPS and (11,11-{sup 2}H{sub 2})DOPS are decreased, indicating that the peptides reduce the order of both the DOPS headgroup and the acyl chains. The extent of the decrease depends on the amount of peptide bound and on the position of the charged moieties in the peptide molecule. Titrations of DOPS with poly(L-lysine){sub 100}, which were included for reasons of comparison, reveal increased {Delta}v{sub q} values. When the peptide-lipid titrations are carried out without applying a freeze-thaw procedure to achieve full equilibration, two-component {sup 2}H NMR spectra occur. The apparently limited accessibility of the lipid to the peptides under these circumstances is discussed in relation to the ability of the peptides to exhibit transbilayer movement. {sup 2}H spin-lattice relaxation time T1 measurements demonstrate a decrease of the rates of motion of both headgroup and acyl chains of DOPS in the presence of the peptides.

  6. 2H nuclear magnetic resonance order parameter profiles suggest a change of molecular shape for phosphatidylcholines containing a polyunsaturated acyl chain.

    PubMed Central

    Holte, L. L.; Peter, S. A.; Sinnwell, T. M.; Gawrisch, K.

    1995-01-01

    Solid-state 2H nuclear magnetic resonance spectroscopy was used to determine the orientational order parameter profiles for a series of phosphatidylcholines with perdeuterated stearic acid, 18:0d35, in position sn-1 and 18:1 omega 9, 18:2 omega 6, 18:3 omega 3, 20:4 omega 6, 20:5 omega 3, or 22:6 omega 3 in position sn-2. The main phase transition temperatures were derived from a first moment analysis, and order parameter profiles of sn-1 chains were calculated from dePaked nuclear magnetic resonance powder patterns. Comparison of the profiles at 37 degrees C showed that unsaturation causes an inhomogenous disordering along the sn-1 chain. Increasing sn-2 chain unsaturation from one to six double bonds resulted in a 1.6-kHz decrease in quadrupolar splittings of the sn-1 chain in the upper half of the chain (or plateau region) and maximum splitting difference of 4.4 kHz at methylene carbon 14. The change in chain order corresponds to a decrease in the 18:0 chain length of 0.4 +/- 0.2 A with 18:2 omega 6 versus 18:1 omega 9 in position sn-2. Fatty acids containing three or more double bonds in sn-2 showed a decrease in sn-1 chain length of 0.7 +/- 0.2 A compared with 18:1 omega 9. The chain length of all lipids decreased with increasing temperature. Highly unsaturated phosphatidylcholines (three or more double bonds in sn-2) had shorter sn-1 chains, but the chain length was somewhat less sensitive to temperature. The profiles reveal that the sn-1 chain exhibits a selective increase in motional freedom in a region located toward the bottom half of the chain as sn-2 unsaturation is increased. This corresponds to an area increase around carbon atom number 14 that is three to four times greater than the increase for the top part of the chain. A similar asymmetric decrease in order, largest toward the methyl end of the chain, was observed when 1 -palmitoyl-2-oleoylphosphatidylethanolamine goes from a lamellar to an inverse hexagonal (H,,) phase. This is consistent with a

  7. The chain-flipping mechanism of ACP (acyl carrier protein)-dependent enzymes appears universal.

    PubMed

    Cronan, John E

    2014-06-01

    ACPs (acyl carrier proteins) play essential roles in the synthesis of fatty acids, polyketides and non-ribosomal polypeptides. ACP function requires the modification of the protein by attachment of 4'-phosphopantetheine to a conserved serine residue. The phosphopantetheine thiol acts to tether the starting materials and intermediates as their thioesters. ACPs are small highly soluble proteins composed of four α-helices. The helices form a bundle that acts as a hydrophobic sleeve that sequesters the acyl chains and activated thioesters from solvent. However, in the synthesis of fatty acids and complex lipids the enzymes of the pathway must access the thioester and the proximal carbon atoms in order to perform the needed chemistry. How such access is provided without exposure of the acyl chains to solvent has been a longstanding question due to the lack of acyl-ACP-enzyme complexes, a situation generally attributed to the brevity of the interactions of acyl-ACPs with their cognate enzymes. As discussed in the present review the access question has now been answered by four recent crystal structures, each of which shows that the entire acyl chain plus the 4'-phosphopantetheine prosthetic group partitions from the ACP hydrophobic sleeve into a hydrophobic pocket or groove of the enzyme protein, a process termed chain flipping. PMID:24825445

  8. Regioselective enzymatic acylation of methyl shikimate. Influence of acyl chain length and solvent polarity on enzyme specificity.

    PubMed

    Armesto, Nuria; Ferrero, Miguel; Fernández, Susana; Gotor, Vicente

    2002-07-12

    Candida antarctica lipase A (CAL-A) selectively catalyzes the acylation at the secondary C-4 hydroxyl group of methyl shikimate (2), which possesses three secondary hydroxyl groups, the C-3 allylic one being chemically more reactive. The effect both of the acyl group of the acylating agents and of the solvent polarity has been studied. The selectivity of CAL-A is almost complete with acyl donors that possess short chains. However, when acyl donors have longer chains, better results are obtained by C. antarctica lipase B (CAL-B). PMID:12098318

  9. Naphthalene Derivatives Induce Acyl Chain Interdigitation in Dipalmitoylphosphatidylcholine Bilayers.

    PubMed

    Kamal, Md Arif; Raghunathan, V A

    2016-01-14

    The interdigitated phase of the lipid bilayer results when acyl chains from opposing monolayers fully interpenetrate such that the terminal methyl groups of the respective lipid chains are located at the interfacial region on the opposite sides of the bilayer. Usually, chain interdigitation is not encountered in a symmetric chain phosphatidylcholine (PC) membrane but can be induced under certain special conditions. In this article, we elucidate the contribution of small amphiphatic molecules in altering the physical properties of a symmetric chain PC bilayer membrane, which results in acyl chain interdigitation. Using small-angle X-ray scattering (SAXS), we have carried out a systematic investigation of the physical interactions of three naphthalene derivatives containing hydroxyl groups: β-naphthol, 2,3-dihydroxynaphthalene, and 2,7-dihydroxynaphthalene, with dipalmitoylphosphatidylcholine (DPPC) bilayers. On the basis of the diffraction patterns, we have determined the temperature-composition phase diagrams of these binary mixtures. The present study not only enables us to gain insight into the role played by small molecules in altering the packing arrangement of the acyl chains of the constituting PC lipids of the bilayer but also brings to light some important features that have not yet been reported hitherto. One such feature is the stabilization of the enigmatic asymmetric ripple phase over a wide temperature and concentration range. The results presented here strongly point toward a clear correlation between chain interdigitation and the stability of the ripple phase. PMID:26687052

  10. Interactions of the acyl chain with the Saccharomyces cerevisiae acyl carrier protein.

    PubMed

    Perez, Daniel R; Leibundgut, Marc; Wider, Gerhard

    2015-04-01

    Acyl carrier protein (ACP) domains are critical integral components of multifunctional type I fatty acid synthases (FAS I) and polyketide synthases (PKSs), where they shuttle the growing adducts of the synthesis between the catalytic domains. In contrast to ACP of mammalian FAS I, PKSs, and the dissociated fatty acid synthase type II systems (FAS II) of bacteria, fungal FAS I ACP consists of two subdomains, one comprising the canonical ACP fold observed in all FAS systems and the other representing an extra structural subdomain. While ACPs of dissociated FAS II are able to sequester the reaction intermediates during substrate shuttling, such a transport mechanism has not been observed in ACP domains of multifunctional FAS I and PKS systems. For a better understanding of the interaction between the canonical subdomain of fungal ACP with the growing acyl chain and the role of the structural subdomain, we determined the structure of the isolated Saccharomyces cerevisiae acyl carrier protein (ScACP) domain by NMR spectroscopy and investigated the interactions between ScACP and covalently attached substrate acyl chains of varying length by monitoring chemical shift perturbations. The interactions were mapped to the hydrophobic core of the canonical subdomain, while no perturbations were detected in the structural subdomain. A population analysis revealed that only approximately 15% of covalently attached decanoyl chains are sequestered by the ACP core, comparable to the mammalian FAS I and multifunctional PKS systems, which do not sequester their substrates. Finally, denaturation experiments show that both ScACP subdomains unfold cooperatively and that the weak interaction of the acyl chain with the hydrophobic core does not significantly affect the ACP stability. PMID:25774789

  11. Mutations in p53 change phosphatidylinositol acyl chain composition

    PubMed Central

    Naguib, Adam; Bencze, Gyula; Engle, Dannielle; Chio, Iok I. C.; Herzka, Tali; Watrud, Kaitlin; Bencze, Szilvia; Tuveson, David A.; Pappin, Darryl J; Trotman, Lloyd C.

    2014-01-01

    Phosphatidylinositol phosphate (PIP) second messengers relay extracellular growth cues through the phosphorylation status of the inositol sugar, a signal transduction system that is deregulated in cancer. In stark contrast to PIP inositol head group phosphorylation, changes in phosphatidylinositol (PI) lipid acyl chains in cancer have remained ill-defined. Here, we apply a mass spectrometry-based method capable of unbiased high-throughput identification and quantification of cellular PI acyl chain composition. Using this approach we find that PI lipid chains represent a cell-specific fingerprint and are unperturbed by serum-mediated signaling in contrast to the inositol head group. We find that mutation of Trp53 results in PIs containing reduced-length fatty acid moieties. Our results suggest that the anchoring tails of lipid second messengers form an additional layer of PIP signaling in cancer that operates independently of PTEN/PI3-Kinase activity, but is instead linked somehow to p53. PMID:25543136

  12. Acyl Chain Disorder and Azelaoyl Orientation in Lipid Membranes Containing Oxidized Lipids.

    PubMed

    Mendes Ferreira, Tiago; Sood, Rohit; Bärenwald, Ruth; Carlström, Göran; Topgaard, Daniel; Saalwächter, Kay; Kinnunen, Paavo K J; Ollila, O H Samuli

    2016-06-28

    Oxidized phospholipids occur naturally in conditions of oxidative stress and have been suggested to play an important role in a number of pathological conditions due to their effects on a lipid membrane acyl chain orientation, ordering, and permeability. Here we investigate the effect of the oxidized phospholipid 1-palmitoyl-2-azelaoyl-sn-glycero-3-phosphocholine (PazePC) on a model membrane of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) using a combination of (13)C-(1)H dipolar-recoupling nuclear magnetic resonance (NMR) experiments and united-atom molecular dynamics (MD) simulations. The obtained experimental order parameter SCH profiles show that the presence of 30 mol % PazePC in the bilayer significantly increases the gauche content of the POPC acyl chains, therefore decreasing the thickness of the bilayer, although with no stable bilayer pore formation. The MD simulations reproduce the disordering effect and indicate that the orientation of the azelaoyl chain is highly dependent on its protonation state with acyl chain reversal for fully deprotonated states and a parallel orientation along the interfacial plane for fully protonated states, deprotonated and protonated azelaoyl chains having negative and positive SCH profiles, respectively. Only fully or nearly fully protonated azelaoyl chain are observed in the (13)C-(1)H dipolar-recoupling NMR experiments. The experiments show positive SCH values for the azelaoyl segments confirming for the first time that oxidized chains with polar termini adopt a parallel orientation to the bilayer plane as predicted in MD simulations. PMID:27260273

  13. Acyl Chain Length of Phosphatidylserine Is Correlated with Plant Lifespan

    PubMed Central

    Tian, Xuejun; Li, Weiqi

    2014-01-01

    Plant lifespan is affected by factors with genetic and environmental bases. The laws governing these two factors and how they affect plant lifespan are unclear. Here we show that the acyl chain length (ACL) of phosphatidylserine (PS) is correlated with plant lifespan. Among the detected eight head-group classes of membrane lipids with lipidomics based on triple quadrupole tandem mass spectrometry, the ACL of PS showed high diversity, in contrast to the ACLs of the other seven classes, which were highly conserved over all stages of development in all plant species and organs and under all conditions that we studied. Further investigation found that acyl chains of PS lengthened during development, senescence, and under environmental stresses and that increasing length was accelerated by promoted- senescence. The acyl chains of PS were limited to a certain carbon number and ceased to increase in length when plants were close to death. These findings suggest that the ACL of PS can count plant lifespan and could be a molecular scale ruler for measuring plant development and senescence. PMID:25058060

  14. Metabolic Glycoengineering with N-Acyl Side Chain Modified Mannosamines.

    PubMed

    Wratil, Paul R; Horstkorte, Rüdiger; Reutter, Werner

    2016-08-01

    In metabolic glycoengineering (MGE), cells or animals are treated with unnatural derivatives of monosaccharides. After entering the cytosol, these sugar analogues are metabolized and subsequently expressed on newly synthesized glycoconjugates. The feasibility of MGE was first discovered for sialylated glycans, by using N-acyl-modified mannosamines as precursor molecules for unnatural sialic acids. Prerequisite is the promiscuity of the enzymes of the Roseman-Warren biosynthetic pathway. These enzymes were shown to tolerate specific modifications of the N-acyl side chain of mannosamine analogues, for example, elongation by one or more methylene groups (aliphatic modifications) or by insertion of reactive groups (bioorthogonal modifications). Unnatural sialic acids are incorporated into glycoconjugates of cells and organs. MGE has intriguing biological consequences for treated cells (aliphatic MGE) and offers the opportunity to visualize the topography and dynamics of sialylated glycans in vitro, ex vivo, and in vivo (bioorthogonal MGE). PMID:27435524

  15. Effects of Nanoparticle Morphology and Acyl Chain Length on Spontaneous Lipid Transfer Rates

    DOE PAGESBeta

    Xia, Yan; Li, Ming; Charubin, Kamil; Liu, Ying; Heberle, Frederick A.; Katsaras, John; Jing, Benxin; Zhu, Yingxi; Nieh, Mu-Ping

    2015-11-05

    In this paper, we report on studies of lipid transfer rates between different morphology nanoparticles and lipids with different length acyl chains. The lipid transfer rate of dimyristoylphosphatidylcholine (di-C14, DMPC) in discoidal “bicelles” (0.156 h–1) is 2 orders of magnitude greater than that of DMPC vesicles (ULVs) (1.1 × 10–3 h–1). For both bicellar and ULV morphologies, increasing the acyl chain length by two carbons [going from di-C14 DMPC to di-C16, dipalmitoylphosphatidylcholine (DPPC)] causes lipid transfer rates to decrease by more than 2 orders of magnitude. Results from small angle neutron scattering (SANS), differential scanning calorimetry (DSC), and fluorescence correlationmore » spectroscopy (FCS) are in good agreement. Finally, the present studies highlight the importance of lipid dynamic processes taking place in different morphology biomimetic membranes.« less

  16. Effects of Nanoparticle Morphology and Acyl Chain Length on Spontaneous Lipid Transfer Rates

    SciTech Connect

    Xia, Yan; Li, Ming; Charubin, Kamil; Liu, Ying; Heberle, Frederick A.; Katsaras, John; Jing, Benxin; Zhu, Yingxi; Nieh, Mu-Ping

    2015-11-05

    In this paper, we report on studies of lipid transfer rates between different morphology nanoparticles and lipids with different length acyl chains. The lipid transfer rate of dimyristoylphosphatidylcholine (di-C14, DMPC) in discoidal “bicelles” (0.156 h–1) is 2 orders of magnitude greater than that of DMPC vesicles (ULVs) (1.1 × 10–3 h–1). For both bicellar and ULV morphologies, increasing the acyl chain length by two carbons [going from di-C14 DMPC to di-C16, dipalmitoylphosphatidylcholine (DPPC)] causes lipid transfer rates to decrease by more than 2 orders of magnitude. Results from small angle neutron scattering (SANS), differential scanning calorimetry (DSC), and fluorescence correlation spectroscopy (FCS) are in good agreement. Finally, the present studies highlight the importance of lipid dynamic processes taking place in different morphology biomimetic membranes.

  17. Trans-unsaturated lipid dynamics: modulation of dielaidoylphosphatidylcholine acyl chain motion by ethanol.

    PubMed Central

    Dalton, L A; Miller, K W

    1993-01-01

    Acyl chain dynamics of the trans-unsaturated lipid, dielaidoylphosphatidylcholine (DEPC), were studied by conventional and saturation transfer electron paramagnetic resonance spectroscopy of aqueous dispersions of DEPC spin labeled with lecithins having doxyl groups at positions 5, 10, and 14 on the sn-2 chain. The gel to liquid crystalline transition is concerted with simultaneous increases in rotational motion about the long axis of the acyl chain (libration) and in gauche-trans conformational interconversions (wobble). Relative to saturated lecithins at similar reduced temperatures the double bond (a) slowed libration by an order of magnitude in both phases, while wobble motions were several times slower, and (b)-produced a pronounced stiffness of the acyl chain near the double bond. Ethanol (0-1.6 M), in addition to its well-known colligative effect on the phase transition, was found to decrease the bilayer order in a concentration-dependent manner. This effect was smaller in the gel than in the liquid crystalline phase, most pronounced next to the double bond, and weakest deep in the bilayer. Ethanol affected slow motions little in the gel phase but wobble and libration correlation times were markedly decreased in the liquid crystalline phase. PMID:8274650

  18. Lipid Gymnastics: Evidence of Complete Acyl Chain Reversal in Oxidized Phospholipids from Molecular Simulations

    PubMed Central

    Khandelia, Himanshu; Mouritsen, Ole G.

    2009-01-01

    In oxidative environments, biomembranes contain oxidized lipids with short, polar acyl chains. Two stable lipid oxidation products are PoxnoPC and PazePC. PoxnoPC has a carbonyl group, and PazePC has an anionic carboxyl group pendant at the end of the short, oxidized acyl chain. We have used MD simulations to explore the possibility of complete chain reversal in OXPLs in POPC-OXPL mixtures. The polar AZ chain of PazePC undergoes chain reversal without compromising the lipid bilayer integrity at concentrations up to 25% OXPL, and the carboxyl group points into the aqueous phase. Counterintuitively, the perturbation of overall membrane structural and dynamic properties is stronger for PoxnoPC than for PazePC. This is because of the overall condensing and ordering effect of sodium ions bound strongly to the lipids in the PazePC simulations. The reorientation of AZ chain is similar for two different lipid force fields. This work provides the first molecular evidence of the “extended lipid conformation” in phospholipid membranes. The chain reversal of PazePC lipids decorates the membrane interface with reactive, negatively charged functional groups. Such chain reversal is likely to exert a profound influence on the structure and dynamics of biological membranes, and on membrane-associated biological processes. PMID:19348756

  19. Characterization of an Archaeal Medium-Chain Acyl Coenzyme A Synthetase from Methanosarcina acetivorans▿

    PubMed Central

    Meng, Yu; Ingram-Smith, Cheryl; Cooper, Leroy L.; Smith, Kerry S.

    2010-01-01

    Short- and medium-chain acyl coenzyme A (acyl-CoA) synthetases catalyze the formation of acyl-CoA from an acyl substrate, ATP, and CoA. These enzymes catalyze mechanistically similar two-step reactions that proceed through an enzyme-bound acyl-AMP intermediate. Here we describe the characterization of a member of this enzyme family from the methane-producing archaeon Methanosarcina acetivorans. This enzyme, a medium-chain acyl-CoA synthetase designated MacsMa, utilizes 2-methylbutyrate as its preferred substrate for acyl-CoA synthesis but cannot utilize acetate and thus cannot catalyze the first step of acetoclastic methanogenesis in M. acetivorans. When propionate or other less favorable acyl substrates, such as butyrate, 2-methylpropionate, or 2-methylvalerate, were utilized, the acyl-CoA was not produced or was produced at reduced levels. Instead, acyl-AMP and PPi were released in the absence of CoA, whereas in the presence of CoA, the intermediate was broken down into AMP and the acyl substrate, which were released along with PPi. These results suggest that although acyl-CoA synthetases may have the ability to utilize a broad range of substrates for the acyl-adenylate-forming first step of the reaction, the intermediate may not be suitable for the thioester-forming second step. The MacsMa structure has revealed the putative acyl substrate- and CoA-binding pockets. Six residues proposed to form the acyl substrate-binding pocket, Lys256, Cys298, Gly351, Trp259, Trp237, and Trp254, were targeted for alteration. Characterization of the enzyme variants indicates that these six residues are critical in acyl substrate binding and catalysis, and even conservative alterations significantly reduced the catalytic ability of the enzyme. PMID:20851904

  20. Cardiolipin molecular species with shorter acyl chains accumulate in Saccharomyces cerevisiae mutants lacking the acyl coenzyme A-binding protein Acb1p: new insights into acyl chain remodeling of cardiolipin.

    PubMed

    Rijken, Pieter J; Houtkooper, Riekelt H; Akbari, Hana; Brouwers, Jos F; Koorengevel, Martijn C; de Kruijff, Ben; Frentzen, Margrit; Vaz, Frédéric M; de Kroon, Anton I P M

    2009-10-01

    The function of the mitochondrial phospholipid cardiolipin (CL) is thought to depend on its acyl chain composition. The present study aims at a better understanding of the way the CL species profile is established in Saccharomyces cerevisiae by using depletion of the acyl-CoA-binding protein Acb1p as a tool to modulate the cellular acyl chain content. Despite the presence of an intact CL remodeling system, acyl chains shorter than 16 carbon atoms (C16) were found to accumulate in CL in cells lacking Acb1p. Further experiments revealed that Taz1p, a key CL remodeling enzyme, was not responsible for the shortening of CL in the absence of Acb1p. This left de novo CL synthesis as the only possible source of acyl chains shorter than C16 in CL. Experiments in which the substrate specificity of the yeast cardiolipin synthase Crd1p and the acyl chain composition of individual short CL species were investigated, indicated that both CL precursors (i.e. phosphatidylglycerol and CDP-diacylglycerol) contribute to comparable extents to the shorter acyl chains in CL in acb1 mutants. Based on the findings, we conclude that the fatty acid composition of mature CL in yeast is governed by the substrate specificity of the CL-specific lipase Cld1p and the fatty acid composition of the Taz1p substrates. PMID:19656950

  1. Acyl chain length and charge effect on Tamoxifen-lipid model membrane interactions

    NASA Astrophysics Data System (ADS)

    Bilge, Duygu; Kazanci, Nadide; Severcan, Feride

    2013-05-01

    Tamoxifen (TAM), which is an antiestrogenic agent, is widely used during chemotherapy of breast, pancreas, brain and liver cancers. In this study, TAM and model membrane interactions in the form of multilamellar vesicles (MLVs) were studied for lipids containing different acyl chain length and different charge status as a function of different TAM (1, 6, 9 and 15 mol%) concentrations. Zwitterionic lipids namely dipalmitoyl phosphatidylcholine (DPPC), and dimyristoylphosphatidylcholine (DMPC) lipids were used to see the acyl chain length effect and anionic dipalmitoyl phosphtidylglycerol (DPPG) lipid was used to see the charge effect. For this purpose Fourier transform-infrared (FTIR) spectroscopic and differential scanning calorimetric (DSC) techniques have been conducted. For zwitterionic lipid, concentration dependent different action of TAM was observed both in the gel and liquid crystalline phases by significantly increasing the lipid order and decreasing the dynamics for 1 mol% TAM, while decreasing the lipid order and increasing the dynamics of the lipids for higher concentrations (6, 9 and 15 mol%). However, different than neutral lipids, the dynamics and disorder of DPPG liposome increased for all TAM concentrations. The interactions between TAM and head group of multilamellar liposomes was monitored by analyzing the Cdbnd O stretching and PO2- antisymmetric double bond stretching bands. Increasing Tamoxifen concentrations led to a dehydration around these functional groups in the polar part of the lipids. DSC studies showed that for all types of lipids, TAM eliminates the pre-transition, shifts the main phase transition to lower temperatures and broadened the phase transition curve. The results indicate that not the acyl chain length but the charge status of the polar head group induces different effects on lipid membranes order and dynamics.

  2. Understanding Acyl Chain and Glycerolipid Metabolism in Plants

    SciTech Connect

    Ohlrogge, John B.

    2013-11-05

    Progress is reported in these areas: acyl-editing in initial eukaryotic lipid assembly in soybean seeds; identification and characterization of two Arabidopsis thaliana lysophosphatidyl acyltransferases with preference for lysophosphatidylethanolamine; and characterization and subcellular distribution of lysolipid acyl transferase activity of pea leaves.

  3. Probing the Lipid-Protein Interface Using Model Transmembrane Peptides with a Covalently Linked Acyl Chain

    PubMed Central

    Nyholm, Thomas K.M.; van Duyl, Bianca; Rijkers, Dirk T.S.; Liskamp, Rob M.J.; Killian, J. Antoinette

    2011-01-01

    The aim of this study was to gain insight into how interactions between proteins and lipids in membranes are sensed at the protein-lipid interface. As a probe to analyze this interface, we used deuterium-labeled acyl chains that were covalently linked to a model transmembrane peptide. First, a perdeuterated palmitoyl chain was coupled to the Trp-flanked peptide WALP23 (Ac-CGWW(LA)8LWWA-NH2), and the deuterium NMR spectrum was analyzed in di-C18:1-phosphatidylcholine (PC) bilayers. We found that the chain order of this peptide-linked chain is rather similar to that of a noncovalently coupled perdeuterated palmitoyl chain, except that it exhibits a slightly lower order. Similar results were obtained when site-specific deuterium labels were used and when the palmitoyl chain was attached to the more-hydrophobic model peptide WLP23 (Ac-CGWWL17WWA-NH2) or to the Lys-flanked peptide KALP23 (Ac-CGKK(LA)8LKKA-NH2). The experiments showed that the order of both the peptide-linked chains and the noncovalently coupled palmitoyl chains in the phospholipid bilayer increases in the order KALP23 < WALP23 < WLP23. Furthermore, changes in the bulk lipid bilayer thickness caused by varying the lipid composition from di-C14:1-PC to di-C18:1-PC or by including cholesterol were sensed rather similarly by the covalently coupled chain and the noncovalently coupled palmitoyl chains. The results indicate that the properties of lipids adjacent to transmembrane peptides mostly reflect the properties of the surrounding lipid bilayer, and hence that (at least for the single-span model peptides used in this study) annular lipids do not play a highly specific role in protein-lipid interactions. PMID:22004750

  4. Acyl-Chain Mismatch Driven Superlattice Arrangements in DPPC/DLPC/Cholesterol Bilayers

    PubMed Central

    Cannon, Brian; Lewis, Anthony; Somerharju, Pentti; Virtanen, Jorma; Huang, Juyang; Cheng, Kwan Hon

    2010-01-01

    Fluorescence and infrared spectroscopy and cholesterol oxidase activity were employed to investigate the effect of phosphatidylcholine (PC) acyl chain length mismatch on the lateral organizations of lipids in liquid-ordered dipalmitoyl-PC/dilauroyl-PC/cholesterol (DPPC/DLPC/CHOL) bilayers. Plots of steady-state fluorescence emission anisotropy of diphenylhexatriene (DPH) labeled PC (DPH-PC) embedded in the DPPC/DLPC/CHOL bilayers revealed significant peaks at several DPPC mole fractions (YDPPC) when the cholesterol mole fraction (XCHOL) was fixed to particular values. Analogously, the DPH-PC anisotropy peaked at several critical XCHOL’s when YDPPC was fixed. Acyl chain C–H and C=O vibrational peak frequencies of native PC as well as the activity of cholesterol oxidase also revealed dips and peaks at similar YDPPC’s. Importantly, most of the observed peaks/dips coincide with the critical mole fractions predicted by the Superlattice (SL) model. A three-dimensional map of DPH-PC anisotropy versus composition in the range 0.32 ≤ XCHOL ≤ 0.50; 0.54 ≤ YDPPC ≤ 0.72 revealed a prominent peak at (XCHOL, YDPPC) ≈ (0.42, 0.64). This suggests a simultaneous presence of two different types of superlattices, one where cholesterol is the quest molecule in a PC host lattice and another where DPPC is the guest in the DLPC host lattice. Time-resolved measurements of DPH-PC fluorescence indicated the existence of an ordered, rotationally hindered environment of acyl chains at that “critical” composition consistent with the existence of SL arrangements. We propose that beside CHOL/PC superlattices, DPPC, and DLPC as well tend to adopt regular SL-like lateral distributions relative to each other, presumably because the less hydrophobic DLPC molecule is slightly displaced toward the aqueous phase, thus allowing more room and mobility for the head groups of both DPPC and DLPC as well as for the acyl chain tails of DPPC. The parallel presence of two kinds of

  5. Synthesis of Long-Chain Acyl-CoA in Chloroplast Envelope Membranes 1

    PubMed Central

    Joyard, Jacques; Stumpf, Paul K.

    1981-01-01

    The chloroplast envelope is the site of a very active long-chain acylcoenzyme A (CoA) synthetase. Furthermore, we have recently shown that an acyl CoA thioesterase is also associated with envelope membrane (Joyard J, PK Stumpf 1980 Plant Physiol 65: 1039-1043). To clarify the interacting roles of both the acyl-CoA thioesterase and the acyl-CoA synthetase, the formation of acyl-CoA in envelope membranes was examined with different techniques which permitted the measurement of the actual rates of acyl-CoA formation. Using [14C]ATP or [14C]oleic acid as labeled substrates, it can be shown that the envelope acyl-CoA synthetase required both Mg2+ and dithiothreitol. Triton X-100 slightly stimulated the activity. The specificity of the acyl-CoA synthetase was determined either with [14C]ATP or with [3H]CoA as substrates. The results obtained in both cases were similar, that is, as substrates, the unsaturated fatty acids were more effective than saturated fatty acids, the velocity of the reaction increased from lauric acid to palmitic acid, and the maximum velocity was obtained with unsaturated C18 fatty acids. The results obtained suggest that the acyl-CoA thioesterase associated with envelope membranes could be an ultimate control to prevent the transport (outside of the chloroplast) or the insertion (into chloroplast lipids) of fatty acids with chains shorter than C16. PMID:16661656

  6. Phosphatidylinositol-4-phosphate 5-Kinase Isoforms Exhibit Acyl Chain Selectivity for Both Substrate and Lipid Activator*

    PubMed Central

    Shulga, Yulia V.; Anderson, Richard A.; Topham, Matthew K.; Epand, Richard M.

    2012-01-01

    Phosphatidylinositol 4,5-bisphosphate is mostly produced in the cell by phosphatidylinositol-4-phosphate 5-kinases (PIP5K) and has a crucial role in numerous signaling events. Here we demonstrate that in vitro all three isoforms of PIP5K, α, β, and γ, discriminate among substrates with different acyl chains for both the substrates phosphatidylinositol 4-phosphate (PtdIns4P) and phosphatidylinositol (PtdIns) although to different extents, with isoform γ being the most selective. Fully saturated dipalmitoyl-PtdIns4P was a poor substrate for all three isoforms, but both the 1-stearoyl-2-arachidonoyl and the 1-stearoyl-2-oleoyl forms of PtdIns4P were good substrates. Vmax was greater for the 1-stearoyl-2-arachidonoyl form compared with the 1-stearoyl-2-oleoyl form, although for PIP5Kβ the difference was small. For the α and γ isoforms, Km was much lower for 1-stearoyl-2-oleoyl PtdIns4P, making this lipid the better substrate of the two under most conditions. Activation of PIP5K by phosphatidic acid is also acyl chain-dependent. Species of phosphatidic acid with two unsaturated acyl chains are much better activators of PIP5K than those containing one saturated and one unsaturated acyl chain. PtdIns is a poor substrate for PIP5K, but it also shows acyl chain selectivity. Curiously, there is no acyl chain discrimination among species of phosphatidic acid in the activation of the phosphorylation of PtdIns. Together, our findings indicate that PIP5K isoforms α, β, and γ act selectively on substrates and activators with different acyl chains. This could be a tightly regulated mechanism of producing physiologically active unsaturated phosphatidylinositol 4,5-bisphosphate species in the cell. PMID:22942276

  7. Long-chain acyl-homoserine lactones from Methylobacterium mesophilicum: synthesis and absolute configuration.

    PubMed

    Pomini, Armando M; Cruz, Pedro L R; Gai, Cláudia; Araújo, Welington L; Marsaioli, Anita J

    2009-12-01

    The acyl-homoserine lactones (acyl-HSLs) produced by Methylobacterium mesophilicum isolated from orange trees infected with the citrus variegated chlorosis (CVC) disease have been studied, revealing the occurrence of six long-chain acyl-HSLs, i.e., the saturated homologues (S)-N-dodecanoyl (1) and (S)-N-tetradecanoyl-HSL (5), the uncommon odd-chain N-tridecanoyl-HSL (3), the new natural product (S)-N-(2E)-dodecenoyl-HSL (2), and the rare unsaturated homologues (S)-N-(7Z)-tetradecenoyl (4) and (S)-N-(2E,7Z)-tetradecadienyl-HSL (6). The absolute configurations of all HSLs were determined as 3S. Compounds 2 and 6 were synthesized for the first time. Antimicrobial assays with synthetic acyl-HSLs against Gram-positive bacterial endophytes co-isolated with M. mesophilicum from CVC-infected trees revealed low or no antibacterial activity. PMID:19919062

  8. Cardiolipin Molecular Species with Shorter Acyl Chains Accumulate in Saccharomyces cerevisiae Mutants Lacking the Acyl Coenzyme A-binding Protein Acb1p

    PubMed Central

    Rijken, Pieter J.; Houtkooper, Riekelt H.; Akbari, Hana; Brouwers, Jos F.; Koorengevel, Martijn C.; de Kruijff, Ben; Frentzen, Margrit; Vaz, Frédéric M.; de Kroon, Anton I. P. M.

    2009-01-01

    The function of the mitochondrial phospholipid cardiolipin (CL) is thought to depend on its acyl chain composition. The present study aims at a better understanding of the way the CL species profile is established in Saccharomyces cerevisiae by using depletion of the acyl-CoA-binding protein Acb1p as a tool to modulate the cellular acyl chain content. Despite the presence of an intact CL remodeling system, acyl chains shorter than 16 carbon atoms (C16) were found to accumulate in CL in cells lacking Acb1p. Further experiments revealed that Taz1p, a key CL remodeling enzyme, was not responsible for the shortening of CL in the absence of Acb1p. This left de novo CL synthesis as the only possible source of acyl chains shorter than C16 in CL. Experiments in which the substrate specificity of the yeast cardiolipin synthase Crd1p and the acyl chain composition of individual short CL species were investigated, indicated that both CL precursors (i.e. phosphatidylglycerol and CDP-diacylglycerol) contribute to comparable extents to the shorter acyl chains in CL in acb1 mutants. Based on the findings, we conclude that the fatty acid composition of mature CL in yeast is governed by the substrate specificity of the CL-specific lipase Cld1p and the fatty acid composition of the Taz1p substrates. PMID:19656950

  9. Retrobiosynthetic Approach Delineates the Biosynthetic Pathway and the Structure of the Acyl Chain of Mycobacterial Glycopeptidolipids*

    PubMed Central

    Vats, Archana; Singh, Anil Kumar; Mukherjee, Raju; Chopra, Tarun; Ravindran, Madhu Sudhan; Mohanty, Debasisa; Chatterji, Dipankar; Reyrat, Jean-Marc; Gokhale, Rajesh S.

    2012-01-01

    Glycopeptidolipids (GPLs) are dominant cell surface molecules present in several non-tuberculous and opportunistic mycobacterial species. GPLs from Mycobacterium smegmatis are composed of a lipopeptide core unit consisting of a modified C26-C34 fatty acyl chain that is linked to a tetrapeptide (Phe-Thr-Ala-alaninol). The hydroxyl groups of threonine and terminal alaninol are further modified by glycosylations. Although chemical structures have been reported for 16 GPLs from diverse mycobacteria, there is still ambiguity in identifying the exact position of the hydroxyl group on the fatty acyl chain. Moreover, the enzymes involved in the biosynthesis of the fatty acyl component are unknown. In this study we show that a bimodular polyketide synthase in conjunction with a fatty acyl-AMP ligase dictates the synthesis of fatty acyl chain of GPL. Based on genetic, biochemical, and structural investigations, we determine that the hydroxyl group is present at the C-5 position of the fatty acyl component. Our retrobiosynthetic approach has provided a means to understand the biosynthesis of GPLs and also resolve the long-standing debate on the accurate structure of mycobacterial GPLs. PMID:22798073

  10. Regulation of Membrane Proteins by Dietary Lipids: Effects of Cholesterol and Docosahexaenoic Acid Acyl Chain-Containing Phospholipids on Rhodopsin Stability and Function

    PubMed Central

    Bennett, Michael P.; Mitchell, Drake C.

    2008-01-01

    Purified bovine rhodopsin was reconstituted into vesicles consisting of 1-stearoyl-2-oleoyl phosphatidylcholine or 1-stearoyl-2-docosahexaenoyl phosphatidylcholine with and without 30 mol % cholesterol. Rhodopsin stability was examined using differential scanning calorimetry (DSC). The thermal unfolding transition temperature (Tm) of rhodopsin was scan rate-dependent, demonstrating the presence of a rate-limited component of denaturation. The activation energy of this kinetically controlled process (Ea) was determined from DSC thermograms by four separate methods. Both Tm and Ea varied with bilayer composition. Cholesterol increased the Tm both the presence and absence of docosahexaenoic acid acyl chains (DHA). In contrast, cholesterol lowered Ea in the absence of DHA, but raised Ea in the presence of 20 mol % DHA-containing phospholipid. The relative acyl chain packing order was determined from measurements of diphenylhexatriene fluorescence anisotropy decay. The Tm for thermal unfolding was inversely related to acyl chain packing order. Rhodopsin kinetic stability (Ea) was reduced in highly ordered or disordered membranes. Maximal kinetic stability was found within the range of acyl chain order found in native bovine rod outer segment disk membranes. The results demonstrate that membrane composition has distinct effects on the thermal versus kinetic stabilities of membrane proteins, and suggests that a balance between membrane constituents with opposite effects on acyl chain packing, such as DHA and cholesterol, may be required for maximum protein stability. PMID:18424497

  11. Carbohydrate Conformation and Lipid Condensation in Monolayers Containing Glycosphingolipid Gb3: Influence of Acyl Chain Structure

    PubMed Central

    Watkins, Erik B.; Gao, Haifei; Dennison, Andrew J.C.; Chopin, Nathalie; Struth, Bernd; Arnold, Thomas; Florent, Jean-Claude; Johannes, Ludger

    2014-01-01

    Globotriaosylceramide (Gb3), a glycosphingolipid found in the plasma membrane of animal cells, is the endocytic receptor of the bacterial Shiga toxin. Using x-ray reflectivity (XR) and grazing incidence x-ray diffraction (GIXD), lipid monolayers containing Gb3 were investigated at the air-water interface. XR probed Gb3 carbohydrate conformation normal to the interface, whereas GIXD precisely characterized Gb3’s influence on acyl chain in-plane packing and area per molecule (APM). Two phospholipids, 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), were used to study Gb3 packing in different lipid environments. Furthermore, the impact on monolayer structure of a naturally extracted Gb3 mixture was compared to synthetic Gb3 species with uniquely defined acyl chain structures. XR results showed that lipid environment and Gb3 acyl chain structure impact carbohydrate conformation with greater solvent accessibility observed for smaller phospholipid headgroups and long Gb3 acyl chains. In general, GIXD showed that Gb3 condensed phospholipid packing resulting in smaller APM than predicted by ideal mixing. Gb3’s capacity to condense APM was larger for DSPC monolayers and exhibited different dependencies on acyl chain structure depending on the lipid environment. The interplay between Gb3-induced changes in lipid packing and the lipid environment’s impact on carbohydrate conformation has broad implications for glycosphingolipid macromolecule recognition and ligand binding. PMID:25185550

  12. Structural Basis for Substrate Fatty Acyl Chain Specificity: Crystal Structure of Human Very-Long-Chain Acyl-CoA Dehydrogenase

    SciTech Connect

    McAndrew, Ryan P.; Wang, Yudong; Mohsen, Al-Walid; He, Miao; Vockley, Jerry; Kim, Jung-Ja P.

    2008-08-26

    Very-long-chain acyl-CoA dehydrogenase (VLCAD) is a member of the family of acyl-CoA dehydrogenases (ACADs). Unlike the other ACADs, which are soluble homotetramers, VLCAD is a homodimer associated with the mitochondrial membrane. VLCAD also possesses an additional 180 residues in the C terminus that are not present in the other ACADs. We have determined the crystal structure of VLCAD complexed with myristoyl-CoA, obtained by co-crystallization, to 1.91-{angstrom} resolution. The overall fold of the N-terminal {approx}400 residues of VLCAD is similar to that of the soluble ACADs including medium-chain acyl-CoA dehydrogenase (MCAD). The novel C-terminal domain forms an {alpha}-helical bundle that is positioned perpendicular to the two N-terminal helical domains. The fatty acyl moiety of the bound substrate/product is deeply imbedded inside the protein; however, the adenosine pyrophosphate portion of the C14-CoA ligand is disordered because of partial hydrolysis of the thioester bond and high mobility of the CoA moiety. The location of Glu-422 with respect to the C2-C3 of the bound ligand and FAD confirms Glu-422 to be the catalytic base. In MCAD, Gln-95 and Glu-99 form the base of the substrate binding cavity. In VLCAD, these residues are glycines (Gly-175 and Gly-178), allowing the binding channel to extend for an additional 12{angstrom} and permitting substrate acyl chain lengths as long as 24 carbons to bind. VLCAD deficiency is among the more common defects of mitochondrial {beta}-oxidation and, if left undiagnosed, can be fatal. This structure allows us to gain insight into how a variant VLCAD genotype results in a clinical phenotype.

  13. Measurement of Long-Chain Fatty Acyl-CoA Synthetase Activity.

    PubMed

    Füllekrug, Joachim; Poppelreuther, Margarete

    2016-01-01

    Long-chain fatty acyl-CoA synthetases (ACS) are a family of essential enzymes of lipid metabolism, activating fatty acids by thioesterification with coenzyme A. Fatty acyl-CoA molecules are then readily utilized for the biosynthesis of storage and membrane lipids, or for the generation of energy by ß-oxidation. Acyl-CoAs also function as transcriptional activators, allosteric inhibitors, or precursors for inflammatory mediators. Recent work suggests that ACS enzymes may drive cellular fatty acid uptake by metabolic trapping, and may also regulate the channeling of fatty acids towards specific metabolic pathways. The implication of ACS enzymes in widespread lipid associated diseases like type 2 diabetes has rekindled interest in this protein family. Here, we describe in detail how to measure long-chain fatty acyl-CoA synthetase activity by a straightforward radiometric assay. Cell lysates are incubated with ATP, coenzyme A, Mg(2+), and radiolabeled fatty acid bound to BSA. Differential phase partitioning of fatty acids and acyl-CoAs is exploited to quantify the amount of generated acyl-CoA by scintillation counting. The high sensitivity of this assay also allows the analysis of small samples like patient biopsies. PMID:26552674

  14. Effect of carbon chain length in acyl coenzyme A on the efficiency of enzymatic transformation of okadaic acid to 7-O-acyl okadaic acid.

    PubMed

    Furumochi, Sachie; Onoda, Tatsuya; Cho, Yuko; Fuwa, Haruhiko; Sasaki, Makoto; Yotsu-Yamashita, Mari; Konoki, Keiichi

    2016-07-01

    Okadaic acid (OA), a product of dinoflagellate Prorocentrum spp., is transformed into 7-O-acyl OA in various bivalve species. The structural transformation proceeds enzymatically in vitro in the presence of the microsomal fraction from the digestive gland of bivalves. We have been using LC-MS/MS to identify OA-transforming enzymes by detecting 7-O-acyl OA, also known as dinophysistoxin 3 (DTX3). However, an alternative assay for DTX3 is required because the OA-transforming enzyme is a membrane protein, and surfactants for solubilizing membrane proteins decrease the sensitivity of LC-MS/MS. The present study examined saturated fatty acyl CoAs with a carbon chain length of 10 (decanoyl), 12 (dodecanoyl), 14 (tetradecanoyl), 16 (hexadecanoyl) and 18 (octadecanoyl) as the substrate for the in vitro acylation reaction. Saturated fatty acyl CoAs with a carbon chain length of 14, 16 and 18 exhibited higher yields than those with a carbon chain length of 10 or 12. Acyl CoAs with carbon chain lengths from 14 to 18 and containing either a diene unit, an alkyne unit, or an azide unit in the carbon chain were synthesized and shown to provide the corresponding DTX3 with a yield comparable to that of hexadecanoyl CoA. The three functional units can be conjugated with fluorescent reagents and are applicable to the development of a novel assay for DTX3. PMID:27231127

  15. Long Chain N-acyl Homoserine Lactone Production by Enterobacter sp. Isolated from Human Tongue Surfaces

    PubMed Central

    Yin, Wai-Fong; Purmal, Kathiravan; Chin, Shenyang; Chan, Xin-Yue; Chan, Kok-Gan

    2012-01-01

    We report the isolation of N-acyl homoserine lactone-producing Enterobacter sp. isolate T1-1 from the posterior dorsal surfaces of the tongue of a healthy individual. Spent supernatants extract from Enterobacter sp. isolate T1-1 activated the biosensor Agrobacterium tumefaciens NTL4(pZLR4), suggesting production of long chain AHLs by these isolates. High resolution mass spectrometry analysis of these extracts confirmed that Enterobacter sp. isolate T1-1 produced a long chain N-acyl homoserine lactone, namely N-dodecanoyl-homoserine lactone (C12-HSL). To the best of our knowledge, this is the first isolation of Enterobacter sp., strain T1-1 from the posterior dorsal surface of the human tongue and N-acyl homoserine lactones production by this bacterium. PMID:23202161

  16. Two Predicted Transmembrane Domains Exclude Very Long Chain Fatty acyl-CoAs from the Active Site of Mouse Wax Synthase

    PubMed Central

    Kawelke, Steffen; Feussner, Ivo

    2015-01-01

    Wax esters are used as coatings or storage lipids in all kingdoms of life. They are synthesized from a fatty alcohol and an acyl-CoA by wax synthases. In order to get insights into the structure-function relationships of a wax synthase from Mus musculus, a domain swap experiment between the mouse acyl-CoA:wax alcohol acyltransferase (AWAT2) and the homologous mouse acyl-CoA:diacylglycerol O-acyltransferase 2 (DGAT2) was performed. This showed that the substrate specificity of AWAT2 is partially determined by two predicted transmembrane domains near the amino terminus of AWAT2. Upon exchange of the two domains for the respective part of DGAT2, the resulting chimeric enzyme was capable of incorporating up to 20% of very long acyl chains in the wax esters upon expression in S. cerevisiae strain H1246. The amount of very long acyl chains in wax esters synthesized by wild type AWAT2 was negligible. The effect was narrowed down to a single amino acid position within one of the predicted membrane domains, the AWAT2 N36R variant. Taken together, we provide first evidence that two predicted transmembrane domains in AWAT2 are involved in determining its acyl chain length specificity. PMID:26714272

  17. Measurement of tissue acyl-CoAs using flow-injection tandem mass spectrometry: acyl-CoA profiles in short-chain fatty acid oxidation defects

    PubMed Central

    Palladino, Andrew A.; Chen, Jie; Kallish, Staci; Stanley, Charles A.; Bennett, Michael J.

    2013-01-01

    The primary accumulating metabolites in fatty acid oxidation defects are intramitochondrial acyl-CoAs. Typically, secondary metabolites such as acylcarnitines, acylglycines and dicarboxylic acids are measured to study these disorders. Methods have not been adapted for tissue acyl-CoA measurement in defects with primarily acyl-CoA accumulation. Our objective was to develop a method to measure fatty acyl-CoA species that are present in tissues of mice with fatty acid oxidation defects using flow-injection tandem mass spectrometry. Following the addition of internal standards of [13C2] acetyl-CoA, [13C8] octanoyl-CoA, and [C17] heptadecanoic CoA, acyl-CoA’s are extracted from tissue samples and are injected directly into the mass spectrometer. Data is acquired using a 506.9 neutral loss scan and multiple reaction-monitoring (MRM). This method can identify all long, medium and short-chain acyl-CoA species in wild type mouse liver including predicted 3-hydroxyacyl-CoA species. We validated the method using liver of the short-chain-acyl-CoA dehydrogenase (SCAD) knock-out mice. As expected, there is a significant increase in [C4] butyryl-CoA species in the SCAD −/− mouse liver compared to wild type. We then tested the assay in liver from the short-chain 3-hydroxyacyl-CoA dehydrogenase (SCHAD) deficient mice to determine the profile of acyl-CoA accumulation in this less predictable model. There was more modest accumulation of medium chain species including 3-hydroxyacyl-CoA’s consistent with the known chain-length specificity of the SCHAD enzyme. PMID:23117082

  18. Genetics Home Reference: short-chain acyl-CoA dehydrogenase deficiency

    MedlinePlus

    ... Download PDF Open All Close All Description Short-chain acyl-CoA dehydrogenase (SCAD) deficiency is a condition that prevents the body from converting certain fats into energy, especially during periods without food (fasting). Signs and symptoms of SCAD deficiency may ...

  19. Dual mesomorphic assemblage of chitin normal acylates and rapid enthalpy relaxation of their side chains.

    PubMed

    Teramoto, Yoshikuni; Miyata, Tomoya; Nishio, Yoshiyuki

    2006-01-01

    Chitin derivatives having normalacyl groups (C(n)H(2n-1)O-; n = 4-20) were synthesized with pyridine, p-toluenesulfonyl chloride, and normal alkanoic acid in an N,N-dimethylacetamide-lithium chloride homogeneous system. The products (C(n)-ACs; degree of acyl substitution, DS = 1.7-1.9) showed an n-dependent thermal transition behavior: no evident transition (n = 4-10), a glass transition (n = 12 and 14), and a pseudo-first-order phase transition (n = 16-20), the latter two occurring usually below room temperature when examined by differential scanning calorimetry. Wide-angle X-ray diffractometry (WAXD) at 20 degrees C displayed a sharp diffraction peak (2theta = 2 degrees -7 degrees ) and a diffuse halo (2theta approximately 20 degrees ) for the respective C(n)-ACs. The former d-spacing (1.5-3.6 nm) increased with an increase in n to yield two stages of mutually different increasing rates, which reflects a systematic n-dependence of the period of a layered structure of the main chains. The molecular assembly of C(n)-ACs exhibited "dual mesomorphy"; nematic ordering for the semirigid carbohydrate trunk and smectic one for the flexible side chains. On the other hand, WAXD profiles of C(n)-ACs (n = 14-18) indicated almost no temperature dependence from -150 to +220 degrees C. Therefore, it was reasonably assumed that the pseudo-first-order transition observed in thermograms of C(n)-ACs (n = 16-20) was due to the enthalpy relaxation of the side-chain assemblage. An insight was provided into the kinetics of the characteristic aging behavior as a liquid-crystalline glass, in comparison with the corresponding data for other noncrystalline macromolecules. PMID:16398515

  20. Interactions of the C-terminus of lung surfactant protein B with lipid bilayers are modulated by acyl chain saturation.

    PubMed

    Antharam, Vijay C; Farver, R Suzanne; Kuznetsova, Anna; Sippel, Katherine H; Mills, Frank D; Elliott, Douglas W; Sternin, Edward; Long, Joanna R

    2008-11-01

    Lung surfactant protein B (SP-B) is critical to minimizing surface tension in the alveoli. The C-terminus of SP-B, residues 59-80, has much of the surface activity of the full protein and serves as a template for the development of synthetic surfactant replacements. The molecular mechanisms responsible for its ability to restore lung compliance were investigated with circular dichroism, differential scanning calorimetry, and (31)P and (2)H solid-state NMR spectroscopy. SP-B(59-80) forms an amphipathic helix which alters lipid organization and acyl chain dynamics in fluid lamellar phase 4:1 DPPC:POPG and 3:1 POPC:POPG MLVs. At higher levels of SP-B(59-80) in the POPC:POPG lipid system a transition to a nonlamellar phase is observed while DPPC:POPG mixtures remain in a lamellar phase. Deuterium NMR shows an increase in acyl chain order in DPPC:POPG MLVs on addition of SP-B(59-80); in POPC:POPG MLVs, acyl chain order parameters decrease. Our results indicate SP-B(59-80) penetrates deeply into DPPC:POPG bilayers and binds more peripherally to POPC:POPG bilayers. Similar behavior has been observed for KL(4), a peptide mimetic of SP-B which was originally designed using SP-B(59-80) as a template and has been clinically demonstrated to be successful in treating respiratory distress syndrome. The ability of these helical peptides to differentially partition into lipid lamellae based on their degree of monounsaturation and subsequent changes in lipid dynamics suggest a mechanism for lipid organization and trafficking within the dynamic lung environment. PMID:18694722

  1. Interactions of the C-terminus of pulmonary surfactant B with lipid bilayers are modulated by acyl chain saturation

    PubMed Central

    Antharam, Vijay C.; Farver, R. Suzanne; Kuznetsova, Anna; Sippel, Katherine H.; Mills, Frank D.; Elliott, Douglas W.; Sternin, Edward; Long, Joanna R.

    2009-01-01

    Summary Lung surfactant protein B (SP-B) is critical to minimizing surface tension in the alveoli. The C-terminus of SP-B, residues 59-80, has much of the surface activity of the full protein and serves as a template for the development of synthetic surfactant replacements. The molecular mechanisms responsible for its ability to restore lung compliance were investigated with circular dichroism, differential scanning calorimetry, and 31P and 2H solid-state NMR spectroscopy. SP-B59-80 forms an amphipathic helix which alters lipid organization and acyl chain dynamics in fluid lamellar phase 4:1 DPPC:POPG and 3:1 POPC:POPG MLVs. At higher levels of SP-B59-80 in the POPC:POPG lipid system a transition to a nonlamellar phase is observed while DPPC:POPG mixtures remain in a lamellar phase. Deuterium NMR shows an increase in acyl chain order in DPPC:POPG MLVs on addition of SP-B59-80; in POPC:POPG MLVs, acyl chain order parameters decrease. Our results indicate SP-B59-80 penetrates deeply into DPPC:POPG bilayers and binds more peripherally to POPC:POPG bilayers. Similar behavior has been observed for KL4, a peptide mimetic of SP-B which was originally designed using SP-B59-80 as a template and has been clinically demonstrated to be successful in treating respiratory distress syndrome. The ability of these helical peptides to differentially partition into lipid lamellae containing varying levels of monounsaturation and subsequent changes in lipid dynamics suggest a mechanism for lipid organization and trafficking within the dynamic lung environment. PMID:18694722

  2. A Thiolate Anion Buried within the Hydrocarbon Ruler Perturbs PagP Lipid Acyl Chain Selection†

    PubMed Central

    Khan, M. Adil; Moktar, Joel; Mott, Patrick J.; Bishop, Russell E.

    2016-01-01

    The Escherichia coli outer membrane phospholipid:lipid A palmitoyltransferase PagP exhibits remarkable selectivity because its binding pocket for lipid acyl chains excludes those differing in length from palmitate by a solitary methylene unit. This narrow detergent-binding hydrophobic pocket buried within the eight-strand antiparallel β-barrel is known as the hydrocarbon ruler. Gly88 lines the acyl chain binding pocket floor, and its substitution can raise the floor to correspondingly shorten the selected acyl chain. An aromatic exciton interaction between Tyr26 and Trp66 provides an intrinsic spectroscopic probe located immediately adjacent to Gly88. The Gly88Cys PagP enzyme was engineered to function as a dedicated myristoyltransferase, but the mutant enzyme instead selected both myristoyl and pentadecanoyl groups, was devoid of the exciton, and displayed a 21 °C reduction in thermal stability. We now demonstrate that the structural perturbation results from a buried thiolate anion attributed to suppression of the Cys sulfhydryl group pKa from 9.4 in aqueous solvent to 7.5 in the hydrocarbon ruler microenvironment. The Cys thiol is sandwiched at the interface between a nonpolar and a polar β-barrel interior milieu, suggesting that local electrostatics near the otherwise hydrophobic hydrocarbon ruler pocket serve to perturb the thiol pKa. Neutralization of the Cys thiolate anion by protonation restores wild-type exciton and thermal stability signatures to Gly88Cys PagP, which then functions as a dedicated myristoyltransferase at pH 7. Gly88Cys PagP assembled in bacterial membranes recapitulates lipid A myristoylation in vivo. Hydrocarbon ruler–exciton coupling in PagP thus reveals a thiol–thiolate ionization mechanism for modulating lipid acyl chain selection. PMID:20175558

  3. Hepatic fatty acid uptake is regulated by the sphingolipid acyl chain length.

    PubMed

    Park, Woo-Jae; Park, Joo-Won; Merrill, Alfred H; Storch, Judith; Pewzner-Jung, Yael; Futerman, Anthony H

    2014-12-01

    Ceramide synthase 2 (CerS2) null mice cannot synthesize very-long acyl chain (C22-C24) ceramides resulting in significant alterations in the acyl chain composition of sphingolipids. We now demonstrate that hepatic triacylglycerol (TG) levels are reduced in the liver but not in the adipose tissue or skeletal muscle of the CerS2 null mouse, both before and after feeding with a high fat diet (HFD), where no weight gain was observed and large hepatic nodules appeared. Uptake of both BODIPY-palmitate and [VH]-palmitate was also abrogated in the hepa- tocytes and liver. The role of a number of key proteins involved in fatty acid uptake was examined, including FATP5, CD36/FAT, FABPpm and cytoplasmic FABP1. Levels of FATP5 and FABP1 were decreased in the CerS2 null mouse liver, whereas CD36/FAT levels were significantly elevated and CD36/FAT was also mislocalized upon insulin treatment. Moreover, treatment of hepatocytes with C22-C24-ceramides down-regulated CD36/FAT levels. Infection of CerS2 null mice with recombinant adeno-associated virus (rAAV)-CerS2 restored normal TG levels and corrected the mislocalization of CD36/FAT, but had no effect on the intracellular localization or levels of FATP5 or FABP1. Together, these results demonstrate that hepatic fatty acid uptake via CD36/FAT can be regulated by altering the acyl chain composition of sphingolipids. PMID:25241943

  4. Cardiac Hypertrophy in Mice with Long-Chain Acyl-CoA Dehydrogenase (LCAD) or Very Long-Chain Acyl-CoA Dehydrogenase (VLCAD) Deficiency

    PubMed Central

    Cox, Keith B.; Liu, Jian; Tian, Liqun; Barnes, Stephen; Yang, Qinglin; Wood, Philip A.

    2009-01-01

    Cardiac hypertrophy is a common finding in human patients with inborn errors of long-chain fatty acid oxidation. Mice with either very long-chain acyl-CoA dehydrogenase deficiency (VLCAD−/−) or long-chain acyl-CoA dehydrogenase deficiency (LCAD−/−) develop cardiac hypertrophy. Cardiac hypertrophy, initially measured using heart/body weight ratios, was manifested most severely in LCAD−/− male mice. VLCAD−/− mice, as a group, showed a mild increase in normalized cardiac mass (8.8% hypertrophy compared to all wild-type [WT] mice). In contrast, LCAD−/− mice as a group showed more severe cardiac hypertrophy (32.2% increase compared to all WT mice). Based on a clear male predilection, we investigated the role of dietary plant estrogenic compounds commonly found in mouse diets due to soy or alfalfa components providing natural phytoestrogens or isoflavones in cardioprotection of LCAD−/− mice. Male LCAD−/− mice fed an isoflavone-free test diet had more severe cardiac hypertrophy (58.1% hypertrophy compared to WT mice fed the same diet. There were no significant differences in the female groups fed any of the diets. Echocardiography measurement performed on male LCAD deficient mice fed a standard diet at ~3 months of age confirmed the substantial cardiac hypertrophy in these mice compared with WT controls. Left ventricular wall thickness of interventricular septum and posterior wall was remarkably increased in LCAD−/− mice compared with that of WT controls. Accordingly, the calculated LV mass after normalization to body weight was increased about 40% in the LCAD−/− mice compared with WT mice. In summary, we found that metabolic cardiomyopathy, expressed as hypertrophy, developed in mice due to either VLCAD deficiency or LCAD deficiency; however, LCAD deficiency was the most profound and appeared to be attenuated either by endogenous estrogen in females or phytoestrogens in the diet as isoflavones in males. PMID:19736549

  5. Inhibitory effect of quinolone antimicrobial and nonsteroidal anti-inflammatory drugs on a medium chain acyl-CoA synthetase.

    PubMed

    Kasuya, F; Hiasa, M; Kawai, Y; Igarashi, K; Fukui, M

    2001-08-01

    The inhibitory effects of quinolone antimicrobial agents and nonsteroidal anti-inflammatory drugs on purified mouse liver mitochondrial medium chain acyl-CoA synthetase catalyzing the first reaction of glycine conjugation were examined, using hexanoic acid as a substrate. Enoxacin, ofloxacin, nalidixic acid, diflunisal, salicylic acid, 2-hydroxynaphthoic acid, and 2-hydroxydodecanoic acid, which do not act as substrates, were potent inhibitors. Diflunisal, nalidixic acid, salicylic acid, 2-hydroxynaphthoic acid, and 2-hydroxydodecanoic acid inhibited competitively this medium chain acyl-CoA synthetase with K(i) values of 0.6, 12.4, 19.6, 13.4, and 15.0 microM, respectively. Enoxacin and ofloxacin inhibited this medium chain acyl-CoA synthetase in a mixed-type manner with K(i) values of 23.7 and 38.2 microM, respectively. Felbinac, which is a substrate, inhibited the activity of this medium chain acyl-CoA synthetase for hexanoic acid (IC50 = 25 microM). The concomitant presence of enoxacin and felbinac strongly inhibited this medium chain acyl-CoA synthetase. These findings indicate that medium chain acyl-CoA synthetases may be influenced by quinolone antimicrobial and nonsteroidal anti-inflammatory drugs. PMID:11434910

  6. Actinobacterial Acyl Coenzyme A Synthetases Involved in Steroid Side-Chain Catabolism

    PubMed Central

    Casabon, Israël; Swain, Kendra; Crowe, Adam M.

    2014-01-01

    Bacterial steroid catabolism is an important component of the global carbon cycle and has applications in drug synthesis. Pathways for this catabolism involve multiple acyl coenzyme A (CoA) synthetases, which activate alkanoate substituents for β-oxidation. The functions of these synthetases are poorly understood. We enzymatically characterized four distinct acyl-CoA synthetases from the cholate catabolic pathway of Rhodococcus jostii RHA1 and the cholesterol catabolic pathway of Mycobacterium tuberculosis. Phylogenetic analysis of 70 acyl-CoA synthetases predicted to be involved in steroid metabolism revealed that the characterized synthetases each represent an orthologous class with a distinct function in steroid side-chain degradation. The synthetases were specific for the length of alkanoate substituent. FadD19 from M. tuberculosis H37Rv (FadD19Mtb) transformed 3-oxo-4-cholesten-26-oate (kcat/Km = 0.33 × 105 ± 0.03 × 105 M−1 s−1) and represents orthologs that activate the C8 side chain of cholesterol. Both CasGRHA1 and FadD17Mtb are steroid-24-oyl-CoA synthetases. CasG and its orthologs activate the C5 side chain of cholate, while FadD17 and its orthologs appear to activate the C5 side chain of one or more cholesterol metabolites. CasIRHA1 is a steroid-22-oyl-CoA synthetase, representing orthologs that activate metabolites with a C3 side chain, which accumulate during cholate catabolism. CasI had similar apparent specificities for substrates with intact or extensively degraded steroid nuclei, exemplified by 3-oxo-23,24-bisnorchol-4-en-22-oate and 1β(2′-propanoate)-3aα-H-4α(3″-propanoate)-7aβ-methylhexahydro-5-indanone (kcat/Km = 2.4 × 105 ± 0.1 × 105 M−1 s−1 and 3.2 × 105 ± 0.3 × 105 M−1 s−1, respectively). Acyl-CoA synthetase classes involved in cholate catabolism were found in both Actinobacteria and Proteobacteria. Overall, this study provides insight into the physiological roles of acyl-CoA synthetases in steroid catabolism and

  7. Plasmodium falciparum Sir2A preferentially hydrolyzes medium and long chain fatty acyl lysine

    PubMed Central

    Zhu, Anita Y.; Zhou, Yeyun; Khan, Saba; Deitsch, Kirk W.; Hao, Quan; Lin, Hening

    2011-01-01

    Plasmodium falciparum Sir2A (PfSir2A), a member of the sirtuin family of nicotinamide adenine dinucleotide-dependent deacetylases, has been shown to regulate the expression of surface antigens to evade the detection by host immune surveillance. It is thought that PfSir2A achieves this by deacetylating histones. However, the deacetylase activity of PfSir2A is weak. Here we present enzymology and structural evidences supporting that PfSir2A catalyzes the hydrolysis of medium and long chain fatty acyl groups from lysine residues more efficiently. Furthermore, P. falciparum proteins are found to contain such fatty acyl lysine modifications that can be removed by purified PfSir2A in vitro. Together, the data suggest that the physiological function of PfSir2A in antigen variation may be achieved by removing medium and long chain fatty acyl groups from protein lysine residues. The robust activity of PfSir2A would also facilitate the development of PfSir2A inhibitors, which may have therapeutic value in malaria treatment. PMID:21992006

  8. Acyl chain composition and coexisting fluid phases in lipid bilayers

    NASA Astrophysics Data System (ADS)

    Gu, Yongwen; Bradley, Miranda; Mitchell, Drake

    2011-10-01

    At room temperature phospholipid bilayers enriched in sphingolipids and cholesterol may form a solid phase as well as two coexisting fluid phases. These are the standard fluid phase, or the liquid-disordered phase, ld, and the liquid-ordered phase, lo, which is commonly associated with lipid rafts. Ternary mixtures of palmitoyl-oleoyl-phosphocholine (POPC; 16:0,18:1 PC), sphingomyelin (SPM), and cholesterol (Chol) form coexisting lo, ld and solid phases over a wide range of molar ratios. We are examining the ability of two fluorescent probes to detect these 2 phases: NBD linked to di-16:0 PE which partitions strongly into the lo phase and NBD linked to di-18:1 PE which partitions strongly into the ld phase. We are also examining the effect of the highly polyunsaturated phospholipid stearoyl-docosahexanoyl-phosphocholine (SDPC; 18:0, 22:6 PC) on the ternary phase diagram of POPC/SPM/Chol with particular focus on the functionally important lo/ld coexistence region. We report on the fluorescence lifetime and anisotropy decay dynamics of these two fluorescent probes.

  9. BROWN ADIPOSE TISSUE FUNCTION IN SHORT-CHAIN ACYL-COA DEHYDROGENASE DEFICIENT MICE

    PubMed Central

    Skilling, Helen; Coen, Paul M.; Fairfull, Liane; Ferrell, Robert E.; Goodpaster, Bret H.; Vockley, Jerry; Goetzman, Eric S.

    2010-01-01

    Brown adipose tissue is a highly specialized organ that uses mitochondrial fatty acid oxidation to fuel nonshivering thermogenesis. In mice, mutations in the acyl-CoA dehydrogenase family of fatty acid oxidation genes are associated with sensitivity to cold. Brown adipose tissue function has not previously been characterized in these knockout strains. Short-chain acyl-CoA dehydrogenase (SCAD) deficient mice were found to have increased brown adipose tissue mass as well as modest cardiac hypertrophy. Uncoupling protein-1 was reduced by 70% in brown adipose tissue and this was not due to a change in mitochondrial number, nor was it due to decreased signal transduction through protein kinase A which is known to be a major regulator of uncoupling protein-1 expression. PKA activity and in vitro lipolysis were normal in brown adipose tissue, although in white adipose tissue a modest increase in basal lipolysis was seen in SCAD−/ − mice. Finally, an in vivo norepinephrine challenge of brown adipose tissue thermogenesis revealed normal heat production in SCAD−/− mice. These results suggest that reduced brown adipose tissue function is not the major factor causing cold sensitivity in acyl-CoA dehydrogenase knockout strains. We speculate that other mechanisms such as shivering capacity, cardiac function, and reduced hepatic glycogen stores are involved. PMID:20727852

  10. Acyl chain-dependent effect of lysophosphatidylcholine on endothelium-dependent vasorelaxation.

    PubMed

    Rao, Shailaja P; Riederer, Monika; Lechleitner, Margarete; Hermansson, Martin; Desoye, Gernot; Hallström, Seth; Graier, Wolfgang F; Frank, Saša

    2013-01-01

    Previously we identified palmitoyl-, oleoyl-, linoleoyl-, and arachidonoyl-lysophosphatidylcholine (LPC 16:0, 18:1, 18:2 and 20:4) as the most prominent LPC species generated by endothelial lipase (EL). In the present study, we examined the impact of those LPC on acetylcholine (ACh)- induced vascular relaxation. All tested LPC attenuated ACh-induced relaxation, measured ex vivo, using mouse aortic rings and wire myography. The rank order of potency was as follows: 18:2>20:4>16:0>18:1. The attenuating effect of LPC 16:0 on relaxation was augmented by indomethacin-mediated cyclooxygenase (COX)-inhibition and CAY10441, a prostacyclin (PGI2)- receptor (IP) antagonist. Relaxation attenuated by LPC 20:4 and 18:2 was improved by indomethacin and SQ29548, a thromboxane A2 (TXA2)- receptor antagonist. The effect of LPC 20:4 could also be improved by TXA2- and PGI2-synthase inhibitors. As determined by EIA assays, the tested LPC promoted secretion of PGI2, TXA2, PGF2α, and PGE2, however, with markedly different potencies. LPC 16:0 was the most potent inducer of superoxide anion production by mouse aortic rings, followed by LPC 18:2, 20:4 and 18:1, respectively. The strong antioxidant tempol recovered relaxation impairment caused by LPC 18:2, 18:1 and 20:4, but not by LPC 16:0. The tested LPC attenuate ACh-induced relaxation through induction of proconstricting prostanoids and superoxide anions. The potency of attenuating relaxation and the relative contribution of underlying mechanisms are strongly related to LPC acyl-chain length and degree of saturation. PMID:23741477

  11. DISTINCT TRANSCRIPTIONAL REGULATION OF LONG-CHAIN ACYL-COA SYNTHETASE ISOFORMS AND CYTOSOLIC THIOESTERASE 1 IN THE RODENT HEART BY FATTY ACIDS AND INSULIN

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The molecular mechanism(s) responsible for channeling long-chain fatty acids (LCFAs) into oxidative versus nonoxidative pathways is (are) poorly understood in the heart. Intracellular LCFAs are converted to long-chain fatty acyl-CoAs (LCFA-CoAs) by a family of long-chain acyl-CoA synthetases (ACSLs)...

  12. Modified branched-chain amino acid pathways give rise to acyl acids of sucrose esters exuded from tobacco leaf trichomes.

    PubMed

    Kandra, G; Severson, R; Wagner, G J

    1990-03-10

    A major diversion of carbon from branched-chain amino acid biosynthesis/catabolism to form acyl moieties of sucrose esters (6-O-acetyl-2,3,4-tri-O-acyl-alpha-D-glucopyranosyl-beta-D- fructofuranosides) was observed to be associated with specialized trichome head cells which secrete large amounts of sucrose esters. Surface chemistry and acetyl and acyl substituent groups of tobacco (T.I. 1068) sucrose esters were identified and quantified by gas chromatography/mass spectrometry. Sucrose esters were prominent surface constituents and 3-methylvaleric acid, 2- and 3-methylbutyric acid, and methylpropionic acid accounted for 60%, 25% and 9%, respectively, of total C3--C7 acyl substituents. Radiolabeled Thr, Ile, Val, Leu, pyruvate and Asp, metabolites of branched-chain amino acid pathways, were compared with radioactively labeled acetate and sucrose as donors of carbon to sucrose, acetyl and acyl components of sucrose esters using epidermal peels with undisturbed trichomes. Preparations of biosynthetically competent trichome heads (site of sucrose ester formation) were also examined. Results indicate that 3-methylvaleryl and 2-methylbutyryl groups are derived from the Thr pathway of branched-chain amino acid metabolism, 3-methylbutyryl and methylpropionyl groups are formed via the pyruvate pathway, and that acetyl groups are principally formed directly via acetyl-CoA. Arguments are presented which rule out participation of fatty acid synthase in the formation of prominent acyl acids. Results suggest that the shunting of carbon away from the biosynthesis of Val, Leu and Ile may be due to a low level of amino acid utilization in protein synthesis in specialized glandular head cells of trichomes. This would result in the availability of corresponding oxo acids for CoA activation and esterification to form sucrose esters. Preliminary evidence was found for the involvement of cycling reactions in oxo-acid-chain lengthening and for utilization of pyruvate-derived 2

  13. Acyl-chain remodeling of dioctanoyl-phosphatidylcholine in Saccharomyces cerevisiae mutant defective in de novo and salvage phosphatidylcholine synthesis

    SciTech Connect

    Kishino, Hideyuki; Eguchi, Hiroki; Takagi, Keiko; Horiuchi, Hiroyuki; Fukuda, Ryouichi; Ohta, Akinori

    2014-03-07

    Highlights: • Dioctanoyl-PC (diC8PC) supported growth of a yeast mutant defective in PC synthesis. • diC8PC was converted to PC species containing longer acyl residues in the mutant. • Both acyl residues of diC8PC were replaced by longer fatty acids in vitro. • This system will contribute to the elucidation of the acyl chain remodeling of PC. - Abstract: A yeast strain, in which endogenous phosphatidylcholine (PC) synthesis is controllable, was constructed by the replacement of the promoter of PCT1, encoding CTP:phosphocholine cytidylyltransferase, with GAL1 promoter in a double deletion mutant of PEM1 and PEM2, encoding phosphatidylethanolamine methyltransferase and phospholipid methyltransferase, respectively. This mutant did not grow in the glucose-containing medium, but the addition of dioctanoyl-phosphatidylcholine (diC8PC) supported its growth. Analyses of the metabolism of {sup 13}C-labeled diC8PC ((methyl-{sup 13}C){sub 3}-diC8PC) in this strain using electrospray ionization tandem mass spectrometry revealed that it was converted to PC species containing acyl residues of 16 or 18 carbons at both sn-1 and sn-2 positions. In addition, both acyl residues of (methyl-{sup 13}C){sub 3}-diC8PC were replaced with 16:1 acyl chains in the in vitro reaction using the yeast cell extract in the presence of palmitoleoyl-CoA. These results indicate that PC containing short acyl residues was remodeled to those with acyl chains of physiological length in yeast.

  14. Sequential Collision- and Ozone-Induced Dissociation Enables Assignment of Relative Acyl Chain Position in Triacylglycerols.

    PubMed

    Marshall, David L; Pham, Huong T; Bhujel, Mahendra; Chin, Jacqueline S R; Yew, Joanne Y; Mori, Kenji; Mitchell, Todd W; Blanksby, Stephen J

    2016-03-01

    Unambiguous identification of isomeric lipids by mass spectrometry represents a significant analytical challenge in contemporary lipidomics. Herein, the combination of collision-induced dissociation (CID) with ozone-induced dissociation (OzID) on an ion-trap mass spectrometer is applied to the identification of triacylglycerol (TG) isomers that vary only by the substitution pattern of fatty acyl (FA) chains esterified to the glycerol backbone. Isolated product ions attributed to loss of a single FA arising from CID of [TG + Na](+) ions react rapidly with ozone within the ion trap. The resulting CID/OzID spectra exhibit abundant ions that unequivocally reveal the relative position of FAs along the backbone. Isomeric TGs containing two or three different FA substituents are readily differentiated by diagnostic ions present in their CID/OzID spectra. Compatibility of this method with chromatographic separations enables the characterization of unusual TGs containing multiple short-chain FAs present in Drosophila. PMID:26799085

  15. Inhibition of Long Chain Fatty Acyl-CoA Synthetase (ACSL) and Ischemia Reperfusion Injury

    PubMed Central

    Prior, Allan M.; Zhang, Man; Blakeman, Nina; Datta, Palika; Pham, Hung; Young, Lindon H.; Weis, Margaret T.; Hua, Duy H.

    2014-01-01

    Various triacsin C analogs, containing different alkenyl chains and carboxylic acid bioisoteres including 4-aminobenzoic acid, isothiazolidine dioxide, hydroxylamine, hydroxytriazene, and oxadiazolidine dione, were synthesized and their inhibitions of long chain fatty acyl-CoA synthetase (ACSL) were examined. Two methods, a cell-based assay of ACSL activity and an in situ [14C]-palmitate incorporation into extractable lipids were used to study the inhibition. Using an in vivo leukocyte recruitment inhibition protocol, the translocation of one or more cell adhesion molecules from the cytoplasm to the plasma membrane on either the endothelium or leukocyte or both was inhibited by inhibitors 1, 9, and triacsin C. The results suggest that inhibition of ACSL may attenuate the vascular inflammatory component associated with ischemia reperfusion injury and lead to a decrease of infarct expansion. PMID:24480468

  16. [Medium chain acyl-CoA dehydrogenase deficiency. Apropos of a case with demonstration of this enzyme deficiency].

    PubMed

    Collet, J P; Divry, P; Blanc, J F; Guibaud, P; David, M; Macabeo, V; Vibert, J; Hermier, M

    1984-12-01

    The medium chain acyl-CoA deshydrogenase defect: a new inherited metabolic disorder. This enzymatic defect blocks the catabolism of non esterified fatty acids during fasting. Thus, this disease is revealed by a coma due to hypoglycemia in a young child; the presence of dicarboxylic aciduria in such a situation is the main evidence for this diagnosis. Finally, the enzymatic studies performed on skin fibroblasts show a defect in medium chain acyl-CoA deshydrogenase. When a child is investigated away from a coma episode, the ketotic diet induces dicarboxylic aciduria but must be performed in an intensive care unit for its dangers. PMID:6535973

  17. Prolonged QTc interval in association with medium-chain acyl-coenzyme A dehydrogenase deficiency.

    PubMed

    Wiles, Jason R; Leslie, Nancy; Knilans, Timothy K; Akinbi, Henry

    2014-06-01

    Medium-chain acyl-coenzyme A dehydrogenase (MCAD) deficiency is the most common disorder of mitochondrial fatty acid oxidation. We report a term male infant who presented at 3 days of age with hypoglycemia, compensated metabolic acidosis, hypocalcemia, and prolonged QTc interval. Pregnancy was complicated by maternal premature atrial contractions and premature ventricular contractions. Prolongation of the QTc interval resolved after correction of metabolic derangements. The newborn screen was suggestive for MCAD deficiency, a diagnosis that was confirmed on genetic analysis that showed homozygosity for the disease-associated missense A985G mutation in the ACADM gene. This is the first report of acquired prolonged QTc in a neonate with MCAD deficiency, and it suggests that MCAD deficiency should be considered in the differential diagnoses of acute neonatal illnesses associated with electrocardiographic abnormality. We review the clinical presentation and diagnosis of MCAD deficiency in neonates. PMID:24799540

  18. Density fluctuations in saturated phospholipid bilayers increase as the acyl-chain length decreases.

    PubMed Central

    Ipsen, J H; Jørgensen, K; Mouritsen, O G

    1990-01-01

    A systematic computer simulation study is conducted for a model of the main phase transition of fully hydrated saturated diacyl phosphatidylcholine bilayers (DMPC, DPPC, and DSPC). With particular focus on the fluctuation effects on the thermal properties in the transition region, the study yields data for the specific heat, the lateral compressibility, and the lipid-domain size distribution. Via a simple model assumption the transmembrane passive ion permeability is derived from the lipid-domain interfacial measure. A comparative analysis of the various data shows, in agreement with a number of experiments, that the lateral density fluctuations and hence the response functions increase as the acyl-chain length is decreased. Images FIGURE 2 PMID:2291936

  19. An investigation into a cardiolipin acyl chain insertion site in cytochrome c.

    PubMed

    Rajagopal, Badri S; Silkstone, Gary G; Nicholls, Peter; Wilson, Michael T; Worrall, Jonathan A R

    2012-05-01

    Mitochondrial cytochrome c associates with the phosphoplipid cardiolipin (CL) through a combination of electrostatic and hydrophobic interactions. The latter occurs by insertion into cytochrome c of an acyl chain, resulting in the dissociation of the axial Met-80 heme-iron ligand. The resulting five coordinate cytochrome c/CL complex has peroxidatic properties leading to peroxidation of CL and dissociation of the complex. These events are considered to be pre-apoptotic and culminate with release of cytochrome c from the mitochondria into the cytoplasm. Two distinct surface regions on cytochrome c have been suggested to mediate CL acyl chain insertion and this study has probed one of these regions. We have constructed a series of alanine mutants aimed at disrupting a surface cleft formed between residues 67-71 and 82-85. The physicochemical properties, peroxidase activity, CL binding, and kinetics of carbon monoxide (CO) binding to the ferrous cytochrome c/CL complex have been assessed for the individual mutants. Our findings reveal that the majority of mutants are capable of binding CL in the same apparent stoichiometry as the wild-type protein, with the extent to which the Met-80 ligand is bound in the ferrous cytochrome c/CL complex being mutant specific at neutral pH. Mutation of the species conserved Arg-91 residue, that anchors the cleft, results in the greatest changes to physicochemical properties of the protein leading to a change in the CL binding ratio required to effect structural changes and to the ligand-exchange properties of the ferrous cytochrome c/CL complex. PMID:22365930

  20. Evidence for involvement of medium chain acyl-CoA dehydrogenase in the metabolism of phenylbutyrate

    PubMed Central

    Kormanik, Kaitlyn; Kang, Heejung; Cuebas, Dean; Vockley, Jerry; Mohsen, Al-Walid

    2012-01-01

    Sodium phenylbutyrate is used for treating urea cycle disorders, providing an alternative for ammonia excretion. Following conversion to its CoA ester, phenylbutyryl-CoA is postulated to undergo one round of β-oxidation to phenylacetyl-CoA, the active metabolite. Molecular modeling suggests that medium chain acyl-CoA dehydrogenase (MCAD; EC 1.3.99.3), a key enzyme in straight chain fatty acid β-oxidation, could utilize phenylbutyryl-CoA as substrate. Moreover, phenylpropionyl-CoA has been shown to be a substrate for MCAD and its intermediates accumulate in patients with MCAD deficiency. We have examined the involvement of MCAD and other acyl-CoA dehydrogenases (ACADs) in the metabolism of phenylbutyryl-CoA. Anaerobic titration of purified recombinant human MCAD with phenylbutyryl-CoA caused changes in the MCAD spectrum that are similar to those induced by octanoyl-CoA, its bona fide substrate, and unique to the development of the charge transfer ternary complex. The calculated apparent dissociation constant (KD app) for these substrates was 2.16 μM and 0.12 μM, respectively. The MCAD reductive and oxidative half reactions were monitored using the electron transfer flavoprotein (ETF) fluorescence reduction assay. The catalytic efficiency and the Km for phenylbutyryl-CoA were 0.2 mM−1· sec−1 and 5.3 μM compared to 4.0 mM−1· sec−1 and 2.8 μM for octanoyl-CoA. Extracts of wild type and MCAD-deficient lymphoblast cells were tested for the ability to reduce ETF using phenylbutyryl-CoA as substrate. While ETF reduction activity was detected in extracts of wild type cells, it was undetectable in extracts of cells deficient in MCAD. The results are consistent with MCAD playing a key role in phenylbutyrate metabolism. PMID:23141465

  1. Identification of a Long-Chain Polyunsaturated Fatty Acid Acyl-Coenzyme A Synthetase from the Diatom Thalassiosira pseudonana1

    PubMed Central

    Tonon, Thierry; Qing, Renwei; Harvey, David; Li, Yi; Larson, Tony Robert; Graham, Ian Alexander

    2005-01-01

    The draft genome of the diatom Thalassiosira pseudonana was searched for DNA sequences showing homology with long-chain acyl-coenzyme A synthetases (LACSs), since the corresponding enzyme may play a key role in the accumulation of health-beneficial polyunsaturated fatty acids (PUFAs) in triacylglycerol. Among the candidate genes identified, an open reading frame named TplacsA was found to be full length and constitutively expressed during cell cultivation. The predicted amino acid sequence of the corresponding protein, TpLACSA, exhibited typical features of acyl-coenzyme A (acyl-CoA) synthetases involved in the activation of long-chain fatty acids. Feeding experiments carried out in yeast (Saccharomyces cerevisiae) transformed with the algal gene showed that TpLACSA was able to activate a number of PUFAs, including eicosapentaenoic acid and docosahexaenoic acid (DHA). Determination of acyl-CoA synthetase activities by direct measurement of acyl-CoAs produced in the presence of different PUFA substrates showed that TpLACSA was most active toward DHA. Heterologous expression also revealed that TplacsA transformants were able to incorporate more DHA in triacylglycerols than the control yeast. PMID:15821149

  2. Crystallization of the C-terminal domain of the mouse brain cytosolic long-chain acyl-CoA thioesterase

    SciTech Connect

    Serek, Robert; Forwood, Jade K.; Hume, David A.; Martin, Jennifer L.; Kobe, Bostjan

    2006-02-01

    The C-terminal domain of the mouse long-chain acyl-CoA thioesterase has been expressed in bacteria and crystallized by vapour diffusion. The crystals diffract to 2.4 Å resolution. The mammalian long-chain acyl-CoA thioesterase, the enzyme that catalyses the hydrolysis of acyl-CoAs to free fatty acids, contains two fused 4HBT (4-hydroxybenzoyl-CoA thioesterase) motifs. The C-terminal domain of the mouse long-chain acyl-CoA thioesterase (Acot7) has been expressed in bacteria and crystallized. The crystals were obtained by vapour diffusion using PEG 2000 MME as precipitant at pH 7.0 and 290 K. The crystals have the symmetry of space group R32 (unit-cell parameters a = b = 136.83, c = 99.82 Å, γ = 120°). Two molecules are expected in the asymmetric unit. The crystals diffract to 2.4 Å resolution using the laboratory X-ray source and are suitable for crystal structure determination.

  3. Mouse very long-chain acyl-CoA synthetase in X-linked adrenoleukodystrophy.

    PubMed

    Heinzer, Ann K; Kemp, Stephan; Lu, Jyh-Feng; Watkins, Paul A; Smith, Kirby D

    2002-08-01

    X-linked adrenoleukodystrophy (X-ALD) is a neurodegenerative disorder characterized by accumulation of very long-chain fatty acids (VLCFA). This accumulation has been attributed to decreased VLCFA beta-oxidation and peroxisomal very long-chain acyl-CoA synthetase (VLCS) activity. The X-ALD gene, ABCD1, encodes a peroxisomal membrane ATP binding cassette transporter, ALDP, that is hypothesized to affect VLCS activity in peroxisomes by direct interaction with the VLCS enzyme. Recently, a VLCS gene that encodes a protein with significant sequence identity to known rat and human peroxisomal VLCS protein has been identified in mice. We find that the mouse VLCS gene (Vlcs) encodes an enzyme (Vlcs) with VLCS activity that localizes to peroxisomes and is expressed in X-ALD target tissues. We show that the expression of Vlcs in the peroxisomes of X-ALD mouse fibroblasts improves VLCFA beta-oxidation in these cells, implying a role for this enzyme in the biochemical abnormality of X-ALD. X-ALD mice, which accumulate VLCFA in tissues, show no change in the expression of Vlcs, the subcellular localization of Vlcs, or general peroxisomal VLCS activity. These observations imply that ALDP is not necessary for the proper expression or localization of Vlcs protein, and the control of VLCFA levels does not depend on the direct interaction of Vlcs and ALDP. PMID:12048192

  4. Comparative studies of Acyl-CoA dehydrogenases for monomethyl branched chain substrates in amino acid metabolism.

    PubMed

    Liu, Xiaojun; Wu, Long; Deng, Guisheng; Chen, Gong; Li, Nan; Chu, Xiusheng; Li, Ding

    2013-04-01

    Short/branched chain acyl-CoA dehydrogenase (SBCAD), isovaleryl-CoA dehydrogenase (IVD), and isobutyryl-CoA dehydrogenase (IBD) are involved in metabolism of isoleucine, leucine, and valine, respectively. These three enzymes all belong to acyl-CoA dehydrogenase (ACD) family, and catalyze the dehydrogenation of monomethyl branched-chain fatty acid (mmBCFA) thioester derivatives. In the present work, the catalytic properties of rat SBCAD, IVD, and IBD, including their substrate specificity, isomerase activity, and enzyme inhibition, were comparatively studied. Our results indicated that SBCAD has its catalytic properties relatively similar to those of straight-chain acyl-CoA dehydrogenases in terms of their isomerase activity and enzyme inhibition, while IVD and IBD are different. IVD has relatively broader substrate specificity than those of the other two enzymes in accommodating various substrate analogs. The present study increased our understanding for the metabolism of monomethyl branched-chain fatty acids (mmBCFAs) and branched-chain amino acids (BCAAs), which should also be useful for selective control of a particular reaction through the design of specific inhibitors. PMID:23474214

  5. Binding of the Cationic Peptide (KL)4K to Lipid Monolayers at the Air-Water Interface: Effect of Lipid Headgroup Charge, Acyl Chain Length, and Acyl Chain Saturation.

    PubMed

    Hädicke, André; Blume, Alfred

    2016-04-28

    The binding of the cationic peptide (KL)4K to monolayers of different anionic lipids was determined by adsorption experiments. The chemical structure of the anionic phospholipids was changed in different ways. First, the hydrophobic region of phosphatidylglycerols was altered by elongation of the acyl chain length. Second, an unsaturated chain was introduced. Third, lipids with negatively charged headgroups of different chemical structure were compared. (KL)4K itself shows no surface activity and does not bind to monolayers of zwitterionic lipids. Analysis of (KL)4K binding to anionic lipid monolayers reveals a competition between two binding processes: (i) incorporation of the peptide into the acyl chain region (surface pressure increase) and (ii) electrostatic interaction screening the negative charges with reduction of charge repulsion (surface pressure decrease due to monolayer condensation). The lipid acyl chain length and the chemical structure of the headgroup have minor effects on the binding properties. However, a strong dependence on the phase state of the monolayer was observed. In the liquid-expanded (LE) phase, the fluid monolayer provides enough space, so that peptide insertion due to hydrophobic interactions dominates. For monolayers in the liquid-condensed (LC) phase, peptide binding followed by monolayer condensation is the main effect. PMID:27049846

  6. Effects of short-chain acyl-CoA dehydrogenase on cardiomyocyte apoptosis.

    PubMed

    Zeng, Zhenhua; Huang, Qiuju; Shu, Zhaohui; Liu, Peiqing; Chen, Shaorui; Pan, Xuediao; Zang, Linquan; Zhou, Sigui

    2016-07-01

    Short-chain acyl-CoA dehydrogenase (SCAD), a key enzyme of fatty acid β-oxidation, plays an important role in cardiac hypertrophy. However, its effect on the cardiomyocyte apoptosis remains unknown. We aimed to determine the role of SCAD in tert-butyl hydroperoxide (tBHP)-induced cardiomyocyte apoptosis. The mRNA and protein expression of SCAD were significantly down-regulated in the cardiomyocyte apoptosis model. Inhibition of SCAD with siRNA-1186 significantly decreased SCAD expression, enzyme activity and ATP content, but obviously increased the content of free fatty acids. Meanwhile, SCAD siRNA treatment triggered the same apoptosis as cardiomyocytes treated with tBHP, such as the increase in cell apoptotic rate, the activation of caspase3 and the decrease in the Bcl-2/Bax ratio, which showed that SCAD may play an important role in primary cardiomyocyte apoptosis. The changes of phosphonate AMP-activated protein kinase α (p-AMPKα) and Peroxisome proliferator-activated receptor α (PPARα) in cardiomyocyte apoptosis were consistent with that of SCAD. Furthermore, PPARα activator fenofibrate and AMPKα activator AICAR treatment significantly increased the expression of SCAD and inhibited cardiomyocyte apoptosis. In conclusion, for the first time our findings directly demonstrated that SCAD may be as a new target to prevent cardiomyocyte apoptosis through the AMPK/PPARα/SCAD signal pathways. PMID:26989860

  7. Biophysical Characterization of a New Phospholipid Analogue with a Spin-Labeled Unsaturated Fatty Acyl Chain

    PubMed Central

    Bunge, Andreas; Windeck, Anne-Katrin; Pomorski, Thomas; Schiller, Jürgen; Herrmann, Andreas; Huster, Daniel; Müller, Peter

    2009-01-01

    Spin-labeled analogs of phospholipids have been used widely to characterize the biophysical properties of membranes. We describe synthesis and application of a new spin-labeled phospholipid analog, SL-POPC. The advantage of this molecule is that the EPR active doxyl group is linked to an unsaturated fatty acyl chain different to saturated phospholipid analogs used so far. The need for those analogs arises from the fact that biological membranes contain unsaturated phospholipids to a large extent. The biophysical properties of SL-POPC in membranes were characterized using EPR and NMR spectroscopy and compared with those of the saturated spin-labeled phospholipid, SL-PSPC. To this end, POPC membranes were labeled with either analog to assess whether the spin-labeled counterpart SL-POPC mimics the membrane properties better than the often used SL-PSPC. The results show that SL-POPC and SL-PSPC explore different molecular environments of the bilayer, and that the type and degree of perturbation of bilayer caused by the label moiety also differs between both analogs. We found that SL-POPC is more appropriate to assess the versatile dynamics of POPC membranes than SL-PSPC. PMID:19186138

  8. Insights into Medium-chain Acyl-CoA Dehydrogenase Structure by Molecular Dynamics Simulations.

    PubMed

    Bonito, Cátia A; Leandro, Paula; Ventura, Fátima V; Guedes, Rita C

    2016-08-01

    The medium-chain acyl-CoA dehydrogenase (MCAD) is a mitochondrial enzyme that catalyzes the first step of mitochondrial fatty acid β-oxidation (mFAO) pathway. Its deficiency is the most common genetic disorder of mFAO. Many of the MCAD disease-causing variants, including the most common p.K304E variant, show loss of function due to protein misfolding. Herein, we used molecular dynamics simulations to provide insights into the structural stability and dynamic behavior of MCAD wild-type (MCADwt) and validate a structure that would allow reliable new studies on its variants. Our results revealed that in both proteins the flavin adenine dinucleotide (FAD) has an important structural role on the tetramer stability and also in maintaining the volume of the enzyme catalytic pockets. We confirmed that the presence of substrate changes the dynamics of the catalytic pockets and increases FAD affinity. A comparison between the porcine MCADwt (pMCADwt) and human MCADwt (hMCADwt) structures revealed that both proteins are essentially similar and that the reversion of the double mutant E376G/T255E of hMCAD enzyme does not affect the structure of the protein neither its behavior in simulation. Our validated hMCADwt structure is crucial for complementing and accelerating the experimental studies aiming for the discovery and development of potential stabilizers of MCAD variants as candidates for the treatment of MCAD deficiency (MCADD). PMID:26992026

  9. Insights into Sphingolipid Miscibility: Separate Observation of Sphingomyelin and Ceramide N-Acyl Chain Melting

    PubMed Central

    Leung, Sherry S.W.; Busto, Jon V.; Keyvanloo, Amir; Goñi, Félix M.; Thewalt, Jenifer

    2012-01-01

    Ceramide produced from sphingomyelin in the plasma membrane is purported to affect signaling through changes in the membrane’s physical properties. Thermal behavior of N-palmitoyl sphingomyelin (PSM) and N-palmitoyl ceramide (PCer) mixtures in excess water has been monitored by 2H NMR spectroscopy and compared to differential scanning calorimetry (DSC) data. The alternate use of either perdeuterated or proton-based N-acyl chain PSM and PCer in our 2H NMR studies has allowed the separate observation of gel-fluid transitions in each lipid in the presence of the other one, and this in turn has provided direct information on the lipids’ miscibility over a wide temperature range. The results provide further evidence of the stabilization of the PSM gel state by PCer. Moreover, overlapping NMR and DSC data reveal that the DSC-signals parallel the melting of the major component (PSM) except at intermediate (20 and 30 mol %) fractions of PCer. In such cases, the DSC endotherm reports on the presumably highly cooperative melting of PCer. Up to at least 50 mol % PCer, PSM and PCer mix ideally in the liquid crystalline phase; in the gel phase, PCer becomes incorporated into PSM:PCer membranes with no evidence of pure solid PCer. PMID:23260048

  10. Electron spin resonance studies of acyl chain motion in reconstituted nicotinic acetylcholine receptor membranes.

    PubMed Central

    Raines, D E; Wu, G; Dalton, L A; Miller, K W

    1995-01-01

    The electron spin resonance spectra of spin-label positional isomers of stearic acid (n-SASL) incorporated into nicotinic acetylcholine receptors (nAcChoR) reconstituted into dioleoylphosphatidylcholine (DOPC) were deconvoluted into bilayer- and protein-associated components by subtraction under conditions of slow exchange. The selectivity of n-SASL (n = 6, 9, 12, and 14) for the lipid-protein interface of the nAcChoR was threefold greater than that of DOPC and independent of the spin label position. The temperature at which exchange became apparent as judged from lineshape broadening of the mobile lipid component spectrum was dependent upon the position of the spin-label moiety; near the bilayer center, exchange broadening occurred at lower temperatures than it did closer to the lipid headgroup. This suggests that the lipid headgroup region of boundary lipids is relatively fixed, whereas its acyl chain whips on and off the protein with increasing frequency near the bilayer center. Motions on the microsecond time scale were examined by microwave power saturation. Each n-SASL saturated more readily when incorporated into vesicles containing the nAcChoR than when in pure DOPC liposomes. Therefore, lipid mobility is perturbed by the nAcChoR on the microsecond time scale with an apparent magnitude that is relatively modest, probably due to exchange on this time scale. PMID:8527664

  11. Altering the sphingolipid acyl chain composition prevents LPS/GLN-mediated hepatic failure in mice by disrupting TNFR1 internalization

    PubMed Central

    Ali, M; Fritsch, J; Zigdon, H; Pewzner-Jung, Y; Schütze, S; Futerman, A H

    2013-01-01

    The involvement of ceramide in death receptor-mediated apoptosis has been widely examined with most studies focusing on the role of ceramide generated from sphingomyelin hydrolysis. We now analyze the effect of the ceramide acyl chain length by studying tumor necrosis factor α receptor-1 (TNFR1)-mediated apoptosis in a ceramide synthase 2 (CerS2) null mouse, which cannot synthesize very-long acyl chain ceramides. CerS2 null mice were resistant to lipopolysaccharide/galactosamine-mediated fulminant hepatic failure even though TNFα secretion from macrophages was unaffected. Cultured hepatocytes were also insensitive to TNFα-mediated apoptosis. In addition, in both liver and in hepatocytes, caspase activities were not elevated, consistent with inhibition of TNFR1 pro-apoptotic signaling. In contrast, Fas receptor activation resulted in the death of CerS2 null mice. Caspase activation was blocked because of the inability of CerS2 null mice to internalize the TNFR1; whereas Fc-TNFα was internalized to a perinuclear region in hepatocytes from wild-type mice, no internalization was detected in CerS2 null mice. Our results indicate that altering the acyl chain composition of sphingolipids inhibits TNFR1 internalization and inhibits selective pro-apoptotic downstream signaling for apoptosis. PMID:24263103

  12. Concentrations of long-chain acyl-acyl carrier proteins during fatty acid synthesis by chloroplasts isolated from pea (Pisum sativum), safflower (Carthamus tinctoris), and amaranthus (Amaranthus lividus) leaves

    SciTech Connect

    Roughan, G.; Nishida, I. )

    1990-01-01

    Fatty acid synthesis from (1-14C)acetate by chloroplasts isolated from peas and amaranthus was linear for at least 15 min, whereas incorporation of the tracer into long-chain acyl-acyl carrier protein (ACP) did not increase after 2-3 min. When reactions were transferred to the dark after 3-5 min, long-chain acyl-ACPs lost about 90% of their radioactivity and total fatty acids retained all of theirs. Half-lives of the long-chain acyl-ACPs were estimated to be 10-15 s. Concentrations of palmitoyl-, stearoyl-, and oleoyl-ACP as indicated by equilibrium labeling during steady-state fatty acid synthesis, ranged from 0.6-1.1, 0.2-0.7, and 0.4-1.6 microM, respectively, for peas and from 1.6-1.9, 1.3-2.6, and 0.6-1.4 microM, respectively, for amaranthus. These values are based on a chloroplast volume of 47 microliters/mg chlorophyll and varied according to the mode of the incubation. A slow increase in activity of the fatty acid synthetase in safflower chloroplasts resulted in long-chain acyl-ACPs continuing to incorporate labeled acetate for 10 min. Upon re-illumination following a dark break, however, both fatty acid synthetase activity and acyl-ACP concentrations increased very rapidly. Palmitoyl-ACP was present at concentrations up to 2.5 microM in safflower chloroplasts, whereas those of stearoyl- and oleoyl-ACPs were in the lower ranges measured for peas. Acyl-ACPs were routinely separated from extracts of chloroplasts that had been synthesising long-chain fatty acids from labeled acetate by a minor modification of the method of Mancha et al. The results compared favorably with those obtained using alternative analytical methods such as adsorption to filter paper and partition chromatography on silicic acid columns.

  13. Medium chain acyl-CoA dehydrogenase deficiency human genome epidemiology review.

    PubMed

    Wang, S S; Fernhoff, P M; Hannon, W H; Khoury, M J

    1999-01-01

    Medium chain acyl-CoA dehydrogenase (MCAD) is a tetrameric flavoprotein essential for the beta-oxidation of medium chain fatty acids. MCAD deficiency (MCADD) is an inherited error of fatty acid metabolism. The gene for MCAD is located on chromosome one (1p31). One variant of the MCAD gene, G985A, a point mutation causing a change from lysine to glutamate at position 304 (K304E) in the mature MCAD protein, has been found in 90% of the alleles in MCADD patients identified retrospectively. There is a high frequency of MCADD among people of Northern European descent, which is believed to be due to a founder effect. MCADD is inherited in an autosomal recessive manner. Of patients clinically diagnosed with MCADD, 81% who have been identified retrospectively are homozygous for K304E, and 18% are compound heterozygotes for K304E. Clinical data on the probability of clinical disease indicates that MCADD patients are at risk for the following outcomes: hypoglycemia, vomiting, lethargy, encephalopathy, respiratory arrest, hepatomegaly, seizures, apnea, cardiac arrest, coma, and sudden and unexpected death. Long-term outcomes include developmental and behavioral disability, chronic muscle weakness, failure to thrive, cerebral palsy, and attention deficit disorder (ADD). Differences in clinical disease specific to allelic variants have not been documented. Factors that may increase risk for disease onset or modify disease severity are age when the first episode occurred, fasting, and presence of infection. Acute attacks must be treated immediately with appropriate intravenous doses of glucose. For those diagnosed, long-term management of the disease includes preventing stress caused by fasting and maintaining a high-carbohydrate, reduced-fat diet, and carnitine supplementation. Hospitalization costs attributable to morbidity and mortality from MCADD are unknown; MCADD is not a diagnosis in the International Classification of Disease, 10th Revision (ICD-10) codebook. Furthermore

  14. Biosynthesis of triacylglycerols containing very long chain monounsaturated acyl moieties in developing seeds. [Lunaria annua L. ; Sinapis alba L

    SciTech Connect

    Fehling, E.; Murphy, D.J.; Mukherjee, K.D. )

    1990-10-01

    Particulate (15,000g) fractions from developing seeds of honesty (Lunaria annua L.) and mustard (Sinapis alba L.) synthesize radioactive very long chain monounsaturated fatty acids (gadoleic, erucic, and nervonic) from (1-{sup 14}C)oleoyl-CoA and malonyl-CoA or from oleoyl-CoA and (2-{sup 14}C)malonyl-CoA. The very long chain monounsaturated fatty acids are rapidly channeled to triacylglycerols and other acyl lipids without intermediate accumulation of their CoA thioesters. When (1-{sup 14}C)oleoyl-CoA is used as the radioactive substrate, phosphatidylcholines and other phospholipids are most extensively radiolabeled by oleoyl moieties rather than by very long chain monounsaturated acyl moieties. When (2-{sup 14}C)malonyl-CoA is used as the radioactive substrate, no radioactive oleic acid is formed and the newly synthesized very long chain monounsaturated fatty acids are extensively incorporated into phosphatidylcholines and other phospholipids as well as triacylglycerols. The pattern of labeling of the key intermediates of the Kennedy pathway, e.g. lysophosphatidic acids, phosphatidic acids, and diacylglycerols by the newly synthesized very long chain monounsaturated fatty acids is consistent with the operation of this pathway in the biosynthesis of triacylglycerols.

  15. Oxidized phosphatidylcholines suggest oxidative stress in patients with medium-chain acyl-CoA dehydrogenase deficiency.

    PubMed

    Najdekr, Lukáš; Gardlo, Alžběta; Mádrová, Lucie; Friedecký, David; Janečková, Hana; Correa, Elon S; Goodacre, Royston; Adam, Tomáš

    2015-07-01

    Inborn errors of metabolism encompass a large group of diseases caused by enzyme deficiencies and are therefore amenable to metabolomics investigations. Medium chain acyl-CoA dehydrogenase deficiency (MCADD) is a defect in β-oxidation of fatty acids, and is one of the most well understood disorders. We report here the use of liquid chromatography-mass spectrometry (LC-MS) based untargeted metabolomics and targeted flow injection analysis-tandem mass spectrometry (FIA-TMS) that lead to discovery of novel compounds of oxidative stress. Dry blood spots of controls (n=25) and patient samples (n=25) were extracted by methanol/water (1/1, v/v) and these supernatants were analyzed by LC-MS method with detection by an Orbitrap Elite MS. Data were processed by XCMS and CAMERA followed by dimension reduction methods. Patients were clearly distinguished from controls in PCA. S-plot derived from OPLS-DA indicated that medium-chain acylcarnitines (octanoyl, decenoyl and decanoyl carnitines) as well as three phosphatidylcholines (PC(16:0,9:0(COOH))), PC(18:0,5:0(COOH)) and PC(16:0,8:0(COOH)) were important metabolites for differentiation between patients and healthy controls. In order to biologically validate these discriminatory molecules as indicators for oxidative stress, a second cohort of individuals were analyzed, including MCADD (n=25) and control (n=250) samples. These were measured by a modified newborn screening method using FIA-TMS (API 4000) in MRM mode. Calculated p-values for PC(16:0,9:0(COOH)), PC(18:0,5:0(COOH)) and PC(16:0,8:0(COOH)) were 1.927×10(-14), 2.391×10(-15) and 3.354×10(-15) respectively. These elevated oxidized phospholipids indeed show an increased presence of oxidative stress in MCADD patients as one of the pathophysiological mechanisms of the disease. PMID:25882409

  16. Clinical aspects of short-chain acyl-CoA dehydrogenase deficiency

    PubMed Central

    Wanders, Ronald J. A.; Wijburg, Frits A.

    2010-01-01

    Short-chain acyl-CoA dehydrogenase deficiency (SCADD) is an autosomal recessive inborn error of mitochondrial fatty acid oxidation. SCADD is biochemically characterized by increased C4-carnitine in plasma and ethylmalonic acid in urine. The diagnosis of SCADD is confirmed by DNA analysis showing SCAD gene mutations and/or variants. SCAD gene variants are present in homozygous form in approximately 6% of the general population and considered to confer susceptibility to development of clinical disease. Clinically, SCADD generally appears to present early in life and to be most frequently associated with developmental delay, hypotonia, epilepsy, behavioral disorders, and hypoglycemia. However, these symptoms often ameliorate and even disappear spontaneously during follow-up and were found to be unrelated to the SCAD genotype. In addition, in some cases, symptoms initially attributed to SCADD could later be explained by other causes. Finally, SCADD relatives of SCADD patients as well as almost all SCADD individuals diagnosed by neonatal screening remained asymptomatic during follow-up. This potential lack of clinical consequences of SCADD has several implications. First, the diagnosis of SCADD should never preclude extension of the diagnostic workup for other potential causes of the observed symptoms. Second, patients and parents should be clearly informed about the potential lack of relevance of the disorder to avoid unfounded anxiety. Furthermore, to date, SCADD is not an optimal candidate for inclusion in newborn screening programs. More studies are needed to fully establish the relevance of SCADD and solve the question as to whether SCADD is involved in a multifactorial disease or represents a nondisease. PMID:20429031

  17. Changes in short-chain acyl-coA dehydrogenase during rat cardiac development and stress

    PubMed Central

    Huang, Jinxian; Xu, Lipeng; Huang, Qiuju; Luo, Jiani; Liu, Peiqing; Chen, Shaorui; Yuan, Xi; Lu, Yao; Wang, Ping; Zhou, Sigui

    2015-01-01

    This study was designed to investigate the expression of short-chain acyl-CoA dehydrogenase (SCAD), a key enzyme of fatty acid β-oxidation, during rat heart development and the difference of SCAD between pathological and physiological cardiac hypertrophy. The expression of SCAD was lowest in the foetal and neonatal heart, which had time-dependent increase during normal heart development. In contrast, a significant decrease in SCAD expression was observed in different ages of spontaneously hypertensive rats (SHR). On the other hand, swim-trained rats developed physiological cardiac hypertrophy, whereas SHR developed pathological cardiac hypertrophy. The two kinds of cardiac hypertrophy exhibited divergent SCAD changes in myocardial fatty acids utilization. In addition, the expression of SCAD was significantly decreased in pathological cardiomyocyte hypertrophy, however, increased in physiological cardiomyocyte hypertrophy. SCAD siRNA treatment triggered the pathological cardiomyocyte hypertrophy, which showed that the down-regulation of SCAD expression may play an important role in pathological cardiac hypertrophy. The changes in peroxisome proliferator-activated receptor α (PPARα) was accordant with that of SCAD. Moreover, the specific PPARα ligand fenofibrate treatment increased the expression of SCAD and inhibited pathological cardiac hypertrophy. Therefore, we speculate that the down-regulated expression of SCAD in pathological cardiac hypertrophy may be responsible for ‘the recapitulation of foetal energy metabolism’. The deactivation of PPARα may result in the decrease in SCAD expression in pathological cardiac hypertrophy. Changes in SCAD are different in pathological and physiological cardiac hypertrophy, which may be used as the molecular markers of pathological and physiological cardiac hypertrophy. PMID:25753319

  18. Regulation of gene expression through a transcriptional repressor that senses acyl-chain length in membrane phospholipids.

    PubMed

    Hofbauer, Harald F; Schopf, Florian H; Schleifer, Hannes; Knittelfelder, Oskar L; Pieber, Bartholomäus; Rechberger, Gerald N; Wolinski, Heimo; Gaspar, Maria L; Kappe, C Oliver; Stadlmann, Johannes; Mechtler, Karl; Zenz, Alexandra; Lohner, Karl; Tehlivets, Oksana; Henry, Susan A; Kohlwein, Sepp D

    2014-06-23

    Membrane phospholipids typically contain fatty acids (FAs) of 16 and 18 carbon atoms. This particular chain length is evolutionarily highly conserved and presumably provides maximum stability and dynamic properties to biological membranes in response to nutritional or environmental cues. Here, we show that the relative proportion of C16 versus C18 FAs is regulated by the activity of acetyl-CoA carboxylase (Acc1), the first and rate-limiting enzyme of FA de novo synthesis. Acc1 activity is attenuated by AMPK/Snf1-dependent phosphorylation, which is required to maintain an appropriate acyl-chain length distribution. Moreover, we find that the transcriptional repressor Opi1 preferentially binds to C16 over C18 phosphatidic acid (PA) species: thus, C16-chain containing PA sequesters Opi1 more effectively to the ER, enabling AMPK/Snf1 control of PA acyl-chain length to determine the degree of derepression of Opi1 target genes. These findings reveal an unexpected regulatory link between the major energy-sensing kinase, membrane lipid composition, and transcription. PMID:24960695

  19. Membrane lateral compressibility determined by NMR and x-ray diffraction: effect of acyl chain polyunsaturation.

    PubMed Central

    Koenig, B W; Strey, H H; Gawrisch, K

    1997-01-01

    The elastic area compressibility modulus, Ka, of lamellar liquid crystalline bilayers was determined by a new experimental approach using 2H-NMR order parameters of lipid hydrocarbon chains together with lamellar repeat spacings measured by x-ray diffraction. The combination of NMR and x-ray techniques yields accurate determination of lateral area per lipid molecule. Samples of saturated, monounsaturated, and polyunsaturated phospholipids were equilibrated with polyethylene glycol (PEG) 20,000 solutions in water at concentrations from 0 to 55 wt % PEG at 30 degrees C. This procedure is equivalent to applying 0 to 8 dyn/cm lateral pressure to the bilayers. The resulting reductions in area per lipid were measured with a resolution of +/-0.2 A2 and the fractional area decrease was proportional to applied lateral pressure. For 1,2-dimyristoyl(d54)-sn-glycero-3-phosphocholine, 1-stearoyl(d35)-2-oleoyl-sn-glycero-3-phosphocholine (SOPC-d35), and 1-stearoyl(d35)-2-docosahexaenoyl-sn-glycero-3-phosphocholine (SDPC-d35) cross-sectional areas per molecule in excess water of 59.5, 61.4, and 69.2 A2 and bilayer elastic area compressibility moduli of 141, 221, and 121 dyn/cm were determined, respectively. Combining NMR and x-ray results enables the determination of compressibility differences between saturated and unsaturated hydrocarbon chains. In mixed-chain SOPC-d35 both chains have similar compressibility moduli; however, in mixed-chain polyunsaturated SDPC-d35, the saturated stearic acid chain appears to be far less compressible than the polyunsaturated docosahexaenoic acid chain. Images FIGURE 3 FIGURE 5 PMID:9336191

  20. Identification of Regiospecific Isomers of Diricinoleoyl-acyl-glycerols containing one non-ricinoleoyl chain in Castor Oil by ESI-MS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    HPLC fractions of diricinoleoyl-acyl-glycerols containing one non-ricinoleoyl chain from castor oil were used to identify the regiospecific location of this non-ricinoleoyl chain on the glycerol backbone using electrospray ionization-MS3 of lithium adducts. The regiospecific ions used were from...

  1. Phospholipid profiling identifies acyl chain elongation as a ubiquitous trait and potential target for the treatment of lung squamous cell carcinoma

    PubMed Central

    Marien, Eyra; Meister, Michael; Muley, Thomas; del Pulgar, Teresa Gomez; Derua, Rita; Spraggins, Jeffrey M.; Van de Plas, Raf; Vanderhoydonc, Frank; Machiels, Jelle; Binda, Maria Mercedes; Dehairs, Jonas; Willette-Brown, Jami; Hu, Yinling; Dienemann, Hendrik; Thomas, Michael; Schnabel, Philipp A.; Caprioli, Richard M.; Lacal, Juan Carlos; Waelkens, Etienne; Swinnen, Johannes V.

    2016-01-01

    Lung cancer is the leading cause of cancer death. Beyond first line treatment, few therapeutic options are available, particularly for squamous cell carcinoma (SCC). Here, we have explored the phospholipidomes of 30 human SCCs and found that they almost invariably (in 96.7% of cases) contain phospholipids with longer acyl chains compared to matched normal tissues. This trait was confirmed using in situ 2D-imaging MS on tissue sections and by phospholipidomics of tumor and normal lung tissue of the L-IkkαKA/KA mouse model of lung SCC. In both human and mouse, the increase in acyl chain length in cancer tissue was accompanied by significant changes in the expression of acyl chain elongases (ELOVLs). Functional screening of differentially expressed ELOVLs by selective gene knockdown in SCC cell lines followed by phospholipidomics revealed ELOVL6 as the main elongation enzyme responsible for acyl chain elongation in cancer cells. Interestingly, inhibition of ELOVL6 drastically reduced colony formation of multiple SCC cell lines in vitro and significantly attenuated their growth as xenografts in vivo in mouse models. These findings identify acyl chain elongation as one of the most common traits of lung SCC discovered so far and pinpoint ELOVL6 as a novel potential target for cancer intervention. PMID:26862848

  2. Chlamydia trachomatis growth and development requires the activity of host Long-chain Acyl-CoA Synthetases (ACSLs)

    PubMed Central

    Recuero-Checa, Maria A.; Sharma, Manu; Lau, Constance; Watkins, Paul A.; Gaydos, Charlotte A.; Dean, Deborah

    2016-01-01

    The obligate-intracellular pathogen Chlamydia trachomatis (Ct) has undergone considerable genome reduction with consequent dependence on host biosynthetic pathways, metabolites and enzymes. Long-chain acyl-CoA synthetases (ACSLs) are key host-cell enzymes that convert fatty acids (FA) into acyl-CoA for use in metabolic pathways. Here, we show that the complete host ACSL family [ACSL1 and ACSL3–6] translocates into the Ct membrane-bound vacuole, termed inclusion, and remains associated with membranes of metabolically active forms of Ct throughout development. We discovered that three different pharmacologic inhibitors of ACSL activity independently impede Ct growth in a dose-dependent fashion. Using an FA competition assay, host ACSLs were found to activate Ct branched-chain FAs, suggesting that one function of the ACSLs is to activate Ct FAs and host FAs (recruited from the cytoplasm) within the inclusion. Because the ACSL inhibitors can deplete lipid droplets (LD), we used a cell line where LD synthesis was switched off to evaluate whether LD deficiency affects Ct growth. In these cells, we found no effect on growth or on translocation of ACSLs into the inclusion. Our findings support an essential role for ACSL activation of host-cell and bacterial FAs within the inclusion to promote Ct growth and development, independent of LDs. PMID:26988341

  3. Long-chain acyl-CoA synthetase 4 modulates prostaglandin E2 release from human arterial smooth muscle cells

    PubMed Central

    Golej, Deidre L.; Askari, Bardia; Kramer, Farah; Barnhart, Shelley; Vivekanandan-Giri, Anuradha; Pennathur, Subramaniam; Bornfeldt, Karin E.

    2011-01-01

    Long-chain acyl-CoA synthetases (ACSLs) catalyze the thioesterification of long-chain FAs into their acyl-CoA derivatives. Purified ACSL4 is an arachidonic acid (20:4)-preferring ACSL isoform, and ACSL4 is therefore a probable regulator of lipid mediator production in intact cells. Eicosanoids play important roles in vascular homeostasis and disease, yet the role of ACSL4 in vascular cells is largely unknown. In the present study, the ACSL4 splice variant expressed in human arterial smooth muscle cells (SMCs) was identified as variant 1. To investigate the function of ACSL4 in SMCs, ACSL4 variant 1 was overexpressed, knocked-down by small interfering RNA, or its enzymatic activity acutely inhibited in these cells. Overexpression of ACSL4 resulted in a markedly increased synthesis of arachidonoyl-CoA, increased 20:4 incorporation into phosphatidylethanolamine, phosphatidylinositol, and triacylglycerol, and reduced cellular levels of unesterified 20:4. Accordingly, secretion of prostaglandin E2 (PGE2) was blunted in ACSL4-overexpressing SMCs compared with controls. Conversely, acute pharmacological inhibition of ACSL4 activity resulted in increased release of PGE2. However, long-term downregulation of ACSL4 resulted in markedly reduced PGE2 secretion. Thus, ACSL4 modulates PGE2 release from human SMCs. ACSL4 may regulate a number of processes dependent on the release of arachidonic acid-derived lipid mediators in the arterial wall. PMID:21242590

  4. Long-chain acyl-CoA synthetase in fatty acid metabolism involved in liver and other diseases: An update

    PubMed Central

    Yan, Sheng; Yang, Xue-Feng; Liu, Hao-Lei; Fu, Nian; Ouyang, Yan; Qing, Kai

    2015-01-01

    Long-chain acyl-CoA synthetase (ACSL) family members include five different ACSL isoforms, each encoded by a separate gene and have multiple spliced variants. ACSLs on endoplasmic reticulum and mitochondrial outer membrance catalyze fatty acids with chain lengths from 12 to 20 carbon atoms to form acyl-CoAs, which are lipid metabolic intermediates and involved in fatty acid metabolism, membrane modifications and various physiological processes. Gain- or loss-of-function studies have shown that the expression of individual ACSL isoforms can alter the distribution and amount of intracellular fatty acids. Changes in the types and amounts of fatty acids, in turn, can alter the expression of intracellular ACSLs. ACSL family members affect not only the proliferation of normal cells, but the proliferation of malignant tumor cells. They also regulate cell apoptosis through different signaling pathways and molecular mechanisms. ACSL members have individual functions in fatty acid metabolism in different types of cells depending on substrate preferences, subcellular location and tissue specificity, thus contributing to liver diseases and metabolic diseases, such as fatty liver disease, obesity, atherosclerosis and diabetes. They are also linked to neurological disorders and other diseases. However, the mechanisms are unclear. This review addresses new findings in the classification and properties of ACSLs and the fatty acid metabolism-associated effects of ACSLs in diseases. PMID:25834313

  5. Crystal structures of SIRT3 reveal that the α2-α3 loop and α3-helix affect the interaction with long-chain acyl lysine.

    PubMed

    Gai, Wei; Li, He; Jiang, Hualiang; Long, Yaqiu; Liu, Dongxiang

    2016-09-01

    SIRT1-7 play important roles in many biological processes and age-related diseases. In addition to a NAD(+) -dependent deacetylase activity, they can catalyze several other reactions, including the hydrolysis of long-chain fatty acyl lysine. To study the binding modes of sirtuins to long-chain acyl lysines, we solved the crystal structures of SIRT3 bound to either a H3K9-myristoylated- or a H3K9-palmitoylated peptide. Interaction of SIRT3 with the palmitoyl group led to unfolding of the α3-helix. The myristoyl and palmitoyl groups bind to the C-pocket and an allosteric site near the α3-helix, respectively. We found that the residues preceding the α3-helix determine the size of the C-pocket. The flexibility of the α2-α3 loop and the plasticity of the α3-helix affect the interaction with long-chain acyl lysine. PMID:27501476

  6. Steady-state concentrations of coenzyme A, acetyl-coenzyme A and long-chain fatty acyl-coenzyme A in rat-liver mitochondria oxidizing palmitate

    PubMed Central

    Garland, P. B.; Shepherd, D.; Yates, D. W.

    1965-01-01

    1. Fluorimetric assays are described for CoASH, acetyl-CoA and long-chain fatty acyl-CoA, and are sensitive to at least 50μμmoles of each. 2. Application of these assays to rat-liver mitochondria oxidizing palmitate in the absence and presence of carnitine indicated two pools of intramitochondrial CoA. One pool could be acylated by palmitate and ATP, and the other pool acylated by palmitate with ATP and carnitine, or by palmitoylcarnitine alone. 3. The intramitochondrial content of acetyl-CoA is increased by the oxidation of palmitate both in the absence and presence of l-malate. 4. The conversion of palmitoyl-CoA into acetyl-CoA by β-oxidation takes place without detectable accumulation of acyl-CoA intermediates. PMID:16749169

  7. The role of Δ6-desaturase acyl-carrier specificity in the efficient synthesis of long-chain polyunsaturated fatty acids in transgenic plants.

    PubMed

    Sayanova, Olga; Ruiz-Lopez, Noemi; Haslam, Richard P; Napier, Johnathan A

    2012-02-01

    The role of acyl-CoA-dependent Δ6-desaturation in the heterologous synthesis of omega-3 long-chain polyunsaturated fatty acids was systematically evaluated in transgenic yeast and Arabidopsis thaliana. The acyl-CoA Δ6-desaturase from the picoalga Ostreococcus tauri and orthologous activities from mouse (Mus musculus) and salmon (Salmo salar) were shown to generate substantial levels of Δ6-desaturated acyl-CoAs, in contrast to the phospholipid-dependent Δ6-desaturases from higher plants that failed to modify this metabolic pool. Transgenic plants expressing the acyl-CoA Δ6-desaturases from either O. tauri or salmon, in conjunction with the two additional activities required for the synthesis of C20 polyunsaturated fatty acids, contained higher levels of eicosapentaenoic acid compared with plants expressing the borage phospholipid-dependent Δ6-desaturase. The use of acyl-CoA-dependent Δ6-desaturases almost completely abolished the accumulation of unwanted biosynthetic intermediates such as γ-linolenic acid in total seed lipids. Expression of acyl-CoA Δ6-desaturases resulted in increased distribution of long-chain polyunsaturated fatty acids in the polar lipids of transgenic plants, reflecting the larger substrate pool available for acylation by enzymes of the Kennedy pathway. Expression of the O. tauriΔ6-desaturase in transgenic Camelina sativa plants also resulted in the accumulation of high levels of Δ6-desaturated fatty acids. This study provides evidence for the efficacy of using acyl-CoA-dependent Δ6-desaturases in the efficient metabolic engineering of transgenic plants with high value traits such as the synthesis of omega-3 LC-PUFAs. PMID:21902798

  8. Determination of membrane cholesterol partition coefficient using a lipid vesicle-cyclodextrin binary system: effect of phospholipid acyl chain unsaturation and headgroup composition.

    PubMed Central

    Niu, Shui-Lin; Litman, Burton J

    2002-01-01

    Lateral domain or raft formation in biological membranes is often discussed in terms of cholesterol-lipid interactions. Preferential interactions of cholesterol with lipids, varying in headgroup and acyl chain unsaturation, were studied by measuring the partition coefficient for cholesterol in unilamellar vesicles. A novel vesicle-cyclodextrin system was used, which precludes the possibility of cross-contamination between donor-acceptor vesicles or the need to modify one of the vesicle populations. Variation in phospholipid headgroup resulted in cholesterol partitioning in the order of sphingomyelin (SM) > phosphatidylserine > phosphatidylcholine (PC) > phosphatidylenthanolamine (PE), spanning a range of partition DeltaG of -1181 cal/mol to +683 cal/mol for SM and PE, respectively. Among the acyl chains examined, the order of cholesterol partitioning was 18:0(stearic acid),18:1n-9(oleic acid) PC > di18:1n-9PC > di18:1n-12(petroselenic acid) PC > di18:2n-6(linoleic acid) PC > 16:0(palmitic acid),22:6n-3(DHA) PC > di18:3n-3(alpha-linolenic acid) PC > di22:6n-3PC with a range in partition DeltaG of 913 cal/mol. Our results suggest that the large differences observed in cholesterol-lipid interactions contribute to the forces responsible for lateral domain formation in plasma membranes. These differences may also be responsible for the heterogeneous cholesterol distribution in cellular membranes, where cholesterol is highly enriched in plasma membranes and relatively depleted in intracellular membranes. PMID:12496107

  9. Phosphatidylinositol-(4,5)-Bisphosphate Acyl Chains Differentiate Membrane Binding of HIV-1 Gag from That of the Phospholipase Cδ1 Pleckstrin Homology Domain

    PubMed Central

    Olety, Balaji; Veatch, Sarah L.

    2015-01-01

    ABSTRACT HIV-1 Gag, which drives virion assembly, interacts with a plasma membrane (PM)-specific phosphoinositide, phosphatidylinositol-(4,5)-bisphosphate [PI(4,5)P2]. While cellular acidic phospholipid-binding proteins/domains, such as the PI(4,5)P2-specific pleckstrin homology domain of phospholipase Cδ1 (PHPLCδ1), mediate headgroup-specific interactions with corresponding phospholipids, the exact nature of the Gag-PI(4,5)P2 interaction remains undetermined. In this study, we used giant unilamellar vesicles (GUVs) to examine how PI(4,5)P2 with unsaturated or saturated acyl chains affect membrane binding of PHPLCδ1 and Gag. Both unsaturated dioleoyl-PI(4,5)P2 [DO-PI(4,5)P2] and saturated dipalmitoyl-PI(4,5)P2 [DP-PI(4,5)P2] successfully recruited PHPLCδ1 to membranes of single-phase GUVs. In contrast, DO-PI(4,5)P2 but not DP-PI(4,5)P2 recruited Gag to GUVs, indicating that PI(4,5)P2 acyl chains contribute to stable membrane binding of Gag. GUVs containing PI(4,5)P2, cholesterol, and dipalmitoyl phosphatidylserine separated into two coexisting phases: one was a liquid phase, and the other appeared to be a phosphatidylserine-enriched gel phase. In these vesicles, the liquid phase recruited PHPLCδ1 regardless of PI(4,5)P2 acyl chains. Likewise, Gag bound to the liquid phase when PI(4,5)P2 had DO-acyl chains. DP-PI(4,5)P2-containing GUVs showed no detectable Gag binding to the liquid phase. Unexpectedly, however, DP-PI(4,5)P2 still promoted recruitment of Gag, but not PHPLCδ1, to the dipalmitoyl-phosphatidylserine-enriched gel phase of these GUVs. Altogether, these results revealed different roles for PI(4,5)P2 acyl chains in membrane binding of two PI(4,5)P2-binding proteins, Gag and PHPLCδ1. Notably, we observed that nonmyristylated Gag retains the preference for PI(4,5)P2 containing an unsaturated acyl chain over DP-PI(4,5)P2, suggesting that Gag sensitivity to PI(4,5)P2 acyl chain saturation is determined directly by the matrix-PI(4,5)P2 interaction, rather

  10. Fatty Acid Oxidation Mediated by Acyl-CoA Synthetase Long Chain 3 Is Required for Mutant KRAS Lung Tumorigenesis.

    PubMed

    Padanad, Mahesh S; Konstantinidou, Georgia; Venkateswaran, Niranjan; Melegari, Margherita; Rindhe, Smita; Mitsche, Matthew; Yang, Chendong; Batten, Kimberly; Huffman, Kenneth E; Liu, Jingwen; Tang, Ximing; Rodriguez-Canales, Jaime; Kalhor, Neda; Shay, Jerry W; Minna, John D; McDonald, Jeffrey; Wistuba, Ignacio I; DeBerardinis, Ralph J; Scaglioni, Pier Paolo

    2016-08-01

    KRAS is one of the most commonly mutated oncogenes in human cancer. Mutant KRAS aberrantly regulates metabolic networks. However, the contribution of cellular metabolism to mutant KRAS tumorigenesis is not completely understood. We report that mutant KRAS regulates intracellular fatty acid metabolism through Acyl-coenzyme A (CoA) synthetase long-chain family member 3 (ACSL3), which converts fatty acids into fatty Acyl-CoA esters, the substrates for lipid synthesis and β-oxidation. ACSL3 suppression is associated with depletion of cellular ATP and causes the death of lung cancer cells. Furthermore, mutant KRAS promotes the cellular uptake, retention, accumulation, and β-oxidation of fatty acids in lung cancer cells in an ACSL3-dependent manner. Finally, ACSL3 is essential for mutant KRAS lung cancer tumorigenesis in vivo and is highly expressed in human lung cancer. Our data demonstrate that mutant KRAS reprograms lipid homeostasis, establishing a metabolic requirement that could be exploited for therapeutic gain. PMID:27477280

  11. Structural basis for selective recognition of acyl chains by the membrane-associated acyltransferase PatA

    PubMed Central

    Albesa-Jové, David; Svetlíková, Zuzana; Tersa, Montse; Sancho-Vaello, Enea; Carreras-González, Ana; Bonnet, Pascal; Arrasate, Pedro; Eguskiza, Ander; Angala, Shiva K.; Cifuente, Javier O.; Korduláková, Jana; Jackson, Mary; Mikušová, Katarína; Guerin, Marcelo E.

    2016-01-01

    The biosynthesis of phospholipids and glycolipids are critical pathways for virtually all cell membranes. PatA is an essential membrane associated acyltransferase involved in the biosynthesis of mycobacterial phosphatidyl-myo-inositol mannosides (PIMs). The enzyme transfers a palmitoyl moiety from palmitoyl–CoA to the 6-position of the mannose ring linked to 2-position of inositol in PIM1/PIM2. We report here the crystal structures of PatA from Mycobacterium smegmatis in the presence of its naturally occurring acyl donor palmitate and a nonhydrolyzable palmitoyl–CoA analog. The structures reveal an α/β architecture, with the acyl chain deeply buried into a hydrophobic pocket that runs perpendicular to a long groove where the active site is located. Enzyme catalysis is mediated by an unprecedented charge relay system, which markedly diverges from the canonical HX4D motif. Our studies establish the mechanistic basis of substrate/membrane recognition and catalysis for an important family of acyltransferases, providing exciting possibilities for inhibitor design. PMID:26965057

  12. Structural basis for selective recognition of acyl chains by the membrane-associated acyltransferase PatA.

    PubMed

    Albesa-Jové, David; Svetlíková, Zuzana; Tersa, Montse; Sancho-Vaello, Enea; Carreras-González, Ana; Bonnet, Pascal; Arrasate, Pedro; Eguskiza, Ander; Angala, Shiva K; Cifuente, Javier O; Korduláková, Jana; Jackson, Mary; Mikušová, Katarína; Guerin, Marcelo E

    2016-01-01

    The biosynthesis of phospholipids and glycolipids are critical pathways for virtually all cell membranes. PatA is an essential membrane associated acyltransferase involved in the biosynthesis of mycobacterial phosphatidyl-myo-inositol mannosides (PIMs). The enzyme transfers a palmitoyl moiety from palmitoyl-CoA to the 6-position of the mannose ring linked to 2-position of inositol in PIM1/PIM2. We report here the crystal structures of PatA from Mycobacterium smegmatis in the presence of its naturally occurring acyl donor palmitate and a nonhydrolyzable palmitoyl-CoA analog. The structures reveal an α/β architecture, with the acyl chain deeply buried into a hydrophobic pocket that runs perpendicular to a long groove where the active site is located. Enzyme catalysis is mediated by an unprecedented charge relay system, which markedly diverges from the canonical HX4D motif. Our studies establish the mechanistic basis of substrate/membrane recognition and catalysis for an important family of acyltransferases, providing exciting possibilities for inhibitor design. PMID:26965057

  13. Hepatic long-chain acyl-CoA synthetase 5 mediates fatty acid channeling between anabolic and catabolic pathways.

    PubMed

    Bu, So Young; Mashek, Douglas G

    2010-11-01

    Long-chain acyl-CoA synthetases (ACSLs) and fatty acid transport proteins (FATPs) activate fatty acids (FAs) to acyl-CoAs prior to their downstream metabolism. Of numerous ACSL and FATP isoforms, ACSL5 is expressed predominantly in tissues with high rates of triacylglycerol (TAG) synthesis, suggesting it may have an anabolic role in lipid metabolism. To characterize the role of ACSL5 in hepatic energy metabolism, we used small interference RNA (siRNA) to knock down ACSL5 in rat primary hepatocytes. Compared with cells transfected with control siRNA, suppression of ACSL5 expression significantly decreased FA-induced lipid droplet formation. These findings were further extended with metabolic labeling studies showing that ACSL5 knockdown resulted in decreased [1-(14)C]oleic acid or acetic acid incorporation into intracellular TAG, phospholipids, and cholesterol esters without altering FA uptake or lipogenic gene expression. ACSL5 knockdown also decreased hepatic TAG secretion proportionate to the observed decrease in neutral lipid synthesis. ACSL5 knockdown did not alter lipid turnover or mediate the effects of insulin on lipid metabolism. Hepatocytes treated with ACSL5 siRNA had increased rates of FA oxidation without changing PPAR-α activity and target gene expression. These results suggest that ACSL5 activates and channels FAs toward anabolic pathways and, therefore, is an important branch point in hepatic FA metabolism. PMID:20798351

  14. Dynamics of the Heat Stress Response of Ceramides with Different Fatty-Acyl Chain Lengths in Baker's Yeast.

    PubMed

    Chen, Po-Wei; Fonseca, Luis L; Hannun, Yusuf A; Voit, Eberhard O

    2015-08-01

    The article demonstrates that computational modeling has the capacity to convert metabolic snapshots, taken sequentially over time, into a description of cellular, dynamic strategies. The specific application is a detailed analysis of a set of actions with which Saccharomyces cerevisiae responds to heat stress. Using time dependent metabolic concentration data, we use a combination of mathematical modeling, reverse engineering, and optimization to infer dynamic changes in enzyme activities within the sphingolipid pathway. The details of the sphingolipid responses to heat stress are important, because they guide some of the longer-term alterations in gene expression, with which the cells adapt to the increased temperature. The analysis indicates that all enzyme activities in the system are affected and that the shapes of the time trends in activities depend on the fatty-acyl CoA chain lengths of the different ceramide species in the system. PMID:26241868

  15. Medium-Chain Acyl-CoA Deficiency: Outlines from Newborn Screening, In Silico Predictions, and Molecular Studies

    PubMed Central

    Catarzi, Serena; Caciotti, Anna; Thusberg, Janita; Tonin, Rodolfo; Malvagia, Sabrina; la Marca, Giancarlo; Pasquini, Elisabetta; Cavicchi, Catia; Ferri, Lorenzo; Donati, Maria A.; Baronio, Federico; Guerrini, Renzo; Mooney, Sean D.; Morrone, Amelia

    2013-01-01

    Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is a disorder of fatty acid oxidation characterized by hypoglycemic crisis under fasting or during stress conditions, leading to lethargy, seizures, brain damage, or even death. Biochemical acylcarnitines data obtained through newborn screening by liquid chromatography-tandem mass spectrometry (LC-MS/MS) were confirmed by molecular analysis of the medium-chain acyl-CoA dehydrogenase (ACADM) gene. Out of 324.000 newborns screened, we identified 14 MCADD patients, in whom, by molecular analysis, we found a new nonsense c.823G>T (p.Gly275∗) and two new missense mutations: c.253G>C (p.Gly85Arg) and c.356T>A (p.Val119Asp). Bioinformatics predictions based on both phylogenetic conservation and functional/structural software were used to characterize the new identified variants. Our findings confirm the rising incidence of MCADD whose existence is increasingly recognized due to the efficacy of an expanded newborn screening panel by LC-MS/MS making possible early specific therapies that can prevent possible crises in at-risk infants. We noticed that the “common” p.Lys329Glu mutation only accounted for 32% of the defective alleles, while, in clinically diagnosed patients, this mutation accounted for 90% of defective alleles. Unclassified variants (UVs or VUSs) are especially critical when considering screening programs. The functional and pathogenic characterization of genetic variants presented here is required to predict their medical consequences in newborns. PMID:24294134

  16. Medium-chain acyl-CoA deficiency: outlines from newborn screening, in silico predictions, and molecular studies.

    PubMed

    Catarzi, Serena; Caciotti, Anna; Thusberg, Janita; Tonin, Rodolfo; Malvagia, Sabrina; la Marca, Giancarlo; Pasquini, Elisabetta; Cavicchi, Catia; Ferri, Lorenzo; Donati, Maria A; Baronio, Federico; Guerrini, Renzo; Mooney, Sean D; Morrone, Amelia

    2013-01-01

    Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is a disorder of fatty acid oxidation characterized by hypoglycemic crisis under fasting or during stress conditions, leading to lethargy, seizures, brain damage, or even death. Biochemical acylcarnitines data obtained through newborn screening by liquid chromatography-tandem mass spectrometry (LC-MS/MS) were confirmed by molecular analysis of the medium-chain acyl-CoA dehydrogenase (ACADM) gene. Out of 324.000 newborns screened, we identified 14 MCADD patients, in whom, by molecular analysis, we found a new nonsense c.823G>T (p.Gly275∗) and two new missense mutations: c.253G>C (p.Gly85Arg) and c.356T>A (p.Val119Asp). Bioinformatics predictions based on both phylogenetic conservation and functional/structural software were used to characterize the new identified variants. Our findings confirm the rising incidence of MCADD whose existence is increasingly recognized due to the efficacy of an expanded newborn screening panel by LC-MS/MS making possible early specific therapies that can prevent possible crises in at-risk infants. We noticed that the "common" p.Lys329Glu mutation only accounted for 32% of the defective alleles, while, in clinically diagnosed patients, this mutation accounted for 90% of defective alleles. Unclassified variants (UVs or VUSs) are especially critical when considering screening programs. The functional and pathogenic characterization of genetic variants presented here is required to predict their medical consequences in newborns. PMID:24294134

  17. Depletion of Phosphatidylcholine in Yeast Induces Shortening and Increased Saturation of the Lipid Acyl Chains: Evidence for Regulation of Intrinsic Membrane Curvature in a Eukaryote

    PubMed Central

    Boumann, Henry A.; Gubbens, Jacob; Koorengevel, Martijn C.; Oh, Chan-Seok; Martin, Charles E.; Heck, Albert J.R.; Patton-Vogt, Jana; Henry, Susan A.; de Kruijff, Ben; de Kroon, Anton I.P.M.

    2006-01-01

    To study the consequences of depleting the major membrane phospholipid phosphatidylcholine (PC), exponentially growing cells of a yeast cho2opi3 double deletion mutant were transferred from medium containing choline to choline-free medium. Cell growth did not cease until the PC level had dropped below 2% of total phospholipids after four to five generations. Increasing contents of phosphatidylethanolamine (PE) and phosphatidylinositol made up for the loss of PC. During PC depletion, the remaining PC was subject to acyl chain remodeling with monounsaturated species replacing diunsaturated species, as shown by mass spectrometry. The remodeling of PC did not require turnover by the SPO14-encoded phospholipase D. The changes in the PC species profile were found to reflect an overall shift in the cellular acyl chain composition that exhibited a 40% increase in the ratio of C16 over C18 acyl chains, and a 10% increase in the degree of saturation. The shift was stronger in the phospholipid than in the neutral lipid fraction and strongest in the species profile of PE. The shortening and increased saturation of the PE acyl chains were shown to decrease the nonbilayer propensity of PE. The results point to a regulatory mechanism in yeast that maintains intrinsic membrane curvature in an optimal range. PMID:16339082

  18. Depletion of phosphatidylcholine in yeast induces shortening and increased saturation of the lipid acyl chains: evidence for regulation of intrinsic membrane curvature in a eukaryote.

    PubMed

    Boumann, Henry A; Gubbens, Jacob; Koorengevel, Martijn C; Oh, Chan-Seok; Martin, Charles E; Heck, Albert J R; Patton-Vogt, Jana; Henry, Susan A; de Kruijff, Ben; de Kroon, Anton I P M

    2006-02-01

    To study the consequences of depleting the major membrane phospholipid phosphatidylcholine (PC), exponentially growing cells of a yeast cho2opi3 double deletion mutant were transferred from medium containing choline to choline-free medium. Cell growth did not cease until the PC level had dropped below 2% of total phospholipids after four to five generations. Increasing contents of phosphatidylethanolamine (PE) and phosphatidylinositol made up for the loss of PC. During PC depletion, the remaining PC was subject to acyl chain remodeling with monounsaturated species replacing diunsaturated species, as shown by mass spectrometry. The remodeling of PC did not require turnover by the SPO14-encoded phospholipase D. The changes in the PC species profile were found to reflect an overall shift in the cellular acyl chain composition that exhibited a 40% increase in the ratio of C16 over C18 acyl chains, and a 10% increase in the degree of saturation. The shift was stronger in the phospholipid than in the neutral lipid fraction and strongest in the species profile of PE. The shortening and increased saturation of the PE acyl chains were shown to decrease the nonbilayer propensity of PE. The results point to a regulatory mechanism in yeast that maintains intrinsic membrane curvature in an optimal range. PMID:16339082

  19. Sirtuin 3 (SIRT3) protein regulates long-chain acyl-CoA dehydrogenase by deacetylating conserved lysines near the active site.

    PubMed

    Bharathi, Sivakama S; Zhang, Yuxun; Mohsen, Al-Walid; Uppala, Radha; Balasubramani, Manimalha; Schreiber, Emanuel; Uechi, Guy; Beck, Megan E; Rardin, Matthew J; Vockley, Jerry; Verdin, Eric; Gibson, Bradford W; Hirschey, Matthew D; Goetzman, Eric S

    2013-11-22

    Long-chain acyl-CoA dehydrogenase (LCAD) is a key mitochondrial fatty acid oxidation enzyme. We previously demonstrated increased LCAD lysine acetylation in SIRT3 knockout mice concomitant with reduced LCAD activity and reduced fatty acid oxidation. To study the effects of acetylation on LCAD and determine sirtuin 3 (SIRT3) target sites, we chemically acetylated recombinant LCAD. Acetylation impeded substrate binding and reduced catalytic efficiency. Deacetylation with recombinant SIRT3 partially restored activity. Residues Lys-318 and Lys-322 were identified as SIRT3-targeted lysines. Arginine substitutions at Lys-318 and Lys-322 prevented the acetylation-induced activity loss. Lys-318 and Lys-322 flank residues Arg-317 and Phe-320, which are conserved among all acyl-CoA dehydrogenases and coordinate the enzyme-bound FAD cofactor in the active site. We propose that acetylation at Lys-318/Lys-322 causes a conformational change which reduces hydride transfer from substrate to FAD. Medium-chain acyl-CoA dehydrogenase and acyl-CoA dehydrogenase 9, two related enzymes with lysines at positions equivalent to Lys-318/Lys-322, were also efficiently deacetylated by SIRT3 following chemical acetylation. These results suggest that acetylation/deacetylation at Lys-318/Lys-322 is a mode of regulating fatty acid oxidation. The same mechanism may regulate other acyl-CoA dehydrogenases. PMID:24121500

  20. Sirtuin 3 (SIRT3) Protein Regulates Long-chain Acyl-CoA Dehydrogenase by Deacetylating Conserved Lysines Near the Active Site

    PubMed Central

    Bharathi, Sivakama S.; Zhang, Yuxun; Mohsen, Al-Walid; Uppala, Radha; Balasubramani, Manimalha; Schreiber, Emanuel; Uechi, Guy; Beck, Megan E.; Rardin, Matthew J.; Vockley, Jerry; Verdin, Eric; Gibson, Bradford W.; Hirschey, Matthew D.; Goetzman, Eric S.

    2013-01-01

    Long-chain acyl-CoA dehydrogenase (LCAD) is a key mitochondrial fatty acid oxidation enzyme. We previously demonstrated increased LCAD lysine acetylation in SIRT3 knockout mice concomitant with reduced LCAD activity and reduced fatty acid oxidation. To study the effects of acetylation on LCAD and determine sirtuin 3 (SIRT3) target sites, we chemically acetylated recombinant LCAD. Acetylation impeded substrate binding and reduced catalytic efficiency. Deacetylation with recombinant SIRT3 partially restored activity. Residues Lys-318 and Lys-322 were identified as SIRT3-targeted lysines. Arginine substitutions at Lys-318 and Lys-322 prevented the acetylation-induced activity loss. Lys-318 and Lys-322 flank residues Arg-317 and Phe-320, which are conserved among all acyl-CoA dehydrogenases and coordinate the enzyme-bound FAD cofactor in the active site. We propose that acetylation at Lys-318/Lys-322 causes a conformational change which reduces hydride transfer from substrate to FAD. Medium-chain acyl-CoA dehydrogenase and acyl-CoA dehydrogenase 9, two related enzymes with lysines at positions equivalent to Lys-318/Lys-322, were also efficiently deacetylated by SIRT3 following chemical acetylation. These results suggest that acetylation/deacetylation at Lys-318/Lys-322 is a mode of regulating fatty acid oxidation. The same mechanism may regulate other acyl-CoA dehydrogenases. PMID:24121500

  1. A multisubstrate assay for lipases/esterases: assessing acyl chain length selectivity by reverse-phase high-performance liquid chromatography.

    PubMed

    Divakar, K; Gautam, Pennathur

    2014-03-01

    Lipases and esterases are hydrolytic enzymes and are known to hydrolyze esters with unique substrate specificity and acyl chain length selectivity. We have developed a simple competitive multiple substrate assay for determination of acyl chain length selectivity of lipases/esterases using RP-HPLC with UV detection. A method for separation and quantification of 4-nitrophenyl fatty acid esters (C4-C18) was developed and validated. The chain length selectivity of five lipases and two esterases was determined in a multisubstrate reaction system containing equimolar concentrations of 4-nitrophenyl esters (C4-C18). This assay is simple, reproducible, and a useful tool for determining chain length selectivity of lipases/esterases. PMID:24316114

  2. Strategies for Correcting Very Long Chain Acyl-CoA Dehydrogenase Deficiency*

    PubMed Central

    Tenopoulou, Margarita; Chen, Jie; Bastin, Jean; Bennett, Michael J.; Ischiropoulos, Harry; Doulias, Paschalis-Thomas

    2015-01-01

    Very long acyl-CoA dehydrogenase (VLCAD) deficiency is a genetic pediatric disorder presenting with a spectrum of phenotypes that remains for the most part untreatable. Here, we present a novel strategy for the correction of VLCAD deficiency by increasing mutant VLCAD enzymatic activity. Treatment of VLCAD-deficient fibroblasts, which express distinct mutant VLCAD protein and exhibit deficient fatty acid β-oxidation, with S-nitroso-N-acetylcysteine induced site-specific S-nitrosylation of VLCAD mutants at cysteine residue 237. Cysteine 237 S-nitrosylation was associated with an 8–17-fold increase in VLCAD-specific activity and concomitant correction of acylcarnitine profile and β-oxidation capacity, two hallmarks of the disorder. Overall, this study provides biochemical evidence for a potential therapeutic modality to correct β-oxidation deficiencies. PMID:25737446

  3. Genetics Home Reference: medium-chain acyl-CoA dehydrogenase deficiency

    MedlinePlus

    ... down (metabolize) a group of fats called medium-chain fatty acids. These fatty acids are found in foods and the body's fat tissues. Fatty acids are a major source of energy for the heart and muscles. During periods of fasting, ... of this enzyme, medium-chain fatty acids are not metabolized properly. As a ...

  4. Genetics Home Reference: very long-chain acyl-CoA dehydrogenase deficiency

    MedlinePlus

    ... metabolize) a group of fats called very long-chain fatty acids. These fatty acids are found in foods and the body's fat tissues. Fatty acids are a major source of energy for the heart and muscles. During periods of fasting, ... of this enzyme, very long-chain fatty acids are not metabolized properly. As a ...

  5. A Peroxisomal Long-Chain Acyl-CoA Synthetase from Glycine max Involved in Lipid Degradation

    PubMed Central

    Jiang, Bingjun; Sun, Xuegang; Gu, Shoulai; Han, Tianfu; Hou, Wensheng

    2014-01-01

    Seed storage oil, in the form of triacylglycerol (TAG), is degraded to provide carbon and energy during germination and early seedling growth by the fatty acid β-oxidation in the peroxisome. Although the pathways for lipid degradation have been uncovered, understanding of the exact involved enzymes in soybean is still limited. Long-chain acyl-CoA synthetase (ACSL) is a critical enzyme that activates free fatty acid released from TAG to form the fatty acyl-CoA. Recent studies have shown the importance of ACSL in lipid degradation and synthesis, but few studies were focused on soybean. In this work, we cloned a ACSL gene from soybean and designated it as GmACSL2. Sequence analysis revealed that GmACSL2 encodes a protein of 733 amino acid residues, which is highly homologous to the ones in other higher plants. Complementation test showed that GmACSL2 could restore the growth of an ACS-deficient yeast strain (YB525). Co-expression assay in Nicotiana benthamiana indicated that GmACSL2 is located at peroxisome. Expression pattern analysis showed that GmACSL2 is highly expressed in germinating seedling and strongly induced 1 day after imbibition, which indicate that GmACSL2 may take part in the seed germination. GmACSL2 overexpression in yeast and soybean hairy root severely reduces the contents of the lipids and fatty acids, compared with controls in both cells, and enhances the β-oxidation efficiency in yeast. All these results suggest that GmACSL2 may take part in fatty acid and lipid degradation. In conclusion, peroxisomal GmACSL2 from Glycine max probably be involved in the lipid degradation during seed germination. PMID:24992019

  6. The Effect of Temperature, Cations, and Number of Acyl Chains on the Lamellar to Non-Lamellar Transition in Lipid-A Membranes: A Microscopic View

    SciTech Connect

    Pontes, Frederico J.; Rusu, Victor H.; Soares, Thereza A.; Lins, Roberto D.

    2012-05-24

    Lipopolysaccharides (LPS) are the main constituent of the outer bacterial membrane of Gram-negative bacteria. Lipid-A is the structural region of LPS that interacts with the innate immune system and induces inflammatory responses. It is formed by a phosphorylated β-d-glucosaminyl-(1→6)-α-N-glucosamine disaccharide backbone containing ester-linked and amide-linked long-chain fatty acids, which may vary in length and number depending on the bacterial strains and the environment. Phenotypical variation (i.e., number of acyl chains), cation type, and temperature influence the phase transition, aggregate structure, and endotoxic activity of Lipid-A. We have applied an extension of the GROMOS force field 45a4 carbohydrate parameter set to investigate the behavior of hexa- and pentaacylated Lipid-A of Pseudomonas aeruginosa at two temperatures (300 and 328 K) and in the presence of mono- and divalent cations (represented by Ca2+ and Na+, respectively) through molecular dynamics simulations. The distinct phase of Lipid-A aggregates was characterized by structural properties, deuterium order parameters, the molecular shape of the lipid units (conical versus cylindrical), and molecular packing. Our results show that Na+ ions induce a transition from the lamellar to nonlamellar phase. In contrast, the bilayer integrity is maintained in the presence of Ca2+ ions. Through these findings, we present microscopic insights on the influence of different cations on the molecular behavior of Lipid-A associated with the lamellar to nonlamellar transition.

  7. The Effect of Temperature, Cations, and Number of Acyl Chains on the Lamellar to Non-Lamellar Transition in Lipid-A Membranes: A Microscopic View.

    PubMed

    Pontes, Frederico J S; Rusu, Victor H; Soares, Thereza A; Lins, Roberto D

    2012-10-01

    Lipopolysaccharides (LPS) are the main constituent of the outer bacterial membrane of Gram-negative bacteria. Lipid-A is the structural region of LPS that interacts with the innate immune system and induces inflammatory responses. It is formed by a phosphorylated β-d-glucosaminyl-(1→6)-α-N-glucosamine disaccharide backbone containing ester-linked and amide-linked long-chain fatty acids, which may vary in length and number depending on the bacterial strains and the environment. Phenotypical variation (i.e., number of acyl chains), cation type, and temperature influence the phase transition, aggregate structure, and endotoxic activity of Lipid-A. We have applied an extension of the GROMOS force field 45a4 carbohydrate parameter set to investigate the behavior of hexa- and pentaacylated Lipid-A of Pseudomonas aeruginosa at two temperatures (300 and 328 K) and in the presence of mono- and divalent cations (represented by Ca(2+) and Na(+), respectively) through molecular dynamics simulations. The distinct phase of Lipid-A aggregates was characterized by structural properties, deuterium order parameters, the molecular shape of the lipid units (conical versus cylindrical), and molecular packing. Our results show that Na(+) ions induce a transition from the lamellar to nonlamellar phase. In contrast, the bilayer integrity is maintained in the presence of Ca(2+) ions. Through these findings, we present microscopic insights on the influence of different cations on the molecular behavior of Lipid-A associated with the lamellar to nonlamellar transition. PMID:26593024

  8. Long-chain bases of sphingolipids are transported into cells via the acyl-CoA synthetases.

    PubMed

    Narita, Tomomi; Naganuma, Tatsuro; Sase, Yurie; Kihara, Akio

    2016-01-01

    Transport of dietary lipids into small-intestinal epithelial cells is pathologically and nutritionally important. However, lipid uptake remains an almost unexplored research area. Although we know that long-chain bases (LCBs), constituents of sphingolipids, can enter into cells efficiently, the molecular mechanism of LCB uptake is completely unclear. Here, we found that the yeast acyl-CoA synthetases (ACSs) Faa1 and Faa4 are redundantly involved in LCB uptake. In addition to fatty acid-activating activity, transporter activity toward long-chain fatty acids (LCFAs) has been suggested for ACSs. Both LCB and LCFA transports were largely impaired in faa1Δ faa4Δ cells. Furthermore, LCB and LCFA uptakes were mutually competitive. However, the energy dependency was different for their transports. Sodium azide/2-deoxy-D-glucose treatment inhibited import of LCFA but not that of LCB. Furthermore, the ATP-AMP motif mutation FAA1 S271A largely impaired the metabolic activity and LCFA uptake, while leaving LCB import unaffected. These results indicate that only LCFA transport requires ATP. Since ACSs do not metabolize LCBs as substrates, Faa1 and Faa4 are likely directly involved in LCB transport. Furthermore, we revealed that ACSs are also involved in LCB transport in mammalian cells. Thus, our findings provide strong support for the hypothesis that ACSs directly transport LCFAs. PMID:27136724

  9. Surface active molecules: preparation and properties of long chain n-acyl-l-alpha-amino-omega-guanidine alkyl acid derivatives.

    PubMed

    Infante, R; Dominguez, J G; Erra, P; Julia, R; Prats, M

    1984-12-01

    Synopsis A new route for the synthesis of long chain N(alpha)-acyl-l-alpha-amino-omega-guamdine alkyl acid derivatives, with cationic or amphoteric character has been established. The general formula of these compounds is shown below. A physico-chemical and antimicrobial study of these products as a function of the alkyl ester or sodium salt (R), the straight chain length of the fatty acid residue (x) and the number of carbons between the omega-guanidine and omega-carboxyl group (n) has been investigated. The water solubility, surface tension, critical micelle concentration (c.m.c.) and minimum inhibitory concentration (MIC) against Gram-positive and Gram-negative bacteria (including Pseudomonas) has been determined. Dicyclohexylcarbodiimide has been used to condense fatty acids and alpha-amino-omega-guanidine alkyl acids. In these conditions protection of the omega-guanidine group is not necessary. The main characteristic of this synthetic procedure is the use of very mild experimental conditions (temperature, pH) to form the amide linkage which leads to pure optical compounds in high yield in the absence of electrolytes. The results show that some structural modifications, particularly the protection of the carboxyl group, promote variations of the surfactant and antimicrobial properties. Only those molecules with the blocked carboxyl group (cationic molecules, where R = Me, Et or Pr) showed a good surfactant and antimicrobial activity. When the carboxyl group was unprotected (amphoteric molecules, where R = Na(+)) the resulting compounds were inactive. PMID:19467126

  10. The adjuvant activity of fatty acid esters. The role of acyl chain length and degree of saturation.

    PubMed Central

    Bomford, R

    1981-01-01

    Water-in-oil emulsions of metabolizable fatty acid esters, with the non-toxic surfactant Pluronic L122 as emulsifying agent, potentiated the humoral response to bovine serum albumin and staphylococcal toxoid in the mouse. Adjuvant activity was increased by changing the chemical nature of the esters as follows: (i) using a series of ethyl esters, adjuvant activity appeared when the acyl chain length of the fatty acid component was 16 or greater; (ii) isobutyl and isopropyl esters of palmitic acid (C16:0) were superior to ethyl; (iii) the ethyl esters of oleic (C18:1) and linoleic (C18:2) acids were better than stearic (C18:0). Since emulsions prepared with longer chain saturated esters are very viscous or solid at room temperature, and unsaturated esters are chemically reactive, emulsions were prepared with differing proportions of ethyl caprate (C10:0) and butyl stearate. At a ratio of 9:1 the emulsions possessed the low viscosity of ethyl caprate, but gained the adjuvant activity of butyl stearate. 125I-labelled BSA was retained in the footpad to a significantly greater extent than with a caprate emulsion, but reasons are given for believing that slow release of antigen is not the only mechanism of adjuvant activity. The ester emulsions caused more acute but less chronic local inflammation (footpad swelling) than Freund's incomplete adjuvant. PMID:7275184

  11. Long-chain bases of sphingolipids are transported into cells via the acyl-CoA synthetases

    PubMed Central

    Narita, Tomomi; Naganuma, Tatsuro; Sase, Yurie; Kihara, Akio

    2016-01-01

    Transport of dietary lipids into small-intestinal epithelial cells is pathologically and nutritionally important. However, lipid uptake remains an almost unexplored research area. Although we know that long-chain bases (LCBs), constituents of sphingolipids, can enter into cells efficiently, the molecular mechanism of LCB uptake is completely unclear. Here, we found that the yeast acyl-CoA synthetases (ACSs) Faa1 and Faa4 are redundantly involved in LCB uptake. In addition to fatty acid-activating activity, transporter activity toward long-chain fatty acids (LCFAs) has been suggested for ACSs. Both LCB and LCFA transports were largely impaired in faa1Δ faa4Δ cells. Furthermore, LCB and LCFA uptakes were mutually competitive. However, the energy dependency was different for their transports. Sodium azide/2-deoxy-D-glucose treatment inhibited import of LCFA but not that of LCB. Furthermore, the ATP-AMP motif mutation FAA1 S271A largely impaired the metabolic activity and LCFA uptake, while leaving LCB import unaffected. These results indicate that only LCFA transport requires ATP. Since ACSs do not metabolize LCBs as substrates, Faa1 and Faa4 are likely directly involved in LCB transport. Furthermore, we revealed that ACSs are also involved in LCB transport in mammalian cells. Thus, our findings provide strong support for the hypothesis that ACSs directly transport LCFAs. PMID:27136724

  12. Biochemical Correction of Very Long–chain Acyl-CoA Dehydrogenase Deficiency Following Adeno-associated Virus Gene Therapy

    PubMed Central

    Merritt, J. Lawrence; Nguyen, Tien; Daniels, Jan; Matern, Dietrich; Schowalter, David B.

    2009-01-01

    We report the development of a gene replacement strategy for very long–chain acyl-CoA dehydrogenase (VLCAD) deficiency. VLCAD is a mitochondrial enzyme involved in fatty acid β-oxidation, a key step in energy production during times of fasting or stress. Deficiency of VLCAD classically presents as hepatic dysfunction, hypoglycemia, cardiomyopathy, rhabdomyolysis, and/or sudden death. While dietary therapy for VLCAD deficiency has proven beneficial in preventing some symptoms, a risk of metabolic catastrophic decompensation remains throughout life during times of increased energy demand. We designed a recombinant adeno-associated virus (AAV) expressing the human VLCAD gene (AAV8-hVLCAD). To demonstrate its in vivo activity, AAV8-hVLCAD was administered via the tail vein to VLCAD-knockout mice. A reduction in accumulated serum long-chain acylcarnitines and increased fasting tolerance judged on blood glucose concentrations were observed as of 11 days postinjections through >100 days. Western analysis of liver, skeletal muscle, and heart extracts using PEP1 anti-hVLCAD antibody revealed short-term hVLCAD expression in the liver and muscle and longer-term expression in heart. This demonstrates the ability of human VLCAD to correct the biochemical phenotype of VLCAD-deficient mice. PMID:19156135

  13. Long-Chain Acyl CoA Synthetase 4A regulates Smad activity and dorsoventral patterning in the zebrafish embryo

    PubMed Central

    Miyares, Rosa Linda; Stein, Cornelia; Renisch, Björn; Anderson, Jennifer Lynn; Hammerschmidt, Matthias; Farber, Steven Arthur

    2013-01-01

    Summary Long-chain polyunsaturated fatty acids (LC-PUFA) and their metabolites are critical players in cell biology and embryonic development. Here we show that long-chain acyl CoA synthetase 4a (Acsl4a), an LC-PUFA activating enzyme, is essential for proper patterning of the zebrafish dorsoventral axis. Loss of Acsl4a results in dorsalized embryos due to attenuated Bmp signaling. We demonstrate that Acsl4a modulates the activity of Smad transcription factors, the downstream mediators of Bmp signaling. Acsl4a promotes the inhibition of p38 MAPK and the Akt-mediated inhibition of glycogen synthase kinase 3 (GSK3), critical inhibitors of Smad activity. Consequently, introduction of a constitutively active Akt can rescue the dorsalized phenotype of Acsl4a deficient embryos. Our results reveal a critical role for Acsl4a in modulating Bmp-Smad activity and provide a potential avenue for LC-PUFAs to influence a variety of developmental processes. PMID:24332754

  14. Deciphering the role of individual acyl chains in the interaction network between phosphatidylserines and a single-spanning membrane protein.

    PubMed

    Mousson, Florence; Coïc, Yves-Marie; Baleux, Françoise; Beswick, Veronica; Sanson, Alain; Neumann, Jean-Michel

    2002-11-19

    PMP1 is a small single-spanning membrane protein functioning as a regulatory subunit of the yeast plasma membrane H(+)-ATPase. This protein forms a unique helix and exhibits a positively charged cytoplasmic domain that is able to specifically segregate phosphatidylserines (PSs). A marked groove formed at the helix surface is thought to play a major role in the related lipid-protein interaction network. Mutational analysis and (1)H NMR experiments were therefore performed on a synthetic PMP1 fragment using DPC-d(38) micelles as a membrane-like environment, in the presence of small amounts of POPS. A mutation designed for altering the helix groove was shown to disfavor the POPS binding specificity as much as that affecting the electrostatic interaction network. From POPS titration experiments monitored by a full set of one- and two-dimensional NOESY spectra, the association between the phospholipids and the PMP1 peptide has been followed. Our data reveal that the clustering of POPS molecules is promoted from a stabilized framework obtained by coupling the PMP1 helix groove to a POPS sn-2 chain. To our knowledge, the NOE-based titration plots displayed in this report constitute the first NMR data that directly distinguish the role of the sn-1 and sn-2 acyl chains in a lipid-protein interaction. The results are discussed while taking into account our accurate knowledge of the yeast plasma membrane composition and its ability to form functional lipid rafts. PMID:12427022

  15. Intestinal acyl-CoA synthetase 5: activation of long chain fatty acids and behind.

    PubMed

    Klaus, Christina; Jeon, Min Kyung; Kaemmerer, Elke; Gassler, Nikolaus

    2013-11-14

    The intestinal mucosa is characterized by a high complexity in terms of structure and functions and allows for a controlled demarcation towards the gut lumen. On the one hand it is responsible for pulping and selective absorption of alimentary substances ensuring the immunological tolerance, on the other hand it prevents the penetration of micro-organisms as well as bacterial outgrowth. The continuous regeneration of surface epithelia along the crypt-villus-axis in the small intestine is crucial to assuring these various functions. The core phenomena of intestinal epithelia regeneration comprise cell proliferation, migration, differentiation, and apoptosis. These partly contrarily oriented processes are molecularly balanced through numerous interacting signaling pathways like Wnt/β-catenin, Notch and Hedgehog, and regulated by various modifying factors. One of these modifiers is acyl-CoA synthetase 5 (ACSL5). It plays a key role in de novo lipid synthesis, fatty acid degradation and membrane modifications, and regulates several intestinal processes, primarily through different variants of protein lipidation, e.g., palmitoylation. ACSL5 was shown to interact with proapoptotic molecules, and besides seems to inhibit proliferation along the crypt-villus-axis. Because of its proapoptotic and antiproliferative characteristics it could be of significant relevance for intestinal homeostasis, cellular disorder and tumor development. PMID:24259967

  16. Influence of the degree of unsaturation of the acyl side chain upon the interaction of analogues of 1-arachidonoylglycerol with monoacylglycerol lipase and fatty acid amide hydrolase

    SciTech Connect

    Vandevoorde, Severine; Saha, Bijali; Mahadevan, Anu; Razdan, Raj K.; Pertwee, Roger G.; Martin, Billy R.; Fowler, Christopher J. . E-mail: cf@pharm.umu.se

    2005-11-11

    Little is known as to the structural requirements of the acyl side chain for interaction of acylglycerols with monoacylglycerol lipase (MAGL), the enzyme chiefly responsible for the metabolism of the endocannabinoid 2-arachidonoylglycerol (2-AG) in the brain. In the present study, a series of twelve analogues of 1-AG (the more stable regioisomer of 2-AG) were investigated with respect to their ability to inhibit the metabolism of 2-oleoylglycerol by cytosolic and membrane-bound MAGL. In addition, the ability of the compounds to inhibit the hydrolysis of anandamide by fatty acid amide hydrolase (FAAH) was investigated. For cytosolic MAGL, compounds with 20 carbon atoms in the acyl chain and 2-5 unsaturated bonds inhibited the hydrolysis of 2-oleoylglycerol with similar potencies (IC{sub 50} values in the range 5.1-8.2 {mu}M), whereas the two compounds with a single unsaturated bond were less potent (IC{sub 50} values 19 and 21 {mu}M). The fully saturated analogue 1-monoarachidin did not inhibit the enzyme, whereas the lower side chain analogues 1-monopalmitin and 1-monomyristin inhibited the enzyme with IC{sub 50} values of 12 and 32 {mu}M, respectively. The 22-carbon chain analogue of 1-AG was also potent (IC{sub 50} value 4.5 {mu}M). Introduction of an {alpha}-methyl group for the C20:4, C20:3, and C22:4 compounds did not affect potency in a consistent manner. For the FAAH and the membrane-bound MAGL, there was no obvious relationship between the degree of unsaturation of the acyl side chain and the ability to inhibit the enzymes. It is concluded that increasing the number of unsaturated bonds on the acyl side chain of 1-AG from 1 to 5 has little effect on the affinity of acylglycerols for cytosolic MAGL.

  17. Fatty acid transport by vectorial acylation in mammals: roles played by different isoforms of rat long-chain acyl-CoA synthetases.

    PubMed

    Tong, Fumin; Black, Paul N; Coleman, Rosalind A; DiRusso, Concetta C

    2006-03-01

    Mammals express multiple isoforms of acyl-CoA synthetase (ACSL1 and ACSL3-6) in various tissues. These enzymes are essential for fatty acid metabolism providing activated intermediates for complex lipid synthesis, protein modification, and beta-oxidation. Yeast in contrast express four major ACSLs, which have well-defined functions. Two, Faa1p and Faa4p, are specifically required for fatty acid transport by vectorial acylation. Four ACSLs from the rat were expressed in a yeast faa1delta faa4delta strain and their roles in fatty acid transport and trafficking characterized. All four restored ACS activity yet varied in substrate preference. ACSL1, 4, and 6 were able to rescue fatty acid transport activity and triglyceride synthesis. ACSL5, however, was unable to facilitate fatty acid transport despite conferring robust oleoyl-CoA synthetase activity. This is the first study evaluating the role of the mammalian ACSLs in fatty acid transport and supports a role for ACSL1, 4, and 6 in transport by vectorial acylation. PMID:16466685

  18. Development and pathomechanisms of cardiomyopathy in very long-chain acyl-CoA dehydrogenase deficient (VLCAD(-/-)) mice.

    PubMed

    Tucci, Sara; Flögel, Ulrich; Hermann, Sven; Sturm, Marga; Schäfers, Michael; Spiekerkoetter, Ute

    2014-05-01

    Hypertrophic cardiomyopathy is a typical manifestation of very long-chain acyl-CoA dehydrogenase deficiency (VLCADD), the most common long-chain β-oxidation defects in humans; however in some patients cardiac function is fully compensated. Cardiomyopathy may also be reversed by supplementation of medium-chain triglycerides (MCT). We here characterize cardiac function of VLCAD-deficient (VLCAD(-/-)) mice over one year. Furthermore, we investigate the long-term effect of a continuous MCT diet on the cardiac phenotype. We assessed cardiac morphology and function in VLCAD(-/-) mice by in vivo MRI. Cardiac energetics were measured by (31)P-MRS and myocardial glucose uptake was quantified by positron-emission-tomography (PET). Metabolic adaptations were identified by the expression of genes regulating glucose and lipid metabolism using real-time-PCR. VLCAD(-/-) mice showed a progressive decrease in heart function over 12 months accompanied by a reduced phosphocreatine-to-ATP-ratio indicative of chronic energy deficiency. Long-term MCT supplementation aggravated the cardiac phenotype into dilated cardiomyopathy with features similar to diabetic heart disease. Cardiac energy production and function in mice with a β-oxidation defect cannot be maintained with age. Compensatory mechanisms are insufficient to preserve the cardiac energy state over time. However, energy deficiency by impaired β-oxidation and long-term MCT induce cardiomyopathy by different mechanisms. Cardiac MRI and MRS may be excellent tools to assess minor changes in cardiac function and energetics in patients with β-oxidation defects for preventive therapy. PMID:24530811

  19. Very Long-Chain Acyl-CoA Synthetase 3: Overexpression and Growth Dependence in Lung Cancer

    PubMed Central

    Pei, Zhengtong; Fraisl, Peter; Shi, Xiaohai; Gabrielson, Edward; Forss-Petter, Sonja; Berger, Johannes; Watkins, Paul A.

    2013-01-01

    Lung cancer is the leading cause of cancer deaths worldwide. In the United States, only one in six lung cancer patients survives five years after diagnosis. These statistics may improve if new therapeutic targets are identified. We previously reported that an enzyme of fatty acid metabolism, very long-chain acyl-CoA synthetase 3 (ACSVL3), is overexpressed in malignant glioma, and that depleting glioblastoma cells of ACSVL3 diminishes their malignant properties. To determine whether ACSVL3 expression was also increased in lung cancer, we studied tumor histologic sections and lung cancer cell lines. Immunohistochemical analysis of normal human lung showed moderate ACSVL3 expression only in bronchial epithelial cells. In contrast, all of 69 different lung tumors tested, including adeno-, squamous cell, large cell, and small cell carcinomas, had robustly elevated ACSVL3 levels. Western blot analysis of lung cancer cell lines derived from these tumor types also had significantly increased ACSVL3 protein compared to normal bronchial epithelial cells. Decreasing the growth rate of lung cancer cell lines did not change ACSVL3 expression. However, knocking down ACSVL3 expression by RNA interference reduced cell growth rates in culture by 65–76%, and the ability of tumor cells to form colonies in soft agar suspension by 65–80%. We also conducted studies to gain a better understanding of the biochemical properties of human ACSVL3. ACSVL3 mRNA was detected in many human tissues, but the expression pattern differed somewhat from that of the mouse. The enzyme activated long- and very long-chain saturated fatty acid substrates, as well as long-chain mono- and polyunsaturated fatty acids to their respective coenzyme A derivatives. Endogenous human ACSVL3 protein was found in a punctate subcellular compartment that partially colocalized with mitochondria as determined by immunofluorescence microscopy and subcellular fractionation. From these studies, we conclude that ACSVL3 is

  20. Bilirubin conjugates of human bile. The excretion of bilirubin as the acyl glycosides of aldobiouronic acid, pseudoaldobiouronic acid and hexuronosylhexuronic acid, with a branched-chain hexuronic acid as one of the components of hexuronosylhexuronide

    PubMed Central

    Kuenzle, Clive C.

    1970-01-01

    Structure elucidations have been performed on the bilirubin conjugates isolated from human hepatic bile as the phenylazo derivatives. The major bilirubin conjugates are excreted, not as was formerly thought in the form of glucuronides, but as the acyl glycosides of aldobiouronic acid, pseudoaldobiouronic acid and hexuronosylhexuronic acid. The isolated aldobiouronides are proposed to have the structures of an acyl 6-O-hexopyranosyluronic acid-hexopyranoside, an acyl 4-O-hexofuranosyluronic acid-d-glucopyranoside, and an acyl 4-O-β-d-glucofuranosyluronic acid-d-glucopyranoside respectively, with the acyl radicals being those of the phenylazo derivative of bilirubin. The pseudoaldobiouronide is suggested to be the acyl 4-O-α-d-glucofuranosyl-β-d -glucopyranosiduronic acid, with the acyl radical being that of the phenylazo derivative of vinylneoxanthobilirubinic acid. The hexuronosylhexuronide presumably is the acyl 4-O-(3-C-hydroxymethylribofuranosyluronic acid)-β-d-glucopyranosiduronic acid, with the acyl radical being that of the phenylazo derivative of bilirubin. The 3-C-hydroxymethylriburonic acid, isolated as one of the components of the hexuronosylhexuronide, is the first natural branched-chain hexuronic acid to be detected, and the first branched-chain sugar ever detected in humans. PMID:5500303

  1. Altered Energetics of Exercise Explain Risk of Rhabdomyolysis in Very Long-Chain Acyl-CoA Dehydrogenase Deficiency.

    PubMed

    Diekman, E F; Visser, G; Schmitz, J P J; Nievelstein, R A J; de Sain-van der Velden, M; Wardrop, M; Van der Pol, W L; Houten, S M; van Riel, N A W; Takken, T; Jeneson, J A L

    2016-01-01

    Rhabdomyolysis is common in very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) and other metabolic myopathies, but its pathogenic basis is poorly understood. Here, we show that prolonged bicycling exercise against a standardized moderate workload in VLCADD patients is associated with threefold bigger changes in phosphocreatine (PCr) and inorganic phosphate (Pi) concentrations in quadriceps muscle and twofold lower changes in plasma acetyl-carnitine levels than in healthy subjects. This result is consistent with the hypothesis that muscle ATP homeostasis during exercise is compromised in VLCADD. However, the measured rates of PCr and Pi recovery post-exercise showed that the mitochondrial capacity for ATP synthesis in VLCADD muscle was normal. Mathematical modeling of oxidative ATP metabolism in muscle composed of three different fiber types indicated that the observed altered energy balance during submaximal exercise in VLCADD patients may be explained by a slow-to-fast shift in quadriceps fiber-type composition corresponding to 30% of the slow-twitch fiber-type pool in healthy quadriceps muscle. This study demonstrates for the first time that quadriceps energy balance during exercise in VLCADD patients is altered but not because of failing mitochondrial function. Our findings provide new clues to understanding the risk of rhabdomyolysis following exercise in human VLCADD. PMID:26881790

  2. Tumor-suppressive functions of long-chain acyl-CoA synthetase 4 in gastric cancer.

    PubMed

    Ye, Xiaojuan; Zhang, Yi; Wang, Xiao; Li, Yandong; Gao, Yong

    2016-04-01

    Long chain acyl CoA synthetase 4 (ACSL4) is a key enzyme in fatty acid metabolism with marked preference for arachidonic acid (AA). Recent reports have implicated its crucial roles in tumorigenesis. However in gastric cancer (GC), the expression and function of ACSL4 remain unclear. In the present study, we identified ACSL4 as a potential tumor suppressor in GC. The ACSL4 expression in GC samples was evaluated by real-time PCR and immunohistochemistry. The results indicated that the mRNA and protein levels of ACSL4 were frequently downregulated in cancer tissues compared with the adjacent non-cancerous mucosa control tissues. Cell-based functional assays exhibited that ectopic expression of ACSL4 inhibits cell growth, colony formation and cell migration, whereas ACSL4 knockdown enhanced these effects. In a nude mice model, ACSL4 knockdown also promoted subcutaneous xenografts' growth in vivo. Moreover, western blot analysis revealed that ACSL4 expression had a significant effect on FAK and P21 protein level. These findings suggest that ACSL4 plays a tumor-suppressive role and could be a potential therapeutic target in GC. PMID:26949059

  3. Altered Energetics of Exercise Explain Risk of Rhabdomyolysis in Very Long-Chain Acyl-CoA Dehydrogenase Deficiency

    PubMed Central

    Diekman, E. F.; Visser, G.; Schmitz, J. P. J.; Nievelstein, R. A. J.; de Sain-van der Velden, M.; Wardrop, M.; Van der Pol, W. L.; Houten, S. M.; van Riel, N. A. W.; Takken, T.; Jeneson, J. A. L.

    2016-01-01

    Rhabdomyolysis is common in very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) and other metabolic myopathies, but its pathogenic basis is poorly understood. Here, we show that prolonged bicycling exercise against a standardized moderate workload in VLCADD patients is associated with threefold bigger changes in phosphocreatine (PCr) and inorganic phosphate (Pi) concentrations in quadriceps muscle and twofold lower changes in plasma acetyl-carnitine levels than in healthy subjects. This result is consistent with the hypothesis that muscle ATP homeostasis during exercise is compromised in VLCADD. However, the measured rates of PCr and Pi recovery post-exercise showed that the mitochondrial capacity for ATP synthesis in VLCADD muscle was normal. Mathematical modeling of oxidative ATP metabolism in muscle composed of three different fiber types indicated that the observed altered energy balance during submaximal exercise in VLCADD patients may be explained by a slow-to-fast shift in quadriceps fiber-type composition corresponding to 30% of the slow-twitch fiber-type pool in healthy quadriceps muscle. This study demonstrates for the first time that quadriceps energy balance during exercise in VLCADD patients is altered but not because of failing mitochondrial function. Our findings provide new clues to understanding the risk of rhabdomyolysis following exercise in human VLCADD. PMID:26881790

  4. Separation of isomeric short-chain acyl-CoAs in plant matrices using ultra-performance liquid chromatography coupled with tandem mass spectrometry.

    PubMed

    Purves, Randy W; Ambrose, Stephen J; Clark, Shawn M; Stout, Jake M; Page, Jonathan E

    2015-02-01

    Acyl coenzyme A (acyl-CoA) thioesters are important intermediates in cellular metabolism and being able to distinguish among them is critical to fully understanding metabolic pathways in plants. Although significant advances have been made in the identification and quantification of acyl-CoAs using liquid chromatography tandem mass spectrometry (LC-MS/MS), separation of isomeric species such as isobutyryl- and n-butyrl-CoA has remained elusive. Here we report an ultra-performance liquid chromatography (UPLC)-MS/MS method for quantifying short-chain acyl-CoAs including isomeric species n-butyryl-CoA and isobutyryl-CoA as well as n-valeryl-CoA and isovaleryl-CoA. The method was applied to the analysis of extracts of hop (Humulus lupulus) and provided strong evidence for the existence of an additional structural isomer of valeryl-CoA, 2-methylbutyryl-CoA, as well as an unexpected isomer of hexanoyl-CoA. The results showed differences in the acyl-CoA composition among varieties of Humulus lupulus, both in glandular trichomes and cone tissues. When compared with the analysis of hemp (Cannabis sativa) extracts, the contribution of isobutyryl-CoAs in hop was greater as would be expected based on the downstream polyketide products. Surprisingly, branched chain valeryl-CoAs (isovaleryl-CoA and 2-methylbutyryl-CoA) were the dominant form of valeryl-CoAs in both hop and hemp. The capability to separate these isomeric forms will help to understand biochemical pathways leading to specialized metabolites in plants. PMID:25553535

  5. Sexual dimorphism of lipid metabolism in very long-chain acyl-CoA dehydrogenase deficient (VLCAD-/-) mice in response to medium-chain triglycerides (MCT).

    PubMed

    Tucci, Sara; Flögel, Ulrich; Spiekerkoetter, Ute

    2015-07-01

    Medium-chain triglycerides (MCT) are widely applied in the treatment of long-chain fatty acid oxidation disorders. Previously it was shown that long-term MCT supplementation strongly affects lipid metabolism in mice. We here investigate sex-specific effects in mice with very-long-chain-acyl-CoA dehydrogenase (VLCAD) deficiency in response to a long-term MCT modified diet. We quantified blood lipids, acylcarnitines, glucose, insulin and free fatty acids, as well as tissue triglycerides in the liver and skeletal muscle under a control and an MCT diet over 1 year. In addition, visceral and hepatic fat content and muscular intramyocellular lipids (IMCL) were assessed by in vivo(1)H magnetic resonance spectroscopy (MRS) techniques. The long-term application of an MCT diet induced a marked alteration of glucose homeostasis. However, only VLCAD-/- female mice developed a severe metabolic syndrome characterized by marked insulin resistance, dyslipidemia, severe hepatic and visceral steatosis, whereas VLCAD-/- males seemed to be protected and only presented with milder insulin resistance. Moreover, the highly saturated MCT diet is associated with a decreased hepatic stearoyl-CoA desaturase 1 (SCD1) activity in females aggravating the harmful effects of a saturated MCT diet. Long-term MCT supplementation deeply affects lipid metabolism in a sexual dimorphic manner resulting in a severe metabolic syndrome only in female mice. These findings are striking since the first signs of insulin resistance already occur in female VLCAD-/- mice during their reproductive period. How these metabolic adaptations are finally regulated needs to be determined. More important, the relevance of these findings for humans under these dietary modifications needs to be investigated. PMID:25887160

  6. Measurement of stable isotopic enrichment and concentration of long-chain fatty acyl-carnitines in tissue by HPLC-MS.

    PubMed

    Sun, Dayong; Cree, Melanie G; Zhang, Xiao-Jun; Bøersheim, Elisabet; Wolfe, Robert R

    2006-02-01

    We have developed a new method for the simultaneous measurements of stable isotopic tracer enrichments and concentrations of individual long-chain fatty acyl-carnitines in muscle tissue using ion-pairing high-performance liquid chromatography-electrospray ionization quadrupole mass spectrometry in the selected ion monitoring (SIM) mode. Long-chain fatty acyl-carnitines were extracted from frozen muscle tissue samples by acetonitrile/methanol. Baseline separation was achieved by reverse-phase HPLC in the presence of the volatile ion-pairing reagent heptafluorobutyric acid. The SIM capability of a single quadrupole mass analyzer allows further separation of the ions of interest from the sample matrixes, providing very clean total and selected ion chromatograms that can be used to calculate the stable isotopic tracer enrichment and concentration of long-chain fatty acyl-carnitines in a single analysis. The combination of these two separation techniques greatly simplifies the sample preparation procedure and increases the detection sensitivity. Applying this protocol to biological muscle samples proves it to be a very sensitive, accurate, and precise analytical tool. PMID:16301738

  7. Gating of the mitochondrial permeability transition pore by long chain fatty acyl analogs in vivo.

    PubMed

    Samovski, Dmitri; Kalderon, Bella; Yehuda-Shnaidman, Einav; Bar-Tana, Jacob

    2010-03-01

    The role played by long chain fatty acids (LCFA) in promoting energy expenditure is confounded by their dual function as substrates for oxidation and as putative classic uncouplers of mitochondrial oxidative phosphorylation. LCFA analogs of the MEDICA (MEthyl-substituted DICarboxylic Acids) series are neither esterified into lipids nor beta-oxidized and may thus simulate the uncoupling activity of natural LCFA in vivo, independently of their substrate role. Treatment of rats or cell lines with MEDICA analogs results in low conductance gating of the mitochondrial permeability transition pore (PTP), with 10-40% decrease in the inner mitochondrial membrane potential. PTP gating by MEDICA analogs is accounted for by inhibition of Raf1 expression and kinase activity, resulting in suppression of the MAPK/RSK1 and the adenylate cyclase/PKA transduction pathways. Suppression of RSK1 and PKA results in a decrease in phosphorylation of their respective downstream targets, Bad(Ser-112) and Bad(Ser-155). Decrease in Bad(Ser-112, Ser-155) phosphorylation results in increased binding of Bad to mitochondrial Bcl2 with concomitant displacement of Bax, followed by PTP gating induced by free mitochondrial Bax. Low conductance PTP gating by LCFA/MEDICA may account for their thyromimetic calorigenic activity in vivo. PMID:20037159

  8. Diacylglycerol-containing docosahexaenoic acid in acyl chain modulates airway smooth muscle tone.

    PubMed

    Hichami, Aziz; Morin, Caroline; Rousseau, Eric; Khan, Naim A

    2005-10-01

    We synthesized and assessed the role of a diacylglycerol (DAG)-containing docosahexaenoic acid (DHA), that is, 1-stearoyl-2-docosahexaenoyl-sn-glycerol (SDHG), in the contraction of guinea pig airway smooth muscle (ASM). We compared its action with 1-stearoyl-2-arachidonoyl-sn-glycerol (SAG) and 1,2-dioctanoyl-sn-glycerol (1,2-DiC8), a stable DAG analog. The three DAGs (SAG, SDHG, and 1,2-DiC8) induced reversible concentration-dependent contraction of ASM. SDHG induced higher guinea pig ASM contraction than did SAG and 1,2-DiC8. The effects of SDHG were blocked, to different extents, by nifedipine (L-type Ca2+ channel blocker). By employing GF-109203X (protein kinase C [PKC] inhibitor) and lanthanum (La3+), a nonselective cation channel blocker, we observed that SDHG evoked ASM contractile response via PKC-dependent and PKC-independent (but Ca2+-dependent) pathways. Interestingly, SAG exerted its action only by increasing [Ca2+]i and did not require PKC activation. To probe the implication of calcium mobilization, we employed thapsigargin (TG), which also induced ASM contraction in a calcium-dependent manner. SDHG and 1,2-DiC8, in a PKC-dependent manner, induced the phosphorylation of CPI-17 (myosin light chain phosphatase inhibitor of 17 kD). Furthermore, SAG and TG failed to phosphorylate CPI-17 in ASM cells. Our results suggest that different DAG species, produced during a dietary supplementation with fatty acids, could modulate the reactivity of airway smooth muscles in a PKC-dependent and -independent manner, and hence, may play a critical role in health and disease. PMID:15961724

  9. Long-chain polyunsaturated fatty acid biosynthesis in the euryhaline herbivorous teleost Scatophagus argus: Functional characterization, tissue expression and nutritional regulation of two fatty acyl elongases.

    PubMed

    Xie, Dizhi; Chen, Fang; Lin, Siyuan; You, Cuihong; Wang, Shuqi; Zhang, Qinghao; Monroig, Óscar; Tocher, Douglas R; Li, Yuanyou

    2016-08-01

    Both the spotted scat Scatophagus argus and rabbitfish Siganus canaliculatus belong to the few cultured herbivorous marine teleost, however, their fatty acyl desaturase (Fad) system involved in long-chain polyunsaturated fatty acid (LC-PUFA) biosynthesis is different. The S. argus has a △6 Fad, while the rabbitfish has △4 and △6/△5 Fads, which were the first report in vertebrate and marine teleost, respectively. In order to compare the characteristics of elongases of very long-chain fatty acids (Elovl) between them, two Elovl cDNAs were cloned from S. argus in the present study. One has 885bp of open read fragment (ORF) encoding a protein with 294 amino acid (aa) showing Elovl5 activity functionally characterized by heterologous expression in yeast, which was primarily active for the elongation of C18 and C20 PUFAs. The other has 915bp of ORF coding for a 305 aa protein showing Elovl4 activity, which was more efficient in the elongation of C20 and C22 PUFAs. Tissue distribution analyses by RT-PCR showed that elovl5 was highly expressed in the liver compared to other tissues determined, whereas elovl4 transcripts were only detected in the eye. The expression of elovl5 and elovl4 were significantly affected by dietary fatty acid composition, with highest expression of mRNA in the liver and eye of fish fed a diet with an 18:3n-3/18:2n-6 ratio of 1.7:1. These results indicated that the S. argus has a similar Elovl system in the LC-PUFA biosynthetic pathway to that of rabbitfish although their Fad system was different, suggesting that the diversification of fish LC-PUFA biosynthesis specificities is more associated with its Fad system. These new insights expand our knowledge and understanding of the molecular basis and regulation of LC-PUFA biosynthesis in fish. PMID:27050407

  10. Effects of hypo- and hyperthyroidism on rat liver microsomal long-chain fatty acyl-CoA synthetase and hydrolase

    SciTech Connect

    Dang, A.Q.; Faas, F.H.; Carter, W.J.

    1986-05-01

    The effects of hyperthyroidism (hyperT/sub 3/), (tri-iodothryonine (T/sub 3/) injected rats), and hypothyroidism (hypoT/sub 3/) (thyroidectomized rats) on the activation of fatty acids by a microsomal long-chain fatty acyl-CoA (LCA-CoA) synthetase and the degradation of LCA-CoA by a microsomal LCA-CoA hydrolase was determined. MAS was assayed by measuring the (1-/sup 14/C)-palmitate or -1-/sup 14/C) oleate incorporated into its water soluble CoA ester. MAH was assayed spectrophotomerically by following the reduction of 5',5'-dithiobis-(2-nitrobenzoic acid) by the CoA released from palmitoyl-CoA or oleoyl-CoA. Enzyme activities are given as mean (nmoles/mg/min) +/- SEM. MAS activities were decreased 36-44% (p < 0.01) in both hypoT/sub 3/ and hyperT/sub 3/ (controls = 101 +/- 4 (n = 11, (1-/sup 14/C)-palmitate) of 72 +/- 2 (n = 5,(1-/sup 14/C)oleate)). These decreases may contribute to the decreased triacelyglycerol (TG) and phospholipid contents in the hyperT/sub 3/ liver and the decreased clearance rate of plasma TG in the hypoT/sub 3/. MAH was decreased 27-42% (p<0.01) only in hypoT/sub 3/ (controls = 77 +/- 3 (n = 11, palmitoyl-CoA) or 45 +/- 1 (n = 5, oleoyl-CoA)). This decrease was corrected by T/sub 3/ treatment. Since the decreased MAH would increase the availability of LCA-CoA, it may contribute to the increased TG synthesis in hypoT/sub 3/.

  11. Diet-Sensitive Sources of Reactive Oxygen Species in Liver Mitochondria: Role of Very Long Chain Acyl-CoA Dehydrogenases

    PubMed Central

    Cardoso, Ariel R.; Kakimoto, Pâmela A. H. B.; Kowaltowski, Alicia J.

    2013-01-01

    High fat diets and accompanying hepatic steatosis are highly prevalent conditions. Previous work has shown that steatosis is accompanied by enhanced generation of reactive oxygen species (ROS), which may mediate further liver damage. Here we investigated mechanisms leading to enhanced ROS generation following high fat diets (HFD). We found that mitochondria from HFD livers present no differences in maximal respiratory rates and coupling, but generate more ROS specifically when fatty acids are used as substrates. Indeed, many acyl-CoA dehydrogenase isoforms were found to be more highly expressed in HFD livers, although only the very long chain acyl-CoA dehydrogenase (VLCAD) was more functionally active. Studies conducted with permeabilized mitochondria and different chain length acyl-CoA derivatives suggest that VLCAD is also a source of ROS production in mitochondria of HFD animals. This production is stimulated by the lack of NAD+. Overall, our studies uncover VLCAD as a novel, diet-sensitive, source of mitochondrial ROS. PMID:24116206

  12. Structure-activity relationship studies on acremomannolipin A, the potent calcium signal modulator with a novel glycolipid structure 4: Role of acyl side chains on d-mannose.

    PubMed

    Tsutsui, Nozomi; Tanabe, Genzoh; Ikeda, Nami; Okamura, Saika; Ogawa, Marika; Miyazaki, Kuniko; Kita, Ayako; Sugiura, Reiko; Muraoka, Osamu

    2016-10-01

    As part of an ongoing study on the structure-activity relationship of acremomannolipin A (1)-the novel glycolipid isolated from Acremonium strictum possessing potent calcium signal-modulating activity-the role of acyl substituents on the d-mannose moiety was examined. Three partially deacylated homologs (2a-2c) and 20 homologs (2d-2w) bearing different acyloxy side chains were synthesized via the stereoselective β-mannosylation of appropriately protected mannosyl sulfoxides (3) with d-mannitol derivatives (4), and their calcium signal-modulating activities were examined. The activities of 2a-2c were completely lost. Homologs bearing relatively short acyloxy groups at C-3, C-4, and C-6 positions (2t-2v) exhibited less activity than 1, whereas a heptanoyl homolog (2w: C7) maintained activity nearly equal to that of 1. When the acyl groups at these three positions were substituted by an octanoyl group (2i: C8), the activity was completely lost. On the other hand, of the 10 homologs in which the octanoyl at C-2 was substituted by other acyloxy moieties (2j-2s), three (2m: C7, 2n: C9, 2o: C10) maintained potent activity. These results suggested that peracylated mannose structure is critical for calcium signal-modulating activity, and this activity is precisely dependent on the length of four acyl side chains on d-mannose. PMID:27243802

  13. Rhizobial homologs of the fatty acid transporter FadL facilitate perception of long-chain acyl-homoserine lactone signals

    PubMed Central

    Krol, Elizaveta; Becker, Anke

    2014-01-01

    Quorum sensing (QS) using N-acyl homoserine lactones (AHLs) as signal molecules is a common strategy used by diverse Gram-negative bacteria. A widespread mechanism of AHL sensing involves binding of these molecules by cytosolic LuxR-type transcriptional regulators, which requires uptake of external AHLs. The outer membrane is supposed to be an efficient barrier for diffusion of long-chain AHLs. Here we report evidence that in Sinorhizobium meliloti, sensing of AHLs with acyl chains composed of 14 or more carbons is facilitated by the outer membrane protein FadLSm, a homolog of the Escherichia coli FadLEc long-chain fatty acid transporter. The effect of fadLSm on AHL sensing was more prominent for longer and more hydrophobic signal molecules. Using reporter gene fusions to QS target genes, we found that fadLSm increased AHL sensitivity and accelerated the course of QS. In contrast to FadLEc, FadLSm did not support uptake of oleic acid, but did contribute to growth on palmitoleic acid. FadLSm homologs from related symbiotic α-rhizobia and the plant pathogen Agrobacterium tumefaciens differed in their ability to facilitate long-chain AHL sensing or to support growth on oleic acid. FadLAt was found to be ineffective toward long-chain AHLs. We obtained evidence that the predicted extracellular loop 5 of FadLSm and further α-rhizobial FadL proteins contains determinants of specificity to long-chain AHLs. Replacement of a part of loop 5 by the corresponding region from α-rhizobial FadL proteins transferred sensitivity for long-chain AHLs to FadLAt. PMID:25002473

  14. Emerging magnetic order in platinum atomic contacts and chains

    PubMed Central

    Strigl, Florian; Espy, Christopher; Bückle, Maximilian; Scheer, Elke; Pietsch, Torsten

    2015-01-01

    The development of atomic-scale structures revealing novel transport phenomena is a major goal of nanotechnology. Examples include chains of atoms that form while stretching a transition metal contact or the predicted formation of magnetic order in these chains, the existence of which is still debated. Here we report an experimental study of the magneto-conductance (MC) and anisotropic MC with atomic-size contacts and mono-atomic chains of the nonmagnetic metal platinum. We find a pronounced and diverse MC behaviour, the amplitude and functional dependence change when stretching the contact by subatomic distances. These findings can be interpreted as a signature of local magnetic order in the chain, which may be of particular importance for the application of atomic-sized contacts in spintronic devices of the smallest possible size. PMID:25649440

  15. Mouse Siglec-1 Mediates trans-Infection of Surface-bound Murine Leukemia Virus in a Sialic Acid N-Acyl Side Chain-dependent Manner.

    PubMed

    Erikson, Elina; Wratil, Paul R; Frank, Martin; Ambiel, Ina; Pahnke, Katharina; Pino, Maria; Azadi, Parastoo; Izquierdo-Useros, Nuria; Martinez-Picado, Javier; Meier, Chris; Schnaar, Ronald L; Crocker, Paul R; Reutter, Werner; Keppler, Oliver T

    2015-11-01

    Siglec-1 (sialoadhesin, CD169) is a surface receptor on human cells that mediates trans-enhancement of HIV-1 infection through recognition of sialic acid moieties in virus membrane gangliosides. Here, we demonstrate that mouse Siglec-1, expressed on the surface of primary macrophages in an interferon-α-responsive manner, captures murine leukemia virus (MLV) particles and mediates their transfer to proliferating lymphocytes. The MLV infection of primary B-cells was markedly more efficient than that of primary T-cells. The major structural protein of MLV particles, Gag, frequently co-localized with Siglec-1, and trans-infection, primarily of surface-bound MLV particles, efficiently occurred. To explore the role of sialic acid for MLV trans-infection at a submolecular level, we analyzed the potential of six sialic acid precursor analogs to modulate the sialylated ganglioside-dependent interaction of MLV particles with Siglec-1. Biosynthetically engineered sialic acids were detected in both the glycolipid and glycoprotein fractions of MLV producer cells. MLV released from cells carrying N-acyl-modified sialic acids displayed strikingly different capacities for Siglec-1-mediated capture and trans-infection; N-butanoyl, N-isobutanoyl, N-glycolyl, or N-pentanoyl side chain modifications resulted in up to 92 and 80% reduction of virus particle capture and trans-infection, respectively, whereas N-propanoyl or N-cyclopropylcarbamyl side chains had no effect. In agreement with these functional analyses, molecular modeling indicated reduced binding affinities for non-functional N-acyl modifications. Thus, Siglec-1 is a key receptor for macrophage/lymphocyte trans-infection of surface-bound virions, and the N-acyl side chain of sialic acid is a critical determinant for the Siglec-1/MLV interaction. PMID:26370074

  16. Synthesis and Th1-immunostimulatory activity of α-galactosylceramide analogues bearing a halogen-containing or selenium-containing acyl chain.

    PubMed

    Hossain, Md Imran; Hanashima, Shinya; Nomura, Takuto; Lethu, Sébastien; Tsuchikawa, Hiroshi; Murata, Michio; Kusaka, Hiroki; Kita, Shunsuke; Maenaka, Katsumi

    2016-08-15

    A novel series of CD1d ligand α-galactosylceramides (α-GalCers) were synthesized by incorporation of the heavy atoms Br and Se in the acyl chain backbone of α-galactosyl-N-cerotoylphytosphingosine. The synthetic analogues are potent CD1d ligands and stimulate mouse invariant natural killer T (iNKT) cells to selectively enhance Th1 cytokine production. These synthetic analogues would be efficient X-ray crystallographic probes to disclose precise atomic positions of alkyl carbons and lipid-protein interactions in KRN7000/CD1d complexes. PMID:27325450

  17. Enhancing supply chain performance with improved order-control policies

    NASA Astrophysics Data System (ADS)

    Nilakantan, K.

    2010-09-01

    This article takes up the study of the dynamics of a single product in a prototype three-stage supply chain system, at the downstream warehouse end of the chain, under a responsive chain strategy. The dynamics under various ordering policies and the parameters which will yield desired responses are systematically analysed, both for deterministic and stochastic systems. Higher-order control policies are then proposed and analysed. The considered key performance criteria are the permanent inventory deviations from the desired levels, or the offset, the maximum dip in inventory, the 'undershoot', the damping effect and decay rates, and the duration of time in the negative region, for deterministic systems; and additionally, the inventory variance for stochastic systems. It is shown that the disadvantages of the conventional (proportional-integral-derivative) control policies, like large negative deviations, low decay rates, and high inventory variance, can be overcome by the use of higher-order control policies proposed herein.

  18. A Methylated Phosphate Group and Four Amide-linked Acyl Chains in Leptospira interrogans Lipid A. The Membrane Anchor of an Unusual Lipopolysaccharide that Activates TLR2*

    PubMed Central

    Que-Gewirth, Nanette L. S.; Ribeiro, Anthony A.; Kalb, Suzanne R.; Cotter, Robert J.; Bulach, Dieter M.; Adler, Ben; Girons, Isabelle Saint; Werts, Catherine; Raetz, Christian R. H.

    2008-01-01

    Leptospira interrogans differs from other spirochetes in that it contains homologs of all the Escherichia coli lpx genes required for the biosynthesis of the lipid A anchor of lipopolysaccharide (LPS). LPS from L. interrogans cells is unusual in that it activates TLR2 rather than TLR4. The structure of L. interrogans lipid A has now been determined by a combination of matrix-assisted laser desorption ionization time-of-flight mass spectrometry, NMR spectroscopy, and biochemical studies. Lipid A was released from LPS of L. interrogans serovar Pomona by 100 °C hydrolysis at pH 4.5 in the presence of SDS. Following purification by anion exchange and thin layer chromatography, the major component was shown to have a molecular weight of 1727. Mild hydrolysis with dilute NaOH reduced this to 1338, consistent with the presence of four N-linked and two O-linked acyl chains. The lipid A molecules of both the virulent and nonvirulent forms of L. interrogans serovar Icterohaemorrhagiae (strain Verdun) were identical to those of L. interrogans Pomona by the above criteria. Given the selectivity of L. interrogans LpxA for 3-hydroxylaurate, we propose that L. interrogans lipid A is acylated with R-3-hydroxylaurate at positions 3 and 3′ and with R-3-hydroxypalmitate at positions 2 and 2′. The hydroxyacyl chain composition was validated by gas chromatography and mass spectrometry of fatty acid methyl esters. Intact hexa-acylated lipid A of L. interrogans Pomona was also analyzed by NMR, confirming the presence a β-1′,6-linked disaccharide of 2,3-diamino-2,3-dideoxy-D-glucopyranose units. Two secondary unsaturated acyl chains are attached to the distal residue. The 1-position of the disaccharide is derivatized with an axial phosphate moiety, but the 4′-OH is unsubstituted. 1H and 31P NMR analyses revealed that the 1-phosphate group is methylated. Purified L. interrogans lipid A is inactive against human THP-1 cells but does stimulate tumor necrosis factor production by

  19. Building Higher-Order Markov Chain Models with EXCEL

    ERIC Educational Resources Information Center

    Ching, Wai-Ki; Fung, Eric S.; Ng, Michael K.

    2004-01-01

    Categorical data sequences occur in many applications such as forecasting, data mining and bioinformatics. In this note, we present higher-order Markov chain models for modelling categorical data sequences with an efficient algorithm for solving the model parameters. The algorithm can be implemented easily in a Microsoft EXCEL worksheet. We give a…

  20. Long N-acyl fatty acids on sphingolipids are responsible for miscibility with phospholipids to form liquid-ordered phase.

    PubMed

    Quinn, Peter J

    2009-10-01

    The structure and thermotropic phase behaviour of aqueous dispersions of dipalmitoylphosphatidylcholine and glucosylceramide rich in C-24 fatty acyl residues was investigated by synchrotron X-ray diffraction methods. Binary mixtures comprised of molar ratios 2.5:100, 6.5:100, 12.6:100, 25:100, 40:100 and 50:100, glucolipid:phospholipid were examined in heating and cooling scans of 2 degrees /min between 25 and 85 degrees C. Small-angle reflections indicated coexisting lamellar structures over the entire temperature range investigated. Reversible thermotropic changes were observed in one lamellar structure that is consistent with transitions between gel, ripple and fluid lamellar phases of pure phospholipid. The temperature of these transitions, however, were progressively shifted up by about 5 degrees C in the mixture containing the highest proportion of glucolipid and coincided with a published endothermic peak observed in this mixture. A higher-temperature endotherm was associated with molecular rearrangements on transition of the gel phase phospholipid to the fluid phase. This rearrangement was associated with the appearance of identifiable transient intermediate structures in the small-angle scattering region. The glucolipid formed stoichiometric mixtures with the phospholipid at all temperatures investigated and there was no evidence of phase separation of pure glucolipid. Analysis of the wide-angle scattering profiles during an initial heating scan of a binary mixture comprised of 40:60 glucolipid:phospholipid was consistent with a phase transition of pure phospholipid at about 43 degrees C coexisting with a liquid-ordered phase formed from the two lipids. This was confirmed by analysis of the small-angle scattering peaks of this mixture recorded at 25 and 65 degrees C which showed that a glucolipid-rich phase coexisted with almost pure bilayers of phospholipid at both temperatures. The glucolipid-rich phase consisted of 45:55 mole ratio glucolipid

  1. Long-chain acyl-CoA synthetase 2 knockdown leads to decreased fatty acid oxidation in fat body and reduced reproductive capacity in the insect Rhodnius prolixus.

    PubMed

    Alves-Bezerra, Michele; Klett, Eric L; De Paula, Iron F; Ramos, Isabela B; Coleman, Rosalind A; Gondim, Katia C

    2016-07-01

    Long-chain acyl-CoA esters are important intermediates in lipid metabolism and are synthesized from fatty acids by long-chain acyl-CoA synthetases (ACSL). The hematophagous insect Rhodnius prolixus, a vector of Chagas' disease, produces glycerolipids in the midgut after a blood meal, which are stored as triacylglycerol in the fat body and eggs. We identified twenty acyl-CoA synthetase genes in R. prolixus, two encoding ACSL isoforms (RhoprAcsl1 and RhoprAcsl2). RhoprAcsl1 transcripts increased in posterior midgut on the second day after feeding, and RhoprAcsl2 was highly transcribed on the tenth day. Both enzymes were expressed in Escherichia coli. Recombinant RhoprACSL1 and RhoprACSL2 had broad pH optima (7.5-9.5 and 6.5-9.5, respectively), were inhibited by triacsin C, and were rosiglitazone-insensitive. Both showed similar apparent Km for palmitic and oleic acid (2-6 μM), but different Km for arachidonic acid (0.5 and 6 μM for RhoprACSL1-Flag and RhoprACSL2-Flag, respectively). The knockdown of RhoprAcsl1 did not result in noticeable phenotypes. However, RhoprACSL2 deficient insects exhibited a 2.5-fold increase in triacylglycerol content in the fat body, and 90% decrease in fatty acid β-oxidation. RhoprAcsl2 knockdown also resulted in 20% increase in lifespan, delayed digestion, 30% reduced oviposition, and 50% reduction in egg hatching. Laid eggs and hatched nymphs showed remarkable alterations in morphology. In summary, R. prolixus ACSL isoforms have distinct roles on lipid metabolism. Although RhoprACSL1 functions remain unclear, we propose that RhoprACSL2 is the main contributor for the formation of the intracellular acyl-CoA pool channeled for β-oxidation in the fat body, and is also required for normal reproduction. PMID:27091636

  2. Mitochondrial respiratory chain disorders in the Old Order Amish population.

    PubMed

    Ghaloul-Gonzalez, Lina; Goldstein, Amy; Walsh Vockley, Catherine; Dobrowolski, Steven F; Biery, Amy; Irani, Afifa; Ibarra, Jordan; Morton, D Holmes; Mohsen, Al-Walid; Vockley, Jerry

    2016-08-01

    The Old Order Amish populations in the US are one of the Plain People groups and are descendants of the Swiss Anabaptist immigrants who came to North America in the early eighteenth century. They live in numerous small endogamous demes that have resulted in reduced genetic diversity along with a high prevalence of specific genetic disorders, many of them autosomal recessive. Mitochondrial respiratory chain deficiencies arising from mitochondrial or nuclear DNA mutations have not previously been reported in the Plain populations. Here we present four different Amish families with mitochondrial respiratory chain disorders. Mutations in two mitochondrial encoded genes leading to mitochondrial respiratory chain disorder were identified in two patients. In the first case, MELAS syndrome caused by a mitochondrial DNA (mtDNA) mutation (m.3243A>G) was identified in an extended Amish pedigree following a presentation of metabolic strokes in the proband. Characterization of the extended family of the proband by a high resolution melting assay identified the same mutation in many previously undiagnosed family members with a wide range of clinical symptoms. A MELAS/Leigh syndrome phenotype caused by a mtDNA mutation [m.13513G>A; p.Asp393Asn] in the ND5 gene encoding the ND5 subunit of respiratory chain complex I was identified in a patient in a second family. Mutations in two nuclear encoded genes leading to mitochondrial respiratory chain disorder were also identified in two patients. One patient presented with Leigh syndrome and had a homozygous deletion in the NDUFAF2 gene, while the second patient had a homozygous mutation in the POLG gene, [c.1399G>A; p.Ala467Thr]. Our findings identify mitochondrial respiratory chain deficiency as a cause of disease in the Old Order Amish that must be considered in the context of otherwise unexplained systemic disease, especially if neuromuscular symptoms are present. PMID:27344355

  3. Increased Long Chain acyl-Coa Synthetase Activity and Fatty Acid Import Is Linked to Membrane Synthesis for Development of Picornavirus Replication Organelles

    PubMed Central

    Scott, Alison J.; Ford, Lauren A.; Pei, Zhengtong; Watkins, Paul A.; Ernst, Robert K.; Belov, George A.

    2013-01-01

    All positive strand (+RNA) viruses of eukaryotes replicate their genomes in association with membranes. The mechanisms of membrane remodeling in infected cells represent attractive targets for designing future therapeutics, but our understanding of this process is very limited. Elements of autophagy and/or the secretory pathway were proposed to be hijacked for building of picornavirus replication organelles. However, even closely related viruses differ significantly in their requirements for components of these pathways. We demonstrate here that infection with diverse picornaviruses rapidly activates import of long chain fatty acids. While in non-infected cells the imported fatty acids are channeled to lipid droplets, in infected cells the synthesis of neutral lipids is shut down and the fatty acids are utilized in highly up-regulated phosphatidylcholine synthesis. Thus the replication organelles are likely built from de novo synthesized membrane material, rather than from the remodeled pre-existing membranes. We show that activation of fatty acid import is linked to the up-regulation of cellular long chain acyl-CoA synthetase activity and identify the long chain acyl-CoA syntheatse3 (Acsl3) as a novel host factor required for polio replication. Poliovirus protein 2A is required to trigger the activation of import of fatty acids independent of its protease activity. Shift in fatty acid import preferences by infected cells results in synthesis of phosphatidylcholines different from those in uninfected cells, arguing that the viral replication organelles possess unique properties compared to the pre-existing membranes. Our data show how poliovirus can change the overall cellular membrane homeostasis by targeting one critical process. They explain earlier observations of increased phospholipid synthesis in infected cells and suggest a simple model of the structural development of the membranous scaffold of replication complexes of picorna-like viruses, that may be

  4. Palladium-Catalyzed Room-Temperature Acylative Suzuki Coupling of High-Order Aryl Borons with Carboxylic Acids.

    PubMed

    Si, Shufen; Wang, Chen; Zhang, Nan; Zou, Gang

    2016-05-20

    This note describes a dimethyl dicarbonate-assisted, Pd(OAc)2/PPh3-catalyzed acylative Suzuki coupling of carboxylic acids with diarylborinic acids or tetraarylboronates for practical and efficient synthesis of sterically undemanding aryl ketones at room temperature. More than just cost-effective alternatives to aryl boronic acids, diarylborinic acids and tetraarylboronates displayed higher reactivity in the acylative Suzuki coupling. A variety of alkyl aryl ketones, including those bearing a hydroxy, bromo, or carbonyl group, could be readily obtained in modest to excellent yields. PMID:27100118

  5. Acyl chain length effects related to glycosphingolipid crypticity in phospholipid membranes: probed by 2H-NMR.

    PubMed

    Hamilton, K S; Briere, K; Jarrell, H C; Grant, C W

    1994-03-23

    Wideline 2H-NMR was used to consider the relationships amongst glycosphingolipid and phospholipid fatty acid chain length and glycosphingolipid receptor function, in a system classically associated with crypticity. Galactosyl ceramide (GalCer), having 18- or 24-carbon fatty acid, was deuterium labelled at the conformationally-restricted fatty acid alpha-carbon (C-2). 2H-NMR spectra of N-[2,2-2H2]stearoyl and N-[2,2-2H2]lignoceroyl GalCer (GalCer with 18-vs. 24-carbon selectively deuterated fatty acid) were then compared over a range of temperatures in phosphatidylcholine/cholesterol membranes in which the host phospholipid had dimyristoyl, dipalmitoyl, or distearoyl fatty acid composition. Findings were evaluated in the light of known sensitivity of antibody interaction with GalCer to temperature and to both glycolipid fatty acid chain length and host matrix fatty acid chain length. Under the conditions of experimentation, spectra were not obtainable for glycolipids having rigid body motions that were slow on the NMR timescale (10(-4)-10(-5) s)-i.e.. motions typical of non-fluid (gel phase) membranes. The systems, DPPC/cholesterol and DSPC/cholesterol, in which the original observation was made of increased antibody binding to GalCer with long fatty acid, proved to be characterised by receptor motions that were in this slow timescale for both 18:0 and 24:0 GalCer at 22-24 degrees C. Under conditions for which spectra could be obtained, those for GalCer with [2,2-2H2]lignoceroyl (24-carbon alpha-deuterated) fatty acid were qualitatively similar to those of its 18-carbon analogue in all (fluid) membranes examined. However, spectral splittings differed quantitatively between deuterated 18:0 and 24:0 GalCer at a given temperature, dependent upon host matrix. These differences were most marked at lower temperatures and in the longer chain (more ordered) matrices, DPPC/cholesterol and DSPC/cholesterol. This suggests that maximum effects of glycolipid chain length on

  6. SIRT3 and SIRT5 Regulate the Enzyme Activity and Cardiolipin Binding of Very Long-Chain Acyl-CoA Dehydrogenase

    PubMed Central

    Zhang, Yuxun; Bharathi, Sivakama S.; Rardin, Matthew J.; Uppala, Radha; Verdin, Eric; Gibson, Bradford W.; Goetzman, Eric S.

    2015-01-01

    SIRT3 and SIRT5 have been shown to regulate mitochondrial fatty acid oxidation but the molecular mechanisms behind the regulation are lacking. Here, we demonstrate that SIRT3 and SIRT5 both target human very long-chain acyl-CoA dehydrogenase (VLCAD), a key fatty acid oxidation enzyme. SIRT3 deacetylates and SIRT5 desuccinylates K299 which serves to stabilize the essential FAD cofactor in the active site. Further, we show that VLCAD binds strongly to cardiolipin and isolated mitochondrial membranes via a domain near the C-terminus containing lysines K482, K492, and K507. Acetylation or succinylation of these residues eliminates binding of VLCAD to cardiolipin. SIRT3 deacetylates K507 while SIRT5 desuccinylates K482, K492, and K507. Sirtuin deacylation of recombinant VLCAD rescues membrane binding. Endogenous VLCAD from SIRT3 and SIRT5 knockout mouse liver shows reduced binding to cardiolipin. Thus, SIRT3 and SIRT5 promote fatty acid oxidation by converging upon VLCAD to promote its activity and membrane localization. Regulation of cardiolipin binding by reversible lysine acylation is a novel mechanism that is predicted to extrapolate to other metabolic proteins that localize to the inner mitochondrial membrane. PMID:25811481

  7. Antiproliferative activity of long chain acylated esters of quercetin-3-O-glucoside in hepatocellular carcinoma HepG2 cells.

    PubMed

    Sudan, Sudhanshu; Rupasinghe, Hp Vasantha

    2015-11-01

    Despite their strong role in human health, poor bioavailability of flavonoids limits their biological effects in vivo. Enzymatically catalyzed acylation of fatty acids to flavonoids is one of the approaches of increasing cellular permeability and hence, biological activities. In this study, six long chain fatty acid esters of quercetin-3-O-glucoside (Q3G) acylated enzymatically and were used for determining their antiproliferative action in hepatocellular carcinoma cells (HepG2) in comparison to precursor compounds and two chemotherapy drugs (Sorafenib and Cisplatin). Fatty acid esters of Q3G showed significant inhibition of HepG2 cell proliferation by 85 to 90% after 6 h and 24 h of treatment, respectively. The cell death due to these novel compounds was associated with cell-cycle arrest in S-phase and apoptosis observed by DNA fragmentation, fluorescent microscopy and elevated caspase-3 activity and strong DNA topoisomerase II inhibition. Interestingly, Q3G esters showed significantly low toxicity to normal liver cells than Sorafenib (P < 0.05), a chemotherapy drug for hepatocellular carcinoma. Among all, oleic acid ester of Q3G displayed the greatest antiproliferation action and a high potential as an anti-cancer therapeutic. Overall, the results of the study suggest strong antiproliferative action of these novel food-derived compounds in treatment of cancer. PMID:25681471

  8. SIRT3 and SIRT5 regulate the enzyme activity and cardiolipin binding of very long-chain acyl-CoA dehydrogenase.

    PubMed

    Zhang, Yuxun; Bharathi, Sivakama S; Rardin, Matthew J; Uppala, Radha; Verdin, Eric; Gibson, Bradford W; Goetzman, Eric S

    2015-01-01

    SIRT3 and SIRT5 have been shown to regulate mitochondrial fatty acid oxidation but the molecular mechanisms behind the regulation are lacking. Here, we demonstrate that SIRT3 and SIRT5 both target human very long-chain acyl-CoA dehydrogenase (VLCAD), a key fatty acid oxidation enzyme. SIRT3 deacetylates and SIRT5 desuccinylates K299 which serves to stabilize the essential FAD cofactor in the active site. Further, we show that VLCAD binds strongly to cardiolipin and isolated mitochondrial membranes via a domain near the C-terminus containing lysines K482, K492, and K507. Acetylation or succinylation of these residues eliminates binding of VLCAD to cardiolipin. SIRT3 deacetylates K507 while SIRT5 desuccinylates K482, K492, and K507. Sirtuin deacylation of recombinant VLCAD rescues membrane binding. Endogenous VLCAD from SIRT3 and SIRT5 knockout mouse liver shows reduced binding to cardiolipin. Thus, SIRT3 and SIRT5 promote fatty acid oxidation by converging upon VLCAD to promote its activity and membrane localization. Regulation of cardiolipin binding by reversible lysine acylation is a novel mechanism that is predicted to extrapolate to other metabolic proteins that localize to the inner mitochondrial membrane. PMID:25811481

  9. Unusual Methyl-Branched α,β-Unsaturated Acyl Chain Substitutions in the Nod Factors of an Arctic Rhizobium, Mesorhizobium sp. Strain N33 (Oxytropis arctobia)

    PubMed Central

    Poinsot, Véréna; Bélanger, Elaine; Laberge, Serge; Yang, Guo-Ping; Antoun, Hani; Cloutier, Jean; Treilhou, Michel; Dénarié, Jean; Promé, Jean-Claude; Debellé, Frédéric

    2001-01-01

    Mesorhizobium sp. strain N33 (Oxytropis arctobia), a rhizobial strain isolated in arctic Canada, is able to fix nitrogen at very low temperatures in association with a few arctic legume species belonging to the genera Astragalus, Onobrychis, and Oxytropis. Using mass spectrometry and nuclear magnetic resonance spectroscopy, we have determined the structure of N33 Nod factors, which are major determinants of nodulation. They are pentameric lipochito-oligosaccharides 6-O sulfated at the reducing end and exhibit other original substitutions: 6-O acetylation of the glucosamine residue next to the nonreducing terminal glucosamine and N acylation of the nonreducing terminal glucosamine by methyl-branched acyl chains of the iso series, some of which are α,β unsaturated. These unusual substitutions may contribute to the peculiar host range of N33. Analysis of N33 whole-cell fatty acids indicated that synthesis of the methyl-branched fatty acids depended on the induction of bacteria by plant flavonoids, suggesting a specific role for these fatty acids in the signaling process between the plant and the bacteria. Synthesis of the methyl-branched α,β-unsaturated fatty acids required a functional nodE gene. PMID:11371536

  10. Cloning of a coconut endosperm cDNA encoding a 1-acyl-sn-glycerol-3-phosphate acyltransferase that accepts medium-chain-length substrates.

    PubMed Central

    Knutzon, D S; Lardizabal, K D; Nelsen, J S; Bleibaum, J L; Davies, H M; Metz, J G

    1995-01-01

    Immature coconut (Cocos nucifera) endosperm contains a 1-acyl-sn-glycerol-3-phosphate acyltransferase (LPAAT) activity that shows a preference for medium-chain-length fatty acyl-coenzyme A substrates (H.M. Davies, D.J. Hawkins, J.S. Nelsen [1995] Phytochemistry 39:989-996). Beginning with solubilized membrane preparations, we have used chromatographic separations to identify a polypeptide with an apparent molecular mass of 29 kD, whose presence in various column fractions correlates with the acyltransferase activity detected in those same fractions. Amino acid sequence data obtained from several peptides generated from this protein were used to isolate a full-length clone from a coconut endosperm cDNA library. Clone pCGN5503 contains a 1325-bp cDNA insert with an open reading frame encoding a 308-amino acid protein with a calculated molecular mass of 34.8 kD. Comparison of the deduced amino acid sequence of pCGN5503 to sequences in the data banks revealed significant homology to other putative LPAAT sequences. Expression of the coconut cDNA in Escherichia coli conferred upon those cells a novel LPAAT activity whose substrate activity profile matched that of the coconut enzyme. PMID:8552723

  11. Imaging Mass Spectrometry Reveals Acyl-Chain- and Region-Specific Sphingolipid Metabolism in the Kidneys of Sphingomyelin Synthase 2-Deficient Mice

    PubMed Central

    Sugimoto, Masayuki; Wakabayashi, Masato; Shimizu, Yoichi; Yoshioka, Takeshi; Higashino, Kenichi; Numata, Yoshito; Okuda, Tomohiko; Zhao, Songji; Sakai, Shota; Igarashi, Yasuyuki; Kuge, Yuji

    2016-01-01

    Obesity was reported to cause kidney injury by excessive accumulation of sphingolipids such as sphingomyelin and ceramide. Sphingomyelin synthase 2 (SMS2) is an important enzyme for hepatic sphingolipid homeostasis and its dysfunction is considered to result in fatty liver disease. The expression of SMS2 is also high in the kidneys. However, the contribution of SMS2 on renal sphingolipid metabolism remains unclear. Imaging mass spectrometry is a powerful tool to visualize the distribution and provide quantitative data on lipids in tissue sections. Thus, in this study, we analyzed the effects of SMS2 deficiency on the distribution and concentration of sphingomyelins in the liver and kidneys of mice fed with a normal-diet or a high-fat-diet using imaging mass spectrometry and liquid chromatography/electrospray ionization-tandem mass spectrometry. Our study revealed that high-fat-diet increased C18–C22 sphingomyelins, but decreased C24-sphingomyelins, in the liver and kidneys of wild-type mice. By contrast, SMS2 deficiency decreased C18–C24 sphingomyelins in the liver. Although a similar trend was observed in the whole-kidneys, the effects were minor. Interestingly, imaging mass spectrometry revealed that sphingomyelin localization was specific to each acyl-chain length in the kidneys. Further, SMS2 deficiency mainly decreased C22-sphingomyelin in the renal medulla and C24-sphingomyelins in the renal cortex. Thus, imaging mass spectrometry can provide visual assessment of the contribution of SMS2 on acyl-chain- and region-specific sphingomyelin metabolism in the kidneys. PMID:27010944

  12. Rat long chain acyl-CoA synthetase 5 increases fatty acid uptake and partitioning to cellular triacylglycerol in McArdle-RH7777 cells.

    PubMed

    Mashek, Douglas G; McKenzie, Michelle A; Van Horn, Cynthia G; Coleman, Rosalind A

    2006-01-13

    Long chain acyl-CoA synthetase (ACSL) catalyzes the initial step in long chain fatty acid metabolism. Of the five mammalian ACSL isoforms cloned and characterized, ACSL5 is the only isoform found to be located, in part, on mitochondria and thus was hypothesized to be involved in fatty acid oxidation. To elucidate the specific roles of ACSL5 in fatty acid metabolism, we used adenoviral-mediated overexpression of ACSL5 (Ad-ACSL5) in rat hepatoma McArdle-RH7777 cells. Confocal microscopy revealed that Ad-ACSL5 colocalized to both mitochondria and endoplasmic reticulum. When compared with cells infected with Ad-GFP, Ad-ACSL5-infected cells at 24 h after infection had 2-fold higher acyl-CoA synthetase activities and 30% higher rates of fatty acid uptake when incubated with 500 microM [1-(14)C]oleic acid. Metabolism of [1-(14)C]oleic acid to cellular triacylglycerol (TAG) increased 42% in Ad-ACSL5-infected cells, but when compared with control cells, metabolism to acid-soluble metabolites, phospholipids, and medium TAG did not differ substantially. The incorporation of [1-(14)C]oleate and [1,2,3-(3)H]glycerol into TAG was similar in Ad-ACSL5-infected cells, thus indicating that Ad-ACSL5 increased TAG synthesis through both de novo and reacylation pathways. However, [1-(14)C]acetic acid incorporation into cellular lipids showed that, when compared with control cells, Ad-ACSL5-infected cells did not increase the metabolism of fatty acids that were derived from de novo synthesis. These results suggest that uptake of fatty acids into cells is regulated by metabolism and that overexpressed ACSL5 partitions exogenously derived fatty acids toward TAG synthesis and storage. PMID:16263710

  13. Modulation of cellulase activity by charged lipid bilayers with different acyl chain properties for efficient hydrolysis of ionic liquid-pretreated cellulose.

    PubMed

    Mihono, Kai; Ohtsu, Takeshi; Ohtani, Mai; Yoshimoto, Makoto; Kamimura, Akio

    2016-10-01

    The stability of cellulase activity in the presence of ionic liquids (ILs) is critical for the enzymatic hydrolysis of insoluble cellulose pretreated with ILs. In this work, cellulase was incorporated in the liposomes composed of negatively charged 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) and zwitterionic phosphatidylcholines (PCs) with different length and degree of unsaturation of the acyl chains. The liposomal cellulase-catalyzed reaction was performed at 45°C in the acetate buffer solution (pH 4.8) with 2.0g/L CC31 as cellulosic substrate. The crystallinity of CC31 was reduced by treating with 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) at 120°C for 30min. The liposomal cellulase continuously catalyzed hydrolysis of the pretreated CC31 for 48h producing glucose in the presence of 15wt% [Bmim]Cl. The charged lipid membranes were interactive with [Bmim](+), as elucidated by the [Bmim]Cl-induced alterations in fluorescence polarization of the membrane-embedded 1,6-diphenyl-1,3,5-hexatriene (DPH) molecules. The charged membranes offered the microenvironment where inhibitory effects of [Bmim]Cl on the cellulase activity was relieved. The maximum glucose productivity GP of 10.8 mmol-glucose/(hmol-lipid) was obtained at the reaction time of 48h with the cellulase incorporated in the liposomes ([lipid]=5.0mM) composed of 50mol% POPG and 1,2-dilauroyl-sn-glycero-3-phosohocholine (DLPC) with relatively short and saturated acyl chains. PMID:27318965

  14. A comparative study of diffusive and osmotic water permeation across bilayers composed of phospholipids with different head groups and fatty acyl chains.

    PubMed Central

    Jansen, M; Blume, A

    1995-01-01

    Osmotic and diffusive water permeability coefficients Pf and Pd were measured for lipid vesicles of 100-250 nm diameter composed of a variety of phospholipids with different head groups and fatty acyl chains. Two different methods were applied: the H2O/D2O exchange technique for diffusive water flow, and the osmotic technique for water flux driven by an osmotic gradient. For phosphatidylcholines in the liquid-crystalline state at 70 degrees C, permeability constants Pd between 3.0 and 5.2.10(-4) cm/s and ratios Pf/Pd 7 and 23 were observed. The observation of a permeability maximum in the phase transition region and the fact that osmotically driven water flux is higher than diffusive water exchange suggest that water is diffusing through small transient pores arising from density fluctuations in the bilayers. The Pd values depend on the nature of the head group, on the chemical structure of the chains, and on the type of chain linkage. In the case of charged lipids, the ionic strength of the solution has a strong influence. For phosphatidylethanolamines, phosphatidic acids, and ether phosphatidylcholines, permeability constants Pd were considerably lower (2-4.10(-6) cm/s at 70 degrees C). For liquid-crystalline phosphatidylcholines, a strong reduction of Pd after addition of ethanol was observed (2-4.10(-6) cm/s at 70 degrees C). The experimental values are discussed in connection with different permeation models. PMID:7756562

  15. Transcriptional Regulation by the Short-Chain Fatty Acyl Coenzyme A Regulator (ScfR) PccR Controls Propionyl Coenzyme A Assimilation by Rhodobacter sphaeroides

    PubMed Central

    Carter, Michael S.

    2015-01-01

    ABSTRACT Propionyl coenzyme A (propionyl-CoA) assimilation by Rhodobacter sphaeroides proceeds via the methylmalonyl-CoA pathway. The activity of the key enzyme of the pathway, propionyl-CoA carboxylase (PCC), was upregulated 20-fold during growth with propionate compared to growth with succinate. Because propionyl-CoA is an intermediate in acetyl-CoA assimilation via the ethylmalonyl-CoA pathway, acetate growth also requires the methylmalonyl-CoA pathway. PCC activities were upregulated 8-fold in extracts of acetate-grown cells compared to extracts of succinate-grown cells. The upregulation of PCC activities during growth with propionate or acetate corresponded to increased expression of the pccB gene, which encodes a subunit of PCC. PccR (RSP_2186) was identified to be a transcriptional regulator required for the upregulation of pccB transcript levels and, consequently, PCC activity: growth substrate-dependent regulation was lost when pccR was inactivated by an in-frame deletion. In the pccR mutant, lacZ expression from a 215-bp plasmid-borne pccB upstream fragment including 27 bp of the pccB coding region was also deregulated. A loss of regulation as a result of mutations in the conserved motifs TTTGCAAA-X4-TTTGCAAA in the presence of PccR allowed the prediction of a possible operator site. PccR, together with homologs from other organisms, formed a distinct clade within the family of short-chain fatty acyl coenzyme A regulators (ScfRs) defined here. Some members from other clades within the ScfR family have previously been shown to be involved in regulating acetyl-CoA assimilation by the glyoxylate bypass (RamB) or propionyl-CoA assimilation by the methylcitrate cycle (MccR). IMPORTANCE Short-chain acyl-CoAs are intermediates in essential biosynthetic and degradative pathways. The regulation of their accumulation is crucial for appropriate cellular function. This work identifies a regulator (PccR) that prevents the accumulation of propionyl-CoA by controlling

  16. Algorithm Optimally Orders Forward-Chaining Inference Rules

    NASA Technical Reports Server (NTRS)

    James, Mark

    2008-01-01

    People typically develop knowledge bases in a somewhat ad hoc manner by incrementally adding rules with no specific organization. This often results in a very inefficient execution of those rules since they are so often order sensitive. This is relevant to tasks like Deep Space Network in that it allows the knowledge base to be incrementally developed and have it automatically ordered for efficiency. Although data flow analysis was first developed for use in compilers for producing optimal code sequences, its usefulness is now recognized in many software systems including knowledge-based systems. However, this approach for exhaustively computing data-flow information cannot directly be applied to inference systems because of the ubiquitous execution of the rules. An algorithm is presented that efficiently performs a complete producer/consumer analysis for each antecedent and consequence clause in a knowledge base to optimally order the rules to minimize inference cycles. An algorithm was developed that optimally orders a knowledge base composed of forwarding chaining inference rules such that independent inference cycle executions are minimized, thus, resulting in significantly faster execution. This algorithm was integrated into the JPL tool Spacecraft Health Inference Engine (SHINE) for verification and it resulted in a significant reduction in inference cycles for what was previously considered an ordered knowledge base. For a knowledge base that is completely unordered, then the improvement is much greater.

  17. Distinct transcriptional regulation of long-chain acyl-CoA synthetase isoforms and cytosolic thioesterase 1 in the rodent heart by fatty acids and insulin.

    PubMed

    Durgan, David J; Smith, Justin K; Hotze, Margaret A; Egbejimi, Oluwaseun; Cuthbert, Karalyn D; Zaha, Vlad G; Dyck, Jason R B; Abel, E Dale; Young, Martin E

    2006-06-01

    The molecular mechanism(s) responsible for channeling long-chain fatty acids (LCFAs) into oxidative versus nonoxidative pathways is (are) poorly understood in the heart. Intracellular LCFAs are converted to long-chain fatty acyl-CoAs (LCFA-CoAs) by a family of long-chain acyl-CoA synthetases (ACSLs). Cytosolic thioesterase 1 (CTE1) hydrolyzes cytosolic LCFA-CoAs to LCFAs, generating a potential futile cycle at the expense of ATP utilization. We hypothesized that ACSL isoforms and CTE1 are differentially regulated in the heart during physiological and pathophysiological conditions. Using quantitative RT-PCR, we report that the five known acsl isoforms (acsl1, acsl3, acsl4, acsl5, and acsl6) and cte1 are expressed in whole rat and mouse hearts, as well as adult rat cardiomyocytes (ARCs). Streptozotocin-induced insulin-dependent diabetes (4 wk) and fasting (

  18. A Single Acyl-CoA Dehydrogenase Is Required For Catabolism Of Isoleucine, Valine And Short-Chain Fatty Acids In Aspergillus nidulans

    PubMed Central

    Maggio-Hall, Lori A.; Lyne, Paul; Wolff, Jon A.; Keller, Nancy P.

    2010-01-01

    An acyl-CoA dehydrogenase has been identified as part of the mitochondrial β-oxidation pathway in the ascomycete fungus Aspergillus nidulans. Disruption of the scdA gene prevented use of butyric acid (C4) and hexanoic acid (C6) as carbon sources and reduced cellular butyryl-CoA dehydrogenase activity by 7.5-fold. While the mutant strain exhibited wild-type levels of growth on erucic acid (C22:1) and oleic acid (C18:1), some reduction in growth was observed with myristic acid (C14). The ΔscdA mutation was found to be epistatic to a mutation downstream in the β-oxidation pathway (disruption of enoyl-CoA hydratase). The ΔscdA mutant was also unable to use isoleucine or valine as a carbon source. Transcription of scdA was observed in the presence of either fatty acids or amino acids. When the mutant was grown in medium containing either isoleucine or valine, organic acid analysis of culture supernatants showed accumulation of 2-oxo acid intermediates of branched chain amino acid catabolism, suggesting feedback inhibition of the upstream branched-chain α-keto acid dehydrogenase. PMID:17656140

  19. Kinetics and thermodynamics of first-order Markov chain copolymerization

    NASA Astrophysics Data System (ADS)

    Gaspard, P.; Andrieux, D.

    2014-07-01

    We report a theoretical study of stochastic processes modeling the growth of first-order Markov copolymers, as well as the reversed reaction of depolymerization. These processes are ruled by kinetic equations describing both the attachment and detachment of monomers. Exact solutions are obtained for these kinetic equations in the steady regimes of multicomponent copolymerization and depolymerization. Thermodynamic equilibrium is identified as the state at which the growth velocity is vanishing on average and where detailed balance is satisfied. Away from equilibrium, the analytical expression of the thermodynamic entropy production is deduced in terms of the Shannon disorder per monomer in the copolymer sequence. The Mayo-Lewis equation is recovered in the fully irreversible growth regime. The theory also applies to Bernoullian chains in the case where the attachment and detachment rates only depend on the reacting monomer.

  20. Kinetics and thermodynamics of first-order Markov chain copolymerization.

    PubMed

    Gaspard, P; Andrieux, D

    2014-07-28

    We report a theoretical study of stochastic processes modeling the growth of first-order Markov copolymers, as well as the reversed reaction of depolymerization. These processes are ruled by kinetic equations describing both the attachment and detachment of monomers. Exact solutions are obtained for these kinetic equations in the steady regimes of multicomponent copolymerization and depolymerization. Thermodynamic equilibrium is identified as the state at which the growth velocity is vanishing on average and where detailed balance is satisfied. Away from equilibrium, the analytical expression of the thermodynamic entropy production is deduced in terms of the Shannon disorder per monomer in the copolymer sequence. The Mayo-Lewis equation is recovered in the fully irreversible growth regime. The theory also applies to Bernoullian chains in the case where the attachment and detachment rates only depend on the reacting monomer. PMID:25084957

  1. Kinetics and thermodynamics of first-order Markov chain copolymerization

    SciTech Connect

    Gaspard, P.; Andrieux, D.

    2014-07-28

    We report a theoretical study of stochastic processes modeling the growth of first-order Markov copolymers, as well as the reversed reaction of depolymerization. These processes are ruled by kinetic equations describing both the attachment and detachment of monomers. Exact solutions are obtained for these kinetic equations in the steady regimes of multicomponent copolymerization and depolymerization. Thermodynamic equilibrium is identified as the state at which the growth velocity is vanishing on average and where detailed balance is satisfied. Away from equilibrium, the analytical expression of the thermodynamic entropy production is deduced in terms of the Shannon disorder per monomer in the copolymer sequence. The Mayo-Lewis equation is recovered in the fully irreversible growth regime. The theory also applies to Bernoullian chains in the case where the attachment and detachment rates only depend on the reacting monomer.

  2. Acyl-lipid metabolism.

    PubMed

    Li-Beisson, Yonghua; Shorrosh, Basil; Beisson, Fred; Andersson, Mats X; Arondel, Vincent; Bates, Philip D; Baud, Sébastien; Bird, David; Debono, Allan; Durrett, Timothy P; Franke, Rochus B; Graham, Ian A; Katayama, Kenta; Kelly, Amélie A; Larson, Tony; Markham, Jonathan E; Miquel, Martine; Molina, Isabel; Nishida, Ikuo; Rowland, Owen; Samuels, Lacey; Schmid, Katherine M; Wada, Hajime; Welti, Ruth; Xu, Changcheng; Zallot, Rémi; Ohlrogge, John

    2013-01-01

    Acyl lipids in Arabidopsis and all other plants have a myriad of diverse functions. These include providing the core diffusion barrier of the membranes that separates cells and subcellular organelles. This function alone involves more than 10 membrane lipid classes, including the phospholipids, galactolipids, and sphingolipids, and within each class the variations in acyl chain composition expand the number of structures to several hundred possible molecular species. Acyl lipids in the form of triacylglycerol account for 35% of the weight of Arabidopsis seeds and represent their major form of carbon and energy storage. A layer of cutin and cuticular waxes that restricts the loss of water and provides protection from invasions by pathogens and other stresses covers the entire aerial surface of Arabidopsis. Similar functions are provided by suberin and its associated waxes that are localized in roots, seed coats, and abscission zones and are produced in response to wounding. This chapter focuses on the metabolic pathways that are associated with the biosynthesis and degradation of the acyl lipids mentioned above. These pathways, enzymes, and genes are also presented in detail in an associated website (ARALIP: http://aralip.plantbiology.msu.edu/). Protocols and methods used for analysis of Arabidopsis lipids are provided. Finally, a detailed summary of the composition of Arabidopsis lipids is provided in three figures and 15 tables. PMID:23505340

  3. Acyl-lipid metabolism.

    PubMed

    Li-Beisson, Yonghua; Shorrosh, Basil; Beisson, Fred; Andersson, Mats X; Arondel, Vincent; Bates, Philip D; Baud, Sébastien; Bird, David; Debono, Allan; Durrett, Timothy P; Franke, Rochus B; Graham, Ian A; Katayama, Kenta; Kelly, Amélie A; Larson, Tony; Markham, Jonathan E; Miquel, Martine; Molina, Isabel; Nishida, Ikuo; Rowland, Owen; Samuels, Lacey; Schmid, Katherine M; Wada, Hajime; Welti, Ruth; Xu, Changcheng; Zallot, Rémi; Ohlrogge, John

    2010-01-01

    Acyl lipids in Arabidopsis and all other plants have a myriad of diverse functions. These include providing the core diffusion barrier of the membranes that separates cells and subcellular organelles. This function alone involves more than 10 membrane lipid classes, including the phospholipids, galactolipids, and sphingolipids, and within each class the variations in acyl chain composition expand the number of structures to several hundred possible molecular species. Acyl lipids in the form of triacylglycerol account for 35% of the weight of Arabidopsis seeds and represent their major form of carbon and energy storage. A layer of cutin and cuticular waxes that restricts the loss of water and provides protection from invasions by pathogens and other stresses covers the entire aerial surface of Arabidopsis. Similar functions are provided by suberin and its associated waxes that are localized in roots, seed coats, and abscission zones and are produced in response to wounding. This chapter focuses on the metabolic pathways that are associated with the biosynthesis and degradation of the acyl lipids mentioned above. These pathways, enzymes, and genes are also presented in detail in an associated website (ARALIP: http://aralip.plantbiology.msu.edu/). Protocols and methods used for analysis of Arabidopsis lipids are provided. Finally, a detailed summary of the composition of Arabidopsis lipids is provided in three figures and 15 tables. PMID:22303259

  4. Acyl-Lipid Metabolism

    PubMed Central

    Li-Beisson, Yonghua; Shorrosh, Basil; Beisson, Fred; Andersson, Mats X.; Arondel, Vincent; Bates, Philip D.; Baud, Sébastien; Bird, David; DeBono, Allan; Durrett, Timothy P.; Franke, Rochus B.; Graham, Ian A.; Katayama, Kenta; Kelly, Amélie A.; Larson, Tony; Markham, Jonathan E.; Miquel, Martine; Molina, Isabel; Nishida, Ikuo; Rowland, Owen; Samuels, Lacey; Schmid, Katherine M.; Wada, Hajime; Welti, Ruth; Xu, Changcheng; Zallot, Rémi; Ohlrogge, John

    2010-01-01

    Acyl lipids in Arabidopsis and all other plants have a myriad of diverse functions. These include providing the core diffusion barrier of the membranes that separates cells and subcellular organelles. This function alone involves more than 10 membrane lipid classes, including the phospholipids, galactolipids, and sphingolipids, and within each class the variations in acyl chain composition expand the number of structures to several hundred possible molecular species. Acyl lipids in the form of triacylglycerol account for 35% of the weight of Arabidopsis seeds and represent their major form of carbon and energy storage. A layer of cutin and cuticular waxes that restricts the loss of water and provides protection from invasions by pathogens and other stresses covers the entire aerial surface of Arabidopsis. Similar functions are provided by suberin and its associated waxes that are localized in roots, seed coats, and abscission zones and are produced in response to wounding. This chapter focuses on the metabolic pathways that are associated with the biosynthesis and degradation of the acyl lipids mentioned above. These pathways, enzymes, and genes are also presented in detail in an associated website (ARALIP: http://aralip.plantbiology.msu.edu/). Protocols and methods used for analysis of Arabidopsis lipids are provided. Finally, a detailed summary of the composition of Arabidopsis lipids is provided in three figures and 15 tables. PMID:22303259

  5. Acyl-Lipid Metabolism

    PubMed Central

    Li-Beisson, Yonghua; Shorrosh, Basil; Beisson, Fred; Andersson, Mats X.; Arondel, Vincent; Bates, Philip D.; Baud, Sébastien; Bird, David; DeBono, Allan; Durrett, Timothy P.; Franke, Rochus B.; Graham, Ian A.; Katayama, Kenta; Kelly, Amélie A.; Larson, Tony; Markham, Jonathan E.; Miquel, Martine; Molina, Isabel; Nishida, Ikuo; Rowland, Owen; Samuels, Lacey; Schmid, Katherine M.; Wada, Hajime; Welti, Ruth; Xu, Changcheng; Zallot, Rémi; Ohlrogge, John

    2013-01-01

    Acyl lipids in Arabidopsis and all other plants have a myriad of diverse functions. These include providing the core diffusion barrier of the membranes that separates cells and subcellular organelles. This function alone involves more than 10 membrane lipid classes, including the phospholipids, galactolipids, and sphingolipids, and within each class the variations in acyl chain composition expand the number of structures to several hundred possible molecular species. Acyl lipids in the form of triacylglycerol account for 35% of the weight of Arabidopsis seeds and represent their major form of carbon and energy storage. A layer of cutin and cuticular waxes that restricts the loss of water and provides protection from invasions by pathogens and other stresses covers the entire aerial surface of Arabidopsis. Similar functions are provided by suberin and its associated waxes that are localized in roots, seed coats, and abscission zones and are produced in response to wounding. This chapter focuses on the metabolic pathways that are associated with the biosynthesis and degradation of the acyl lipids mentioned above. These pathways, enzymes, and genes are also presented in detail in an associated website (ARALIP: http://aralip.plantbiology.msu.edu/). Protocols and methods used for analysis of Arabidopsis lipids are provided. Finally, a detailed summary of the composition of Arabidopsis lipids is provided in three figures and 15 tables. PMID:23505340

  6. De novo fatty acid biosynthesis and elongation in very long-chain acyl-CoA dehydrogenase-deficient mice supplemented with odd or even medium-chain fatty acids.

    PubMed

    Tucci, Sara; Behringer, Sidney; Spiekerkoetter, Ute

    2015-11-01

    An even medium-chain triglyceride (MCT)-based diet is the mainstay of treatment in very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency (VLCADD). Previous studies with magnetic resonance spectroscopy have shown an impact of MCT on the average fatty acid chain length in abdominal fat. We therefore assume that medium-chain fatty acids (MCFAs) are elongated and accumulate in tissue as long-chain fatty acids. In this study, we explored the hepatic effects of long-term supplementation with MCT or triheptanoin, an odd-chain C7-based triglyceride, in wild-type and VLCAD-deficient (VLCAD(-/-) ) mice after 1 year of supplementation as compared with a control diet. The de novo biosynthesis and elongation of fatty acids, and peroxisomal β-oxidation, were quantified by RT-PCR. This was followed by a comprehensive analysis of hepatic and cardiac fatty acid profiles by GC-MS. Long-term application of even and odd MCFAs strongly induced de novo biosynthesis and elongation of fatty acids in both wild-type and VLCAD(-/-) mice, leading to an alteration of the hepatic fatty acid profiles. We detected de novo-synthesized and elongated fatty acids, such as heptadecenoic acid (C17:1n9), eicosanoic acid (C20:1n9), erucic acid (C22:1n9), and mead acid (C20:3n9), that were otherwise completely absent in mice under control conditions. In parallel, the content of monounsaturated fatty acids was massively increased. Furthermore, we observed strong upregulation of peroxisomal β-oxidation in VLCAD(-/-) mice, especially when they were fed an MCT diet. Our data raise the question of whether long-term MCFA supplementation represents the most efficient treatment in the long term. Studies on the hepatic toxicity of triheptanoin are still ongoing. PMID:26284828

  7. Structure of a Specialized Acyl Carrier Protein Essential for Lipid A Biosynthesis with Very Long-chain Fatty Acids in Open and Closed Conformations

    SciTech Connect

    Ramelot, Theresa A.; Rossi, Paolo M.; Forouhar, Farhad; Lee, Hsiau-Wei; Yang, Yunhuang; Ni, Shuisong; Unser, Sarah; Lew, Scott; Seetharaman, Jayaraman; Xiao, Rong; Acton, Thomas; Everett, John K.; Prestegard, James H.; Hunt, John F.; Montelione, Gaetano; Kennedy, Michael A.

    2012-09-18

    The solution nuclear magnetic resonance (NMR) structures and backbone (15)N dynamics of the specialized acyl carrier protein (ACP), RpAcpXL, from Rhodopseudomonas palustris, in both the apo form and holo form modified by covalent attachment of 4'-phosphopantetheine at S37, are virtually identical, monomeric, and correspond to the closed conformation. The structures have an extra α-helix compared to the archetypical ACP from Escherichia coli, which has four helices, resulting in a larger opening to the hydrophobic cavity. Chemical shift differences between apo- and holo-RpAcpXL indicated some differences in the hinge region between α2 and α3 and in the hydrophobic cavity environment, but corresponding changes in nuclear Overhauser effect cross-peak patterns were not detected. In contrast to the NMR structures, apo-RpAcpXL was observed in an open conformation in crystals that diffracted to 2.0 Å resolution, which resulted from movement of α3. On the basis of the crystal structure, the predicted biological assembly is a homodimer. Although the possible biological significance of dimerization is unknown, there is potential that the resulting large shared hydrophobic cavity could accommodate the very long-chain fatty acid (28-30 carbons) that this specialized ACP is known to synthesize and transfer to lipid A. These structures are the first representatives of the AcpXL family and the first to indicate that dimerization may be important for the function of these specialized ACPs.

  8. Myopathy in very-long-chain acyl-CoA dehydrogenase deficiency: clinical and biochemical differences with the fatal cardiac phenotype.

    PubMed

    Scholte, H R; Van Coster, R N; de Jonge, P C; Poorthuis, B J; Jeneson, J A; Andresen, B S; Gregersen, N; de Klerk, J B; Busch, H F

    1999-07-01

    A 30-year-old man suffered since the age of 13 years from exercise induced episodes of intense generalised muscle pain, weakness and myoglobinuria. Fasting ketogenesis was low, while blood glucose remained normal. Muscle mitochondria failed to oxidise palmitoylcarnitine. Palmitoyl-CoA dehydrogenase was deficient in muscle and fibroblasts, consistent with deficiency of very-long-chain acyl-CoA dehydrogenase (VLCAD). The gene of this enzyme had a homozygous deletion of three base pairs in exon 9, skipping lysine residue 238. Fibroblasts oxidised myristate, palmitate and oleate at a rate of 129, 62 and 38% of controls. In contrast to patients with cardiac VLCAD deficiency, our patient had no lipid storage, a normal heart function, a higher rate of oleate oxidation in fibroblasts and normal free carnitine in plasma and fibroblasts. 31P-nuclear magnetic resonance spectroscopy of muscle showed a normal oxidative phosphorylation as assessed by phosphocreatine recovery, but a significant increase in pH and in Pi/ATP ratio. PMID:10407852

  9. Rat long-chain acyl-CoA synthetase mRNA, protein, and activity vary in tissue distribution and in response to diet.

    PubMed

    Mashek, Douglas G; Li, Lei O; Coleman, Rosalind A

    2006-09-01

    Distinct isoforms of long-chain acyl-CoA synthetases (ACSLs) may partition fatty acids toward specific metabolic cellular pathways. For each of the five members of the rat ACSL family, we analyzed tissue mRNA distributions, and we correlated the mRNA, protein, and activity of ACSL1 and ACSL4 after fasting and refeeding a 69% sucrose diet. Not only did quantitative real-time PCR analyses reveal unique tissue expression patterns for each ACSL isoform, but expression varied markedly in different adipose depots. Fasting increased ACSL4 mRNA abundance in liver, muscle, and gonadal and inguinal adipose tissues, and refeeding decreased ACSL4 mRNA. A similar pattern was observed for ACSL1, but both fasting and refeeding decreased ACSL1 mRNA in gonadal adipose. Fasting also decreased ACSL3 and ACSL5 mRNAs in liver and ACSL6 mRNA in muscle. Surprisingly, in nearly every tissue measured, the effects of fasting and refeeding on the mRNA abundance of ACSL1 and ACSL4 were discordant with changes in protein abundance. These data suggest that the individual ACSL isoforms are distinctly regulated across tissues and show that mRNA expression may not provide useful information about isoform function. They further suggest that translational or posttranslational modifications are likely to contribute to the regulation of ACSL isoforms. PMID:16772660

  10. Short-chain acyl-CoA dehydrogenase (SCAD) deficiency: An examination of the medical and neurodevelopmental characteristics of 14 cases identified through newborn screening or clinical symptoms

    PubMed Central

    Waisbren, S.E.; Levy, H.L.; Noble, M.; Matern, D.; Gregersen, N.; Pasley, K.; Marsden, D.

    2014-01-01

    The medical and neurodevelopmental characteristics of 14 children with short-chain acyl-CoA dehydrogenase deficiency (SCADD) are described. Eight were detected as neonates by newborn screening. Three children diagnosed on the basis of clinical symptoms had normal newborn screening results while 3 were born in states that did not screen for SCADD. Treatment included frequent feedings and a low fat diet. All children identified by newborn screening demonstrated medical and neuropsychological development within the normative range on follow-up, although one child had a relative weakness in the motor area and another child exhibited mild speech delay. Of the 3 clinically identified children with newborn screening results below the cut-off value, 2 were healthy and performed within the normal range on cognitive and motor tests at follow-up. Four clinically identified children with SCADD experienced persistent symptoms and/or developmental delay. However, in each of these cases, there were supplementary or alternative explanations for medical and neuropsychological deficits. Results indicated no genotype-phenotype correlations. These findings suggest that SCADD might be benign and the clinical symptoms ascribed to SCADD reflective of ascertainment bias or that early identification and treatment prevented complications that may have occurred due to interaction between genetic susceptibility and other genetic factors or environmental stressors. PMID:18676165

  11. Complete amino acid sequence of the medium-chain S-acyl fatty acid synthetase thio ester hydrolase from rat mammary gland

    SciTech Connect

    Randhawa, Z.I.; Smith, S.

    1987-03-10

    The complete amino acid sequence of the medium-chain S-acyl fatty acid synthetase thio ester hydrolase (thioesterase II) from rat mammary gland is presented. Most of the sequence was derived by analysis of (/sup 14/C)-labelled peptide fragments produced by cleavage at methionyl, glutamyl, lysyl, arginyl, and tryptophanyl residues. A small section of the sequence was deduced from a previously analyzed cDNA clone. The protein consists of 260 residues and has a blocked amino-terminal methionine and calculated M/sub r/ of 29,212. The carboxy-terminal sequence, verified by Edman degradation of the carboxy-terminal cyanogen bromide fragment and carboxypeptidase Y digestion of the intact thioesterase II, terminates with a serine residue and lacks three additional residues predicted by the cDNA sequence. The native enzyme contains three cysteine residues but no disulfide bridges. The active site serine residue is located at position 101. The rat mammary gland thioesterase II exhibits approximately 40% homology with a thioesterase from mallard uropygial gland, the sequence of which was recently determined by cDNA analysis. Thus the two enzymes may share similar structural features and a common evolutionary origin. The location of the active site in these thioesterases differs from that of other serine active site esterases; indeed, the enzymes do not exhibit any significant homology with other serine esterases, suggesting that they may constitute a separate new family of serine active site enzymes.

  12. Different effects of fibrates on the microsomal fatty acid chain elongation and the acyl composition of phospholipids in guinea-pigs.

    PubMed Central

    Vázquez, M.; Alegret, M.; López, M.; Rodríguez, C.; Adzet, T.; Merlos, M.; Laguna, J. C.

    1995-01-01

    1. The effects in vitro and in vivo of three fibric acid derivatives, clofibrate (CFB), bezafibrate (BFB) and gemfibrozil (GFB) on some enzyme activities related to fatty acid biosynthesis, namely palmitoyl-CoA synthetase and hydrolases (microsomal and cytosolic), NADH and NADPH cytochrome c reductases and acyl-CoA elongases were investigated in guinea-pigs. 2. The three fibrates inhibited acyl-CoA elongation in vitro, irrespective of the substrate of elongation used (saturated, monounsaturated, polyunsaturated) and with an order of potency GFB > BFB > CFB. In the case of GFB, inhibition occurred at concentrations that can be reached in vivo. 3. Microsomal palmitoyl-CoA hydrolase and synthetase were also inhibited in vitro (GFB > or = BFB > CFB), whereas NADH cytochrome c reductase activity was increased by GFB. Nevertheless, the magnitude of changes were lower than those observed in elongation activities. 4. Treatment with fibrates did not produce peroxisomal proliferation in guinea-pigs, as measured by peroxisomal beta-oxidation activity and liver weight/body weight ratio. Nevertheless, fibrates provoked a reduction in plasma cholesterol and triglycerides, at least in GFB- and BFB-treated animals. 5. Fatty acid elongation was significantly modified by GFB treatment in vivo. The remaining enzyme activities studied were only slightly changed by fibrate treatment. 6. Treatment with BFB and to a lesser extent with CFB, increased the relative proportion of MUFA (palmitoleic and oleic acids) in microsomal phospholipids, whereas PUFA (mainly linoleic acid) decreased. GFB behaved differently, increasing palmitic and linoleic acids and decreasing stearic and oleic acids. The latter changes are attributable to an inhibition of elongation activity by GFB. 7. The changes observed after fibrate treatment in both rats and guinea-pigs, as they are not directly related to peroxisome proliferation, could be more reliably extrapolated to man than those observed only in rats. PMID

  13. Riboflavin-Responsive and -Non-responsive Mutations in FAD Synthase Cause Multiple Acyl-CoA Dehydrogenase and Combined Respiratory-Chain Deficiency.

    PubMed

    Olsen, Rikke K J; Koňaříková, Eliška; Giancaspero, Teresa A; Mosegaard, Signe; Boczonadi, Veronika; Mataković, Lavinija; Veauville-Merllié, Alice; Terrile, Caterina; Schwarzmayr, Thomas; Haack, Tobias B; Auranen, Mari; Leone, Piero; Galluccio, Michele; Imbard, Apolline; Gutierrez-Rios, Purificacion; Palmfeldt, Johan; Graf, Elisabeth; Vianey-Saban, Christine; Oppenheim, Marcus; Schiff, Manuel; Pichard, Samia; Rigal, Odile; Pyle, Angela; Chinnery, Patrick F; Konstantopoulou, Vassiliki; Möslinger, Dorothea; Feichtinger, René G; Talim, Beril; Topaloglu, Haluk; Coskun, Turgay; Gucer, Safak; Botta, Annalisa; Pegoraro, Elena; Malena, Adriana; Vergani, Lodovica; Mazzà, Daniela; Zollino, Marcella; Ghezzi, Daniele; Acquaviva, Cecile; Tyni, Tiina; Boneh, Avihu; Meitinger, Thomas; Strom, Tim M; Gregersen, Niels; Mayr, Johannes A; Horvath, Rita; Barile, Maria; Prokisch, Holger

    2016-06-01

    Multiple acyl-CoA dehydrogenase deficiencies (MADDs) are a heterogeneous group of metabolic disorders with combined respiratory-chain deficiency and a neuromuscular phenotype. Despite recent advances in understanding the genetic basis of MADD, a number of cases remain unexplained. Here, we report clinically relevant variants in FLAD1, which encodes FAD synthase (FADS), as the cause of MADD and respiratory-chain dysfunction in nine individuals recruited from metabolic centers in six countries. In most individuals, we identified biallelic frameshift variants in the molybdopterin binding (MPTb) domain, located upstream of the FADS domain. Inasmuch as FADS is essential for cellular supply of FAD cofactors, the finding of biallelic frameshift variants was unexpected. Using RNA sequencing analysis combined with protein mass spectrometry, we discovered FLAD1 isoforms, which only encode the FADS domain. The existence of these isoforms might explain why affected individuals with biallelic FLAD1 frameshift variants still harbor substantial FADS activity. Another group of individuals with a milder phenotype responsive to riboflavin were shown to have single amino acid changes in the FADS domain. When produced in E. coli, these mutant FADS proteins resulted in impaired but detectable FADS activity; for one of the variant proteins, the addition of FAD significantly improved protein stability, arguing for a chaperone-like action similar to what has been reported in other riboflavin-responsive inborn errors of metabolism. In conclusion, our studies identify FLAD1 variants as a cause of potentially treatable inborn errors of metabolism manifesting with MADD and shed light on the mechanisms by which FADS ensures cellular FAD homeostasis. PMID:27259049

  14. Contribution of the Distal Pocket Residue to the Acyl-Chain-Length Specificity of (R)-Specific Enoyl-Coenzyme A Hydratases from Pseudomonas spp.

    PubMed Central

    Sato, Shun; Hiroe, Ayaka; Ishizuka, Koya; Kanazawa, Hiromi; Shiro, Yoshitsugu

    2015-01-01

    (R)-Specific enoyl-coenzyme A (enoyl-CoA) hydratases (PhaJs) are capable of supplying monomers from fatty acid β-oxidation to polyhydroxyalkanoate (PHA) biosynthesis. PhaJ1Pp from Pseudomonas putida showed broader substrate specificity than did PhaJ1Pa from Pseudomonas aeruginosa, despite sharing 67% amino acid sequence identity. In this study, the substrate specificity characteristics of two Pseudomonas PhaJ1 enzymes were investigated by site-directed mutagenesis, chimeragenesis, X-ray crystallographic analysis, and homology modeling. In PhaJ1Pp, the replacement of valine with isoleucine at position 72 resulted in an increased preference for enoyl-coenzyme A (CoA) elements with shorter chain lengths. Conversely, at the same position in PhaJ1Pa, the replacement of isoleucine with valine resulted in an increased preference for enoyl-CoAs with longer chain lengths. These changes suggest a narrowing and broadening in the substrate specificity range of the PhaJ1Pp and PhaJ1Pa mutants, respectively. However, the substrate specificity remains broader in PhaJ1Pp than in PhaJ1Pa. Additionally, three chimeric PhaJ1 enzymes, composed from PhaJ1Pp and PhaJ1Pa, all showed significant hydratase activity, and their substrate preferences were within the range exhibited by the parental PhaJ1 enzymes. The crystal structure of PhaJ1Pa was determined at a resolution of 1.7 Å, and subsequent homology modeling of PhaJ1Pp revealed that in the acyl-chain binding pocket, the amino acid at position 72 was the only difference between the two structures. These results indicate that the chain-length specificity of PhaJ1 is determined mainly by the bulkiness of the amino acid residue at position 72, but that other factors, such as structural fluctuations, also affect specificity. PMID:26386053

  15. Highly Ordered Single Conjugated Polymer Chain Rod Morphologies

    SciTech Connect

    Adachi, Takuji; Brazard, Johanna; Chokshi, Paresh; Ganesan, Venkat; Bolinger, Joshua; Barbara, Paul F.

    2010-10-15

    We have reexamined the fluorescence polarization anisotropy of single polymer chains of the prototypical conjugated polymer poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) isolated in a poly(methyl methacrylate) (PMMA) matrix employing improved synthetic samples that contain a much smaller number of tetrahedral chemical defects per chain. The new measurements reveal a much larger fraction of highly anisotropic MEH-PPV chains, with >70% of the chains exhibiting polarization anisotropy values falling in the range of 0.6-0.9. High anisotropy is strong evidence for a rod-shaped conformation. A comparison of the experimental results with coarse grain, beads on a chain simulations reveals that simulations with the usual bead-bead pairwise additive potentials cannot reproduce the observed large fraction of high polarization values. Apparently, this type of potential lacks some yet to be identified molecular feature that is necessary to accurately simulate the experimental results.

  16. Long Chain Fatty Acid Acylated Derivatives of Quercetin-3-O-Glucoside as Antioxidants to Prevent Lipid Oxidation

    PubMed Central

    Warnakulasuriya, Sumudu N.; Ziaullah; Rupasinghe, H.P. Vasantha

    2014-01-01

    Flavonoids have shown promise as natural plant-based antioxidants for protecting lipids from oxidation. It was hypothesized that their applications in lipophilic food systems can be further enhanced by esterification of flavonoids with fatty acids. Quercetin-3-O-glucoside (Q3G) was esterified individually with six selected long chain fatty acids: stearic acid (STA), oleic acid (OLA), linoleic acid (LNA), α-linolenic acid (ALA), eicosapentaenoic acid (EPA) and decosahexaenoic acid (DHA), using Candida antarctica B lipase as the biocatalyst. The antioxidant activity of esterified flavonoids was evaluated using lipid oxidation model systems of poly-unsaturated fatty acids-rich fish oil and human low density lipoprotein (LDL), in vitro. In the oil-in-water emulsion, Q3G esters exhibited 50% to 100% inhibition in primary oxidation and 30% to 75% inhibition in secondary oxidation. In bulk oil, Q3G esters did not provide considerable protection from lipid oxidation; however, Q3G demonstrated more than 50% inhibition in primary oxidation. EPA, DHA and ALA esters of Q3G showed significantly higher inhibition in Cu2+- and peroxyl radical-induced LDL oxidation in comparison to Q3G. PMID:25384198

  17. RNA SHAPE chemistry with aromatic acylating reagents.

    PubMed

    Nodin, Laura; Noël, Olivier; Chaminade, Françoise; Maskri, Ouerdia; Barbier, Vincent; David, Olivier; Fossé, Philippe; Xie, Juan

    2015-02-01

    As chemical methods for RNA secondary structure determination, SHAPE chemistry (selective 2'-hydroxyl acylation analyzed by primer extension) has been developed to specifically target flexible nucleotides (often unpaired nucleotides) independently to their purine or pyrimidine nature. In order to improve the specificity of acylating reagents towards unpaired nucleotides, we have explored the reactivity of symmetric anhydrides, acyl fluorides, active esters like succinimidyl ester and cyanomethyl esters for 2'-O-acylation reaction. Among the tested compounds, only the acyl fluoride 4 showed a low reactivity (compared to NMIA). However, this study is the first to show that nucleophilic catalysts like DMAP greatly improved the selective 2'-hydroxyl acylation by symmetric anhydrides, acyl fluorides and succinimidyl ester, with the 2-fluorobenzoic anhydride 5 being the most reactive. PMID:25557357

  18. Three RFLPs defining a haplotype associated with the common mutation in a human medium-chain acyl-CoA dehydrogenase (MCAD) deficiency occur in Alu repeats

    SciTech Connect

    Zhifang Zhang; Yeqing Zhou; Kelly, D.P.; Strauss, A.W. St. Louis Children's Hospital, MO ); Kolvraa, S.; Gregersen, N. )

    1993-06-01

    Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is a common inborn error of fatty-acid oxidation and may cause sudden infant death. Previous studies revealed that (i) homozygosity for an A-to-G mutation at nucleotide 985 of the mRNA coding region (A985G) is an extremely common cause of MCAD deficiency and (ii) MCAD deficiency is strongly associated with a particular haplotype for RFLPs for BanII, PstI, and TaqI. TaqI allele 2 is always associated with the A985G mutation in human MCAD deficiency. In this study, the authors have delineated the molecular basis of the RFLPs for PstI, BamHI, and TaqI in the human MCAD gene. Their results prove that the three RFLPs are caused by point mutations in the 8 kb of DNA encompassing exons 8--10 of the human MCAD gene. The TaqI polymorphism is caused by a C-to-A substitution 392 bp upstream of the exon 8, and the PstI and BamHI polymorphisms are due to T-to-C and G-to-A substitutions, respectively, which are 727 and 931 bp downstream of exon 10, respectively. All three RFLPs lie within Alu repetitive sequences. Comparison of intronic sequences immediately following exon 10 from two normal individuals with different haplotypes showed that this region contains densely packed Alu repeats and is highly polymorphic. The results are consistent both with a founder effect as the cause of the high prevalence of a single (A985G) mutation in MCAD deficiency and with its association with a particular haplotype for these intragenic RFLPs. 27 refs., 6 figs., 1 tab.

  19. Energy Transfers in Coupled Ordered Granular Chains with No Precompression

    NASA Astrophysics Data System (ADS)

    Vakakis, Alexander; Hasan, Arif M.; Starosvetsky, Yuli; Manevitch, Leonid I.

    2013-03-01

    We study the dynamics of coupled one-dimensional granular chains mounted on elastic foundations. No dissipative effects, such as plasticity or dry friction effects are taken into account in our analysis. Assuming no pre-compression between beads, the dynamics of the system under consideration is strongly nonlinear and, in an acoustic analogy they can be viewed as `sonic vacua'. Sources of strong nonlinearity in these systems are nonlinearizable Hertzian interactions between adjacent beads in compression, and also possible separations between beads in the absence of compressive forces leading to bead collisions. We find that demonstrate that in weakly coupled granular chains there can occur strong energy exchanges in the form of nonlinear beat phenomena of spatially periodic traveling waves, stationary breathers or propagating breathers. We employ analytical techniques to study these dynamical phenomena. This work was supported by MURI grant US ARO W911NF-09-1-0436. Dr. David Stepp is the grant monitor.

  20. The Physiology of Protein S-acylation

    PubMed Central

    Chamberlain, Luke H.; Shipston, Michael J.

    2015-01-01

    Protein S-acylation, the only fully reversible posttranslational lipid modification of proteins, is emerging as a ubiquitous mechanism to control the properties and function of a diverse array of proteins and consequently physiological processes. S-acylation results from the enzymatic addition of long-chain lipids, most typically palmitate, onto intracellular cysteine residues of soluble and transmembrane proteins via a labile thioester linkage. Addition of lipid results in increases in protein hydrophobicity that can impact on protein structure, assembly, maturation, trafficking, and function. The recent explosion in global S-acylation (palmitoyl) proteomic profiling as a result of improved biochemical tools to assay S-acylation, in conjunction with the recent identification of enzymes that control protein S-acylation and de-acylation, has opened a new vista into the physiological function of S-acylation. This review introduces key features of S-acylation and tools to interrogate this process, and highlights the eclectic array of proteins regulated including membrane receptors, ion channels and transporters, enzymes and kinases, signaling adapters and chaperones, cell adhesion, and structural proteins. We highlight recent findings correlating disruption of S-acylation to pathophysiology and disease and discuss some of the major challenges and opportunities in this rapidly expanding field. PMID:25834228

  1. Systematic Analysis of Gene Expression Alterations and Clinical Outcomes for Long-Chain Acyl-Coenzyme A Synthetase Family in Cancer

    PubMed Central

    Chen, Wei-Ching; Wang, Chih-Yang; Hung, Yu-Hsuan; Weng, Tzu-Yang; Yen, Meng-Chi; Lai, Ming-Derg

    2016-01-01

    Dysregulated lipid metabolism contributes to cancer progression. Our previous study indicates that long-chain fatty acyl-Co A synthetase (ACSL) 3 is essential for lipid upregulation induced by endoplasmic reticulum stress. In this report, we aimed to identify the role of ACSL family in cancer with systematic analysis and in vitro experiment. We explored the ACSL expression using Oncomine database to determine the gene alteration during carcinogenesis and identified the association between ACSL expression and the survival of cancer patient using PrognoScan database. ACSL1 may play a potential oncogenic role in colorectal and breast cancer and play a potential tumor suppressor role in lung cancer. Co-expression analysis revealed that ACSL1 was coexpressed with MYBPH, PTPRE, PFKFB3, SOCS3 in colon cancer and with LRRFIP1, TSC22D1 in lung cancer. In accordance with PrognoScan analysis, downregulation of ACSL1 in colon and breast cancer cell line inhibited proliferation, migration, and anchorage-independent growth. In contrast, increase of oncogenic property was observed in lung cancer cell line by attenuating ACSL1. High ACSL3 expression predicted a better prognosis in ovarian cancer; in contrast, high ACSL3 predicted a worse prognosis in melanoma. ACSL3 was coexpressed with SNUPN, TRIP13, and SEMA5A in melanoma. High expression of ACSL4 predicted a worse prognosis in colorectal cancer, but predicted better prognosis in breast, brain and lung cancer. ACSL4 was coexpressed with SERPIN2, HNRNPCL1, ITIH2, PROCR, LRRFIP1. High expression of ACSL5 predicted good prognosis in breast, ovarian, and lung cancers. ACSL5 was coexpressed with TMEM140, TAPBPL, BIRC3, PTPRE, and SERPINB1. Low ACSL6 predicted a worse prognosis in acute myeloid leukemia. ACSL6 was coexpressed with SOX6 and DARC. Altogether, different members of ACSLs are implicated in diverse types of cancer development. ACSL-coexpressed molecules may be used to further investigate the role of ACSL family in

  2. Systematic Analysis of Gene Expression Alterations and Clinical Outcomes for Long-Chain Acyl-Coenzyme A Synthetase Family in Cancer.

    PubMed

    Chen, Wei-Ching; Wang, Chih-Yang; Hung, Yu-Hsuan; Weng, Tzu-Yang; Yen, Meng-Chi; Lai, Ming-Derg

    2016-01-01

    Dysregulated lipid metabolism contributes to cancer progression. Our previous study indicates that long-chain fatty acyl-Co A synthetase (ACSL) 3 is essential for lipid upregulation induced by endoplasmic reticulum stress. In this report, we aimed to identify the role of ACSL family in cancer with systematic analysis and in vitro experiment. We explored the ACSL expression using Oncomine database to determine the gene alteration during carcinogenesis and identified the association between ACSL expression and the survival of cancer patient using PrognoScan database. ACSL1 may play a potential oncogenic role in colorectal and breast cancer and play a potential tumor suppressor role in lung cancer. Co-expression analysis revealed that ACSL1 was coexpressed with MYBPH, PTPRE, PFKFB3, SOCS3 in colon cancer and with LRRFIP1, TSC22D1 in lung cancer. In accordance with PrognoScan analysis, downregulation of ACSL1 in colon and breast cancer cell line inhibited proliferation, migration, and anchorage-independent growth. In contrast, increase of oncogenic property was observed in lung cancer cell line by attenuating ACSL1. High ACSL3 expression predicted a better prognosis in ovarian cancer; in contrast, high ACSL3 predicted a worse prognosis in melanoma. ACSL3 was coexpressed with SNUPN, TRIP13, and SEMA5A in melanoma. High expression of ACSL4 predicted a worse prognosis in colorectal cancer, but predicted better prognosis in breast, brain and lung cancer. ACSL4 was coexpressed with SERPIN2, HNRNPCL1, ITIH2, PROCR, LRRFIP1. High expression of ACSL5 predicted good prognosis in breast, ovarian, and lung cancers. ACSL5 was coexpressed with TMEM140, TAPBPL, BIRC3, PTPRE, and SERPINB1. Low ACSL6 predicted a worse prognosis in acute myeloid leukemia. ACSL6 was coexpressed with SOX6 and DARC. Altogether, different members of ACSLs are implicated in diverse types of cancer development. ACSL-coexpressed molecules may be used to further investigate the role of ACSL family in

  3. Identification of N-Acyl Phosphatidylserine Molecules in Eukaryotic Cells

    PubMed Central

    Guan, Ziqiang; Li, Shengrong; Smith, Dale C.; Shaw, Walter A.; Raetz, Christian R. H.

    2008-01-01

    While profiling the lipidome of the mouse brain by mass spectrometry, we discovered a novel family of N-acyl phosphatidylserine (N-acyl-PS) molecules. These N-acyl-PS species were enriched by DEAE-cellulose column chromatography, and they were then characterized by accurate mass measurements, tandem mass spectrometry, liquid chromatography/mass spectrometry, and comparison to an authentic standard. Mouse brain N-acyl-PS molecules are heterogeneous and constitute about 0.1 % of the total lipid. In addition to various ester-linked fatty acyl chains on their glycerol backbones, the complexity of the N-acyl-PS series is further increased by the presence of diverse amide-linked N-acyl chains, which include saturated, mono-unsaturated and poly-unsaturated species. N-acyl-PS molecular species were also detected in the lipids of pig brain, mouse RAW264.7 macrophage tumor cells and yeast, but not E. coli. N-acyl-PSs may be biosynthetic precursors of N-acyl serine molecules, such as the recently reported signaling lipid N-arachidonoyl serine from bovine brain. We suggest that a phospholipase D might cleave N-acyl-PS to generate N-acyl serine, in analogy to the biosynthesis of the endocannabinoid N-arachidonoyl ethanolamine (anadamide) from N-arachidonoyl phosphatidylethanolamine. PMID:18031065

  4. Specificity of acyl-homoserine lactone synthases examined by mass spectrometry.

    PubMed

    Gould, Ty A; Herman, Jake; Krank, Jessica; Murphy, Robert C; Churchill, Mair E A

    2006-01-01

    Many gram-negative bacteria produce a specific set of N-acyl-L-homoserine-lactone (AHL) signaling molecules for the purpose of quorum sensing, which is a means of regulating coordinated gene expression in a cell-density-dependent manner. AHLs are produced from acylated acyl-carrier protein (acyl-ACP) and S-adenosyl-L-methionine by the AHL synthase enzyme. The appearance of specific AHLs is due in large part to the intrinsic specificity of the enzyme for subsets of acyl-ACP substrates. Structural studies of the Pantoea stewartii enzyme EsaI and AHL-sensitive bioassays revealed that threonine 140 in the acyl chain binding pocket directs the enzyme toward production of 3-oxo-homoserine lactones. Mass spectrometry was used to examine the range of AHL molecular species produced by AHL synthases under a variety of conditions. An AHL selective normal-phase chromatographic purification with addition of a deuterated AHL internal standard was followed by reverse-phase liquid chromatography-tandem mass spectrometry in order to obtain estimates of the relative amounts of different AHLs from biological samples. The AHLs produced by wild-type and engineered EsaI and LasI AHL synthases show that intrinsic specificity and different cellular conditions influence the production of AHLs. The threonine at position 140 in EsaI is important for the preference for 3-oxo-acyl-ACPs, but the role of the equivalent threonine in LasI is less clear. In addition, LasI expressed in Escherichia coli produces a high proportion of unusual AHLs with acyl chains consisting of an odd number of carbons. Furthermore, these studies offer additional methods that will be useful for surveying and quantitating AHLs from different sources. PMID:16385066

  5. The capacity for long-chain polyunsaturated fatty acid synthesis in a carnivorous vertebrate: Functional characterisation and nutritional regulation of a Fads2 fatty acyl desaturase with Δ4 activity and an Elovl5 elongase in striped snakehead (Channa striata).

    PubMed

    Kuah, Meng-Kiat; Jaya-Ram, Annette; Shu-Chien, Alexander Chong

    2015-03-01

    The endogenous production of long-chain polyunsaturated fatty acids (LC-PUFA) in carnivorous teleost species inhabiting freshwater environments is poorly understood. Although a predatory lifestyle could potentially supply sufficient LC-PUFA to satisfy the requirements of these species, the nutrient-poor characteristics of the freshwater food web could impede this advantage. In this study, we report the cloning and functional characterisation of an elongase enzyme in the LC-PUFA biosynthesis pathway from striped snakehead (Channa striata), which is a strict freshwater piscivore that shows high deposition of LC-PUFA in its flesh. We also functionally characterised a previously isolated fatty acyl desaturase cDNA from this species. Results showed that the striped snakehead desaturase is capable of Δ4 and Δ5 desaturation activities, while the elongase showed the characteristics of Elovl5 elongases. Collectively, these findings reveal that striped snakehead exhibits the genetic resources to synthesise docosahexaenoic acid (DHA; 22:6n-3) from eicosapentaenoic acid (EPA; 20:5n-3). Both genes are expressed at considerable levels in the brain and the liver. In liver, both genes were up-regulated by dietary C18 PUFA, although this increase did not correspond to a significant rise in the deposition of muscle LC-PUFA. Brain tissue of fish fed with plant oil diets showed higher expression of fads2 gene compared to fish fed with fish oil-based diet, which could ensure DHA levels remain constant under limited dietary DHA intake. This suggests the importance of DHA production from EPA via the ∆4 desaturation step in order to maintain an optimal reserve of DHA in the neuronal tissues of carnivores. PMID:25542509

  6. Preparation of fatty-acylated derivatives of acyl carrier protein using Vibrio harveyi acyl-ACP synthetase.

    PubMed

    Shen, Z; Fice, D; Byers, D M

    1992-07-01

    A simple two-step purification of Vibrio harveyi fatty acyl-acyl carrier protein (acyl-ACP) synthetase, which is useful for the quantitative preparation and analysis of fatty-acylated derivatives of ACP, is described. Acyl-ACP synthetase can be partially purified from extracts of this bioluminescent bacterium by Cibacron blue chromatography and Sephacryl S-300 gel filtration and is stable for months at -20 degrees C in the presence of glycerol. Incubation of ACP from Escherichia coli with ATP and radiolabeled fatty acids (6 to 16 carbons in length) in the presence of the enzyme resulted in quantitative conversion to biologically active acylated derivatives. The enzyme reaction can be monitored by a filter disk assay to quantitate levels of ACP or by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography to detect ACP in cell extracts. With its broad fatty acid chain length specificity and optimal activity in mild nondenaturing buffers, the soluble V. harveyi acyl-ACP synthetase provides an attractive alternative to current chemical and enzymatic methods of acyl-ACP preparation and analysis. PMID:1514693

  7. Production of long chain alcohols and alkanes upon coexpression of an acyl-ACP reductase and aldehyde-deformylating oxgenase with a bacterial type-I fatty acid synthase in E. coli

    DOE PAGESBeta

    Coursolle, Dan; Shanklin, John; Lian, Jiazhang; Zhao, Huimin

    2015-06-23

    Microbial long chain alcohols and alkanes are renewable biofuels that could one day replace petroleum-derived fuels. Here we report a novel pathway for high efficiency production of these products in Escherichia coli strain BL21(DE3). We first identified the acyl-ACP reductase/aldehyde deformylase combinations with the highest activity in this strain. Next, we used catalase coexpression to remove toxic byproducts and increase the overall titer. Finally, by introducing the type-I fatty acid synthase from Corynebacterium ammoniagenes, we were able to bypass host regulatory mechanisms of fatty acid synthesis that have thus far hampered efforts to optimize the yield of acyl-ACP-derived products inmore » BL21(DE3). When all these engineering strategies were combined with subsequent optimization of fermentation conditions, we were able to achieve a final titer around 100 mg/L long chain alcohol/alkane products including a 57 mg/L titer of pentadecane, the highest titer reported in E. coli BL21(DE3) to date. The expression of prokaryotic type-I fatty acid synthases offer a unique strategy to produce fatty acid-derived products in E. coli that does not rely exclusively on the endogenous type-II fatty acid synthase system.« less

  8. Production of long chain alcohols and alkanes upon coexpression of an acyl-ACP reductase and aldehyde-deformylating oxgenase with a bacterial type-I fatty acid synthase in E. coli

    SciTech Connect

    Coursolle, Dan; Shanklin, John; Lian, Jiazhang; Zhao, Huimin

    2015-06-23

    Microbial long chain alcohols and alkanes are renewable biofuels that could one day replace petroleum-derived fuels. Here we report a novel pathway for high efficiency production of these products in Escherichia coli strain BL21(DE3). We first identified the acyl-ACP reductase/aldehyde deformylase combinations with the highest activity in this strain. Next, we used catalase coexpression to remove toxic byproducts and increase the overall titer. Finally, by introducing the type-I fatty acid synthase from Corynebacterium ammoniagenes, we were able to bypass host regulatory mechanisms of fatty acid synthesis that have thus far hampered efforts to optimize the yield of acyl-ACP-derived products in BL21(DE3). When all these engineering strategies were combined with subsequent optimization of fermentation conditions, we were able to achieve a final titer around 100 mg/L long chain alcohol/alkane products including a 57 mg/L titer of pentadecane, the highest titer reported in E. coli BL21(DE3) to date. The expression of prokaryotic type-I fatty acid synthases offer a unique strategy to produce fatty acid-derived products in E. coli that does not rely exclusively on the endogenous type-II fatty acid synthase system.

  9. Production of long chain alcohols and alkanes upon coexpression of an acyl-ACP reductase and aldehyde-deformylating oxygenase with a bacterial type-I fatty acid synthase in E. coli.

    PubMed

    Coursolle, Dan; Lian, Jiazhang; Shanklin, John; Zhao, Huimin

    2015-09-01

    Microbial long chain alcohols and alkanes are renewable biofuels that could one day replace petroleum-derived fuels. Here we report a novel pathway for high efficiency production of these products in Escherichia coli strain BL21(DE3). We first identified the acyl-ACP reductase/aldehyde deformylase combinations with the highest activity in this strain. Next, we used catalase coexpression to remove toxic byproducts and increase the overall titer. Finally, by introducing the type-I fatty acid synthase from Corynebacterium ammoniagenes, we were able to bypass host regulatory mechanisms of fatty acid synthesis that have thus far hampered efforts to optimize the yield of acyl-ACP-derived products in BL21(DE3). When all these engineering strategies were combined with subsequent optimization of fermentation conditions, we were able to achieve a final titer around 100 mg L(-1) long chain alcohol/alkane products including a 57 mg L(-1) titer of pentadecane, the highest titer reported in E. coli BL21(DE3) to date. The expression of prokaryotic type-I fatty acid synthases offer a unique strategy to produce fatty acid-derived products in E. coli that does not rely exclusively on the endogenous type-II fatty acid synthase system. PMID:26135500

  10. Prevalence and mutation analysis of short/branched chain acyl-CoA dehydrogenase deficiency (SBCADD) detected on newborn screening in Wisconsin

    PubMed Central

    Van Calcar, Sandra C.; Baker, Mei W.; Williams, Phillip; Jones, Susan A.; Xiong, Blia; Thao, Mai Choua; Lee, Sheng; Yang, Mai Khou; Rice, Greg M.; Rhead, William; Vockley, Jerry; Hoffman, Gary; Durkin, Maureen S.

    2015-01-01

    Short/branched chain acyl-CoA dehydrogenase deficiency (SBCADD), also called 2-methylbutyryl CoA dehydrogenase deficiency (2-MBCDD), is a disorder of L-isoleucine metabolism of uncertain clinical significance. SBCADD is inadvertently detected on expanded newborn screening by elevated 2-methylbutyrylcarnitine (C5), which has the same mass to charge (m/s) on tandem mass spectrometry (MS/MS) as isovalerylcarnitine (C5), an analyte that is elevated in isovaleric acidemia (IVA), a disorder in leucine metabolism. SBCADD cases identified in the Hmong-American population have been found in association with the c.1165 A>G mutation in the ACADSB gene. The purposes of this study were to: (a) estimate the prevalence of SBCADD and carrier frequency of the c.1165 A>G mutation in the Hmong ethnic group; (b) determine whether the c.1 165 A>G mutation is common to all Hmong newborns screening positive for SBCADD; and (c) evaluate C5 acylcarnitine cut-off values to detect and distinguish between SBCADD and IVA diagnoses. During the first 10 years of expanded newborn screening using MS/MS in Wisconsin (2001–2011), 97 infants had elevated C5 values (≥0.44 μmol/L), of whom five were Caucasian infants confirmed to have IVA Of the remaining 92 confirmed SBCADD cases, 90 were of Hmong descent. Mutation analysis was completed on an anonymous, random sample of newborn screening cards (n = 1139) from Hmong infants. Fifteen infants, including nine who had screened positive for SBCADD based on a C5 acylcarnitine concentrations ≥0.44 μmol/L, were homozygous for the c.1165 A>G mutation. This corresponds to a prevalence in this ethnic group of being homozygous for the mutation of 1.3% (95% confidence interval 0.8–2.2%) and of being heterozygous for the mutation of 21.8% (95% confidence interval 19.4–24.3%), which is consistent with the Hardy-Weinberg equilibrium. Detection of homozygous individuals who were not identified on newborn screening suggests that the C5 screening cut

  11. Modified acyl-ACP desaturase

    DOEpatents

    Cahoon, Edgar B.; Shanklin, John; Lindgvist, Ylva; Schneider, Gunter

    1998-01-06

    Disclosed is a methods for modifying the chain length and double bond positional specificities of a soluble plant fatty acid desaturase. More specifically, the method involves modifying amino acid contact residues in the substrate binding channel of the soluble fatty acid desaturase which contact the fatty acid. Specifically disclosed is the modification of an acyl-ACP desaturase. Amino acid contact residues which lie within the substrate binding channel are identified, and subsequently replaced with different residues to effect the modification of activity.

  12. Modified Acyl-ACP desaturase

    DOEpatents

    Cahoon, Edgar B.; Shanklin, John; Lindqvist, Ylva; Schneider, Gunter

    1999-03-30

    Disclosed is a method for modifying the chain length and double bond positional specificities of a soluble plant fatty acid desaturase. More specifically, the method involves modifying amino acid contact residues in the substrate binding channel of the soluble fatty acid desaturase which contact the fatty acid. Specifically disclosed is the modification of an acyl-ACP desaturase. Amino acid contact residues which lie within the substrate binding channel are identified, and subsequently replaced with different residues to effect the modification of activity.

  13. Confinement-induced order of tethered alkyl chains at the water/vapor interface.

    PubMed

    Fukuto, M; Heilmann, R K; Pershan, P S; Yu, S M; Soto, C M; Tirrell, D A

    2002-07-01

    Packing of tethered alkyl chains in Langmuir monolayers of a hairy-rod polypeptide poly[gamma-4-(n-hexadecyloxy)benzyl alpha,L-glutamate] on water has been studied by x-ray scattering measurements at room temperature. The rods lie parallel to the surface while the alkyl side chains segregate toward the vapor. Results indicate that the herringbone order of the alkyl chains is established initially by one-dimensionally confined chains between aligned rods and grows laterally with compression. PMID:12241332

  14. The Analysis of Rush Orders Risk in Supply Chain: A Simulation Approach

    NASA Technical Reports Server (NTRS)

    Mahfouz, Amr; Arisha, Amr

    2011-01-01

    Satisfying customers by delivering demands at agreed time, with competitive prices, and in satisfactory quality level are crucial requirements for supply chain survival. Incidence of risks in supply chain often causes sudden disruptions in the processes and consequently leads to customers losing their trust in a company's competence. Rush orders are considered to be one of the main types of supply chain risks due to their negative impact on the overall performance, Using integrated definition modeling approaches (i.e. IDEF0 & IDEF3) and simulation modeling technique, a comprehensive integrated model has been developed to assess rush order risks and examine two risk mitigation strategies. Detailed functions sequence and objects flow were conceptually modeled to reflect on macro and micro levels of the studied supply chain. Discrete event simulation models were then developed to assess and investigate the mitigation strategies of rush order risks, the objective of this is to minimize order cycle time and cost.

  15. Effect of unsaturation on the chain order of phosphatidylcholines in a dioleoylphosphatidylethanolamine matrix.

    PubMed Central

    Separovic, F; Gawrisch, K

    1996-01-01

    The properties of phosphatidylcholines (PCs) having a perdeuterated stearic acid, 18:0d35, in the sn-1 position and the fatty acid 18:0, 18:1 omega 9, 18:2 omega 6, 18:3 omega 3, 20:4 omega 6, 20:5 omega 3, or 22:6 omega 3 at the sn-2 position were investigated in a matrix of dioleoylphosphatidylethanolamine (DOPE) by 2H and 31P NMR spectroscopy. At a mole ratio of DOPE/PC = 5:1, the lipids form liquid crystalline lamellar phases below 40 degrees C and coexisting lamellar, inverse hexagonal (Hll), and cubic phases at higher temperatures. The sn-1 chain of the PCs in a DOPE matrix is appreciably more ordered than in pure PCs, corresponding to an increase in the hydrophobic bilayer thickness of approximately 1 A. Distearoylphosphatidylcholine in the DOPE matrix has a higher sn-1 chain order than the unsaturated PCs. We observed distinct differences in the lipid order of upper and lower sections of the hydrocarbon chains caused by changes of temperature, unsaturation, headgroups, and ethanol. Unsaturation lowers chain order, mostly in the lower third of the hydrocarbon chains. By contrast, the increase in chain order caused by the DOPE matrix and the decrease in order with increasing temperature have a constant magnitude for the upper two-thirds of the chain and are smaller for the lower third. Addition of 2 M ethanol reduced order parameters, in effect reversing the increase in chain order caused by the DOPE matrix. PMID:8804610

  16. SREBP2 Activation Induces Hepatic Long-chain Acyl-CoA Synthetase 1 (ACSL1) Expression in Vivo and in Vitro through a Sterol Regulatory Element (SRE) Motif of the ACSL1 C-promoter.

    PubMed

    Singh, Amar Bahadur; Kan, Chin Fung Kelvin; Dong, Bin; Liu, Jingwen

    2016-03-01

    Long-chain acyl-CoA synthetase 1 (ACSL1) plays a key role in fatty acid metabolism. To identify novel transcriptional modulators of ACSL1, we examined ACSL1 expression in liver tissues of hamsters fed a normal diet, a high fat diet, or a high cholesterol and high fat diet (HCHFD). Feeding hamsters HCHFD markedly reduced hepatic Acsl1 mRNA and protein levels as well as acyl-CoA synthetase activity. Decreases in Acsl1 expression strongly correlated with reductions in hepatic Srebp2 mRNA level and mature Srebp2 protein abundance. Conversely, administration of rosuvastatin (RSV) to hamsters increased hepatic Acsl1 expression. These new findings were reproduced in mice treated with RSV or fed the HCHFD. Furthermore, the RSV induction of acyl-CoA activity in mouse liver resulted in increases in plasma and hepatic cholesterol ester concentrations and reductions in free cholesterol amounts. Investigations on different ACSL1 transcript variants in HepG2 cells revealed that the mRNA expression of C-ACSL1 was specifically regulated by the sterol regulatory element (SRE)-binding protein (SREBP) pathway, and RSV treatment increased the C-ACSL1 abundance from a minor mRNA species to an abundant transcript. We analyzed 5'-flanking sequence of exon 1C of the human ACSL1 gene and identified one putative SRE site. By performing a promoter activity assay and DNA binding assays, we firmly demonstrated the key role of this SRE motif in SREBP2-mediated activation of C-ACSL1 gene transcription. Finally, we demonstrated that knockdown of endogenous SREBP2 in HepG2 cells lowered ACSL1 mRNA and protein levels. Altogether, this work discovered an unprecedented link between ACSL1 and SREBP2 via the specific regulation of the C-ACSL1 transcript. PMID:26728456

  17. Site-specific analysis of protein S-acylation by resin-assisted capture[S

    PubMed Central

    Forrester, Michael T.; Hess, Douglas T.; Thompson, J. Will; Hultman, Rainbo; Moseley, M. Arthur; Stamler, Jonathan S.; Casey, Patrick J.

    2011-01-01

    Protein S-acylation is a major posttranslational modification whereby a cysteine thiol is converted to a thioester. A prototype is S-palmitoylation (fatty acylation), in which a protein undergoes acylation with a hydrophobic 16 carbon lipid chain. Although this modification is a well-recognized determinant of protein function and localization, current techniques to study cellular S-acylation are cumbersome and/or technically demanding. We recently described a simple and robust methodology to rapidly identify S-nitrosylation sites in proteins via resin-assisted capture (RAC) and provided an initial description of the applicability of the technique to S-acylated proteins (acyl-RAC). Here we expand on the acyl-RAC assay, coupled with mass spectrometry-based proteomics, to characterize both previously reported and novel sites of endogenous S-acylation. Acyl-RAC should therefore find general applicability in studies of both global and individual protein S-acylation in mammalian cells. PMID:21044946

  18. Simulation of the gel-fluid transition in a membrane composed of lipids with two connected acyl chains: application of a dimer-move step.

    PubMed Central

    Jerala, R; Almeida, P F; Biltonen, R L

    1996-01-01

    Phospholipids have been treated as dimers on a hexagonal lattice, and a move has been introduced that allows the dimers to move and change their orientation on the lattice. Simulations have been performed in which phospholipid chains have been treated as being either independent or infinitely coupled thermodynamically with regard to their conformational state. Both types of simulation have reproduced well experimental heat-capacity curves of dipalmitoyl phosphatidylcholine small unilamellar vesicles. Apart from a different gel-fluid interaction parameter and a different number of unlike nearest-neighbor contacts, most of the averages and thermodynamic quantities were essentially the same in the two types of simulation. These results indicate that the transition is not first order and validate those of previous Monte Carlo simulations that have neglected the dimeric nature of phospholipids in the sense that they show that for the thermotropic transition the approximation of phospholipids as monomers is valid. Images FIGURE 1 FIGURE 5 PMID:8842200

  19. Aberrant protein acylation is a common observation in inborn errors of acyl-CoA metabolism.

    PubMed

    Pougovkina, Olga; Te Brinke, Heleen; Wanders, Ronald J A; Houten, Sander M; de Boer, Vincent C J

    2014-09-01

    Inherited disorders of acyl-CoA metabolism, such as defects in amino acid metabolism and fatty acid oxidation can present with severe clinical symptoms either neonatally or later in life, but the pathophysiological mechanisms are often incompletely understood. We now report the discovery of a novel biochemical mechanism that could contribute to the pathophysiology of these disorders. We identified increased protein lysine butyrylation in short-chain acyl-CoA dehydrogenase (SCAD) deficient mice as a result of the accumulation of butyryl-CoA. Similarly, in SCAD deficient fibroblasts, lysine butyrylation was increased. Furthermore, malonyl-CoA decarboxylase (MCD) deficient patient cells had increased levels of malonylated lysines and propionyl-CoA carboxylase (PCC) deficient patient cells had increased propionylation of lysines. Since lysine acylation can greatly impact protein function, aberrant lysine acylation in inherited disorders associated with acyl-CoA accumulation may well play a role in their disease pathophysiology. PMID:24531926

  20. Overexpression of human fatty acid transport protein 2/very long chain acyl-CoA synthetase 1 (FATP2/Acsvl1) reveals distinct patterns of trafficking of exogenous fatty acids

    SciTech Connect

    Melton, Elaina M.; Cerny, Ronald L.; DiRusso, Concetta C.; Black, Paul N.

    2013-11-01

    Highlights: •Roles of FATP2 in fatty acid transport/activation contribute to lipid homeostasis. •Use of 13C- and D-labeled fatty acids provide novel insights into FATP2 function. •FATP2-dependent trafficking of FA into phospholipids results in distinctive profiles. •FATP2 functions in the transport and activation pathways for exogenous fatty acids. -- Abstract: In mammals, the fatty acid transport proteins (FATP1 through FATP6) are members of a highly conserved family of proteins, which function in fatty acid transport proceeding through vectorial acylation and in the activation of very long chain fatty acids, branched chain fatty acids and secondary bile acids. FATP1, 2 and 4, for example directly function in fatty acid transport and very long chain fatty acids activation while FATP5 does not function in fatty acid transport but activates secondary bile acids. In the present work, we have used stable isotopically labeled fatty acids differing in carbon length and saturation in cells expressing FATP2 to gain further insights into how this protein functions in fatty acid transport and intracellular fatty acid trafficking. Our previous studies showed the expression of FATP2 modestly increased C16:0-CoA and C20:4-CoA and significantly increased C18:3-CoA and C22:6-CoA after 4 h. The increases in C16:0-CoA and C18:3-CoA suggest FATP2 must necessarily partner with a long chain acyl CoA synthetase (Acsl) to generate C16:0-CoA and C18:3-CoA through vectorial acylation. The very long chain acyl CoA synthetase activity of FATP2 is consistent in the generation of C20:4-CoA and C22:6-CoA coincident with transport from their respective exogenous fatty acids. The trafficking of exogenous fatty acids into phosphatidic acid (PA) and into the major classes of phospholipids (phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), and phosphatidyserine (PS)) resulted in distinctive profiles, which changed with the expression of FATP2. The

  1. Order preserving contact transformations and dynamical symmetries of scalar and coupled Riccati and Abel chains

    NASA Astrophysics Data System (ADS)

    Gladwin Pradeep, R.; Chandrasekar, V. K.; Mohanasubha, R.; Senthilvelan, M.; Lakshmanan, M.

    2016-07-01

    We identify contact transformations which linearize the given equations in the Riccati and Abel chains of nonlinear scalar and coupled ordinary differential equations to the same order. The identified contact transformations are not of Cole-Hopf type and are new to the literature. The linearization of Abel chain of equations is also demonstrated explicitly for the first time. The contact transformations can be utilized to derive dynamical symmetries of the associated nonlinear ODEs. The wider applicability of identifying this type of contact transformations and the method of deriving dynamical symmetries by using them is illustrated through two dimensional generalizations of the Riccati and Abel chains as well.

  2. Fitting optimum order of Markov chain models for daily rainfall occurrences in Peninsular Malaysia

    NASA Astrophysics Data System (ADS)

    Deni, Sayang Mohd; Jemain, Abdul Aziz; Ibrahim, Kamarulzaman

    2009-06-01

    The analysis of the daily rainfall occurrence behavior is becoming more important, particularly in water-related sectors. Many studies have identified a more comprehensive pattern of the daily rainfall behavior based on the Markov chain models. One of the aims in fitting the Markov chain models of various orders to the daily rainfall occurrence is to determine the optimum order. In this study, the optimum order of the Markov chain models for a 5-day sequence will be examined in each of the 18 rainfall stations in Peninsular Malaysia, which have been selected based on the availability of the data, using the Akaike’s (AIC) and Bayesian information criteria (BIC). The identification of the most appropriate order in describing the distribution of the wet (dry) spells for each of the rainfall stations is obtained using the Kolmogorov-Smirnov goodness-of-fit test. It is found that the optimum order varies according to the levels of threshold used (e.g., either 0.1 or 10.0 mm), the locations of the region and the types of monsoon seasons. At most stations, the Markov chain models of a higher order are found to be optimum for rainfall occurrence during the northeast monsoon season for both levels of threshold. However, it is generally found that regardless of the monsoon seasons, the first-order model is optimum for the northwestern and eastern regions of the peninsula when the level of thresholds of 10.0 mm is considered. The analysis indicates that the first order of the Markov chain model is found to be most appropriate for describing the distribution of wet spells, whereas the higher-order models are found to be adequate for the dry spells in most of the rainfall stations for both threshold levels and monsoon seasons.

  3. Cloning and characterization of cDNAs encoding for long-chain saturated acyl-ACP thioesterases from the developing seeds of Brassica juncea.

    PubMed

    Jha, Saheli Sinha; Jha, Jyoti K; Chattopadhyaya, Banani; Basu, Asitava; Sen, Soumitra K; Maiti, Mrinal K

    2010-06-01

    Four types of cDNAs corresponding to the fatty acyl-acyl carrier protein (ACP) thioesterase (Fat) enzyme were isolated from the developing seeds of Brassica juncea, a widely cultivated species amongst the oil-seed crops. The mature polypeptides deduced from the cDNAs showed sequence identity with the FatB class of plant thioesterases. Southern hybridization revealed the presence of at least four copies of BjFatB gene in the genome of this amphidiploid species. Western blot and RT-PCR analyses showed that the BjFatB class thioesterase is expressed poorly in flowers and leaves, but significantly in seeds at the mid-maturation stage. The enzymatic activities of different BjFatB isoforms were established upon heterologous expression of the four BjFatB CDSs in Escherichia coli K27fadD88, a mutant strain of fatty acid beta-oxidation pathway. The substrate specificity of each BjFatB isoform was determined in vivo by fatty acid profile analyses of the culture supernatant and membrane lipid of the recombinant K27fadD88 and E. coli DH10B (fadD(+)) clones, respectively. The BjFatB1 and BjFatB3 were predominantly active on C18:0-ACP substrate, whereas BjFatB2 and BjFatB4 were specific towards C18:0-ACP as well as C16:0-ACP. These novel FatB genes may find potential application in metabolic engineering of crop plants through their over-expression in seed tissues to generate stearate-rich vegetable fats/oils of commercial importance. PMID:20356753

  4. State space orderings for Gauss-Seidel in Markov chains revisited

    SciTech Connect

    Dayar, T.

    1996-12-31

    Symmetric state space orderings of a Markov chain may be used to reduce the magnitude of the subdominant eigenvalue of the (Gauss-Seidel) iteration matrix. Orderings that maximize the elemental mass or the number of nonzero elements in the dominant term of the Gauss-Seidel splitting (that is, the term approximating the coefficient matrix) do not necessarily converge faster. An ordering of a Markov chain that satisfies Property-R is semi-convergent. On the other hand, there are semi-convergent symmetric state space orderings that do not satisfy Property-R. For a given ordering, a simple approach for checking Property-R is shown. An algorithm that orders the states of a Markov chain so as to increase the likelihood of satisfying Property-R is presented. The computational complexity of the ordering algorithm is less than that of a single Gauss-Seidel iteration (for sparse matrices). In doing all this, the aim is to gain an insight for faster converging orderings. Results from a variety of applications improve the confidence in the algorithm.

  5. Phylogenetic and experimental characterization of an acyl-ACP thioesterase family reveals significant diversity in enzymatic specificity and activity

    PubMed Central

    2011-01-01

    Background Acyl-acyl carrier protein thioesterases (acyl-ACP TEs) catalyze the hydrolysis of the thioester bond that links the acyl chain to the sulfhydryl group of the phosphopantetheine prosthetic group of ACP. This reaction terminates acyl chain elongation of fatty acid biosynthesis, and in plant seeds it is the biochemical determinant of the fatty acid compositions of storage lipids. Results To explore acyl-ACP TE diversity and to identify novel acyl ACP-TEs, 31 acyl-ACP TEs from wide-ranging phylogenetic sources were characterized to ascertain their in vivo activities and substrate specificities. These acyl-ACP TEs were chosen by two different approaches: 1) 24 TEs were selected from public databases on the basis of phylogenetic analysis and fatty acid profile knowledge of their source organisms; and 2) seven TEs were molecularly cloned from oil palm (Elaeis guineensis), coconut (Cocos nucifera) and Cuphea viscosissima, organisms that produce medium-chain and short-chain fatty acids in their seeds. The in vivo substrate specificities of the acyl-ACP TEs were determined in E. coli. Based on their specificities, these enzymes were clustered into three classes: 1) Class I acyl-ACP TEs act primarily on 14- and 16-carbon acyl-ACP substrates; 2) Class II acyl-ACP TEs have broad substrate specificities, with major activities toward 8- and 14-carbon acyl-ACP substrates; and 3) Class III acyl-ACP TEs act predominantly on 8-carbon acyl-ACPs. Several novel acyl-ACP TEs act on short-chain and unsaturated acyl-ACP or 3-ketoacyl-ACP substrates, indicating the diversity of enzymatic specificity in this enzyme family. Conclusion These acyl-ACP TEs can potentially be used to diversify the fatty acid biosynthesis pathway to produce novel fatty acids. PMID:21831316

  6. Treatment of disordered and ordered systems of polymer chains by lattice methods

    PubMed Central

    Flory, Paul J.

    1982-01-01

    Classical lattice theories of systems of long-chain molecules provide estimates of the number Z of random configurations to the exclusion of ordered ones. The decrease of Z thus estimated to values [unk]1 with decrease in chain flexibility at high densities is genuine, but it does not take account of eligible ordered configurations; the latter are not a subset of the configurations whose numbers are estimated by classical lattice methods. Failure to recognize this fact and the fundamental distinction between disordered and ordered states has engendered misinterpretations and has cast doubt on the validity of lattice-statistical methods. In a system at equilibrium, the decline of Z (disordered) with decrease in chain flexibility must be arrested by a first order transition to an ordered state. The inference that approach of Z (disordered) to values <1 presages a thermodynamic transition of second order is tenable only if the array of ordered configurations, not comprehended by theories in which the mean field of unoccupied lattice sites is random, can be ignored. PMID:16593214

  7. Some aspects of the orientational order distribution of flexible chains in a diblock mesophase

    SciTech Connect

    Lorthioir, Cédric Randriamahefa, Solo

    2013-12-14

    The segmental motions of flexible chains in the lamellar structure of a strongly segregated poly(styrene)-poly(dimethylsiloxane) (PS-PDMS) diblock were investigated over a time scale of a few tens of microseconds. {sup 2}H NMR experiments were performed on the PDMS block, selectively perdeuterated. Transverse relaxation measurements show that the main part of the PDMS repeat units display anisotropic reorientational motions within the diblock lamellae and such a segmental ordering essentially results from interchain steric repulsions. {sup 2}H double quantum-based experiments evidenced a non-uniform local stretching of PDMS chains and enabled the underlying distribution of the orientational order parameter to be determined quantitatively. Besides, a fraction of the PDMS chain segments, about 14%, were found to display isotropic – or nearly isotropic – reorientations, which could be assigned to repeat units located within a thin sublayer (about 1–2 nm) at the lamellae midplane, but also deeper in the lamellae, close to folded parts of the chains. These experimental results were confronted to theoretical descriptions of opposing polymer brushes and, in particular, to the strong-stretching theory (SST) including the entropic contribution of free chain ends.

  8. Modified Acyl-ACP desaturase

    DOEpatents

    Cahoon, E.B.; Shanklin, J.; Lindqvist, Y.; Schneider, G.

    1999-03-30

    Disclosed is a method for modifying the chain length and double bond positional specificities of a soluble plant fatty acid desaturase. More specifically, the method involves modifying amino acid contact residues in the substrate binding channel of the soluble fatty acid desaturase which contact the fatty acid. Specifically disclosed is the modification of an acyl-ACP desaturase. Amino acid contact residues which lie within the substrate binding channel are identified, and subsequently replaced with different residues to effect the modification of activity. 2 figs.

  9. Modified acyl-ACP desaturase

    DOEpatents

    Cahoon, E.B.; Shanklin, J.; Lindgvist, Y.; Schneider, G.

    1998-01-06

    Disclosed is a method for modifying the chain length and double bond positional specificities of a soluble plant fatty acid desaturase. More specifically, the method involves modifying amino acid contact residues in the substrate binding channel of the soluble fatty acid desaturase which contact the fatty acid. Specifically disclosed is the modification of an acyl-ACP desaturase. Amino acid contact residues which lie within the substrate binding channel are identified, and subsequently replaced with different residues to effect the modification of activity. 1 fig.

  10. Characterization of the molecular species of glycerophospholipids from rabbit kidney: an alternative approach to the determination of the fatty acyl chain position by negative ion fast atom bombardment combined with mass-analysed ion kinetic energy analysis.

    PubMed

    Chen, S; Curcuruto, O; Catinella, S; Traldi, P; Menon, G

    1992-12-01

    An alternative approach to identifying fatty acid chain position in the molecular species of glycerophospholipids has been studied and developed. The fatty acyl groups esterified to the glycerol backbone in isomeric glycerophosphatidyl-choline, -serine and -ethanolamine as well as glycerophosphatidic acid can be detected by the presence of a pair of anions derived from phosphatidic acid parent ions (M minus the polar head groups in glycerophospholipids), designed to be [M--polar head--R2COOH]- and [M--polar head--R2CO--H]-, produced by negative ion fast atom bombardment combined with mass-analysed ion kinetic energy analysis. Because of the significant abundance of [M--polar head--R2COOH]- anion, fatty acid chains differing by 2 Da can be distinguished by accurate measurements of the electrostatic voltage related to this ion. Three-volt differences can be evidenced. Using this approach, the molecular species of glycerophosphatidyl-choline, -serine, -ethanolamine and -inositol from rabbit kidney were characterized after the separation of both class and species by normal and reversed-phase high-performance liquid chromatography, respectively. We identified 11 arachidonoyl-containing molecular species of glycerophospholipids and the other 17 lipid molecules in this biological material. A couple of 1- alkenyl-2-arachidonoyl-sn-glycerol-3-phosphoethanolamine species, identified as plasmalogen GPE 16:0-20:4 and plasmalogen GPE 18:0-20:4, were found for the first time in rabbit kidney. PMID:1477110

  11. LIGNIN ACYLATION IN GRASSES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Acylation of lignin during growth and development is a commonly found among some plant species. Grasses form unique acylated lignins involving p-coumarate (pCA). In corn rind tissue, it is exclusively attached to the gamma-carbon of lignin monomers, with a strong preference (over 90%) for attachment...

  12. Platypus chain reaction: directional and ordered meiotic pairing of the multiple sex chromosome chain in Ornithorhynchus anatinus.

    PubMed

    Daish, Tasman; Casey, Aaron; Grützner, Frank

    2009-01-01

    Monotremes are phylogenetically and phenotypically unique animals with an unusually complex sex chromosome system that is composed of ten chromosomes in platypus and nine in echidna. These chromosomes are alternately linked (X1Y1, X2Y2, ...) at meiosis via pseudoautosomal regions and segregate to form spermatozoa containing either X or Y chromosomes. The physical and epigenetic mechanisms involved in pairing and assembly of the complex sex chromosome chain in early meiotic prophase I are completely unknown. We have analysed the pairing dynamics of specific sex chromosome pseudoautosomal regions in platypus spermatocytes during prophase of meiosis I. Our data show a highly coordinated pairing process that begins at the terminal Y5 chromosome and completes with the union of sex chromosomes X1Y1. The consistency of this ordered assembly of the chain is remarkable and raises questions about the mechanisms and factors that regulate the differential pairing of sex chromosomes and how this relates to potential meiotic silencing mechanisms and alternate segregation. PMID:19874721

  13. Pseudo-enzymatic S-acylation of a myristoylated yes protein tyrosine kinase peptide in vitro may reflect non-enzymatic S-acylation in vivo.

    PubMed Central

    Bañó, M C; Jackson, C S; Magee, A I

    1998-01-01

    Covalent attachment of a variety of lipid groups to proteins is now recognized as a major group of post-translational modifications. S-acylation of proteins at cysteine residues is the only modification considered dynamic and thus has the potential for regulating protein function and/or localization. The activities that catalyse reversible S-acylation have not been well characterized and it is not clear whether both the acylation and the deacylation steps are regulated, since in principle it would be sufficient to control only one of them. Both apparently enzymatic and non-enzymatic S-acylation of proteins have previously been reported. Here we show that a synthetic myristoylated c-Yes protein tyrosine kinase undecapeptide undergoes spontaneous S-acylation in vitro when using a long chain acyl-CoA as acyl donor in the absence of any protein. The S-acylation was dependent on myristoylation of the substrate, the length of the incubation period, temperature and substrate concentration. When COS cell fractions were added to the S-acylation reaction no additional peptide:S-acyltransferase activity was detected. These results are consistent with the possibility that membrane-associated proteins may undergo S-acylation in vivo by non-enzymatic transfer of acyl groups from acyl-CoA. In this case, the S-acylation-deacylation process could be controlled by a regulated depalmitoylation mechanism. PMID:9480882

  14. Oxidative acylation using thioacids

    NASA Technical Reports Server (NTRS)

    Liu, R.; Orgel, L. E.

    1997-01-01

    Several important prebiotic reactions, including the coupling of amino acids into polypeptides by the formation of amide linkages, involve acylation. Theae reactions present a challenge to the understanding of prebiotic synthesis. Condensation reactions relying on dehydrating agents are either inefficient in aqueous solution or require strongly acidic conditions and high temperatures. Activated amino acids such as thioester derivatives have therefore been suggested as likely substrates for prebiotic peptide synthesis. Here we propose a closely related route to amide bond formation involving oxidative acylation by thioacids. We find that phenylalanine, leucine and phenylphosphate are acylated efficiently in aqueous solution by thioacetic acid and an oxidizing agent. From a prebiotic point of view, oxidative acylation has the advantage of proceeding efficiently in solution and under mild conditions. We anticipate that oxidative acylation should prove to be a general method for activating carboxylic acids, including amino acids.

  15. An order insertion scheduling model of logistics service supply chain considering capacity and time factors.

    PubMed

    Liu, Weihua; Yang, Yi; Wang, Shuqing; Liu, Yang

    2014-01-01

    Order insertion often occurs in the scheduling process of logistics service supply chain (LSSC), which disturbs normal time scheduling especially in the environment of mass customization logistics service. This study analyses order similarity coefficient and order insertion operation process and then establishes an order insertion scheduling model of LSSC with service capacity and time factors considered. This model aims to minimize the average unit volume operation cost of logistics service integrator and maximize the average satisfaction degree of functional logistics service providers. In order to verify the viability and effectiveness of our model, a specific example is numerically analyzed. Some interesting conclusions are obtained. First, along with the increase of completion time delay coefficient permitted by customers, the possible inserting order volume first increases and then trends to be stable. Second, supply chain performance reaches the best when the volume of inserting order is equal to the surplus volume of the normal operation capacity in mass service process. Third, the larger the normal operation capacity in mass service process is, the bigger the possible inserting order's volume will be. Moreover, compared to increasing the completion time delay coefficient, improving the normal operation capacity of mass service process is more useful. PMID:25276851

  16. An Order Insertion Scheduling Model of Logistics Service Supply Chain Considering Capacity and Time Factors

    PubMed Central

    Yang, Yi; Wang, Shuqing; Liu, Yang

    2014-01-01

    Order insertion often occurs in the scheduling process of logistics service supply chain (LSSC), which disturbs normal time scheduling especially in the environment of mass customization logistics service. This study analyses order similarity coefficient and order insertion operation process and then establishes an order insertion scheduling model of LSSC with service capacity and time factors considered. This model aims to minimize the average unit volume operation cost of logistics service integrator and maximize the average satisfaction degree of functional logistics service providers. In order to verify the viability and effectiveness of our model, a specific example is numerically analyzed. Some interesting conclusions are obtained. First, along with the increase of completion time delay coefficient permitted by customers, the possible inserting order volume first increases and then trends to be stable. Second, supply chain performance reaches the best when the volume of inserting order is equal to the surplus volume of the normal operation capacity in mass service process. Third, the larger the normal operation capacity in mass service process is, the bigger the possible inserting order's volume will be. Moreover, compared to increasing the completion time delay coefficient, improving the normal operation capacity of mass service process is more useful. PMID:25276851

  17. Acyl-coenzyme A:cholesterol acyltransferases

    PubMed Central

    Chang, Ta-Yuan; Li, Bo-Liang; Chang, Catherine C. Y.; Urano, Yasuomi

    2009-01-01

    The enzymes acyl-coenzyme A (CoA):cholesterol acyltransferases (ACATs) are membrane-bound proteins that utilize long-chain fatty acyl-CoA and cholesterol as substrates to form cholesteryl esters. In mammals, two isoenzymes, ACAT1 and ACAT2, encoded by two different genes, exist. ACATs play important roles in cellular cholesterol homeostasis in various tissues. This chapter summarizes the current knowledge on ACAT-related research in two areas: 1) ACAT genes and proteins and 2) ACAT enzymes as drug targets for atherosclerosis and for Alzheimer's disease. PMID:19141679

  18. Effects of conformational ordering on protein/polyelectrolyte electrostatic complexation: ionic binding and chain stiffening.

    PubMed

    Cao, Yiping; Fang, Yapeng; Nishinari, Katsuyoshi; Phillips, Glyn O

    2016-01-01

    Coupling of electrostatic complexation with conformational transition is rather general in protein/polyelectrolyte interaction and has important implications in many biological processes and practical applications. This work studied the electrostatic complexation between κ-carrageenan (κ-car) and type B gelatin, and analyzed the effects of the conformational ordering of κ-car induced upon cooling in the presence of potassium chloride (KCl) or tetramethylammonium iodide (Me4NI). Experimental results showed that the effects of conformational ordering on protein/polyelectrolyte electrostatic complexation can be decomposed into ionic binding and chain stiffening. At the initial stage of conformational ordering, electrostatic complexation can be either suppressed or enhanced due to the ionic bindings of K(+) and I(-) ions, which significantly alter the charge density of κ-car or occupy the binding sites of gelatin. Beyond a certain stage of conformational ordering, i.e., helix content θ > 0.30, the effect of chain stiffening, accompanied with a rapid increase in helix length ζ, becomes dominant and tends to dissociate the electrostatic complexation. The effect of chain stiffening can be theoretically interpreted in terms of double helix association. PMID:27030165

  19. Effects of conformational ordering on protein/polyelectrolyte electrostatic complexation: ionic binding and chain stiffening

    NASA Astrophysics Data System (ADS)

    Cao, Yiping; Fang, Yapeng; Nishinari, Katsuyoshi; Phillips, Glyn O.

    2016-03-01

    Coupling of electrostatic complexation with conformational transition is rather general in protein/polyelectrolyte interaction and has important implications in many biological processes and practical applications. This work studied the electrostatic complexation between κ-carrageenan (κ-car) and type B gelatin, and analyzed the effects of the conformational ordering of κ-car induced upon cooling in the presence of potassium chloride (KCl) or tetramethylammonium iodide (Me4NI). Experimental results showed that the effects of conformational ordering on protein/polyelectrolyte electrostatic complexation can be decomposed into ionic binding and chain stiffening. At the initial stage of conformational ordering, electrostatic complexation can be either suppressed or enhanced due to the ionic bindings of K+ and I‑ ions, which significantly alter the charge density of κ-car or occupy the binding sites of gelatin. Beyond a certain stage of conformational ordering, i.e., helix content θ > 0.30, the effect of chain stiffening, accompanied with a rapid increase in helix length ζ, becomes dominant and tends to dissociate the electrostatic complexation. The effect of chain stiffening can be theoretically interpreted in terms of double helix association.

  20. Effects of conformational ordering on protein/polyelectrolyte electrostatic complexation: ionic binding and chain stiffening

    PubMed Central

    Cao, Yiping; Fang, Yapeng; Nishinari, Katsuyoshi; Phillips, Glyn O.

    2016-01-01

    Coupling of electrostatic complexation with conformational transition is rather general in protein/polyelectrolyte interaction and has important implications in many biological processes and practical applications. This work studied the electrostatic complexation between κ-carrageenan (κ-car) and type B gelatin, and analyzed the effects of the conformational ordering of κ-car induced upon cooling in the presence of potassium chloride (KCl) or tetramethylammonium iodide (Me4NI). Experimental results showed that the effects of conformational ordering on protein/polyelectrolyte electrostatic complexation can be decomposed into ionic binding and chain stiffening. At the initial stage of conformational ordering, electrostatic complexation can be either suppressed or enhanced due to the ionic bindings of K+ and I− ions, which significantly alter the charge density of κ-car or occupy the binding sites of gelatin. Beyond a certain stage of conformational ordering, i.e., helix content θ > 0.30, the effect of chain stiffening, accompanied with a rapid increase in helix length ζ, becomes dominant and tends to dissociate the electrostatic complexation. The effect of chain stiffening can be theoretically interpreted in terms of double helix association. PMID:27030165

  1. High-order sampling schemes for path integrals and Gaussian chain simulations of polymers

    SciTech Connect

    Müser, Martin H.; Müller, Marcus

    2015-05-07

    In this work, we demonstrate that path-integral schemes, derived in the context of many-body quantum systems, benefit the simulation of Gaussian chains representing polymers. Specifically, we show how to decrease discretization corrections with little extra computation from the usual O(1/P{sup 2}) to O(1/P{sup 4}), where P is the number of beads representing the chains. As a consequence, high-order integrators necessitate much smaller P than those commonly used. Particular emphasis is placed on the questions of how to maintain this rate of convergence for open polymers and for polymers confined by a hard wall as well as how to ensure efficient sampling. The advantages of the high-order sampling schemes are illustrated by studying the surface tension of a polymer melt and the interface tension in a binary homopolymers blend.

  2. Acyl-ACP Substrate Recognition in Burkholderia mallei BmaI1 Acyl-Homoserine Lactone Synthase

    PubMed Central

    2015-01-01

    The acyl-homoserine lactone (AHL) autoinducer mediated quorum sensing regulates virulence in several pathogenic bacteria. The hallmark of an efficient quorum sensing system relies on the tight specificity in the signal generated by each bacterium. Since AHL signal specificity is derived from the acyl-chain of the acyl-ACP (ACP = acyl carrier protein) substrate, AHL synthase enzymes must recognize and react with the native acyl-ACP with high catalytic efficiency while keeping reaction rates with non-native acyl-ACPs low. The mechanism of acyl-ACP substrate recognition in these enzymes, however, remains elusive. In this study, we investigated differences in catalytic efficiencies for shorter and longer chain acyl-ACP substrates reacting with an octanoyl-homoserine lactone synthase Burkholderia mallei BmaI1. With the exception of two-carbon shorter hexanoyl-ACP, the catalytic efficiencies of butyryl-ACP, decanoyl-ACP, and octanoyl-CoA reacting with BmaI1 decreased by greater than 20-fold compared to the native octanoyl-ACP substrate. Furthermore, we also noticed kinetic cooperativity when BmaI1 reacted with non-native acyl-donor substrates. Our kinetic data suggest that non-native acyl-ACP substrates are unable to form a stable and productive BmaI1·acyl-ACP·SAM ternary complex and are thus effectively discriminated by the enzyme. These results offer insights into the molecular basis of substrate recognition for the BmaI1 enzyme. PMID:25215658

  3. The mitogenic activities of phosphatidate are acyl-chain-length dependent and calcium independent in C3H/10T1/2 cells.

    PubMed Central

    Krabak, M J; Hui, S W

    1991-01-01

    Phosphatidates (PA or phosphatidic acid) were shown to have mitogenic properties, including the stimulation of DNA synthesis and calcium mobilization in C3H/10T1/2 cells. Their continuous presence for a minimum of 7 h induced DNA synthesis with kinetics similar to that observed when 10% fetal bovine serum was used as a mitogen. PAs with long chain saturated fatty acid moieties were more mitogenic, in a dose-dependent fashion, than PAs with short saturated or unsaturated fatty acid moieties. When compared with lysostearoyl-PA (LSPA), distearoyl-PA (DSPA) was as potent with respect to the induction of DNA synthesis. Lysooleoyl-PA (LOPA) was slightly more potent than dioleoyl-PA (DOPA), but much weaker than DSPA and LSPA. Preincubation with dilauroyl-PA (DLPA) reduces the mitogenic effect of DSPA by 85%. The pattern of mitogenic inhibition suggests that a chain-length-independent, yet PA-specific, mechanism is involved. Both DSPA and DLPA are equally taken up by the cells after 30 min. LOPA, but not LSPA, produced a large calcium transient (1.3 microM), which we found to be derived from intracellular sources. DSPA, the most mitogenic PA tested, produced a weaker transient (0.6 microM). Interestingly, LSPA did not produce any detectable calcium transient. These results suggest that the chain-length-specific step in the signaling mechanism of PA occurs after the initial chain-length-independent partitioning and/or binding to the membrane and that the induction of DNA synthesis is not related to the observed calcium transients. PMID:2007185

  4. The optimum order of a Markov chain model for daily rainfall in Nigeria

    NASA Astrophysics Data System (ADS)

    Jimoh, O. D.; Webster, P.

    1996-11-01

    Markov type models are often used to describe the occurrence of daily rainfall. Although models of Order 1 have been successfully employed, there remains uncertainty concerning the optimum order for such models. This paper is concerned with estimation of the optimum order of Markov chains and, in particular, the use of objective criteria of the Akaike and Bayesian Information Criteria (AIC and BIC, respectively). Using daily rainfall series for five stations in Nigeria, it has been found that the AIC and BIC estimates vary with month as well as the value of the rainfall threshold used to define a wet day. There is no apparent system to this variation, although AIC estimates are consistently greater than or equal to BIC estimates, with values of the latter limited to zero or unity. The optimum order is also investigated through generation of synthetic sequences of wet and dry days using the transition matrices of zero-, first- and second-order Markov chains. It was found that the first-order model is superior to the zero-order model in representing the characteristics of the historical sequence as judged using frequency duration curves. There was no discernible difference between the model performance for first- and second-order models. There was no seasonal varation in the model performance, which contrasts with the optimum models identified using AIC and BIC estimates. It is concluded that caution is needed with the use of objective criteria for determining the optimum order of the Markov model and that the use of frequency duration curves can provide a robust alternative method of model identification. Comments are also made on the importance of record length and non-stationarity for model identification

  5. Clinical relevance of short-chain acyl-CoA dehydrogenase (SCAD) deficiency: Exploring the role of new variants including the first SCAD-disease-causing allele carrying a synonymous mutation

    PubMed Central

    Tonin, Rodolfo; Caciotti, Anna; Funghini, Silvia; Pasquini, Elisabetta; Mooney, Sean D.; Cai, Binghuang; Proncopio, Elena; Donati, Maria Alice; Baronio, Federico; Bettocchi, Ilaria; Cassio, Alessandra; Biasucci, Giacomo; Bordugo, Andrea; la Marca, Giancarlo; Guerrini, Renzo; Morrone, Amelia

    2016-01-01

    Short-chain acyl-coA dehydrogenase deficiency (SCADD) is an autosomal recessive inborn error of mitochondrial fatty acid oxidation caused by ACADS gene alterations. SCADD is a heterogeneous condition, sometimes considered to be solely a biochemical condition given that it has been associated with variable clinical phenotypes ranging from no symptoms or signs to metabolic decompensation occurring early in life. A reason for this variability is due to SCAD alterations, such as the common p.Gly209Ser, that confer a disease susceptibility state but require a complex multifactorial/polygenic condition to manifest clinically. Our study focuses on 12 SCADD patients carrying 11 new ACADS variants, with the purpose of defining genotype–phenotype correlations based on clinical data, metabolite evaluation, molecular analyses, and in silico functional analyses. Interestingly, we identified a synonymous variant, c.765G > T (p.Gly255Gly) that influences ACADS mRNA splicing accuracy. mRNA characterisation demonstrated that this variant leads to an aberrant splicing product, harbouring a premature stop codon. Molecular analysis and in silico tools are able to characterise ACADS variants, identifying the severe mutations and consequently indicating which patients could benefit from a long term follow- up. We also emphasise that synonymous mutations can be relevant features and potentially associated with SCADD. PMID:27051597

  6. Characterization of the promoter region of the bovine long-chain acyl-CoA synthetase 1 gene: Roles of E2F1, Sp1, KLF15, and E2F4

    PubMed Central

    Zhao, Zhi-Dong; Zan, Lin-Sen; Li, An-Ning; Cheng, Gong; Li, Shi-Jun; Zhang, Ya-Ran; Wang, Xiao-Yu; Zhang, Ying-Ying

    2016-01-01

    The nutritional value and eating qualities of beef are enhanced when the unsaturated fatty acid content of fat is increased. Long-chain acyl-CoA synthetase 1 (ACSL1) plays key roles in fatty acid transport and degradation, as well as lipid synthesis. It has been identified as a plausible functional and positional candidate gene for manipulations of fatty acid composition in bovine skeletal muscle. In the present study, we determined that bovine ACSL1was highly expressed in subcutaneous adipose tissue and longissimus thoracis. To elucidate the molecular mechanisms involved in bovine ACSL1 regulation, we cloned and characterized the promoter region of ACSL1. Applying 5′-rapid amplification of cDNA end analysis (RACE), we identified multiple transcriptional start sites (TSSs) in its promoter region. Using a series of 5′ deletion promoter plasmids in luciferase reporter assays, we found that the proximal minimal promoter of ACSL1 was located within the region −325/−141 relative to the TSS and it was also located in the predicted CpG island. Mutational analysis and electrophoretic mobility shift assays demonstrated that E2F1, Sp1, KLF15 and E2F4 binding to the promoter region drives ACSL1 transcription. Together these interactions integrate and frame a key functional role for ACSL1 in mediating the lipid composition of beef. PMID:26782942

  7. Clinical relevance of short-chain acyl-CoA dehydrogenase (SCAD) deficiency: Exploring the role of new variants including the first SCAD-disease-causing allele carrying a synonymous mutation.

    PubMed

    Tonin, Rodolfo; Caciotti, Anna; Funghini, Silvia; Pasquini, Elisabetta; Mooney, Sean D; Cai, Binghuang; Proncopio, Elena; Donati, Maria Alice; Baronio, Federico; Bettocchi, Ilaria; Cassio, Alessandra; Biasucci, Giacomo; Bordugo, Andrea; la Marca, Giancarlo; Guerrini, Renzo; Morrone, Amelia

    2016-06-01

    Short-chain acyl-coA dehydrogenase deficiency (SCADD) is an autosomal recessive inborn error of mitochondrial fatty acid oxidation caused by ACADS gene alterations. SCADD is a heterogeneous condition, sometimes considered to be solely a biochemical condition given that it has been associated with variable clinical phenotypes ranging from no symptoms or signs to metabolic decompensation occurring early in life. A reason for this variability is due to SCAD alterations, such as the common p.Gly209Ser, that confer a disease susceptibility state but require a complex multifactorial/polygenic condition to manifest clinically. Our study focuses on 12 SCADD patients carrying 11 new ACADS variants, with the purpose of defining genotype-phenotype correlations based on clinical data, metabolite evaluation, molecular analyses, and in silico functional analyses. Interestingly, we identified a synonymous variant, c.765G > T (p.Gly255Gly) that influences ACADS mRNA splicing accuracy. mRNA characterisation demonstrated that this variant leads to an aberrant splicing product, harbouring a premature stop codon. Molecular analysis and in silico tools are able to characterise ACADS variants, identifying the severe mutations and consequently indicating which patients could benefit from a long term follow- up. We also emphasise that synonymous mutations can be relevant features and potentially associated with SCADD. PMID:27051597

  8. A Genetically Amenable Platensimycin- and Platencin- Overproducer as a Platform for Biosynthetic Explorations: a Showcase of PtmO4, a Long-Chain Acyl-CoA Dehydrogenase

    PubMed Central

    Rudolf, Jeffrey D.; Dong, Liao-Bin; Huang, Tingting; Shen, Ben

    2015-01-01

    Platensimycin (PTM) and platencin (PTN) are members of a new class of promising drug leads that target bacterial and mammalian fatty acid synthases. We previously cloned and sequenced the PTM and PTN gene clusters, discovered six additional PTM-PTN dual producing strains, and demonstrated the dramatic overproduction of PTM and PTN by inactivating the pathway-specific regulators ptmR1 or ptnR1 in four different strains. Our ability to utilize these PTM-PTN dual overproducing strains was limited by their lack of genetic amenability. Here we report the construction of Streptomyces platensis SB12029, a genetically amenable, in-frame ΔptmR1 dual PTM-PTN overproducing strain. To highlight the potential of this strain for future PTM and PTN biosynthetic studies, we created the ΔptmR1 ΔptmO4 double mutant S. platensis SB12030. Fourteen PTM and PTN congeners, ten of which were new, were isolated from SB12030, shedding new insights into PTM and PTN biosynthesis. PtmO4, a long-chain acyl-CoA dehydrogenase, is strongly implicated to catalyze β-oxidation of the diterpenoid intermediates in to the PTM and PTN scaffolds. SB12029 sets the stage for future biosynthetic and bioengineering studies of the PTM and PTN family of natural products. PMID:26055255

  9. Dynamical behavior of fractional-order Hastings-Powell food chain model and its discretization

    NASA Astrophysics Data System (ADS)

    Matouk, A. E.; Elsadany, A. A.; Ahmed, E.; Agiza, H. N.

    2015-10-01

    In this work, the dynamical behavior of fractional-order Hastings-Powell food chain model is investigated and a new discretization method of the fractional-order system is introduced. A sufficient condition for existence and uniqueness of the solution of the proposed system is obtained. Local stability of the equilibrium points of the fractional-order system is studied. Furthermore, the necessary and sufficient conditions of stability of the discretized system are also studied. It is shown that the system's fractional parameter has effect on the stability of the discretized system which shows rich variety of dynamical behaviors such as Hopf bifurcation, an attractor crisis and chaotic attractors. Numerical simulations show the tea-cup chaotic attractor of the fractional-order system and the richer dynamical behavior of the corresponding discretized system.

  10. Fluorescently labelled bovine acyl-CoA-binding protein acting as an acyl-CoA sensor: interaction with CoA and acyl-CoA esters and its use in measuring free acyl-CoA esters and non-esterified fatty acids.

    PubMed Central

    Wadum, Majken C T; Villadsen, Jens K; Feddersen, Søren; Møller, Rikke S; Neergaard, Thomas B F; Kragelund, Birthe B; Højrup, Peter; Faergeman, Nils J; Knudsen, Jens

    2002-01-01

    Long-chain acyl-CoA esters are key metabolites in lipid synthesis and beta-oxidation but, at the same time, are important regulators of intermediate metabolism, insulin secretion, vesicular trafficking and gene expression. Key tools in studying the regulatory functions of acyl-CoA esters are reliable methods for the determination of free acyl-CoA concentrations. No such method is presently available. In the present study, we describe the synthesis of two acyl-CoA sensors for measuring free acyl-CoA concentrations using acyl-CoA-binding protein as a scaffold. Met24 and Ala53 of bovine acyl-CoA-binding protein were replaced by cysteine residues, which were covalently modified with 6-bromoacetyl-2-dimethylaminonaphthalene to make the two fluorescent acyl-CoA indicators (FACIs) FACI-24 and FACI-53. FACI-24 and FACI-53 showed fluorescence emission maximum at 510 and 525 nm respectively, in the absence of ligand (excitation 387 nm). Titration of FACI-24 and FACI-53 with hexadecanoyl-CoA and dodecanoyl-CoA increased the fluorescence yield 5.5-and 4.7-fold at 460 and 495 nm respectively. FACI-24 exhibited a high, and similar increase in, fluorescence yield at 460 nm upon binding of C14-C20 saturated and unsaturated acyl-CoA esters. Both indicators bind long-chain (>C14) acyl-CoA esters with high specificity and affinity (K(d)=0.6-1.7 nM). FACI-53 showed a high fluorescence yield for C8-C12 acyl chains. It is shown that FACI-24 acts as a sensitive acyl-CoA sensor for measuring the concentration of free acyl-CoA, acyl-CoA synthetase activity and the concentrations of free fatty acids after conversion of the fatty acid into their respective acyl-CoA esters. PMID:12071849

  11. First and second order semi-Markov chains for wind speed modeling

    NASA Astrophysics Data System (ADS)

    Prattico, F.; Petroni, F.; D'Amico, G.

    2012-04-01

    The increasing interest in renewable energy leads scientific research to find a better way to recover most of the available energy. Particularly, the maximum energy recoverable from wind is equal to 59.3% of that available (Betz law) at a specific pitch angle and when the ratio between the wind speed in output and in input is equal to 1/3. The pitch angle is the angle formed between the airfoil of the blade of the wind turbine and the wind direction. Old turbine and a lot of that actually marketed, in fact, have always the same invariant geometry of the airfoil. This causes that wind turbines will work with an efficiency that is lower than 59.3%. New generation wind turbines, instead, have a system to variate the pitch angle by rotating the blades. This system able the wind turbines to recover, at different wind speed, always the maximum energy, working in Betz limit at different speed ratios. A powerful system control of the pitch angle allows the wind turbine to recover better the energy in transient regime. A good stochastic model for wind speed is then needed to help both the optimization of turbine design and to assist the system control to predict the value of the wind speed to positioning the blades quickly and correctly. The possibility to have synthetic data of wind speed is a powerful instrument to assist designer to verify the structures of the wind turbines or to estimate the energy recoverable from a specific site. To generate synthetic data, Markov chains of first or higher order are often used [1,2,3]. In particular in [3] is presented a comparison between a first-order Markov chain and a second-order Markov chain. A similar work, but only for the first-order Markov chain, is conduced by [2], presenting the probability transition matrix and comparing the energy spectral density and autocorrelation of real and synthetic wind speed data. A tentative to modeling and to join speed and direction of wind is presented in [1], by using two models, first-order

  12. Thermal stability and ordering study of long- and short-alkyl chain phosphonic acid multilayers.

    PubMed

    de Pauli, Muriel; Prado, Mariana de Castro; Matos, Matheus Josue Souza; Fontes, Giselle Nogueira; Perez, Carlos Alberto; Mazzoni, Mario Sergio Carvalho; Neves, Bernardo Ruegger Almeida; Malachias, Angelo

    2012-10-30

    Long-range order evolution of self-assembled phosphonic acid multilayers as a function of temperature is studied here for two molecules with different alkyl chain length. By using synchrotron conventional diffraction, distinct order configurations are retrieved on phosphonic acid multilayers and their thermodynamic behavior monitored by energy-dispersive diffraction. This later technique allows us to observe the system behavior near order-disorder temperatures, as well as to determine the most stable configurations in the range from room temperature up to 120 °C. Planar order is also addressed by wide-angle X-ray scattering (WAXS) transmission experiments. Order parameter phase diagrams are built based on the experimental results, showing the dominant configuration at each temperature. The multilayer molecular long-range order retrieved from the experiments is corroborated by first principles calculations based on the Density Functional Theory. The bulk configurations depicted in this work are produced by molecule-molecule interactions and allow for future comparisons with the behavior of ordered molecules in few-monolayers configurations, commonly used in organic devices, where the presence of surfaces and interfaces strongly affects the molecule packing. PMID:23009090

  13. Reinforcing Lipid A Acylation on the Cell Surface of Acinetobacter baumannii Promotes Cationic Antimicrobial Peptide Resistance and Desiccation Survival

    PubMed Central

    Boll, Joseph M.; Tucker, Ashley T.; Klein, Dustin R.; Beltran, Alexander M.; Brodbelt, Jennifer S.; Davies, Bryan W.

    2015-01-01

    ABSTRACT Acinetobacter baumannii is an emerging Gram-negative pathogen found in hospitals and intensive care units. In order to persist in hospital environments, A. baumannii withstands desiccative conditions and can rapidly develop multidrug resistance to conventional antibiotics. Cationic antimicrobial peptides (CAMPs) have served as therapeutic alternatives because they target the conserved lipid A component of the Gram-negative outer membrane to lyse the bacterial cell. However, many Gram-negative pathogenic bacteria, including A. baumannii, fortify their outer membrane with hepta-acylated lipid A to protect the cell from CAMP-dependent cell lysis. Whereas in Escherichia coli and Salmonella, increased production of the outer membrane acyltransferase PagP results in formation of protective hepta-acylated lipid A, which reinforces the lipopolysaccharide portion of the outer membrane barrier, A. baumannii does not carry a gene that encodes a PagP homolog. Instead, A. baumannii has evolved a PagP-independent mechanism to synthesize protective hepta-acylated lipid A. Taking advantage of a recently adapted A. baumannii genetic recombineering system, we characterized two putative acyltransferases in A. baumannii designated LpxLAb (A. baumannii LpxL) and LpxMAb (A. baumannii LpxM), which transfer one and two lauroyl (C12:0) acyl chains, respectively, during lipid A biosynthesis. Hepta-acylation of A. baumannii lipid A promoted resistance to vertebrate and polymyxin CAMPs, which are prescribed as last-resort treatment options. Intriguingly, our analysis also showed that LpxMAb-dependent acylation of lipid A is essential for A. baumannii desiccation survival, a key resistance mechanism for survival in hospital environments. Compounds that inhibit LpxMAb-dependent hepta-acylation of lipid A could act synergistically with CAMPs to provide innovative transmission prevention strategies and treat multidrug-resistant infections. PMID:25991684

  14. Effect of the non-steroidal anti-inflammatory drugs on the acyl-CoA synthetase activity toward medium-chain, long-chain and polyunsaturated fatty acids in mitochondria of mouse liver and brain.

    PubMed

    Kasuya, Fumiyo; Kazuhiro, Misumi; Tatsuya, Hasegawa; Nakamoto, Kazuo; Tokuyama, Shogo; Masuyama, Teiichi

    2013-02-01

    Effect of eleven non-steroidal anti-inflammatory drugs on the acyl-CoA synthetase activities toward octanoic, palmitic, arachidonic and docosahexaenoic acids was evaluated in mouse liver and brain mitochondria. The drugs tested were aspirin, salicylic acid, diflunisal, mefenamic acid, indomethacin, etodolac, ibuprofen, ketoprofen, naproxen, loxoprofen, flurbiprofen. In mouse liver mitochondria, diflunisal and mefenamic acid exhibited the inhibitory activities not only for octanoic acid (IC(50) = 78.7 and 64.7 µM) and but also for palmitic acid (IC(50) = 236.5 and 284.4 µM), respectively. Aspirin was an inhibitor for the activation of octanoic acid only (IC(50) = 411.0 µM). In the brain, mefenamic acid and diflunisal inhibited strongly palmitoyl-CoA formation (IC(50) = 57.3 and 114.0 µM), respectively. The activation of docosahexaenoic acid in brain was sensitive to inhibition by diflunisal and mefenamic acid compared with liver. PMID:22299587

  15. Characterization of the "Escherichia Coli" Acyl Carrier Protein Phosphodiesterase

    ERIC Educational Resources Information Center

    Thomas, Jacob

    2009-01-01

    Acyl carrier protein (ACP) is a small essential protein that functions as a carrier of the acyl intermediates of fatty acid synthesis. ACP requires the posttranslational attachment of a 4'phosphopantetheine functional group, derived from CoA, in order to perform its metabolic function. A Mn[superscript 2+] dependent enzymatic activity that removes…

  16. Essential role of the donor acyl carrier protein in stereoselective chain translocation to a fully reducing module of the nanchangmycin polyketide synthase.

    PubMed

    Guo, Xun; Liu, Tiangang; Deng, Zixin; Cane, David E

    2012-01-31

    Incubation of recombinant module 2 of the polyether nanchangmycin synthase (NANS), carrying an appended thioesterase domain, with the ACP-bound substrate (2RS)-2-methyl-3-ketobutyryl-NANS_ACP1 (2-ACP1) and methylmalonyl-CoA in the presence of NADPH gave diastereomerically pure (2S,4R)-2,4-dimethyl-5-ketohexanoic acid (4a). These results contrast with the previously reported weak discrimination by NANS module 2+TE between the enantiomers of the corresponding N-acetylcysteamine-conjugated substrate analogue (±)-2-methyl-3-ketobutyryl-SNAC (2-SNAC), which resulted in formation of a 5:3 mixture of 4a and its (2S,4S)-diastereomer 4b. Incubation of NANS module 2+TE with 2-ACP1 in the absence of NADPH gave unreduced 3,5,6-trimethyl-4-hydroxypyrone (3) with a k(cat) of 4.4 ± 0.9 min⁻¹ and a k(cat)/K(m) of 67 min⁻¹ mM⁻¹, corresponding to a ∼2300-fold increase compared to the k(cat)/K(m) for the diffusive substrate 2-SNAC. Covalent tethering of the 2-methyl-3-ketobutyryl thioester substrate to the NANS ACP1 domain derived from the natural upstream PKS module of the nanchangmycin synthase significantly enhanced both the stereospecificity and the kinetic efficiency of the sequential polyketide chain translocation and condensation reactions catalyzed by the ketosynthase domain of NANS module 2. PMID:22229794

  17. Engineering a Disulfide Bond in the Lid Hinge Region of Rhizopus chinensis Lipase: Increased Thermostability and Altered Acyl Chain Length Specificity

    PubMed Central

    Yu, Xiao-Wei; Tan, Nian-Jiang; Xiao, Rong; Xu, Yan

    2012-01-01

    The key to enzyme function is the maintenance of an appropriate balance between molecular stability and structural flexibility. The lid domain which is very important for “interfacial activation” is the most flexible part in the lipase structure. In this work, rational design was applied to explore the relationship between lid rigidity and lipase activity by introducing a disulfide bond in the hinge region of the lid, in the hope of improving the thermostability of R. chinensis lipase through stabilization of the lid domain without interfering with its catalytic performance. A disulfide bridge between F95C and F214C was introduced into the lipase from R. chinensis in the hinge region of the lid according to the prediction of the “Disulfide by Design” algorithm. The disulfide variant showed substantially improved thermostability with an eleven-fold increase in the t1/2 value at 60°C and a 7°C increase of Tm compared with the parent enzyme, probably contributed by the stabilization of the geometric structure of the lid region. The additional disulfide bond did not interfere with the catalytic rate (kcat) and the catalytic efficiency towards the short-chain fatty acid substrate, however, the catalytic efficiency of the disulfide variant towards pNPP decreased by 1.5-fold probably due to the block of the hydrophobic substrate channel by the disulfide bond. Furthermore, in the synthesis of fatty acid methyl esters, the maximum conversion rate by RCLCYS reached 95% which was 9% higher than that by RCL. This is the first report on improving the thermostability of the lipase from R. chinensis by introduction of a disulfide bond in the lid hinge region without compromising the catalytic rate. PMID:23056295

  18. Non-chain pulsed DF laser with an average power of the order of 100 W

    NASA Astrophysics Data System (ADS)

    Pan, Qikun; Xie, Jijiang; Wang, Chunrui; Shao, Chunlei; Shao, Mingzhen; Chen, Fei; Guo, Jin

    2016-07-01

    The design and performance of a closed-cycle repetitively pulsed DF laser are described. The Fitch circuit and thyratron switch are introduced to realize self-sustained volume discharge in SF6-D2 mixtures. The influences of gas parameters and charging voltage on output characteristics of non-chain pulsed DF laser are experimentally investigated. In order to improve the laser power stability over a long period of working time, zeolites with different apertures are used to scrub out the de-excitation particles produced in electric discharge. An average output power of the order of 100 W was obtained at an operating repetition rate of 50 Hz, with amplitude difference in laser pulses <8 %. And under the action of micropore alkaline zeolites, the average power fell by 20 % after the laser continuing working 100 s at repetition frequency of 50 Hz.

  19. Ordering of anisotropic polarizable polymer chains on the full many-body level.

    PubMed

    Dean, David S; Podgornik, Rudolf

    2012-04-21

    We study the effect of dielectric anisotropy of polymers on their equilibrium ordering within mean-field theory, but with a formalism that takes into account the full n-body nature of van der Waals (vdW) forces. Dielectric anisotropy within polymers is to be expected as the electronic properties of the polymer will typically be different along the polymer than across its cross section. It is therefore physically intuitive that larger charge fluctuations can be induced along the chain than perpendicular to it. We show that this dielectric anisotropy leads to n-body interactions which can induce an isotropic-nematic transition. The two body and three body components of the full vdW interaction are extracted and it is shown how the two body term behaves like the phenomenological self-aligning-pairwise nematic interaction. At the three body interaction level we see that the nematic phase that is energetically favorable is discotic, however, on the full n-body interaction level we find that the normal axial nematic phase is always the stable ordered phase. The n-body nature of our approach also shows that the key parameter driving the nematic-isotropic transition is the bare persistence length of the polymer chain. PMID:22519348

  20. Enzymatic acylation of starch.

    PubMed

    Alissandratos, Apostolos; Halling, Peter J

    2012-07-01

    Starch a cheap, abundant and renewable natural material has been chemically modified for many years. The popular modification acylation has been used to adjust rheological properties as well as deliver polymers with internal plasticizers and other potential uses. However the harsh reaction conditions required to produce these esters may limit their use, especially in sensitive applications (foods, pharmaceuticals, etc.). The use of enzymes to catalyse acylation may provide a suitable alternative due to high selectivities and mild reaction conditions. Traditional hydrolase-catalysed synthesis in non-aqueous apolar media is hard due to lack of polysaccharide solubility. However, acylated starch derivatives have recently been successfully produced in other non-conventional systems: (a) surfactant-solubilised subtilisin and suspended amylose in organic media; (b) starch nanoparticles dispersed in organic medium with immobilised lipase; (c) aqueous starch gels with lipase and dispersed fatty acids. We attempt a systematic review that draws parallels between the seemingly unrelated approaches described. PMID:22138593

  1. Nonideal mixing and phase separation in phosphatidylcholine-phosphatidic acid mixtures as a function of acyl chain length and pH.

    PubMed Central

    Garidel, P; Johann, C; Blume, A

    1997-01-01

    The miscibilities of phosphatidic acids (PAs) and phosphatidylcholines (PCs) with different chain lengths (n = 14, 16) at pH 4, pH 7, and pH 12 were examined by differential scanning calorimetry. Simulation of heat capacity curves was performed using a new approach that incorporates changes of cooperativity of the transition in addition to nonideal mixing in the gel and the liquid-crystalline phase as a function of composition. From the simulations of the heat capacity curves, first estimates for the nonideality parameters for nonideal mixing as a function of composition were obtained, and phase diagrams were constructed using temperatures for onset and end of melting, which were corrected for the broadening effect caused by a decrease in cooperativity. In all cases the composition dependence of the nonideality parameters indicated nonsymmetrical mixing behavior. The phase diagrams were therefore further refined by simulations of the coexistence curves using a four-parameter approximation to account for nonideal and nonsymmetrical mixing in the gel and the liquid-crystalline phase. The mixing behavior was studied at three different pH values to investigate how changes in headgroup charge of the PA influences the miscibility. The experiments showed that at pH 7, where the PA component is negatively charged, the nonideality parameters are in most cases negative, indicating that electrostatic effects favor a mixing of the two components. Partial protonation of the PA component at pH 4 leads to strong changes in miscibility; the nonideality parameters for the liquid-crystalline phase are now in most cases positive, indicating clustering of like molecules. The phase diagram for 1,2-dimyristoyl-sn-glycero-3-phosphatidic acid:1,2-dipalmitoyl-sn-glycero-3-phosphorylcholine mixtures at pH 4 indicates that a fluid-fluid immiscibility is likely. The results show that a decrease in ionization of PAs can induce large changes in mixing behavior. This occurs because of a

  2. A pleiotropic element in the medium-chain acyl coenzyme A dehydrogenase gene promoter mediates transcriptional regulation by multiple nuclear receptor transcription factors and defines novel receptor-DNA binding motifs.

    PubMed Central

    Carter, M E; Gulick, T; Moore, D D; Kelly, D P

    1994-01-01

    We previously identified a complex regulatory element in the medium-chain acyl coenzyme A dehydrogenase gene promoter that confers transcriptional regulation by the retinoid receptors RAR and RXR and the orphan nuclear receptor HNF-4. In this study we demonstrate a trans-repressing regulatory function for the orphan receptor COUP-TF at this same nuclear receptor response element (NRRE-1). The transcriptional regulatory properties and receptor binding sequences of each nuclear receptor response element within NRRE-1 are also characterized. NRRE-1 consists of four potential nuclear hormone receptor hexamer binding sites, arranged as [<--1-(n)s-2-->-3-->(n)4<--4], three of which are used in alternative pairwise binding by COUP-TF and HNF-4 homodimers and by RAR-RXR heterodimers, as demonstrated by mobility shift assays and methylation interference analysis. Binding and transactivation studies with mutant NRRE-1 elements confirmed the existence of distinct retinoid, COUP-TF, and HNF-4 response elements that define novel receptor binding motifs: COUP-TF homodimers bound sites 1 and 3 (two hexamer repeat sequences arranged as an everted imperfect repeat separated by 14 bp or ER14), RAR-RXR heterodimers bound sites 1 and 2 (ER8), and HNF-4 homodimers bound sites 2 and 3 (imperfect DR0). Mixing cotransfection experiments demonstrated that the nuclear receptor dimers compete at NRRE-1 to modulate constitutive and ligand-mediated transcriptional activity. These data suggest a mechanism for the transcriptional modulation of genes encoding enzymes involved in cellular metabolism. Images PMID:8007945

  3. Exact ground states and topological order in interacting Kitaev/Majorana chains

    NASA Astrophysics Data System (ADS)

    Katsura, Hosho; Schuricht, Dirk; Takahashi, Masahiro

    2015-09-01

    We study a system of interacting spinless fermions in one dimension that, in the absence of interactions, reduces to the Kitaev chain [Kitaev, Phys. Usp. 44, 131 (2001), 10.1070/1063-7869/44/10S/S29]. In the noninteracting case, a signal of topological order appears as zero-energy modes localized near the edges. We show that the exact ground states can be obtained analytically even in the presence of nearest-neighbor repulsive interactions when the on-site (chemical) potential is tuned to a particular function of the other parameters. As with the noninteracting case, the obtained ground states are twofold degenerate and differ in fermionic parity. We prove the uniqueness of the obtained ground states and show that they can be continuously deformed to the ground states of the noninteracting Kitaev chain without gap closing. We also demonstrate explicitly that there exists a set of operators each of which maps one of the ground states to the other with opposite fermionic parity. These operators can be thought of as an interacting generalization of Majorana edge zero modes.

  4. Disorder from order among anisotropic next-nearest-neighbor Ising spin chains in SrHo2O4

    DOE PAGESBeta

    Wen, J. -J.; Tian, W.; Garlea, V. O.; Koohpayeh, S. M.; McQueen, T. M.; Li, H. -F.; Yan, J. -Q.; Rodriguez-Rivera, J. A.; Vaknin, D.; Broholm, C. L.

    2015-02-26

    In this study, we describe why Ising spin chains with competing interactions in SrHo2O4 segregate into ordered and disordered ensembles at low temperatures (T). Using elastic neutron scattering, magnetization, and specific heat measurements, the two distinct spin chains are inferred to have Néel (↑↓↑↓) and double-Néel (↑↑↓↓) ground states, respectively. Below TN = 0.68(2)K, the Néel chains develop three-dimensional long range order (LRO), which arrests further thermal equilibration of the double-Néel chains so they remain in a disordered incommensurate state for T below TS = 0.52(2)K. SrHo2O4 distills an important feature of incommensurate low dimensional magnetism: kinetically trapped topological defectsmore » in a quasi–d–dimensional spin system can preclude order in d + 1 dimensions.« less

  5. Acylation of lysolecithin in the intestinal mucosa of rats

    PubMed Central

    Subbaiah, P. V.; Sastry, P. S.; Ganguly, J.

    1970-01-01

    1. The presence of an active acyl-CoA–lysolecithin (1-acylglycerophosphorylcholine) acyltransferase was demonstrated in rat intestinal mucosa. 2. ATP and CoA were necessary for the incorporation of free [1-14C]oleic acid into lecithin (phosphatidylcholine). 3. The reaction was about 20 times as fast with [1-14C]oleoyl-CoA as with free oleic acid, CoA and ATP. 4. With 1-acylglycerophosphorylcholine as the acceptor, both oleic acid and palmitic acid were incorporated into the β-position of lecithin; the incorporation of palmitic acid was 60% of that of oleic acid. 5. Of the various analogues of lysolecithin tested as acyl acceptors from [1-14C]oleoyl CoA, a lysolecithin with a long-chain fatty acid at the 1-position was most efficient. 6. The enzyme was mostly present in the brush-border-free particulate fraction of the intestinal mucosa. 7. Of the various tissues of rats tested for the activity, intestinal mucosa was found to be the most active, with testes, liver, kidneys and spleen following it in decreasing order. PMID:5484668

  6. Separation and quantification of 2-acyl-1-lysophospholipids and 1-acyl-2-lysophospholipids in biological samples by LC-MS/MS

    PubMed Central

    Okudaira, Michiyo; Inoue, Asuka; Shuto, Akira; Nakanaga, Keita; Kano, Kuniyuki; Makide, Kumiko; Saigusa, Daisuke; Tomioka, Yoshihisa; Aoki, Junken

    2014-01-01

    Lysophospholipids (LysoGPs) serve as lipid mediators and precursors for synthesis of diacyl phospholipids (GPs). LysoGPs detected in cells have various acyl chains attached at either the sn-1 or sn-2 position of the glycerol backbone. In general, acyl chains at the sn-2 position of 2-acyl-1-LysoGPs readily move to the sn-1 position, generating 1-acyl-2-lyso isomers by a nonenzymatic reaction called intra-molecular acyl migration, which has hampered the detection of 2-acyl-1-LysoGPs in biological samples. In this study, we developed a simple and versatile method to separate and quantify 2-acyl-1- and 1-acyl-2-LysoGPs. The main point of the method was to extract LysoGPs at pH 4 and 4°C, conditions that were found to completely eliminate the intra-molecular acyl migration. Under the present conditions, the relative amounts of 2-acyl-1-LysoGPs and 1-acyl-2-LysoGPs did not change at least for 1 week. Further, in LysoGPs extracted from cells and tissues under the present conditions, most of the saturated fatty acids (16:0 and 18:0) were found in the sn-1 position of LysoGPs, while most of the PUFAs (18:2, 20:4, 22:6) were found in the sn-2 position. Thus the method can be used to elucidate the in vivo role of 2-acyl-1-LysoGPs. PMID:25114169

  7. The natural history of elevated tetradecenoyl-L-carnitine detected by newborn screening in New Zealand: implications for very long chain acyl-CoA dehydrogenase deficiency screening and treatment.

    PubMed

    Ryder, Bryony; Knoll, Detlef; Love, Donald R; Shepherd, Phillip; Love, Jennifer M; Reed, Peter W; de Hora, Mark; Webster, Dianne; Glamuzina, Emma; Wilson, Callum

    2016-05-01

    Very long chain acyl-CoA dehydrogenase deficiency (VLCADD, OMIM #201475) has been increasingly diagnosed since the advent of expanded newborn screening (NBS). Elevated levels of tetradecenoyl-L-carnitine (C14:1) in newborn screening blood spot samples are particularly common in New Zealand, however this has not translated into increased VLCADD clinical presentations. A high proportion of screen-positive cases in NZ are of Maori or Pacific ethnicity and positive for the c.1226C > T (p.Thr409Met) ACADVL gene variant. We performed a retrospective, blinded, case-control study of 255 cases, born between 2006 and 2013, with elevated NBS C14:1 levels between 0.9 and 2.4 μmol/L, below the NZ C14:1 notification cut-off of 2.5 μmol/L. Coded healthcare records were audited for cases and age- and ethnicity- matched controls. The clinical records of those with possible VLCADD-related symptoms were reviewed. The follow-up period was 6 months to 7 years. Two of 247 cases (0.8 %) had possible VLCADD-like symptoms while four of 247 controls (2 %) had VLCADD-like symptoms (p = 0.81). Maori were overrepresented (68 % of the cohort vs 15 % of population). Targeted analysis of the c.1226 locus revealed the local increase in screening C14:1 levels is associated with the c.1226C > T variant (97/152 alleles tested), found predominantly in Maori and Pacific people. There was no increase in clinically significant childhood disease, irrespective of ethnicity. The study suggests that children with elevated C14:1, between 0.9-2.4 μmol/L, on NBS are at very low risk of clinically significant childhood disease. A minimally interventional approach to managing these patients is indicated, at least in the New Zealand population. PMID:26743058

  8. Orientational Ordering of Carotenoids in Myelin Membranes Resolved by Polarized Raman Microspectroscopy

    PubMed Central

    Kutuzov, Nikolay P.; Brazhe, Alexey R.; Maksimov, Georgy V.; Dracheva, Olga E.; Lyaskovskiy, Vladimir L.; Bulygin, Fedor V.; Rubin, Andrey B.

    2014-01-01

    We study orientational ordering of membrane compounds in the myelinated nerve fiber by means of polarized Raman microspectroscopy. The theory of orientational distribution functions was adapted to live-cell measurements. The obtained orientational distribution functions of carotenoids and lipid acyl chain clearly indicated a predominantly radial-like orientation in membranes of the myelin. Two-dimensional Raman images, made under optimal polarization of incident laser beam, corroborated the proposed carotenoid orientation within the bilayer. Experimental data suggested the tilted orientation of both carotenoid polyenic and lipid acyl chains. The values of maximum tilt angles were similar, with possible implication of carotenoid-induced ordering effect on lipid acyl chains, and hence change of myelin membrane properties. This study stages carotenoids of the nerve as possible mediators of excitation and leverages underlying activity-dependent membrane reordering. PMID:25140424

  9. Acyl-acyl carrier protein: Lysomonogalactosyldiacylglycerol acyl transferase in Anabaena variabilis

    SciTech Connect

    Chen, H.H.

    1989-01-01

    Monogalactosyldiacylglycerol was produced when membranes isolated from the cyanobacterium, Anabaena variabilis, and washed free of soluble endogenous constituents, were incubated with ({sup 14}C)acyl-acyl carrier protein. This enzymatic synthesis of monogalactosyldiacylglycerol localized in the membranes was not dependent on any added cofactors, such as ATP, coenzyme A, and dithiothreitol. Palmitoyl-, stearoyl-, and oleoyl-acyl carrier proteins were approximately equally active as substrates with Km of 0.37, 0.36, and 0.23 {mu}M, respectively. The ({sup 14}C)acyl group was exclusively transferred to the sn-1 hydroxyl of the glycerol backbone of monogalactosyldiacylglycerol as demonstrated by hydrolysis of all incorporated acyl groups by the lipase from Rhizopus arrhizus delamar. Using a double labelled ({sup 14}C)acyl-({sup 14}C)acyl carrier protein, this enzyme catalyzed the direct transfer of the acyl group from acyl-acyl carrier protein to an endogenous lysomonogalactosyldiacylglycerol to form monogalactosyldiacylglycerol. The transfer reaction mechanism was also confirmed by the increased activity with the addition of the lysomonogalactosyldiacylglycerol suspension. A specific galactolipid acyl hydrolase activity was released into the soluble protein fraction when the membranes of Anabaena variabilis were treated with 2% Triton X-100. The positional specificity of this acyl hydrolase was demonstrated to be similar to that of Rhizopus lipase, i.e. only the acyl group at the sn-1 position was hydrolyzed. The acyl hydrolase which was also localized in the membrane fraction of Anabaena variabilis was presumably responsible for producing endogenous lysomonogalactosyldiacylglycerol used by the acyltransferase.

  10. Biochemical analysis of the substrate specificity of the beta-ketoacyl-acyl carrier protein synthase domain of module 2 of the erythromycin polyketide synthase.

    PubMed

    Wu, Jiaquan; Kinoshita, Kenji; Khosla, Chaitan; Cane, David E

    2004-12-28

    The beta-ketoacyl-acyl carrier protein synthase (KS) domain of the modular 6-deoxyerythronolide B synthase (DEBS) catalyzes the fundamental chain building reaction of polyketide biosynthesis. The KS-catalyzed reaction involves two discrete steps consisting of formation of an acyl-enzyme intermediate generated from the incoming acylthioester substrate and an active site cysteine residue, and the conversion of this intermediate to the beta-ketoacyl-acyl carrier protein product by a decarboxylative condensation with a paired methylmalonyl-SACP. We have determined the rate constants for the individual biochemical steps by a combination of protein acylation and transthioesterification experiments. The first-order rate constant (k(2)) for formation of the acyl-enzyme intermediate from [1-(14)C]-(2S,3R)-2-methyl-3-hydroxypentanoyl-SNAC (2) and recombinant DEBS module 2 is 5.8 +/- 2.6 min(-)(1), with a dissociation constant (K(S)) of 3.5 +/- 2.8 mM. The acyl-enzyme adduct was formed at a near-stoichiometric ratio of approximately 0.8:1. Transthioesterification between unlabeled diketide-SNAC 2 and N-[1-(14)C-acetyl]cysteamine gave a k(exch) of 0.15 +/- 0.06 min(-)(1), with a K(m) for HSNAC of 5.7 +/- 4.9 mM and a K(m) for 2 of 5.3 +/- 0.9 mM. Under the conditions that were used, k(exch) was equal to k(-)(2), the first-order rate constant for reversal of the acyl-enzyme-forming reaction. Since the rate of the decarboxylative condensation is much greater that the rate of reversion to the starting material (k(3) > k(-)(2)), formation of the acyl-enzyme adduct is effectively irreversible, thereby establishing that the observed value of the specificity constant (k(cat)/K(m)) is solely a reflection of the intrinsic substrate specificity of the KS-catalyzed acyl-enzyme-forming reaction. These findings were also extended to a panel of diketide- and triketide-SNAC analogues, revealing that some substrate analogues that are not converted to product by DEBS module 2 form dead

  11. Chain-based order and quantum spin liquids in dipolar spin ice

    NASA Astrophysics Data System (ADS)

    McClarty, P. A.; Sikora, O.; Moessner, R.; Penc, K.; Pollmann, F.; Shannon, N.

    2015-09-01

    Recent experiments on the spin-ice material Dy2Ti2O7 suggest that the Pauling "ice entropy," characteristic of its classical Coulombic spin-liquid state, may be lost at low temperatures [Pomaranski et al., Nat. Phys. 9, 353 (2013), 10.1038/nphys2591]. However, despite nearly two decades of intensive study, the nature of the equilibrium ground state of spin ice remains uncertain. Here we explore how long-range dipolar interactions D , short-range exchange interactions, and quantum fluctuations combine to determine the ground state of dipolar spin ice. We identify the organizational principle that ordered ground states are selected from a set of "chain states" in which dipolar interactions are exponentially screened. Using both quantum and classical Monte Carlo simulation, we establish phase diagrams as a function of quantum tunneling g and temperature T , and find that only a very small gc≪D is needed to stabilize a quantum spin liquid ground state. We discuss the implications of these results for Dy2Ti2O7 .

  12. Helical order in one-dimensional magnetic atom chains and possible emergence of Majorana bound states

    NASA Astrophysics Data System (ADS)

    Kim, Younghyun; Cheng, Meng; Bauer, Bela; Lutchyn, Roman M.; Das Sarma, S.

    2014-08-01

    We theoretically obtain the phase diagram of localized magnetic impurity spins arranged in a one-dimensional chain on top of a one- or two-dimensional electron gas. The interactions between the spins are mediated by the Ruderman-Kittel-Kasuya-Yosida mechanism through the electron gas. Recent work predicts that such a system may intrinsically support topological superconductivity without spin-orbit coupling when a helical spin-density wave is spontaneously formed in the spins, and superconductivity is induced in the electron gas. We analyze, using both analytical and numerical techniques, the conditions under which such a helical spin state is stable in a realistic situation in the presence of disorder. We show that (i) it appears only when the spins are coupled to a (quasi-) one-dimensional electron gas, and (ii) it becomes unstable towards the formation of (anti)ferromagnetic domains if the disorder in the impurity spin positions δR becomes comparable with the Fermi wavelength. We also examine the stability of the helical state against Gaussian potential disorder in the electronic system using a diagrammatic approach. Our results suggest that in order to stabilize the helical spin state and thus the emergent topological superconductivity under realistic experimental conditions, a sufficiently strong Rashba spin-orbit coupling, giving rise to Dzyaloshinskii-Moriya interactions, is required.

  13. Direct visualization of quasi-ordered oxygen chain structures on Au(110)-(1 × 2)

    NASA Astrophysics Data System (ADS)

    Hiebel, F.; Montemore, M. M.; Kaxiras, E.; Friend, C. M.

    2016-08-01

    The Au(110) surface offers unique advantages for atomically-resolved model studies of catalytic oxidation processes on gold. We investigate the adsorption of oxygen on Au(110) using a combination of scanning tunneling microscopy (STM) and density functional theory (DFT) methods. We identify the typical (empty-states) STM contrast resulting from adsorbed oxygen as atomic-sized dark features of electronic origin. DFT-based image simulations confirm that chemisorbed oxygen is generally detected indirectly, from the binding-induced electronic structure modification of gold. STM images show that adsorption occurs without affecting the general structure of the pristine Au(110) missing-row reconstruction. The tendency to form one-dimensional structures is observed already at low coverage (< 0.05 ML), with oxygen adsorbing on alternate sides of the reconstruction ridges. Consistently, calculations yield preferred adsorption on the (111) facets of the reconstruction, on a 3-fold coordination site, with increased stability when adsorbed in chains. Gold atoms with two oxygen neighbors exhibit enhanced electronic hybridization with the O states. Finally, the species observed are reactive to CO oxidation at 200 K and desorption of CO2 leaves a clean and ordered gold surface.

  14. Effect of side-chain asymmetry on the intermolecular structure and order-disorder transition in alkyl-substituted polyfluorenes

    NASA Astrophysics Data System (ADS)

    Knaapila, M.; Stepanyan, R.; Torkkeli, M.; Haase, D.; Fröhlich, N.; Helfer, A.; Forster, M.; Scherf, U.

    2016-04-01

    We study relations among the side-chain asymmetry, structure, and order-disorder transition (ODT) in hairy-rod-type poly(9,9-dihexylfluorene) (PF6) with two identical side chains and atactic poly(9-octyl-9-methyl-fluorene) (PF1-8) with two different side chains per repeat. PF6 and PF1-8 organize into alternating side-chain and backbone layers that transform into an isotropic phase at TODT(PF 6 ) and TbiODT(PF 1 -8 ) . We interpret polymers in terms of monodisperse and bidisperse brushes and predict scenarios TODTchain length above or below the average grafting distance). Calorimetry and x-ray scattering indicate the condition TODT(PF 6 ) ˜TbiODT(PF 1 -8 ) following the low grafting prediction. PF6 side chains coming from the alternating backbone layers appear as two separate layers with thickness H (PF 6 ) , whereas PF1-8 side chains appear as an indistinguishable bilayer with a half thickness Hbilayer(PF 1 -8 ) /2 ≈H (PF 6 ) . The low grafting density region is structurally possible but not certain for PF6 and confirmed for PF1-8.

  15. Plant Microsomal Phospholipid Acyl Hydrolases Have Selectivities for Uncommon Fatty Acids.

    PubMed Central

    Stahl, U.; Banas, A.; Stymne, S.

    1995-01-01

    Developing endosperms and embryos accumulating triacylglycerols rich in caproyl (decanoyl) groups (i.e. developing embryos of Cuphea procumbens and Ulmus glabra) had microsomal acyl hydrolases with high selectivities toward phosphatidylcholine with this acyl group. Similarly, membranes from Euphorbia lagascae and Ricinus communis endosperms, which accumulate triacylglycerols with vernoleate (12-epoxy-octadeca-9-enoate) and ricinoleate (12-hydroxy-octadeca-9-enoate), respectively, had acyl hydrolases that selectively removed their respective oxygenated acyl group from the phospholipids. The activities toward phospholipid substrates with epoxy, hydroxy, and medium-chain acyl groups varied greatly between microsomal preparations from different plant species. Epoxidated and hydroxylated acyl groups in sn-1 and sn-2 positions of phosphatidylcholine and in sn-1-lysophosphatidylcholine were hydrolyzed to a similar extent, whereas the hydrolysis of caproyl groups was highly dependent on the positional localization. PMID:12228415

  16. Acyl-acyl carrier protein as a source of fatty acids for bacterial bioluminescence

    SciTech Connect

    Byers, D.M.; Meighen, E.A.

    1985-09-01

    Pulse-chase experiments with (/sup 3/H)tetradecanoic acid and ATP showed that the bioluminescence-related 32-kDa acyltransferase from Vibrio harveyi can specifically catalyze the deacylation of a /sup 3/H-labeled 18-kDa protein observed in extracts of this bacterium. The 18-kDa protein has been partially purified and its physical and chemical properties strongly indicate that it is fatty acyl-acyl carrier protein (acyl-ACP). Both this V. harveyi (/sup 3/H)acylprotein and (/sup 3/H)palmitoyl-ACP from Escherichia coli were substrates in vitro for either the V. harveyi 32-kDa acyltransferase or the analogous enzyme (34K) from Photobacterium phosphoreum. TLC analysis indicated that the hexane-soluble product of the reaction is fatty acid. No significant cleavage of either E. coli or V. harveyi tetradecanoyl-ACP was observed in extracts of these bacteria unless the 32-kDa or 34K acyltransferase was present. Since these enzymes are believed to be responsible for the supply of fatty acids for reduction to form the aldehyde substrate of luciferase, the above results suggest that long-chain acyl-ACP is the source of fatty acids for bioluminescence.

  17. Long-Chain Fatty Acid Oxidation Disorders (LC-FAOD) Extension Study for Subjects Previously Enrolled in Triheptanoin Studies.

    ClinicalTrials.gov

    2016-02-26

    Carnitine Palmitoyltransferase (CPT I or CPT II) Deficiency; Very Long Chain Acyl-CoA Dehydrogenase (VLCAD) Deficiency; Long-chain 3-hydroxy-acyl-CoA Dehydrogenase (LCHAD) Deficiency; Trifunctional Protein (TFP) Deficiency; Carnitine-acylcarnitine Translocase (CACT) Deficiency

  18. Acyl migration kinetics of vegetable oil 1,2-diacylglycerols

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The acyl migration kinetics of long-chain 1,2-diacylglycerol (1,2-DAG) to form 1,3-diacylglycerol (1,3-DAG) over the temperature range of 25 to 80 degrees Celsius were examined using proton NMR spectroscopy. The 1,2-DAG mole fraction of 0.32 at equilibrium was found to be insensitive to temperature...

  19. Magnetic ordering in the ultrapure site-diluted spin chain materials SrCu1 -xNixO2

    NASA Astrophysics Data System (ADS)

    Simutis, G.; Thede, M.; Saint-Martin, R.; Mohan, A.; Baines, C.; Guguchia, Z.; Khasanov, R.; Hess, C.; Revcolevschi, A.; Büchner, B.; Zheludev, A.

    2016-06-01

    The muon spin rotation technique is used to study magnetic ordering in ultrapure samples of SrCu1 -xNixO2 , an archetypical S =1 /2 antiferromagnetic Heisenberg chain system with a small number of S =1 defects. The ordered state in the parent compound is shown to be highly homogeneous, contrary to a previous report [M. Matsuda et al., Phys. Rev. B 55, R11953 (1997), 10.1103/PhysRevB.55.R11953]. Even a minute number of Ni impurities results in inhomogeneous order and a decrease of the transition temperature. At as little as 0.5 % Ni concentration, magnetic ordering is entirely suppressed. The results are compared to previous theoretical studies of weakly coupled spin chains with site defects.

  20. Photoinduced changes of surface order in coumarin side-chain polymer films used for liquid crystal photoalignment

    SciTech Connect

    Bergmann, G.; Jackson, P.O.; Hogg, J.H.C.; Stirner, T.; O'Neill, M.; Duffy, W.L.; Kelly, S.M.; Clark, G.F.

    2005-08-08

    Specular x-ray reflectivity probes morphological changes in a crosslinkable coumarin photoalignment polymer film resulting from ultraviolet irradiation. An ordered surface layer with density oscillations compatible with planar side-chain alignment is obtained before irradiation. The ordering is enhanced in the early stages of crosslinking. This is attributed to the photoinduced increase of mobility of the side-chains resulting from the creation of free volume by the crosslinking process. The expansion of the thin film confirms that free volume is created. The surface ordering decreases with prolonged ultraviolet irradiation because of increased material viscosity resulting from a high crosslinked density. The implications of surface ordering on liquid crystal photoalignment are discussed.

  1. Endophytic Actinomycetes: A Novel Source of Potential Acyl Homoserine Lactone Degrading Enzymes

    PubMed Central

    Chankhamhaengdecha, Surang; Hongvijit, Suphatra; Srichaisupakit, Akkaraphol; Charnchai, Pattra; Panbangred, Watanalai

    2013-01-01

    Several Gram-negative pathogenic bacteria employ N-acyl-L-homoserine lactone (HSL) quorum sensing (QS) system to control their virulence traits. Degradation of acyl-HSL signal molecules by quorum quenching enzyme (QQE) results in a loss of pathogenicity in QS-dependent organisms. The QQE activity of actinomycetes in rhizospheric soil and inside plant tissue was explored in order to obtain novel strains with high HSL-degrading activity. Among 344 rhizospheric and 132 endophytic isolates, 127 (36.9%) and 68 (51.5%) of them, respectively, possessed the QQE activity. The highest HSL-degrading activity was at 151.30 ± 3.1 nmole/h/mL from an endophytic actinomycetes isolate, LPC029. The isolate was identified as Streptomyces based on 16S  rRNA gene sequence similarity. The QQE from LPC029 revealed HSL-acylase activity that was able to cleave an amide bond of acyl-side chain in HSL substrate as determined by HPLC. LPC029 HSL-acylase showed broad substrate specificity from C6- to C12-HSL in which C10HSL is the most favorable substrate for this enzyme. In an in vitro pathogenicity assay, the partially purified HSL-acylase efficiently suppressed soft rot of potato caused by Pectobacterium carotovorum ssp. carotovorum as demonstrated. To our knowledge, this is the first report of HSL-acylase activity derived from an endophytic Streptomyces. PMID:23484156

  2. Magnetic ordering in the frustrated J1 - J2 Ising chain candidate BaNd2O4

    DOE PAGESBeta

    Aczel, Adam A.; Li, Ling; Garlea, Vasile O.; Yan, Jiaqiang; Weickert, Franziska; Jaime, M.; Maiorov, B.; Movshovich, R.; Civale, L.; Keppens, V.; et al

    2014-10-06

    The AR2O4 family (R = rare earth) has recently been attracting interest as a new series of frustrated magnets, with the magnetic R atoms forming zigzag chains running along the c axis. In this paper, we have investigated polycrystalline BaNd2O4 with a combination of magnetization, heat-capacity, and neutron powder diffraction measurements. Magnetic Bragg peaks are observed below TN = 1.7 K, and they can be indexed with a propagation vector of k = (0,1/2,1/2). The signal from magnetic diffraction is well described by long-range ordering of only one of the two types of Nd zigzag chains, with collinear up-up-down-down intrachainmore » spin configurations (double Néel state). Furthermore, low-temperature magnetization and heat-capacity measurements reveal two magnetic-field-induced spin transitions at 2.75 and 4 T for T = 0.46 K. The high-field phase is paramagnetic, while the intermediate-field state may arise from a spin transition of the long-range ordered Nd chains. Finally, one possible candidate for the field-induced ordered state corresponds to an up-up-down intrachain spin configuration, as predicted for a classical J1-J2 Ising chain with a double Néel ground state in zero field.« less

  3. The 2.1Å Crystal Structure of an Acyl-CoA Synthetase from Methanosarcina acetivorans reveals an alternate acyl binding pocket for small branched acyl substrates†,‡

    PubMed Central

    Shah, Manish B.; Ingram-Smith, Cheryl; Cooper, Leroy L.; Qu, Jun; Meng, Yu; Smith, Kerry S.; Gulick, Andrew M.

    2009-01-01

    The acyl-AMP forming family of adenylating enzymes catalyze two-step reactions to activate a carboxylate with the chemical energy derived from ATP hydrolysis. X-ray crystal structures have been determined for multiple members of this family and, together with biochemical studies, provide insights into the active site and catalytic mechanisms used by these enzymes. These studies have shown that the enzymes use a domain rotation of 140° to reconfigure a single active site to catalyze the two partial reactions. We present here the crystal structure of a new medium chain acyl-CoA synthetase from Methanosarcina acetivorans. The binding pocket for the three substrates is analyzed, with many conserved residues present in the AMP binding pocket. The CoA binding pocket is compared to the pockets of both acetyl-CoA synthetase and 4-chlorobenzoate:CoA ligase. Most interestingly, the acyl binding pocket of the new structure is compared with other acyl- and aryl-CoA synthetases. A comparison of the acyl-binding pocket of the acyl-CoA synthetase from M. acetivorans with other structures identifies a shallow pocket that is used to bind the medium chain carboxylates. These insights emphasize the high sequence and structural diversity among this family in the area of the acyl binding pocket. PMID:19544569

  4. Efficient free fatty acid production in Escherichia coli using plant acyl-ACP thioesterases.

    PubMed

    Zhang, Xiujun; Li, Mai; Agrawal, Arpita; San, Ka-Yiu

    2011-11-01

    Microbial biosynthesis of fatty acid-like chemicals from renewable carbon sources has attracted significant attention in recent years. Free fatty acids can be used as precursors for the production of fuels or chemicals. Free fatty acids can be produced by introducing an acyl-acyl carrier protein thioesterase gene into Escherichia coli. The presence of the acyl-ACP thioesterase will break the fatty acid elongation cycle and release free fatty acid. Depending on their sequence similarity and substrate specificity, class FatA thioesterase is active on unsaturated acyl-ACPs and class FatB prefers saturated acyl group. Different acyl-ACP thioesterases have different degrees of chain length specificity. Although some of these enzymes have been characterized from a number of sources, information on their ability to produce free fatty acid in microbial cells has not been extensively examined until recently. In this study, we examined the effect of the overexpression of acyl-ACP thioesterase genes from Diploknema butyracea, Gossypium hirsutum, Ricinus communis and Jatropha curcas on free fatty acid production. In particular, we are interested in studying the effect of different acyl-ACP thioesterase on the quantities and compositions of free fatty acid produced by an E. coli strain ML103 carrying these constructs. It is shown that the accumulation of free fatty acid depends on the acyl-ACP thioesterase used. The strain carrying the acyl-ACP thioesterase gene from D. butyracea produced approximately 0.2g/L of free fatty acid while the strains carrying the acyl-ACP thioesterase genes from R. communis and J. curcas produced the most free fatty acid at a high level of more than 2.0 g/L at 48 h. These two strains accumulated three major straight chain free fatty acids, C14, C16:1 and C16 at levels about 40%, 35% and 20%, respectively. PMID:22001432

  5. Acylation of Ferrocene: A Greener Approach

    ERIC Educational Resources Information Center

    Birdwhistell, Kurt R.; Nguyen, Andy; Ramos, Eric J.; Kobelja, Robert

    2008-01-01

    The acylation of ferrocene is a common reaction used in organic laboratories to demonstrate Friedel-Crafts acylation and the purification of compounds using column chromatography. This article describes an acylation of ferrocene experiment that is more eco-friendly than the conventional acylation experiment. The traditional experiment was modified…

  6. Optimal economic order quantity for buyer-distributor-vendor supply chain with backlogging derived without derivatives

    NASA Astrophysics Data System (ADS)

    Teng, Jinn-Tsair; Cárdenas-Barrón, Leopoldo Eduardo; Lou, Kuo-Ren; Wee, Hui Ming

    2013-05-01

    In this article, we first complement an inappropriate mathematical error on the total cost in the previously published paper by Chung and Wee [2007, 'Optimal the Economic Lot Size of a Three-stage Supply Chain With Backlogging Derived Without Derivatives', European Journal of Operational Research, 183, 933-943] related to buyer-distributor-vendor three-stage supply chain with backlogging derived without derivatives. Then, an arithmetic-geometric inequality method is proposed not only to simplify the algebraic method of completing prefect squares, but also to complement their shortcomings. In addition, we provide a closed-form solution to integral number of deliveries for the distributor and the vendor without using complex derivatives. Furthermore, our method can solve many cases in which their method cannot, because they did not consider that a squared root of a negative number does not exist. Finally, we use some numerical examples to show that our proposed optimal solution is cheaper to operate than theirs.

  7. Exogenous myristic acid can be partially degraded prior to activation to form acyl-acyl carrier protein intermediates and lipid A in Vibrio harveyi.

    PubMed Central

    Shen, Z; Byers, D M

    1994-01-01

    To study the involvement of acyl carrier protein (ACP) in the metabolism of exogenous fatty acids in Vibrio harveyi, cultures were incubated in minimal medium with [9,10-3H]myristic acid, and labeled proteins were analyzed by gel electrophoresis. Labeled acyl-ACP was positively identified by immunoprecipitation with anti-V. harveyi ACP serum and comigration with acyl-ACP standards and [3H]beta-alanine-labeled bands on both sodium dodecyl sulfate- and urea-polyacrylamide gels. Surprisingly, most of the acyl-ACP label corresponded to fatty acid chain lengths of less than 14 carbons: C14, C12, C10, and C8 represented 33, 40, 14, and 8% of total [3H]14:0-derived acyl-ACPs, respectively, in a dark mutant (M17) of V. harveyi which lacks myristoyl-ACP esterase activity; however, labeled 14:0-ACP was absent in the wild-type strain. 14:0- and 12:0-ACP were also the predominant species labeled in complex medium. In contrast, short-chain acyl-ACPs (< or = C6) were the major labeled derivatives when V. harveyi was incubated with [3H]acetate, indicating that acyl-ACP labeling with [3H]14:0 in vivo is not due to the total degradation of [3H]14:0 to [3H]acetyl coenzyme A followed by resynthesis. Cerulenin increased the mass of medium- to long-chain acyl-ACPs (> or = C8) labeled with [3H]beta-alanine fivefold, while total incorporation of [3H]14:0 was not affected, although a shift to shorter chain lengths was noted. Additional bands which comigrated with acyl-ACP on sodium dodecyl sulfate gels were identified as lipopolysaccharide by acid hydrolysis and thin-layer chromatography. The levels of incorporation of [3H] 14:0 into acyl-ACP and lipopolysaccharide were 2 and 15%, respectively, of that into phospholipid by 10 min. Our results indicate that in contrast to the situation in Escherichia coli, exogenous fatty acids can be activated to acyl-ACP intermediates after partial degradation in V. harveyi and can effectively label products (i.e., lipid A) that require ACP as an acyl

  8. Infrared and Fluorescence Spectroscopic Investigations of the Acyl Surface Modification of Hydrogel Beads for the Deposition of a Phospholipid Coating.

    PubMed

    Grossutti, Michael; Seenath, Ryan; Lipkowski, Jacek

    2015-10-27

    The scaffolded vesicle has been employed as an alternative means of developing natural model membranes and envisioned as a potential nutraceutical transporter. Furthering the research of the scaffolded vesicle system, a nucleophilic substitution reaction was implemented to form an ester linkage between palmitate and terminal hydroxyl groups of dextran in order to hydrophobically modify the hydrogel scaffold. An average tilt angle of 38° of the hydrophobic palmitate modifying layer on the surface of the hydrogel was determined from dichroic ratios obtained from infrared spectra collected in the attenuated total reflection (ATR) configuration. ATR-IR studies of the DMPC-coated acylated hydrogel demonstrated that the hydrocarbon chains of the DMPC coating was similar to those of the DMPC bilayers and that the underlying palmitate layer had a negligible effect on the average tilt angle (26°) of the DMPC coating. The permeability of this acylated hydrogel was investigated with fluorescence spectroscopy and the terbium/dipicolinic acid assay. The hydrophobic modification on the surface of the hydrogel bead allowed for an efficient deposition of a DMPC layer that served as an impermeable barrier to terbium efflux. About 72% of DMPC-coated acylated hydrogel beads showed ideal barrier properties. The remaining 28% were leaking, but the half-life of terbium efflux of the DMPC-coated acylated hydrogel was increasing, and the total amount of leaked terbium was decreasing with the incubation time. The half-life time and the retention were considered a marked improvement relative to past scaffolded vesicle preparations. The process of acylating hydrogel beads for efficient DMPC deposition has been identified as another viable method for controlling the permeability of the scaffolded vesicle. PMID:26429738

  9. The mechanism of acyl specific phospholipid remodeling by tafazzin

    PubMed Central

    Schlame, Michael; Acehan, Devrim; Berno, Bob; Xu, Yang; Valvo, Salvatore; Ren, Mindong; Stokes, David L.; Epand, Richard M.

    2013-01-01

    Cardiolipin is a mitochondrial phospholipid with a characteristic acyl chain composition that depends on the function of tafazzin, a phospholipid-lysophospholipid transacylase, although the enzyme itself lacks acyl specificity. We incubated isolated tafazzin with various mixtures of phospholipids and lysophospholipids, characterized the lipid phase by 31P-NMR, and measured newly formed molecular species by mass spectrometry. Significant transacylation was observed only in non-bilayer lipid aggregates and the substrate specificity was highly sensitive to the lipid phase. In particular, tetralinoleoyl-cardiolipin, a prototype molecular species, formed only under conditions that favor the inverted hexagonal phase. In isolated mitochondria, <1 percent of lipids participated in transacylations, suggesting that the action of tafazzin is limited to privileged lipid domains. We propose that tafazzin reacts with non-bilayer type lipid domains that occur in curved or hemifused membrane zones, and that acyl specificity is driven by the packing properties of these domains. PMID:22941046

  10. N-Acylation During Glidobactin Biosynthesis by the Tridomain Nonribosomal Peptide Synthetase Module GlbF

    PubMed Central

    Imker, Heidi J.; Krahn, Daniel; Clerc, Jérôme; Kaiser, Markus; Walsh, Christopher T.

    2011-01-01

    Summary Glidobactins are hybrid NRPS-PKS natural products that function as irreversible proteasome inhibitors. A variety of medium chain 2(E),4(E)-diene fatty acids N-acylate the peptidolactam core and contribute significantly to the potency of proteasome inhibition. We have expressed the initiation NRPS module GlbF (C-A-T) in Escherichia coli and observe soluble active protein only on co-expression with the 8 kDa MbtH-like protein, GlbE. Following adenylation and installation of Thr as a T-domain thioester, the starter condensation domain utilizes fatty acyl-CoA donors to acylate the Thr1 amino group and generate the fatty acyl-Thr1-S-pantetheinyl-GlbF intermediate to be used in subsequent chain elongation. Previously proposed to be mediated via acyl carrier protein fatty acid donors, direct utilization of fatty acyl-CoA donors for N-acylation of T-domain tethered amino acids is likely a common strategy for chain initiation in NRPS-mediated lipopeptide biosynthesis. PMID:21035730

  11. An Open-label Phase 2 Study of UX007 (Triheptanoin) in Subjects With Long-Chain Fatty Acid Oxidation Disorders (LC-FAOD)

    ClinicalTrials.gov

    2015-12-15

    Long-chain Fatty Acid Oxidation Disorders (LC-FAOD); Carnitine Palmitoyltransferase (CPT II) Deficiency; Very Long Chain Acyl-CoA Dehydrogenase (VLCAD) Deficiency; Longchain 3-hydroxy-acyl-CoA Dehydrogenase (LCHAD) Deficiency; Trifunctional Protein (TFP) Deficiency

  12. A law of order estimation and leading-order terms for a family of averaged quantities on a multibaker chain system

    NASA Astrophysics Data System (ADS)

    Ishida, Hideshi

    2014-06-01

    In this study, a family of local quantities defined on each partition and its averaging on a macroscopic small region, site, are defined on a multibaker chain system. On its averaged quantities, a law of order estimation in the bulk system is proved, making it possible to estimate the order of the quantities with respect to the representative partition scale parameter Δ. Moreover, the form of the leading-order terms of the averaged quantities is obtained, and the form enables us to have the macroscopic quantity in the continuum limit, as Δ → 0, and to confirm its partitioning independency. These deliverables fully explain the numerical results obtained by Ishida, consistent with the irreversible thermodynamics.

  13. A law of order estimation and leading-order terms for a family of averaged quantities on a multibaker chain system

    SciTech Connect

    Ishida, Hideshi

    2014-06-15

    In this study, a family of local quantities defined on each partition and its averaging on a macroscopic small region, site, are defined on a multibaker chain system. On its averaged quantities, a law of order estimation in the bulk system is proved, making it possible to estimate the order of the quantities with respect to the representative partition scale parameter Δ. Moreover, the form of the leading-order terms of the averaged quantities is obtained, and the form enables us to have the macroscopic quantity in the continuum limit, as Δ → 0, and to confirm its partitioning independency. These deliverables fully explain the numerical results obtained by Ishida, consistent with the irreversible thermodynamics.

  14. On the ability of molecular dynamics force fields to recapitulate NMR derived protein side chain order parameters.

    PubMed

    O'Brien, Evan S; Wand, A Joshua; Sharp, Kim A

    2016-06-01

    Molecular dynamics (MD) simulations have become a central tool for investigating various biophysical questions with atomistic detail. While many different proxies are used to qualify MD force fields, most are based on largely structural parameters such as the root mean square deviation from experimental coordinates or nuclear magnetic resonance (NMR) chemical shifts and residual dipolar couplings. NMR derived Lipari-Szabo squared generalized order parameter (O(2) ) values of amide NH bond vectors of the polypeptide chain were also often employed for refinement and validation. However, with a few exceptions, side chain methyl symmetry axis order parameters have not been incorporated into experimental reference sets. Using a test set of five diverse proteins, the performance of several force fields implemented in the NAMDD simulation package was examined. It was found that simulations employing explicit water implemented using the TIP3 model generally performed significantly better than those using implicit water in reproducing experimental methyl symmetry axis O(2) values. Overall the CHARMM27 force field performs nominally better than two implementations of the Amber force field. It appeared that recent quantum mechanics modifications to side chain torsional angles of leucine and isoleucine in the Amber force field have significantly hindered proper motional modeling for these residues. There remained significant room for improvement as even the best correlations of experimental and simulated methyl group Lipari-Szabo generalized order parameters fall below an R(2) of 0.8. PMID:26990788

  15. Two fatty acyl reductases involved in moth pheromone biosynthesis.

    PubMed

    Antony, Binu; Ding, Bao-Jian; Moto, Ken'Ichi; Aldosari, Saleh A; Aldawood, Abdulrahman S

    2016-01-01

    Fatty acyl reductases (FARs) constitute an evolutionarily conserved gene family found in all kingdoms of life. Members of the FAR gene family play diverse roles, including seed oil synthesis, insect pheromone biosynthesis, and mammalian wax biosynthesis. In insects, FAR genes dedicated to sex pheromone biosynthesis (pheromone-gland-specific fatty acyl reductase, pgFAR) form a unique clade that exhibits substantial modifications in gene structure and possesses unique specificity and selectivity for fatty acyl substrates. Highly selective and semi-selective 'single pgFARs' produce single and multicomponent pheromone signals in bombycid, pyralid, yponomeutid and noctuid moths. An intriguing question is how a 'single reductase' can direct the synthesis of several fatty alcohols of various chain lengths and isomeric forms. Here, we report two active pgFARs in the pheromone gland of Spodoptera, namely a semi-selective, C14:acyl-specific pgFAR and a highly selective, C16:acyl-specific pgFAR, and demonstrate that these pgFARs play a pivotal role in the formation of species-specific signals, a finding that is strongly supported by functional gene expression data. The study envisages a new area of research for disclosing evolutionary changes associated with C14- and C16-specific FARs in moth pheromone biosynthesis. PMID:27427355

  16. Two fatty acyl reductases involved in moth pheromone biosynthesis

    PubMed Central

    Antony, Binu; Ding, Bao-Jian; Moto, Ken’Ichi; Aldosari, Saleh A.; Aldawood, Abdulrahman S.

    2016-01-01

    Fatty acyl reductases (FARs) constitute an evolutionarily conserved gene family found in all kingdoms of life. Members of the FAR gene family play diverse roles, including seed oil synthesis, insect pheromone biosynthesis, and mammalian wax biosynthesis. In insects, FAR genes dedicated to sex pheromone biosynthesis (pheromone-gland-specific fatty acyl reductase, pgFAR) form a unique clade that exhibits substantial modifications in gene structure and possesses unique specificity and selectivity for fatty acyl substrates. Highly selective and semi-selective ‘single pgFARs’ produce single and multicomponent pheromone signals in bombycid, pyralid, yponomeutid and noctuid moths. An intriguing question is how a ‘single reductase’ can direct the synthesis of several fatty alcohols of various chain lengths and isomeric forms. Here, we report two active pgFARs in the pheromone gland of Spodoptera, namely a semi-selective, C14:acyl-specific pgFAR and a highly selective, C16:acyl-specific pgFAR, and demonstrate that these pgFARs play a pivotal role in the formation of species-specific signals, a finding that is strongly supported by functional gene expression data. The study envisages a new area of research for disclosing evolutionary changes associated with C14- and C16-specific FARs in moth pheromone biosynthesis. PMID:27427355

  17. Regioselective self-acylating cyclodextrins in organic solvent

    PubMed Central

    Cho, Eunae; Yun, Deokgyu; Jeong, Daham; Im, Jieun; Kim, Hyunki; Dindulkar, Someshwar D.; Choi, Youngjin; Jung, Seunho

    2016-01-01

    Amphiphilic cyclodextrins have been synthesized with self-acylating reaction using vinyl esters in dimethylformamide. In the present study no base, catalyst, or enzyme was used, and the structural analyses using thin layer chromatography, nuclear magnetic resonance spectroscopy and mass spectrometry show that the cyclodextrin is substituted preferentially by one acyl moiety at the C2 position of the glucose unit, suggesting that cyclodextrin functions as a regioselective catalytic carbohydrate in organic solvent. In the self-acylation, the most acidic OH group at the 2-position and the inclusion complexing ability of cyclodextrin were considered to be significant. The substrate preference was also observed in favor of the long-chain acyl group, which could be attributed to the inclusion ability of cyclodextrin cavity. Furthermore, using the model amphiphilic building block, 2-O-mono-lauryl β-cyclodextrin, the self-organized supramolecular architecture with nano-vesicular morphology in water was investigated by fluorescence spectroscopy, dynamic light scattering and transmission electron microscopy. The cavity-type nano-assembled vesicle and the novel synthetic methods for the preparation of mono-acylated cyclodextrin should be of great interest with regard to drug/gene delivery systems, functional surfactants, and carbohydrate derivatization methods. PMID:27020946

  18. Regioselective self-acylating cyclodextrins in organic solvent.

    PubMed

    Cho, Eunae; Yun, Deokgyu; Jeong, Daham; Im, Jieun; Kim, Hyunki; Dindulkar, Someshwar D; Choi, Youngjin; Jung, Seunho

    2016-01-01

    Amphiphilic cyclodextrins have been synthesized with self-acylating reaction using vinyl esters in dimethylformamide. In the present study no base, catalyst, or enzyme was used, and the structural analyses using thin layer chromatography, nuclear magnetic resonance spectroscopy and mass spectrometry show that the cyclodextrin is substituted preferentially by one acyl moiety at the C2 position of the glucose unit, suggesting that cyclodextrin functions as a regioselective catalytic carbohydrate in organic solvent. In the self-acylation, the most acidic OH group at the 2-position and the inclusion complexing ability of cyclodextrin were considered to be significant. The substrate preference was also observed in favor of the long-chain acyl group, which could be attributed to the inclusion ability of cyclodextrin cavity. Furthermore, using the model amphiphilic building block, 2-O-mono-lauryl β-cyclodextrin, the self-organized supramolecular architecture with nano-vesicular morphology in water was investigated by fluorescence spectroscopy, dynamic light scattering and transmission electron microscopy. The cavity-type nano-assembled vesicle and the novel synthetic methods for the preparation of mono-acylated cyclodextrin should be of great interest with regard to drug/gene delivery systems, functional surfactants, and carbohydrate derivatization methods. PMID:27020946

  19. Regioselective self-acylating cyclodextrins in organic solvent

    NASA Astrophysics Data System (ADS)

    Cho, Eunae; Yun, Deokgyu; Jeong, Daham; Im, Jieun; Kim, Hyunki; Dindulkar, Someshwar D.; Choi, Youngjin; Jung, Seunho

    2016-03-01

    Amphiphilic cyclodextrins have been synthesized with self-acylating reaction using vinyl esters in dimethylformamide. In the present study no base, catalyst, or enzyme was used, and the structural analyses using thin layer chromatography, nuclear magnetic resonance spectroscopy and mass spectrometry show that the cyclodextrin is substituted preferentially by one acyl moiety at the C2 position of the glucose unit, suggesting that cyclodextrin functions as a regioselective catalytic carbohydrate in organic solvent. In the self-acylation, the most acidic OH group at the 2-position and the inclusion complexing ability of cyclodextrin were considered to be significant. The substrate preference was also observed in favor of the long-chain acyl group, which could be attributed to the inclusion ability of cyclodextrin cavity. Furthermore, using the model amphiphilic building block, 2-O-mono-lauryl β-cyclodextrin, the self-organized supramolecular architecture with nano-vesicular morphology in water was investigated by fluorescence spectroscopy, dynamic light scattering and transmission electron microscopy. The cavity-type nano-assembled vesicle and the novel synthetic methods for the preparation of mono-acylated cyclodextrin should be of great interest with regard to drug/gene delivery systems, functional surfactants, and carbohydrate derivatization methods.

  20. Alpha-synuclein and familial variants affect the chain order and the thermotropic phase behavior of anionic lipid vesicles.

    PubMed

    Pantusa, Manuela; Vad, Brian; Lillelund, Ove; Kjær, Lars; Otzen, Daniel; Bartucci, Rosa

    2016-09-01

    Alpha-synuclein (aSN) is a presynaptic protein with a pathological role in Parkinson's disease (PD). The mutants A30P, E46K and A53T are involved in PD early-onset forms. aSN is natively unfolded but can self-assemble to oligomers and fibrils and binds anionic membranes in a helical conformation. We study the influence of wild-type (wt) aSN and familial variants on the chain order and thermotropic phase behavior of anionic dimyristoylphosphatidylglycerol (DMPG) bilayers by using electron spin resonance and calorimetry, respectively. The alpha-helical conformation of the proteins in the membrane-bound state is assessed by circular dichroism thermal scans. wt and mutated aSN upon binding to fluid DMPG vesicles progressively increase chain order. Lipid:protein molar binding stoichiometries correspond to 50 for A30P, 35-36 for aSN and A53T, 30 for E46K. The temperature range over which the variants assume the α-helical fold correlates directly with the density of proteins on vesicle surfaces. All variants preserve the characteristic chain flexibility gradient and impart motional restriction in the lipid chain. This is evident at the first CH2 segments and is markedly reduced at the chain termini, disappearing completely for A30P. The proteins slightly reduce DMPG main transition temperature, revealing preferential affinity for the fluid phase, and broaden the transition, promoting gel-fluid phase coexistence. The overall results are consistent with protein surface association in which the degree of binding correlates with the degree of folding and perturbation of the membrane bilayer. However, the degree of binding of monomer to membrane does not correlate directly with aSN toxicity in vivo. PMID:27177693

  1. Hierarchical self-assembly: Self-organized nanostructures in a nematically ordered matrix of self-assembled polymeric chains

    NASA Astrophysics Data System (ADS)

    Mubeena, Shaikh; Chatterji, Apratim

    2015-03-01

    We report many different nanostructures which are formed when model nanoparticles of different sizes (diameter σn) are allowed to aggregate in a background matrix of semiflexible self-assembled polymeric wormlike micellar chains. The different nanostructures are formed by the dynamical arrest of phase-separating mixtures of micellar monomers and nanoparticles. The different morphologies obtained are the result of an interplay of the available free volume, the elastic energy of deformation of polymers, the density (chemical potential) of the nanoparticles in the polymer matrix, and, of course, the ratio of the size of self-assembling nanoparticles and self-avoidance diameter of polymeric chains. We have used a hybrid semi-grand-canonical Monte Carlo simulation scheme to obtain the (nonequilibrium) phase diagram of the self-assembled nanostructures. We observe rodlike structures of nanoparticles which get self-assembled in the gaps between the nematically ordered chains, as well as percolating gel-like network of conjoined nanotubes. We also find a totally unexpected interlocked crystalline phase of nanoparticles and monomers, in which each crystal plane of nanoparticles is separated by planes of perfectly organized polymer chains. We identified the condition which leads to such interlocked crystal structure. We suggest experimental possibilities of how the results presented in this paper could be used to obtain different nanostructures in the laboratory.

  2. Chain ordering of regioregular polythiophene films through blending with a nickel bisdithiolene complex

    SciTech Connect

    Hernandez-Maldonado, D.; Université de Toulouse, UPS, INPT, LCC, F-31077 Toulouse ; Ramos, B.; Bedel-Pereira, E.; Séguy, I.; Université de Toulouse, UPS, INPT, LCC, F-31077 Toulouse ; Villeneuve-Faure, C.; Sournia-Saquet, A.; Moineau-Chane Ching, K. I.; Alary, F.; Heully, J. L.

    2014-03-10

    An “annealing-free” strategy consisting of using a planar nickel bisdithiolene complex nickel bis[1,2-di(3′,4′-di-n-decyloxyphenyl)ethene-1,2-dithiolene] ([Ni(4dopedt){sub 2}]) is proposed for structuring poly(3-hexyl-thiophene) (P3HT). Photoluminescence (PL) and Raman spectroscopies, in conjunction with electronic absorption, have been used for evidencing P3HT changes due to blending. PL and absorption observations are consistent and show a correlation between polymer chain organization and increasing amounts of [Ni(4dopedt){sub 2}]. Blending with [Ni(4dopedt){sub 2}] do not modify the Raman ring-breathing modes energies indicating that blending does not induce strongly disorder in P3HT chains. Atomic force microscopic measurements show that blends nanoscale morphology presents a homogeneous matrix and small fibrils related to [Ni(4dopedt){sub 2}] concentration, especially for blends with a [Ni(4dopedt){sub 2}] weight ratio lower than 50%.

  3. Anti-proliferative effects of O-acyl-low-molecular-weight heparin derivatives on bovine pulmonary artery smooth muscle cells

    PubMed Central

    Garg, Hari G.; Mrabat, Hicham; Yu, Lunyin; Hales, Charles A.; Li, Boyangzi; Moore, Casey N.; Zhang, Fuming; Linhardt, Robert J.

    2011-01-01

    Heparin (HP) inhibits the growth of several cell types in vitro including bovine pulmonary artery (BPA) smooth muscle cells (SMCs). In initial studies we discovered that an O-hexanoylated low-molecular-weight (LMW) HP derivative having acyl groups with 6-carbon chain length was more potent inhibitor of BPA-SMCs than the starting HP. We prepared several O-acylated LMWHP derivatives having 4-, 6-, 8-, 10-, 12-, and 18- carbon acyl chain lengths to determine the optimal acyl chain length for maximum anti-proliferative properties of BPA-SMCs. The starting LMWHP was prepared from unfractionated HP by sodium periodate treatment followed by sodium borohydride reduction. The tri-n-butylammonium salt of this LMWHP was O-acylated with butanoic, hexanoic, octanoic, decanoic, dodecanoic, and stearyl anhydrides separately to give respective O-acylated LMWHP derivatives. Gradient polyacrylamide gel electrophoresis (PAGE) was used to examine the average molecular weights of those O-acylated LMWHP derivatives. NMR analysis indicated the presence of one O-acyl group per disaccharide residue. Measurement of the inhibition of BPA-SMCS as a function of O-acyl chain length shows two optima, at a carbon chain length of 6 (O-hexanoylated LMWHP) and at a carbon chain length 12–18 (O-dodecanoyl and O-stearyl LMWHPs). A solution competition SPR study was performed to test the ability of different O-acylated LMWHP derivatives to inhibit fibroblast growth factor (FGF) 1 and FGF2 binding to surface-immobilized heparin. All the LMWHP derivatives bound to FGF1 and FGF2 but each exhibited slightly different binding affinity. PMID:21773727

  4. Acylation Type Determines Ghrelin's Effects on Energy Homeostasis in Rodents

    PubMed Central

    Heppner, Kristy M.; Chaudhary, Nilika; Müller, Timo D.; Kirchner, Henriette; Habegger, Kirk M.; Ottaway, Nickki; Smiley, David L.; DiMarchi, Richard; Hofmann, Susanna M.; Woods, Stephen C.; Sivertsen, Bjørn; Holst, Birgitte; Pfluger, Paul T.; Perez-Tilve, Diego

    2012-01-01

    Ghrelin is a gastrointestinal polypeptide that acts through the ghrelin receptor (GHSR) to promote food intake and increase adiposity. Activation of GHSR requires the presence of a fatty-acid (FA) side chain on amino acid residue serine 3 of the ghrelin molecule. However, little is known about the role that the type of FA used for acylation plays in the biological action of ghrelin. We therefore evaluated a series of differentially acylated peptides to determine whether alterations in length or stability of the FA side chain have an impact on the ability of ghrelin to activate GHSR in vitro or to differentially alter food intake, body weight, and body composition in vivo. Fatty acids principally available in the diet (such as palmitate C16) and therefore representing potential substrates for the ghrelin-activating enzyme ghrelin O-acyltransferase (GOAT) were used for dose-, time-, and administration/route-dependent effects of ghrelin on food intake, body weight, and body composition in rats and mice. Our data demonstrate that altering the length of the FA side chain of ghrelin results in the differential activation of GHSR. Additionally, we found that acylation of ghrelin with a long-chain FA (C16) delays the acute central stimulation of food intake. Lastly, we found that, depending on acylation length, systemic and central chronic actions of ghrelin on adiposity can be enhanced or reduced. Together our data suggest that modification of the FA side-chain length can be a novel approach to modulate the efficacy of pharmacologically administered ghrelin. PMID:22865372

  5. Palmitoyl-acyl carrier protein (ACP) thioesterase and the evolutionary origin of plant acyl-ACP thioesterases.

    PubMed Central

    Jones, A; Davies, H M; Voelker, T A

    1995-01-01

    Acyl-acyl carrier protein (ACP) thioesterases play an essential role in chain termination during de novo fatty acid synthesis and in the channeling of carbon flux between the two lipid biosynthesis pathways in plants. We have discovered that there are two distinct but related thioesterase gene classes in higher plants, termed FatA and FatB, whose evolutionary divergence appears to be ancient. FatA encodes the already described 18:1-ACP thioesterase. In contrast, FatB representatives encode thioesterases preferring acyl-ACPs having saturated acyl groups. We unexpectedly obtained a 16:0-ACP thioesterase cDNA from Cuphea hookeriana seed, which accumulate predominantly 8:0 and 10:0. The 16:0 thioesterase transcripts were found in non-seed tissues, and expression in transgenic Brassica napus led to the production of a 16:0-rich oil. We present evidence that this type of FatB gene is ancient and ubiquitous in plants and that specialized plant medium-chain thioesterases have evolved independently from such enzymes several times during angiosperm evolution. Also, the ubiquitous 18:1-ACP thioesterase appears to be a derivative of a 16:0 thioesterase. PMID:7734968

  6. Quantum Breathers in Anisotropy Ferromagnetic Chains with Second-Order Coupling

    NASA Astrophysics Data System (ADS)

    Tang, Bing

    2016-08-01

    Under considering the next-nearest-neighbor interaction, quantum breathers in one-dimensional anisotropy ferromagnetic chains are theortically studied. By introducing the Dyson-Maleev transformation for spin operators, a map to a Heisenberg ferromagnetic spin lattice into an extended Bose-Hubbard model can be established. In the case of a small number of bosons, by means of the numerical diagonalization technique, the energy spectrum of the corresponding extended Bose-Hubbard model containing two bosons is calculated. When the strength of the single-ion anisotropy is enough large, a isolated single band appears. This isolated single band corresponds to two-boson bound state, which is the simplest quantum breather state. It is shown that the introduction of the next-nearest-neighbor interaction will lead to interesting band structures. In the case of a large number of bosons, by applying the time-dependent Hartree approximation, quantum breather states for the system is constructed. In this case, the effect of the next-nearest-neighbor interaction on quantum breathers is also analyzed.

  7. Quantum Breathers in Anisotropy Ferromagnetic Chains with Second-Order Coupling

    NASA Astrophysics Data System (ADS)

    Tang, Bing

    2016-03-01

    Under considering the next-nearest-neighbor interaction, quantum breathers in one-dimensional anisotropy ferromagnetic chains are theortically studied. By introducing the Dyson-Maleev transformation for spin operators, a map to a Heisenberg ferromagnetic spin lattice into an extended Bose-Hubbard model can be established. In the case of a small number of bosons, by means of the numerical diagonalization technique, the energy spectrum of the corresponding extended Bose-Hubbard model containing two bosons is calculated. When the strength of the single-ion anisotropy is enough large, a isolated single band appears. This isolated single band corresponds to two-boson bound state, which is the simplest quantum breather state. It is shown that the introduction of the next-nearest-neighbor interaction will lead to interesting band structures. In the case of a large number of bosons, by applying the time-dependent Hartree approximation, quantum breather states for the system is constructed. In this case, the effect of the next-nearest-neighbor interaction on quantum breathers is also analyzed.

  8. Sub- and supercritical defect scattering in Schrödinger chains with higher-order hopping

    NASA Astrophysics Data System (ADS)

    Stockhofe, J.; Schmelcher, P.

    2015-08-01

    We theoretically analyze a discrete Schrödinger chain with hopping to the first and second neighbors, as can be realized with zigzag arrangements of optical waveguides or lattice sites for cold atoms. Already at moderate values, second-neighbor hopping has a strong impact on the band structure, leading to the emergence of a new extremum located inside the band, accompanied by a van Hove singularity in the density of states. The energy band is then divided into a subcritical regime, with the usual unique correspondence between wave number and energy of the traveling waves, and a supercritical regime, in which waves of different wave number are degenerate in energy. We study the consequences of these features in a scattering setup, introducing a defect that locally breaks the translational invariance. The notion of a local probability current is generalized beyond the nearest-neighbor approximation and bound states with energies outside the band are discussed. At subcritical energies inside the band, an evanescent mode coexists with the traveling plane wave, giving rise to resonance phenomena in scattering. At weak coupling to the defect, we identify a prototypical Fano-Feshbach resonance of tunable shape and provide analytical expressions for its profile parameters. At supercritical energies, we observe coupling of the degenerate traveling waves, leading to an intricate wave-packet fragmentation dynamics. The corresponding branching ratios are analyzed.

  9. Novel Magnetic and Charge Orders in Dimer-Chain Iridate Ba5AlIr2O11

    NASA Astrophysics Data System (ADS)

    Ye, Feng; Terzic, J.; Wang, J. C.; Song, W. H.; Yuan, S. J.; Aswartham, S.; Cao, G.

    2015-03-01

    We report a novel magnetic state coexisting with a charge ordering state in a dimer-chain system Ba5AlIr2O11. This newly synthesized single-crystal iridate features both tetravalent Ir4+ and pentavalent Ir5+ ions in each of dimers that are only linked via AlO4-tetrahedra along the b-axis. Despite the evident one-dimensional characteristic, the dimer-chains undergo an unexpected long-rang order at TM = 4.5 K with a large magnetic anisotropy. The magnetic transition is unusually resilient to magnetic field up to 14 T but more susceptible to even modest hydrostatic pressure up to 10 kbar. Furthermore, a subtle structural change discerned at TS = 200 K marks a charge ordering that accompanies a huge enhancement in the dielectric constant and changes in the electrical resistivity. It is evident that the strong SOC imposes a j =1/2 (Ir4+) and singlet j =0 (Ir5+) states in each dimer, which critically hinges on the orbital and lattice degrees of freedom. This work was supported by NSF via Grant DMR 1265162.

  10. Metabolic alkene labeling and in vitro detection of histone acylation via the aqueous oxidative Heck reaction

    PubMed Central

    Ourailidou, Maria E.; Dockerty, Paul; Witte, Martin; Poelarends, Gerrit J.; Dekker, Frank J.

    2016-01-01

    The detection of protein lysine acylations remains a challenge due to a lack of specific antibodies for acylations with various chain lengths. This problem can be addressed by metabolic labeling techniques using carboxylates with reactive functionalities. Subsequent chemoselective reactions with a complementary moiety connected to a detection tag enable the visualization and quantification of the protein lysine acylome. In this study, we present EDTA-Pd(II) as a novel catalyst for the oxidative Heck reaction on protein-bound alkenes, which allows employment of fully aqueous reaction conditions. We used this reaction to monitor histone lysine acylation in vitro after metabolic incorporation of olefinic carboxylates as chemical reporters. PMID:25672493

  11. Remote control of regioselectivity in acyl-acyl carrier protein-desaturases

    PubMed Central

    Guy, Jodie E.; Whittle, Edward; Moche, Martin; Lengqvist, Johan; Lindqvist, Ylva; Shanklin, John

    2011-01-01

    Regiospecific desaturation of long-chain saturated fatty acids has been described as approaching the limits of the discriminatory power of enzymes because the substrate entirely lacks distinguishing features close to the site of dehydrogenation. To identify the elusive mechanism underlying regioselectivity, we have determined two crystal structures of the archetypal Δ9 desaturase from castor in complex with acyl carrier protein (ACP), which show the bound ACP ideally situated to position C9 and C10 of the acyl chain adjacent to the diiron active site for Δ9 desaturation. Analysis of the structures and modeling of the complex between the highly homologous ivy Δ4 desaturase and ACP, identified a residue located at the entrance to the binding cavity, Asp280 in the castor desaturase (Lys275 in the ivy desaturase), which is strictly conserved within Δ9 and Δ4 enzymes but differs between them. We hypothesized that interaction between Lys275 and the phosphate of the pantetheine, seen in the ivy model, is key to positioning C4 and C5 adjacent to the diiron center for Δ4 desaturation. Mutating castor Asp280 to Lys resulted in a major shift from Δ9 to Δ4 desaturation. Thus, interaction between desaturase side-chain 280 and phospho-serine 38 of ACP, approximately 27 Å from the site of double-bond formation, predisposes ACP binding that favors either Δ9 or Δ4 desaturation via repulsion (acidic side chain) or attraction (positively charged side chain), respectively. Understanding the mechanism underlying remote control of regioselectivity provides the foundation for reengineering desaturase enzymes to create designer chemical feedstocks that would provide alternatives to those currently obtained from petrochemicals. PMID:21930947

  12. Remote control of regioselectivity in acyl-acyl carrier protein-desaturases.

    PubMed

    Guy, Jodie E; Whittle, Edward; Moche, Martin; Lengqvist, Johan; Lindqvist, Ylva; Shanklin, John

    2011-10-01

    Regiospecific desaturation of long-chain saturated fatty acids has been described as approaching the limits of the discriminatory power of enzymes because the substrate entirely lacks distinguishing features close to the site of dehydrogenation. To identify the elusive mechanism underlying regioselectivity, we have determined two crystal structures of the archetypal Δ9 desaturase from castor in complex with acyl carrier protein (ACP), which show the bound ACP ideally situated to position C9 and C10 of the acyl chain adjacent to the diiron active site for Δ9 desaturation. Analysis of the structures and modeling of the complex between the highly homologous ivy Δ4 desaturase and ACP, identified a residue located at the entrance to the binding cavity, Asp280 in the castor desaturase (Lys275 in the ivy desaturase), which is strictly conserved within Δ9 and Δ4 enzymes but differs between them. We hypothesized that interaction between Lys275 and the phosphate of the pantetheine, seen in the ivy model, is key to positioning C4 and C5 adjacent to the diiron center for Δ4 desaturation. Mutating castor Asp280 to Lys resulted in a major shift from Δ9 to Δ4 desaturation. Thus, interaction between desaturase side-chain 280 and phospho-serine 38 of ACP, approximately 27 Å from the site of double-bond formation, predisposes ACP binding that favors either Δ9 or Δ4 desaturation via repulsion (acidic side chain) or attraction (positively charged side chain), respectively. Understanding the mechanism underlying remote control of regioselectivity provides the foundation for reengineering desaturase enzymes to create designer chemical feedstocks that would provide alternatives to those currently obtained from petrochemicals. PMID:21930947

  13. Process-chain approach to high-order perturbation calculus for quantum lattice models

    SciTech Connect

    Eckardt, Andre

    2009-05-15

    A method based on Rayleigh-Schroedinger perturbation theory is developed that allows to obtain high-order series expansions for ground-state properties of quantum lattice models. The approach is capable of treating both lattice geometries of large spatial dimensionalities d and on-site degrees of freedom with large state space dimensionalities. It has recently been used to accurately compute the zero-temperature phase diagram of the Bose-Hubbard model on a hypercubic lattice, up to arbitrary large filling and for d=2, 3, and greater [Teichmann et al., Phys. Rev. B 79, 100503(R) (2009)].0.

  14. Structural basis for acyl-group discrimination by human Gcn5L2

    PubMed Central

    Ringel, Alison E.; Wolberger, Cynthia

    2016-01-01

    Gcn5 is a conserved acetyltransferase that regulates transcription by acetylating the N-terminal tails of histones. Motivated by recent studies identifying a chemically diverse array of lysine acyl modifications in vivo, the acyl-chain specificity of the acetyltransferase human Gcn5 (Gcn5L2) was examined. Whereas Gcn5L2 robustly catalyzes lysine acetylation, the acyltransferase activity of Gcn5L2 becomes progressively weaker with increasing acyl-chain length. To understand how Gcn5 discriminates between different acyl-CoA molecules, structures of the catalytic domain of human Gcn5L2 bound to propionyl-CoA and butyryl-CoA were determined. Although the active site of Gcn5L2 can accommodate propionyl-CoA and butyryl-CoA without major structural rearrangements, butyryl-CoA adopts a conformation incompatible with catalysis that obstructs the path of the incoming lysine residue and acts as a competitive inhibitor of Gcn5L2 versus acetyl-CoA. These structures demonstrate how Gcn5L2 discriminates between acyl-chain donors and explain why Gcn5L2 has weak activity for acyl moieties that are larger than an acetyl group. PMID:27377381

  15. Chain ordering of hybrid lipids can stabilize domains in saturated/hybrid/cholesterol lipid membranes

    NASA Astrophysics Data System (ADS)

    Yamamoto, T.; Brewster, R.; Safran, S. A.

    2010-07-01

    We use a liquid-crystal model to predict that hybrid lipids (lipids that have one saturated and one unsaturated tail) can stabilize line interfaces between domains in mixed membranes of saturated lipids, hybrid lipids, and cholesterol (SHC membranes). The model predicts the phase separation of SHC membranes with both parabolic and loop binodals depending on the cholesterol concentration, modeled via an effective pressure. In some cases, the hybrid lipids can reduce the line tension to zero in SHC membranes at temperatures that approach the critical temperature as the pressure is increased. The differences in the hybrid saturated tail conformational order in bulk and at the interface are responsible for the reduction of the line tension.

  16. Acyl-CoA-Binding Proteins (ACBPs) in Plant Development.

    PubMed

    Lung, Shiu-Cheung; Chye, Mee-Len

    2016-01-01

    Acyl-CoA-binding proteins (ACBPs) play a pivotal role in fatty acid metabolism because they can transport medium- and long-chain acyl-CoA esters. In eukaryotic cells, ACBPs are involved in intracellular trafficking of acyl-CoA esters and formation of a cytosolic acyl-CoA pool. In addition to these ubiquitous functions, more specific non-redundant roles of plant ACBP subclasses are implicated by the existence of multigene families with variable molecular masses, ligand specificities, functional domains (e.g. protein-protein interaction domains), subcellular locations and gene expression patterns. In this chapter, recent progress in the characterization of ACBPs from the model dicot plant, Arabidopsis thaliana, and the model monocot, Oryza sativa, and their emerging roles in plant growth and development are discussed. The functional significance of respective members of the plant ACBP families in various developmental and physiological processes such as seed development and germination, stem cuticle formation, pollen development, leaf senescence, peroxisomal fatty acid β-oxidation and phloem-mediated lipid transport is highlighted. PMID:27023243

  17. Fatty acylation of proteins: The long and the short of it.

    PubMed

    Resh, Marilyn D

    2016-07-01

    Long, short and medium chain fatty acids are covalently attached to hundreds of proteins. Each fatty acid confers distinct biochemical properties, enabling fatty acylation to regulate intracellular trafficking, subcellular localization, protein-protein and protein-lipid interactions. Myristate and palmitate represent the most common fatty acid modifying groups. New insights into how fatty acylation reactions are catalyzed, and how fatty acylation regulates protein structure and function continue to emerge. Myristate is typically linked to an N-terminal glycine, but recent studies reveal that lysines can also be myristoylated. Enzymes that remove N-terminal myristoyl-glycine or myristate from lysines have now been identified. DHHC proteins catalyze S-palmitoylation, but the mechanisms that regulate substrate recognition by individual DHHC family members remain to be determined. New studies continue to reveal thioesterases that remove palmitate from S-acylated proteins. Another area of rapid expansion is fatty acylation of the secreted proteins hedgehog, Wnt and Ghrelin, by Hhat, Porcupine and GOAT, respectively. Understanding how these membrane bound O-acyl transferases recognize their protein and fatty acyl CoA substrates is an active area of investigation, and is punctuated by the finding that these enzymes are potential drug targets in human diseases. PMID:27233110

  18. DHHC Protein S-Acyltransferases Use Similar Ping-Pong Kinetic Mechanisms but Display Different Acyl-CoA Specificities*

    PubMed Central

    Jennings, Benjamin C.; Linder, Maurine E.

    2012-01-01

    DHHC proteins catalyze the reversible S-acylation of proteins at cysteine residues, a modification important for regulating protein localization, stability, and activity. However, little is known about the kinetic mechanism of DHHC proteins. A high-performance liquid chromatography (HPLC), fluorescent peptide-based assay for protein S-acylation activity was developed to characterize mammalian DHHC2 and DHHC3. Time courses and substrate saturation curves allowed the determination of Vmax and Km values for both the peptide N-myristoylated-GCG and palmitoyl-coenzyme A. DHHC proteins acylate themselves upon incubation with palmitoyl-CoA, which is hypothesized to reflect a transient acyl enzyme transfer intermediate. Single turnover assays with DHHC2 and DHHC3 demonstrated that a radiolabeled acyl group on the enzyme transferred to the protein substrate, consistent with a two-step ping-pong mechanism. Enzyme autoacylation and acyltransfer to substrate displayed the same acyl-CoA specificities, further supporting a two-step mechanism. Interestingly, DHHC2 efficiently transferred acyl chains 14 carbons and longer, whereas DHHC3 activity was greatly reduced by acyl-CoAs with chain lengths longer than 16 carbons. The rate and extent of autoacylation of DHHC3, as well as the rate of acyl chain transfer to protein substrate, were reduced with stearoyl-CoA when compared with palmitoyl-CoA. This is the first observation of lipid substrate specificity among DHHC proteins and may account for the differential S-acylation of proteins observed in cells. PMID:22247542

  19. Chain dynamics of selectively deuterated fatty acids in high-density lipoproteins studied by deuterium NMR

    SciTech Connect

    Parmar, Y.I.; Gorrissen, H.; Wassall, S.R.; Cushley, R.J.

    1985-01-01

    Deuterium order parameters have been determined for approximately 5 mol% selectively deuterated palmitic acid incorporated into the outer monolayer of high-density lipoproteins (HDL/sub 3/). The values are SCD = 0.38 for (2,2-/sup 2/H/sub 2/)palmitic acid, 0.38 for (4,4-/sup 2/H/sub 2/)palmitic acid, 0.37 for (5,5,6,6-/sup 2/H/sub 4/)palmitic acid, 0.23 for (11,11,12,12-/sup 2/H/sub 4/)palmitic acid, and 0.05 for (16,16,16-/sup 2/H/sub 3/)palmitic acid. Comparison of the acyl chain order parameters in HDL/sub 3/ with acyl chain order parameters determined recently for approximately 5 mol% deuterated palmitic acid in sonicated unilamellar vesicles, composed of the same ratio of phosphatidylcholine/sphingomyelin (85/15 w/w) found in HDL/sub 3/, shows that acyl chain order in the HDL/sub 3/ monolayer is approximately 3-5 times higher than in the vesicle bilayer. The acyl chain order in the lipoprotein monolayer is approximately 1.5-2 times higher than in the bilayer of phosphatidylcholine multilamellar dispersions. Deuterium longitudinal relaxation times have been measured for deuterated palmitic acid in HDL/sub 3/, and the values T/sub 1/ approximately 16 ms for C/sub 2/H/sub 2/ and 170 ms for C/sub 2/H/sub 3/ groups are a factor of more than 2 times smaller than found in phospholipid bilayers.

  20. Plant fatty acyl reductases: enzymes generating fatty alcohols for protective layers with potential for industrial applications.

    PubMed

    Rowland, Owen; Domergue, Frédéric

    2012-09-01

    Primary fatty alcohols are found throughout the biological world, either in free form or in a combined state. They are common components of plant surface lipids (i.e. cutin, suberin, sporopollenin, and associated waxes) and their absence can significantly perturb these essential barriers. Fatty alcohols and/or derived compounds are also likely to have direct functions in plant biotic and abiotic interactions. An evolutionarily related set of alcohol-forming fatty acyl reductases (FARs) is present in all kingdoms of life. Plant microsomal and plastid-associated FAR enzymes have been characterized, acting on acyl-coenzymeA (acyl-CoA) or acyl-acyl carrier protein (acyl-ACP) substrates, respectively. FARs have distinct substrate specificities both with regard to chain length and chain saturation. Fatty alcohols and wax esters, which are a combination of fatty alcohol and fatty acid, have a variety of commercial applications. The expression of FARs with desired specificities in transgenic microbes or oilseed crops would provide a novel means of obtaining these valuable compounds. In the present review, we report on recent progress in characterizing plant FAR enzymes and in understanding the biological roles of primary fatty alcohols, as well as describe the biotechnological production and industrial uses of fatty alcohols. PMID:22794916

  1. Metabolic and Tissue-Specific Regulation of Acyl-CoA Metabolism

    PubMed Central

    Ellis, Jessica M.; Bowman, Caitlyn E.; Wolfgang, Michael J.

    2015-01-01

    Acyl-CoA formation initiates cellular fatty acid metabolism. Acyl-CoAs are generated by the ligation of a fatty acid to Coenzyme A mediated by a large family of acyl-CoA synthetases (ACS). Conversely, acyl-CoAs can be hydrolyzed by a family of acyl-CoA thioesterases (ACOT). Here, we have determined the transcriptional regulation of all ACS and ACOT enzymes across tissues and in response to metabolic perturbations. We find patterns of coordinated regulation within and between these gene families as well as distinct regulation occurring in a tissue- and physiologically-dependent manner. Due to observed changes in long-chain ACOT mRNA and protein abundance in liver and adipose tissue, we determined the consequence of increasing cytosolic long-chain thioesterase activity on fatty acid metabolism in these tissues by generating transgenic mice overexpressing a hyperactive mutant of Acot7 in the liver or adipose tissue. Doubling cytosolic acyl-CoA thioesterase activity failed to protect mice from diet-induced obesity, fatty liver or insulin resistance, however, overexpression of Acot7 in adipocytes rendered mice cold intolerant. Together, these data suggest distinct modes of regulation of the ACS and ACOT enzymes and that these enzymes act in a coordinated fashion to control fatty acid metabolism in a tissue-dependent manner. PMID:25760036

  2. Reaction path determination for quantum mechanical/molecular mechanical modeling of enzyme reactions by combining first order and second order ``chain-of-replicas'' methods

    NASA Astrophysics Data System (ADS)

    Cisneros, G. Andrés; Liu, Haiyan; Lu, Zhenyu; Yang, Weitao

    2005-03-01

    A two-step procedure for the determination of reaction paths in enzyme systems is presented. This procedure combines two chain-of-states methods: a quantum mechanical/molecular mechanical (QM/MM) implementation of the nudged elastic band (NEB) method and a second order parallel path optimizer method both recently developed in our laboratory. In the first step, a reaction path determination is performed with the NEB method, along with a restrained minimization procedure for the MM environment to obtain a first approximation to the reaction path. In the second step, the calculated path is refined with the parallel path optimizer method. By combining these two methods the reaction paths are determined accurately, and in addition, the number of path optimization iterations are significantly reduced. This procedure is tested by calculating both steps of the isomerization of 2-oxo-4-hexenedioate by 4-oxalocrotonate tautomerase, which have been previously determined by our group. The calculated paths agree with the previously reported results and we obtain a reduction of 45%-55% in the number of path optimization cycles.

  3. Structural properties of pepsin-solubilized collagen acylated by lauroyl chloride along with succinic anhydride.

    PubMed

    Li, Conghu; Tian, Zhenhua; Liu, Wentao; Li, Guoying

    2015-10-01

    The structural properties of pepsin-solubilized calf skin collagen acylated by lauroyl chloride along with succinic anhydride were investigated in this paper. Compared with native collagen, acylated collagen retained the unique triple helix conformation, as determined by amino acid analysis, circular dichroism and X-ray diffraction. Meanwhile, the thermostability of acylated collagen using thermogravimetric measurements was enhanced as the residual weight increased by 5%. With the temperature increased from 25 to 115 °C, the secondary structure of native and acylated collagens using Fourier transform infrared spectroscopy measurements was destroyed since the intensity of the major amide bands decreased and the positions of the major amide bands shifted to lower wavenumber, respectively. Meanwhile, two-dimensional correlation spectroscopy revealed that the most sensitive bands for acylated and native collagens were amide I and II bands, respectively. Additionally, the corresponding order of the groups between native and acylated collagens was different and the correlation degree for acylated collagen was weaker than that of native collagen, suggesting that temperature played a small influence on the conformation of acylated collagen, which might be concluded that the hydrophobic interaction improved the thermostability of collagen. PMID:26117763

  4. Fatty acyl-CoA reductases of birds

    PubMed Central

    2011-01-01

    Background Birds clean and lubricate their feathers with waxes that are produced in the uropygial gland, a holocrine gland located on their back above the tail. The type and the composition of the secreted wax esters are dependent on the bird species, for instance the wax ester secretion of goose contains branched-chain fatty acids and unbranched fatty alcohols, whereas that of barn owl contains fatty acids and alcohols both of which are branched. Alcohol-forming fatty acyl-CoA reductases (FAR) catalyze the reduction of activated acyl groups to fatty alcohols that can be esterified with acyl-CoA thioesters forming wax esters. Results cDNA sequences encoding fatty acyl-CoA reductases were cloned from the uropygial glands of barn owl (Tyto alba), domestic chicken (Gallus gallus domesticus) and domestic goose (Anser anser domesticus). Heterologous expression in Saccharomyces cerevisiae showed that they encode membrane associated enzymes which catalyze a NADPH dependent reduction of acyl-CoA thioesters to fatty alcohols. By feeding studies of transgenic yeast cultures and in vitro enzyme assays with membrane fractions of transgenic yeast cells two groups of isozymes with different properties were identified, termed FAR1 and FAR2. The FAR1 group mainly synthesized 1-hexadecanol and accepted substrates in the range between 14 and 18 carbon atoms, whereas the FAR2 group preferred stearoyl-CoA and accepted substrates between 16 and 20 carbon atoms. Expression studies with tissues of domestic chicken indicated that FAR transcripts were not restricted to the uropygial gland. Conclusion The data of our study suggest that the identified and characterized avian FAR isozymes, FAR1 and FAR2, can be involved in wax ester biosynthesis and in other pathways like ether lipid synthesis. PMID:22151413

  5. Alteration of lipid membrane structure and dynamics by diacylglycerols with unsaturated chains.

    PubMed

    Alwarawrah, Mohammad; Hussain, Fazle; Huang, Juyang

    2016-02-01

    Diacylglycerols (DAGs) with unsaturated acyl chains play many important roles in biomembranes, such as a second messenger and activator for protein kinase C. In this study, three DAGs of distinctly different chain unsaturations (i.e. di16:0DAG (DPG), 16:0-18:1DAG (POG), and di18:1DAG (DOG)) are studied using atomistic MD simulation to compare their roles in the structure and dynamics of 16:0-18:1phosphatidylcholine (POPC) membranes. All three DAGs are able to produce the so-called 'condensing effect' in POPC membranes: decreasing area-per-lipid, and increasing acyl chain order and bilayer thickness. Our visual and quantitative analyses clearly show that DAG with unsaturated chains induce larger spacing between POPC headgroups, compared with DAG with saturated chains; this particular effect has long been hypothesized to be crucial for activating enzymes and receptors in cell membranes. DAGs with unsaturated chains are also located closer to the bilayer/aqueous interface than DPG and are more effective in slowing down lateral diffusion of molecules. We show that DAG molecules seek the "umbrella coverage" from neighboring phospholipid headgroups - similar to cholesterol. Unlike cholesterol, DAGs also hide their chains from water by laterally inserting their chains into the surrounding. Thus, acyl chains of DAG are more spread and disordered than those of PC due to the insertion. By calculating the potential of mean force (PMF) for POPC in POPC/DAG bilayers, we found that all three DAGs can significantly increase the free energy barrier for POPC to flip-flop, but only DAGs with unsaturated chains can additionally increase the free energy of POPC desorption. PMID:26607007

  6. Measurement and Development of Humanware and Technoware Competencies in Order to Meet Pintle Chain Product Requirements in Bandung Manufacture Polytechnic

    NASA Astrophysics Data System (ADS)

    Akbar, Jodi; Akbar, Muhammad; Irianto, Dradjad

    2016-02-01

    Politeknik Manufaktur Bandung (Bandung Manufacture Polytechnic) is a polytechnic education that is not only to educate their students, but also manufactures order from customers at its teaching factory. This polytechnic is usually not responsive with the number of reject due to amateur operators from newcomer students. However, customers will be displeased if the reject rate is too high which can cause delay of delivery. At the foundry section, pintle chain is a product that has the highest amount of quantity but the lowest product standard fulfilment. Realizing this problem, it is a strong need to give more focus on quality improvement. The polytechnic considers that bad quality is not only related to low level of humanware (operator) but also related to low level of technoware (machine and equipment). In this research, QFD model was used as a tool for identifying target of improvement of non conforming factors of humanware and technoware using UNESCAP's technometric model. An improvement was done by implementing new scheduling strategy at foundry unit in order to minimize waiting time from molding to pouring process because of deterioration problem. This strategy provides an opportunity to reduce completion times about 50% and waiting time about 95% compared to the existing scheduling strategy.

  7. Acyl CoA synthetase 5 (ACSL5) ablation in mice increases energy expenditure and insulin sensitivity and delays fat absorption

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Objective: The family of acyl-CoA synthetase enzymes (ACSL) activates fatty acids within cells to generate long chain fatty acyl CoA (FACoA). The differing metabolic fates of FACoAs such as incorporation into neutral lipids, phospholipids, and oxidation pathways are differentially regulated by the ...

  8. Pricing and ordering policies for price-dependent demand in a supply chain of a single retailer and a single manufacturer

    NASA Astrophysics Data System (ADS)

    Kim, Jungkyu; Hong, Yushin; Kim, Taebok

    2011-01-01

    This article discusses joint pricing and ordering policies for price-dependent demand in a supply chain consisting of a single retailer and a single manufacturer. The retailer places orders for products according to an EOQ policy and the manufacturer produces them on a lot-for-lot basis. Four mechanisms with differing levels of coordination are presented. Mathematical models are formulated and solution procedures are developed to determine the optimal retail prices and order quantities. Through extensive numerical experiments, we analyse and compare the behaviours and characteristics of the proposed mechanisms, and find that enhancing the level of coordination has important benefits for the supply chain.

  9. Enzyme-coupled assays for flip-flop of acyl-Coenzyme A in liposomes.

    PubMed

    Bavdek, Andrej; Vazquez, Hector M; Conzelmann, Andreas

    2015-11-01

    Acyl-Coenzyme A is made in the cytosol. Certain enzymes using acyl-CoA seem to operate in the lumen of the ER but no corresponding flippases for acyl-CoA or an activated acyl have been described. In order to test the ability of purified candidate flippases to operate the transport of acyl-CoA through lipid bilayers in vitro we developed three enzyme-coupled assays using large unilamellar vesicles (LUVs) obtained by detergent removal. The first assay uses liposomes encapsulating a water-soluble acyl-CoA:glycerol-3-phosphate acyl transferase plus glycerol-3-phosphate (G3P). It measures formation of [(3)H]lyso-phosphatidic acid inside liposomes after [(3)H]palmitoyl-CoA has been added from outside. Two other tests use empty liposomes containing [(3)H]palmitoyl-CoA in the inner membrane leaflet, to which either soluble acyl-CoA:glycerol-3-phosphate acyl transferase plus glycerol-3-phosphate or alkaline phosphatase are added from outside. Here one can follow the appearance of [(3)H]lyso-phosphatidic acid or of dephosphorylated [(3)H]acyl-CoA, respectively, both being made outside the liposomes. Although the liposomes may retain small amounts of detergent, all these tests show that palmitoyl-CoA crosses the lipid bilayer only very slowly and that the lipid composition of liposomes barely affects the flip-flop rate. Thus, palmitoyl-CoA cannot cross the membrane spontaneously implying that in vivo some transport mechanism is required. PMID:26325346

  10. Topological degeneracy (Majorana zero-mode) and 1 + 1D fermionic topological order in a magnetic chain on superconductor via spontaneous Z₂(f) symmetry breaking.

    PubMed

    Klassen, Joel; Wen, Xiao-Gang

    2015-10-14

    We study a chain of ferromagnetic sites, ie nano-particles, molecules or atoms, on a substrate of fully gapped superconductors. We find that under quite realistic conditions, the fermion-number-parity symmetry Z₂(f) can spontaneously break. In other words, such a chain can realize a 1  +  1D fermionic topologically ordered state and the corresponding two-fold topological degeneracy on an open chain. Such a topological degeneracy becomes the so called Majorana zero mode in the non-interacting limit. PMID:26401725

  11. Expression of poly-3-(R)-hydroxyalkanoate (PHA) polymerase and acyl-CoA-transacylase in plastids of transgenic potato leads to the synthesis of a hydrophobic polymer, presumably medium-chain-length PHAs.

    PubMed

    Romano, Andrea; van der Plas, Linus H W; Witholt, Bernard; Eggink, Gerrit; Mooibroek, Hans

    2005-01-01

    Medium-chain-length poly-3-(R)-hydroxyalkanoates (mcl-PHAs) belong to the group of microbial polyesters. The minimum gene-set for the accumulation of mcl-PHAs from de novo fatty acid biosynthesis has been identified in prokaryotes as consisting of the Pha-C1 polymerase and the ACP-CoA-transacylase. In this paper, the synthesis of mcl-PHAs has been attempted in transgenic potato (Solanum tuberosum L.) using the same set of genes that were introduced into potato by particle bombardment. Polymer contents of transgenic lines were analysed by gas chromatography and by a new simple method employing a size-exclusion filter column. The expression of the Pha-C1 polymerase and the ACP-CoA-transacylase in the plastids of transgenic potato led to the synthesis of a hydrophobic polymer composed of mcl-hydroxy-fatty acids with carbon chain lengths ranging from C-6 to C-12 in leaves of the selected transgenic lines. We strongly suggest that the polymer observed consists of mcl-PHAs and that this report establishes for the first time a possible route for the production of mcl-PHAs from de novo fatty acid biosynthesis in plants. PMID:15351883

  12. Deuterium nuclear magnetic resonance investigation of the effects of proteins and polypeptides on hydrocarbon chain order in model membrane systems

    PubMed Central

    Oldfield, E.; Gilmore, R.; Glaser, M.; Gutowsky, H. S.; Hshung, J. C.; Kang, S. Y.; King, Tsoo E.; Meadows, M.; Rice, D.

    1978-01-01

    Deuterium Fourier-transform nuclear magnetic resonance spectra have been obtained of 1-myristoyl 2-(14,14,14-trideutero)myristoyl phosphatidylcholine bilayers at 34.1 MHz by using the quadrupole echo pulse technique. Thereby, we have investigated the effects upon the deuterated dimyristoyl phosphatidylcholine bilayers of the following proteins and polypeptides: gramicidin A, bacteriophage f1 coat protein, beef brain myelin proteolipid apoprotein, cytochrome b5, and cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1). Above Tc, the transition temperature between the gel and liquid crystal phases, the quadrupole splitting of the deuterium-labeled methyl group is reduced or collapsed in the presence of protein or polypeptide. No evidence has been found for ordered “boundary lipid.” Below Tc, the spectra show that the hydrocarbon chains are prevented from crystallizing by the protein (or polypeptide) incorporated in the membrane. Similar disordering effects above Tc are also seen when an unsaturated lipid, 1-(16,16,16-trideutero)palmitoyl 2-palmitoleyl phosphatidylcholine is complexed with cytochrome oxidase. PMID:16592570

  13. Antiferromagnetic order in single crystals of the S =2 quasi-one-dimensional chain MnCl3(bpy)

    NASA Astrophysics Data System (ADS)

    Shinozaki, Shin-ichi; Okutani, Akira; Yoshizawa, Daichi; Kida, Takanori; Takeuchi, Tetsuya; Yamamoto, Shoji; Risset, Olivia N.; Talham, Daniel R.; Meisel, Mark W.; Hagiwara, Masayuki

    2016-01-01

    A suite of experimental tools, including high-field magnetization and electron spin resonance (ESR) studies in magnetic fields of up to 50 T and heat capacity studies up to 9 T, have revealed antiferromagnetic order in single crystals of the Heisenberg S =2 chain compound MnCl3(bpy), where bpy is 2 ,2'-bipyridine . The Néel temperature, which depends on the strength of the applied magnetic field and its orientation with respect to the crystalline axes that was revealed by heat capacity measurements, is near 11.5 K in zero field. The spin-flop transition is identified in the magnetization curve acquired at 1.7 K and at μoHSFc=24 T along the c axis. The transition field HSF is lower than that expected from the previous antiferromagnetic resonance (AFMR) studies on a powder sample. The identification of the long-range antiferromagnetic order resolves an earlier report by Granroth et al. [Phys. Rev. Lett. 77, 1616 (1996)], 10.1103/PhysRevLett.77.1616 that identified MnCl3(bpy) as an S =2 Haldane system down to 40 mK. The ESR studies identify a wide range of antiferromagnetic resonance modes that provide additional microscopic information about the g values (ga*=2.09 , gb=1.92 , and gc=2.07 ), the zero-field splitting constants, D /kB=-1.5 K and E /kB=-0.17 K when the nearest-neighbor spin interaction J /kB=31.2 K, which is evaluated from fitting the susceptibility, and the anisotropy of this compound (easy axis is the c axis, the second easy-axis is the b axis, and the hard axis is the a* axis), when using a standard (two-sublattice) AFMR analysis that does not quantitatively reproduce the observed HSFc value. The observed resonance mode indicates the frequency minimum at HSFc.

  14. The mitochondrial acyl carrier protein (ACP) coordinates mitochondrial fatty acid synthesis with iron sulfur cluster biogenesis

    PubMed Central

    Van Vranken, Jonathan G; Jeong, Mi-Young; Wei, Peng; Chen, Yu-Chan; Gygi, Steven P; Winge, Dennis R; Rutter, Jared

    2016-01-01

    Mitochondrial fatty acid synthesis (FASII) and iron sulfur cluster (FeS) biogenesis are both vital biosynthetic processes within mitochondria. In this study, we demonstrate that the mitochondrial acyl carrier protein (ACP), which has a well-known role in FASII, plays an unexpected and evolutionarily conserved role in FeS biogenesis. ACP is a stable and essential subunit of the eukaryotic FeS biogenesis complex. In the absence of ACP, the complex is destabilized resulting in a profound depletion of FeS throughout the cell. This role of ACP depends upon its covalently bound 4’-phosphopantetheine (4-PP)-conjugated acyl chain to support maximal cysteine desulfurase activity. Thus, it is likely that ACP is not simply an obligate subunit but also exploits the 4-PP-conjugated acyl chain to coordinate mitochondrial fatty acid and FeS biogenesis. DOI: http://dx.doi.org/10.7554/eLife.17828.001 PMID:27540631

  15. The mitochondrial acyl carrier protein (ACP) coordinates mitochondrial fatty acid synthesis with iron sulfur cluster biogenesis.

    PubMed

    Van Vranken, Jonathan G; Jeong, Mi-Young; Wei, Peng; Chen, Yu-Chan; Gygi, Steven P; Winge, Dennis R; Rutter, Jared

    2016-01-01

    Mitochondrial fatty acid synthesis (FASII) and iron sulfur cluster (FeS) biogenesis are both vital biosynthetic processes within mitochondria. In this study, we demonstrate that the mitochondrial acyl carrier protein (ACP), which has a well-known role in FASII, plays an unexpected and evolutionarily conserved role in FeS biogenesis. ACP is a stable and essential subunit of the eukaryotic FeS biogenesis complex. In the absence of ACP, the complex is destabilized resulting in a profound depletion of FeS throughout the cell. This role of ACP depends upon its covalently bound 4'-phosphopantetheine (4-PP)-conjugated acyl chain to support maximal cysteine desulfurase activity. Thus, it is likely that ACP is not simply an obligate subunit but also exploits the 4-PP-conjugated acyl chain to coordinate mitochondrial fatty acid and FeS biogenesis. PMID:27540631

  16. Ligand binding to the ACBD6 protein regulates the acyl-CoA transferase reactions in membranes.

    PubMed

    Soupene, Eric; Kuypers, Frans A

    2015-10-01

    The binding determinants of the human acyl-CoA binding domain-containing protein (ACBD) 6 and its function in lipid renewal of membranes were investigated. ACBD6 binds acyl-CoAs of a chain length of 6 to 20 carbons. The stoichiometry of the association could not be fitted to a 1-to-1 model. Saturation of ACBD6 by C16:0-CoA required higher concentration than less abundant acyl-CoAs. In contrast to ACBD1 and ACBD3, ligand binding did not result in the dimerization of ACBD6. The presence of fatty acids affected the binding of C18:1-CoA to ACBD6, dependent on the length, the degree of unsaturation, and the stereoisomeric conformation of their aliphatic chain. ACBD1 and ACBD6 negatively affected the formation of phosphatidylcholine (PC) and phosphatidylethanolamine in the red blood cell membrane. The acylation rate of lysophosphatidylcholine into PC catalyzed by the red cell lysophosphatidylcholine-acyltransferase 1 protein was limited by the transfer of the acyl-CoA substrate from ACBD6 to the acyltransferase enzyme. These findings provide evidence that the binding properties of ACBD6 are adapted to prevent its constant saturation by the very abundant C16:0-CoA and protect membrane systems from the detergent nature of free acyl-CoAs by controlling their release to acyl-CoA-utilizing enzymes. PMID:26290611

  17. Natural variability in acyl moieties of sugar esters produced by certain tobacco and other Solanaceae species.

    PubMed

    Kroumova, Antoaneta B M; Zaitlin, Dave; Wagner, George J

    2016-10-01

    A unique feature of glandular trichomes of plants in the botanical family Solanaceae is that they produce sugar esters (SE), chemicals that have been shown to possess insecticidal, antifungal, and antibacterial properties. Sugar esters of tobacco (Nicotiana tabacum) provide pest resistance, and are important flavor precursors in oriental tobacco cultivars. Acyl moieties of SEs in Nicotiana spp., petunia, and tomato are shown to vary with respect to carbon length and isomer structure (2-12 carbon chain length; anteiso-, iso-, and straight-chain). Sugar esters and their acyl groups could serve as a model to explore the basis of phenotypic diversity and adaptation to natural and agricultural environments. However, information on the diversity of acyl composition among species, cultivars, and accessions is lacking. Herein, described is the analysis of SE acyl groups found in 21 accessions of Nicotiana obtusifolia (desert tobacco), six of Nicotiana occidentalis subsp. hesperis, three of Nicotiana alata, two of N. occidentalis, four modern tobacco cultivars, five petunia hybrids, and one accession each of a primitive potato (Solanum berthaultii) and tomato (Solanum pennellii). A total of 20 different acyl groups was observed that were represented differently among cultivars, species, and accessions. In Nicotiana species, acetate and iso- and anteiso-branched acids prevailed. Straight-chain groups (2-8 carbons) were prominent in petunias, while octanoic acid was prominent in N. alata and N. × sanderae. Two unexpected acyl groups, 8-methyl nonanoate and decanoate were found in N. occidentalis subsp. hesperis. Longer chain groups were found in the petunia, tomato, and potato species studied. PMID:27262877

  18. Stratum corneum lipid matrix: Location of acyl ceramide and cholesterol in the unit cell of the long periodicity phase.

    PubMed

    Mojumdar, E H; Gooris, G S; Groen, D; Barlow, D J; Lawrence, M J; Demé, B; Bouwstra, J A

    2016-08-01

    The extracellular lipid matrix in the skin's outermost layer, the stratum corneum, is crucial for the skin barrier. The matrix is composed of ceramides (CERs), cholesterol (CHOL) and free fatty acids (FFAs) and involves two lamellar phases: the short periodicity phase (SPP) and the long periodicity phase (LPP). To understand the skin barrier thoroughly, information about the molecular arrangement in the unit cell of these lamellar phases is paramount. Previously we examined the molecular arrangement in the unit cell of the SPP. Furthermore X-ray and neutron diffraction revealed a trilayer arrangement of lipids within the unit cell of the LPP [D. Groen et al., Biophysical Journal, 97, 2242-2249, 2009]. In the present study, we used neutron diffraction to obtain more details about the location of lipid (sub)classes in the unit cell of the LPP. The diffraction pattern revealed at least 8 diffraction orders of the LPP with a repeating unit of 129.6±0.5Å. To determine the location of lipid sub(classes) in the unit cell, samples were examined with either only protiated lipids or selectively deuterated lipids. The diffraction data obtained by means of D2O/H2O contrast variation together with a gradual replacement of one particular CER, the acyl CER, by its partly deuterated counterpart, were used to construct the scattering length density profiles. The acyl chain of the acyl CER subclass is located at a position of ~21.4±0.2Å from the unit cell centre of the LPP. The position and orientation of CHOL in the LPP unit cell were determined using tail and head-group deuterated forms of the sterol. CHOL is located with its head-group positioned ~26±0.2Å from the unit cell centre. This allows the formation of a hydrogen bond with the ester group of the acyl CER located in close proximity. Based on the positions of the deuterated moieties of the acyl CER, CHOL and the previously determined location of two other lipid subclasses [E.H. Mojumdar et al., Biophysical Journal

  19. Kinetic and Structural Basis for Acyl-Group Selectivity and NAD(+) Dependence in Sirtuin-Catalyzed Deacylation.

    PubMed

    Feldman, Jessica L; Dittenhafer-Reed, Kristin E; Kudo, Norio; Thelen, Julie N; Ito, Akihiro; Yoshida, Minoru; Denu, John M

    2015-05-19

    Acylation of lysine is an important protein modification regulating diverse biological processes. It was recently demonstrated that members of the human Sirtuin family are capable of catalyzing long chain deacylation, in addition to the well-known NAD(+)-dependent deacetylation activity [Feldman, J. L., Baeza, J., and Denu, J. M. (2013) J. Biol. Chem. 288, 31350-31356]. Here we provide a detailed kinetic and structural analysis that describes the interdependence of NAD(+)-binding and acyl-group selectivity for a diverse series of human Sirtuins, SIRT1-SIRT3 and SIRT6. Steady-state and rapid-quench kinetic analyses indicated that differences in NAD(+) saturation and susceptibility to nicotinamide inhibition reflect unique kinetic behavior displayed by each Sirtuin and depend on acyl substrate chain length. Though the rate of nucleophilic attack of the 2'-hydroxyl on the C1'-O-alkylimidate intermediate varies with acyl substrate chain length, this step remains rate-determining for SIRT2 and SIRT3; however, for SIRT6, this step is no longer rate-limiting for long chain substrates. Cocrystallization of SIRT2 with myristoylated peptide and NAD(+) yielded a co-complex structure with reaction product 2'-O-myristoyl-ADP-ribose, revealing a latent hydrophobic cavity to accommodate the long chain acyl group, and suggesting a general mechanism for long chain deacylation. Comparing two separately determined co-complex structures containing either a myristoylated peptide or 2'-O-myristoyl-ADP-ribose indicates there are conformational changes at the myristoyl-ribose linkage with minimal structural differences in the enzyme active site. During the deacylation reaction, the fatty acyl group is held in a relatively fixed position. We describe a kinetic and structural model to explain how various Sirtuins display unique acyl substrate preferences and how different reaction kinetics influence NAD(+) dependence. The biological implications are discussed. PMID:25897714

  20. Charge ordering and nonlinear electrical transport in quasi-one-dimensional organic chains with strong electrostatic interchain interactions

    NASA Astrophysics Data System (ADS)

    Okamoto, Kentaro; Tanaka, Toshiyuki; Fujita, Wataru; Awaga, Kunio; Inabe, Tamotsu

    2007-08-01

    We here examine the electrical and magnetic properties of the isostructural NT3•MCl4 ( NT=naphtho [2,1- d :6,5- d' ]bis([1,2,3] dithiazole and M=Ga and Fe). The crystal structure of NT3•MCl4 consists of one-dimensional π -stacking chains of NT with strong interchain interactions caused by electrostatic Sδ+•••Nδ- contacts. This structure includes four NT molecules with significant differences in molecular structure and charge, exhibiting a characteristic charge ordering, namely, three-dimensional alternation of charge-rich (or -intermediate) and -poor molecules. NT3•GaCl4 and NT3•FeCl4 are found to be semiconductors with σRT˜0.5Scm-1 and to exhibit a nonlinear electrical transport at room temperature with a very low threshold field of 80Vcm-1 for the negative differential resistance. This threshold field significantly increases with a decrease in temperature. The X -band electron paramagnetic resonance (EPR) spectra of NT3•GaCl4 consist of a single-line absorption ascribable to that of the NT+ cation. When the sample is exposed to a current at room temperature, this signal exhibits a drastic decrease in intensity with little change in linewidth. This is attributed to the inhomogeneous formation of EPR-silent conducting pathways for the nonlinear transport. The temperature dependence of the EPR spin susceptibility χs of NT3•GaCl4 suggests a transition toward a spin-gap state below 20K ; χs exhibits a Bonner-Fisher-type temperature dependence above 20K , but gradually collapses to zero below this temperature.

  1. Echium oil increased the expression of a Δ4 Fads2 fatty acyl desaturase and the deposition of n-3 long-chain polyunsaturated fatty acid in comparison with linseed oil in striped snakehead (Channa striata) muscle.

    PubMed

    Jaya-Ram, Annette; Shu-Chien, Alexander Chong; Kuah, Meng-Kiat

    2016-08-01

    Despite the potential of vegetable oils as aquafeed ingredients, a major drawback associated with their utilization is the inferior level of beneficial n-3 long-chain polyunsaturated fatty acids (LC-PUFA). Echium oil (EO), which is rich in stearidonic acid (SDA, 18:4n-3), could potentially improve the deposition of n-3 LC-PUFA as the biosynthesis of LC-PUFA is enhanced through bypassing the rate-limiting ∆6 desaturation step. We report for the first time an attempt to investigate whether the presence of a desaturase (Fads2) capable of ∆4 desaturation activities and an elongase (Elovl5) will leverage the provision of dietary SDA to produce a higher rate of LC-PUFA bioconversion. Experimental diets were designed containing fish oil (FO), EO or linseed oil (LO) (100FO, 100EO, 100LO), and diets which comprised equal mixtures of the designated oils (50EOFO and 50EOLO) were evaluated in a 12-week feeding trial involving striped snakeheads (Channa striata). There was no significant difference in growth and feed conversion efficiency. The hepatic fatty acid composition and higher expression of fads2 and elovl5 genes in fish fed EO-based diets indicate the utilization of dietary SDA for LC-PUFA biosynthesis. Collectively, this resulted in a higher deposition of muscle eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) compared to LO-based diets. Dietary EO improved the ratio of n-3 LC-PUFA to n-6 LC-PUFA in fish muscle, which is desirable for human populations with excessive consumption of n-6 PUFA. This study validates the contribution of SDA in improving the content of n-3 LC-PUFA and the ratio of EPA to arachidonic acid (ARA, 20:4n-6) in a freshwater carnivorous species. PMID:26842427

  2. Stability-increasing effects of anthocyanin glycosyl acylation.

    PubMed

    Zhao, Chang-Ling; Yu, Yu-Qi; Chen, Zhong-Jian; Wen, Guo-Song; Wei, Fu-Gang; Zheng, Quan; Wang, Chong-De; Xiao, Xing-Lei

    2017-01-01

    This review comprehensively summarizes the existing knowledge regarding the chemical implications of anthocyanin glycosyl acylation, the effects of acylation on the stability of acylated anthocyanins and the corresponding mechanisms. Anthocyanin glycosyl acylation commonly refers to the phenomenon in which the hydroxyl groups of anthocyanin glycosyls are esterified by aliphatic or aromatic acids, which is synthetically represented by the acylation sites as well as the types and numbers of acyl groups. Generally, glycosyl acylation increases the in vitro and in vivo chemical stability of acylated anthocyanins, and the mechanisms primarily involve physicochemical, stereochemical, photochemical, biochemical or environmental aspects under specific conditions. Additionally, the acylation sites as well as the types and numbers of acyl groups influence the stability of acylated anthocyanins to different degrees. This review could provide insight into the optimization of the stability of anthocyanins as well as the application of suitable anthocyanins in food, pharmaceutical and cosmetic industries. PMID:27507456

  3. Acyl lipidation of a peptide: effects on activity and epidermal permeability in vitro

    PubMed Central

    Rocco, Daniel; Ross, James; Murray, Paul E; Caccetta, Rima

    2016-01-01

    Short-chain lipid conjugates can increase permeability of a small peptide across human epidermis; however, the emerging lipoaminoacid (LAA) conjugation technique is costly and can deliver mixed synthetic products of varied biological potential. LAA conjugation using a racemic mixture produces a mixture of D- and L-stereoisomers. Individual enantiomers can be produced at an extra cost. We investigated an affordable technique that produces only one synthetic product: short-chain (C7–C8) acyl lipidation. Acyl lipidation of Ala-Ala-Pro-Val, an inhibitor of human neutrophil elastase (HNE; believed to lead to abnormal tissue destruction and disease development), was investigated as an alternative to LAA conjugation. The current study aimed to assess the effects of acyl lipidation (either at the N-terminal or at the C-terminal) on neutrophil elastase activity in vitro and on transdermal delivery ex vivo. The inhibitory capacity of the acyl conjugates was compared to LAA conjugates (conjugated at the N-terminal) of the same peptide. The L-stereoisomer appears to rapidly degrade, but it represents a significantly (P<0.05) better inhibitor of HNE than the parent peptide (Ala-Ala-Pro-Val). Although the D-stereoisomer appears to permeate human epidermal skin sections in a better fashion than the L-stereoisomer, it is not a significantly better inhibitor of HNE than the parent peptide. Acyl lipidation (with a C7 lipid chain) at either end of the peptide substantially enhances the permeability of the peptide across human skin epidermis as well as significantly (P<0.005) increases its elastase inhibitory potential. Therefore, our current study indicates that acyl lipidation of a peptide is a more economical and effective alternative to LAA conjugation. PMID:27468224

  4. Sticky swinging arm dynamics: studies of an acyl carrier protein domain from the mycolactone polyketide synthase

    PubMed Central

    Vance, Steven; Tkachenko, Olga; Thomas, Ben; Bassuni, Mona; Hong, Hui; Nietlispach, Daniel; Broadhurst, William

    2016-01-01

    Type I modular polyketide synthases (PKSs) produce polyketide natural products by passing a growing acyl substrate chain between a series of enzyme domains housed within a gigantic multifunctional polypeptide assembly. Throughout each round of chain extension and modification reactions, the substrate stays covalently linked to an acyl carrier protein (ACP) domain. In the present study we report on the solution structure and dynamics of an ACP domain excised from MLSA2, module 9 of the PKS system that constructs the macrolactone ring of the toxin mycolactone, cause of the tropical disease Buruli ulcer. After modification of apo ACP with 4′-phosphopantetheine (Ppant) to create the holo form, 15N nuclear spin relaxation and paramagnetic relaxation enhancement (PRE) experiments suggest that the prosthetic group swings freely. The minimal chemical shift perturbations displayed by Ppant-attached C3 and C4 acyl chains imply that these substrate-mimics remain exposed to solvent at the end of a flexible Ppant arm. By contrast, hexanoyl and octanoyl chains yield much larger chemical shift perturbations, indicating that they interact with the surface of the domain. The solution structure of octanoyl-ACP shows the Ppant arm bending to allow the acyl chain to nestle into a nonpolar pocket, whereas the prosthetic group itself remains largely solvent exposed. Although the highly reduced octanoyl group is not a natural substrate for the ACP from MLSA2, similar presentation modes would permit partner enzyme domains to recognize an acyl group while it is bound to the surface of its carrier protein, allowing simultaneous interactions with both the substrate and the ACP. PMID:26920023

  5. Alkylation and acylation of cyclotriphosphazenes.

    PubMed

    Benson, Mark A; Zacchini, Stefano; Boomishankar, Ramamoorthy; Chan, Yuri; Steiner, Alexander

    2007-08-20

    Phosphazenes (RNH)6P3N3 (R = n-propyl, isobutyl, isopropyl, cyclohexyl, tert-butyl, benzyl) are readily alkylated at ring N sites by alkyl halides forming N-alkyl phosphazenium cations. Alkylation of two ring N sites occurred after prolonged heating in the presence of methyl iodide or immediately at room temperature with methyl triflate yielding N,N'-dimethyl phosphazenium dications. Geminal dichloro derivatives Cl2(RNH)4P3N3 are methylated by methyl iodide at the ring N site adjacent to both P centers carrying four RNH groups. X-ray crystal structures showed that the alkylation of ring N sites leads to substantial elongation of the associated P-N bonds. Both N-alkyl and N,N'-dialkyl phosphazenium salts form complex supramolecular networks in the solid state via NH...X interactions. Systems carrying less-bulky RNH groups show additional NH...N bonds between N-alkyl phosphazenium ions. N-Alkyl phosphazenium halides form complexes with silver ions upon treatment with silver nitrate. Depending on the steric demand of RNH substituents, either one or both of the vacant ring N sites engage in coordination to silver ions. Treatment of (RNH)6P3N3 (R = isopropyl) with acetyl chloride and benzoyl chloride, respectively, yielded N-acyl phosphazenium ions. X-ray crystal structures revealed that elongation of P-N bonds adjacent to the acylated ring N site is more pronounced than it is in the case of N-alkylated species. Salts containing N-alkyl phosphazenium ions are stable toward water and other mild nucleophiles, while N,N'-dialkyl and N-acyl phosphazenium salts are readily hydrolyzed. The reaction of (RNH)6P3N3 with bromoacetic acid led to N-alkylation at one ring N site in addition to formation of an amide via condensation of an adjacent RNH substituent with the carboxylic acid group. The resulting bromide salt contains mono cations of composition (RNH)5P3N3CH2CONR in which a CH2-C(O) unit is embedded between a ring N and an exocyclic N site of the phosphazene. PMID

  6. Disorder from order among anisotropic next-nearest-neighbor Ising spin chains in SrHo2O4

    SciTech Connect

    Wen, J. -J.; Tian, W.; Garlea, V. O.; Koohpayeh, S. M.; McQueen, T. M.; Li, H. -F.; Yan, J. -Q.; Rodriguez-Rivera, J. A.; Vaknin, D.; Broholm, C. L.

    2015-02-26

    In this study, we describe why Ising spin chains with competing interactions in SrHo2O4 segregate into ordered and disordered ensembles at low temperatures (T). Using elastic neutron scattering, magnetization, and specific heat measurements, the two distinct spin chains are inferred to have Néel (↑↓↑↓) and double-Néel (↑↑↓↓) ground states, respectively. Below TN = 0.68(2)K, the Néel chains develop three-dimensional long range order (LRO), which arrests further thermal equilibration of the double-Néel chains so they remain in a disordered incommensurate state for T below TS = 0.52(2)K. SrHo2O4 distills an important feature of incommensurate low dimensional magnetism: kinetically trapped topological defects in a quasi–d–dimensional spin system can preclude order in d + 1 dimensions.

  7. Effect of Saturated Very Long-Chain Fatty Acids on the Organization of Lipid Membranes: A Study Combining (2)H NMR Spectroscopy and Molecular Dynamics Simulations.

    PubMed

    Paz Ramos, Adrian; Lagüe, Patrick; Lamoureux, Guillaume; Lafleur, Michel

    2016-07-21

    Little is known about the interaction of very long-chain saturated fatty acids (VLCFAs) with biological membranes. However, this could play an important role on interleaflet interactions and signal transduction mechanisms in cells. The aim of this work is to determine how VLCFA structurally adapts in fluid phospholipid bilayers, since both species must exhibit a significant hydrophobic mismatch. The membrane organization has been described by means of (2)H NMR and molecular dynamics simulations. Our results show that the protonation state affects the position and order of free fatty acids (FFAs) in phospholipid membranes. It was shown that the protonated FFA-C24 carboxyl group is located slightly under the POPC head group and therefore its acyl chain can interact with the lipids of the opposite leaflet. This interdigitation of the end of the acyl chain causes a second plateau observed in SC-D profiles, a very unusual feature in lipid systems. PMID:27351151

  8. Study of Triheptanoin for Treatment of Long-Chain Fatty Acid Oxidation Disorder

    ClinicalTrials.gov

    2015-04-20

    Very Long-chain acylCoA Dehydrogenase (VLCAD) Deficiency; Carnitine Palmitoyltransferase 2 (CPT2) Deficiency; Mitochondrial Trifunctional Protein (TFP) Deficiency; Long-chain 3 hydroxyacylCoA Dehydrogenase (LCHAD) Deficiency

  9. Long chain acyl-CoA synthetases and other acyl activating enzymes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Proper synthesis and breakdown of molecules containing carboxylic acids is a vital part of metabolism in all living organisms. Given the relatively inert chemical nature of many carboxylic acids, activation is a necessary step prior to use in the various anabolic and catabolic pathways that utilize...

  10. Friedel-Crafts Acylation with Amides

    PubMed Central

    Raja, Erum K.; DeSchepper, Daniel J.; Nilsson Lill, Sten O.; Klumpp, Douglas A.

    2012-01-01

    Friedel-Crafts acylation has been known since the 1870s and it is an important organic synthetic reaction leading to aromatic ketone products. Friedel-Crafts acylation is usually done with carboxylic acid chlorides or anhydrides while amides are generally not useful substrates in these reactions. Despite being the least reactive carboxylic acid derivative, we have found a series of amides capable of providing aromatic ketones in good yields (55–96%, 17 examples). We propose a mechanism involving diminished C-N resonance through superelectrophilic activation and subsequent cleavage to acyl cations. PMID:22690740

  11. Equilibrium pricing and ordering policies in a two-echelon supply chain in the presence of strategic customers.

    PubMed

    Sadjadi, Seyed J; Naeij, Jafar; Shavandi, Hasan; Makui, Ahmad

    2016-06-01

    This paper studying the impact of strategic customer behavior on decentralized supply chain gains and decisions, which includes a supplier, and a monopoly firm as a retailer who sells a single product over a finite two periods of selling season. We consider three types of customers: myopic, strategic and low-value customers. The problem is formulated as a bi-level game where at the second level (e.g. horizontal game), the retailer determines his/her equilibrium pricing strategy in a non-cooperative simultaneous general game with strategic customers who choose equilibrium purchasing strategy to maximize their expected surplus. At the first level (e.g. vertical game), the supplier competes with the retailer as leader and follower in the Stackelberg game. They set the wholesale price and initial stocking capacity to maximize their profits. Finally, a numerical study is presented to demonstrate the impacts of strategic behavior on supply chain gain and decisions; subsequently the effects of market parameters on decision variables and total profitability of supply chain's members is studied through a sensitivity analysis. PMID:27276375

  12. Pharmacokinetics of naproxen, its metabolite O-desmethylnaproxen, and their acyl glucuronides in humans.

    PubMed

    Vree, T B; van den Biggelaar-Martea, M; Verwey-van Wissen, C P; Vree, J B; Guelen, P J

    1993-08-01

    The aim of this investigation was to assess the pharmacokinetics of naproxen in 10 human subjects after an oral dose of 500 mg using a direct HPLC analysis of the acyl glucuronide conjugates of naproxen and its metabolite O-desmethylnaproxen. The mean t1/2 of naproxen in 9 subjects was 24.7 +/- 6.4 h (range 16 to 36 h). The t1/2 of 7.4 as found in subject number 10 must, therefore, be regarded as an extraordinary case (p < 0.0153). Naproxen acyl glucuronide accounts for 50.8 +/- 7.32 per cent of the dose, its isomerized conjugate isoglucuronide for 6.5 +/- 2.0 per cent, O-desmethylnaproxen acyl glucuronide for 14.3 +/- 3.4 per cent, and its isoglucuronide for 5.5 +/- 1.3 per cent (n = 10; 100 h collection period). Naproxen and O-desmethylnaproxen are excreted in negligible amounts (< 1 per cent). Even though urine pH of the subjects was kept acid (range pH 5.0-5.5) in order to stabilize the acyl glucuronides, isomerization takes place in blood when the acyl glucuronide is released from the liver for excretion by the kidney. Binding to plasma proteins was measured as 98 per cent and 100 per cent, respectively for the unconjugated compounds naproxen and O-desmethylnaproxen. Binding of the acyl glucuronides was less, being 92 per cent; for naproxen acyl glucuronide, 66 per cent for naproxen isoglucuronide, 72 per cent for O-desmethylnaproxen acyl glucuronide and 42 per cent for O-desmethylnaproxen isoglucuronide. PMID:8218967

  13. Non-Monotonic Concentration Effects in the Phase Behavior and Nematic Orders: Mixtures of Side-Chain Liquid Crystalline Polymers and Low-Molecular-Weight Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Zhuang, Bilin; Wang, Zhen-Gang

    2012-02-01

    Mixtures of side-chain liquid crystal polymers (SCLCPs) and low-molecular-weight liquid crystals (LMWLCs) are novel materials with applications such as optical data storage, non-linear optics, solid polymer electrolytes, chromatography and display materials. Recent experiments showed that the nematic-isotropic transition temperature and the nematic orders of each component vary non-monotonically with concentration. Existing theories, which combine the Flory-Huggins theory for isotropic mixing and the Maier-Saupe theory for nematic order, cannot explain such non-monotonicity. Here, we extend the existing theories by, first, incorporating the local steric constraints between the side-chain and the polymer backbone on the SCLCPs, and second, accounting for the crowding effects at high SCLCP concentrations. The new extended theory is able to resolve the discrepancies between the predictions of existing theories and the experimental observations.

  14. Finite-time tracking control of nth-order chained-form non-holonomic systems in the presence of disturbances.

    PubMed

    Bayat, Farhad; Mobayen, Saleh; Javadi, Shamsi

    2016-07-01

    This paper addresses the problem of finite-time tracking controller design for nth-order chained-form non-holonomic systems in the presence of unknown disturbances. To this aim, a generalized disturbance observer based controller is proposed and combined with a recursive terminal sliding mode approach which guarantees finite-time convergence of the disturbance observer dynamic. By introducing a time-varying transformation and introducing a new control law, the existence of the sliding around the recursive terminal sliding mode surfaces is guaranteed. Finally, the proposed approach is applied for a wheeled mobile robot with a fourth-order chained-form non-holonomic model. The simulation results demonstrate the desirable and robust tracking performance of the proposed approach in the presence of unknown disturbance. PMID:27000631

  15. Fatty acyl-CoA reductase

    SciTech Connect

    Reiser, Steven E.; Somerville, Chris R.

    1998-12-01

    The present invention relates to bacterial enzymes, in particular to an acyl-CoA reductase and a gene encoding an acyl-CoA reductase, the amino acid and nucleic acid sequences corresponding to the reductase polypeptide and gene, respectively, and to methods of obtaining such enzymes, amino acid sequences and nucleic acid sequences. The invention also relates to the use of such sequences to provide transgenic host cells capable of producing fatty alcohols and fatty aldehydes.

  16. Unique acyl-carnitine profiles are potential biomarkers for acquired mitochondrial disease in autism spectrum disorder

    PubMed Central

    Frye, R E; Melnyk, S; MacFabe, D F

    2013-01-01

    Autism spectrum disorder (ASD) has been associated with mitochondrial disease (MD). Interestingly, most individuals with ASD and MD do not have a specific genetic mutation to explain the MD, raising the possibility of that MD may be acquired, at least in a subgroup of children with ASD. Acquired MD has been demonstrated in a rodent ASD model in which propionic acid (PPA), an enteric bacterial fermentation product of ASD-associated gut bacteria, is infused intracerebroventricularly. This animal model shows validity as it demonstrates many behavioral, metabolic, neuropathologic and neurophysiologic abnormalities associated with ASD. This animal model also demonstrates a unique pattern of elevations in short-chain and long-chain acyl-carnitines suggesting abnormalities in fatty-acid metabolism. To determine if the same pattern of biomarkers of abnormal fatty-acid metabolism are present in children with ASD, the laboratory results from a large cohort of children with ASD (n=213) who underwent screening for metabolic disorders, including mitochondrial and fatty-acid oxidation disorders, in a medically based autism clinic were reviewed. Acyl-carnitine panels were determined to be abnormal if three or more individual acyl-carnitine species were abnormal in the panel and these abnormalities were verified by repeated testing. Overall, 17% of individuals with ASD demonstrated consistently abnormal acyl-carnitine panels. Next, it was determined if specific acyl-carnitine species were consistently elevated across the individuals with consistently abnormal acyl-carnitine panels. Significant elevations in short-chain and long-chain, but not medium-chain, acyl-carnitines were found in the ASD individuals with consistently abnormal acyl-carnitine panels—a pattern consistent with the PPA rodent ASD model. Examination of electron transport chain function in muscle and fibroblast culture, histological and electron microscopy examination of muscle and other biomarkers of

  17. Solution Structure of 4'-Phosphopantetheine - GmACP3 from Geobacter Metallireducens: A Specialized Acyl Carrier Protein with Atypical Structural Features and a Putative Role in Lipopolysaccharide Biosyntheses

    SciTech Connect

    Ramelot, Theresa A.; Smola, Matthew J.; Lee, Hsiau-Wei; Ciccosanti, Colleen; Hamilton, Keith; Acton, Thomas; Xiao, Rong; Everett, John K.; Prestegard, James H.; Montelione, Gaetano; Kennedy, Michael A.

    2011-03-08

    GmACP3 from Geobacter metallireducens is a specialized acyl carrier protein (ACP) whose gene, gmet_2339, is located near genes encoding many proteins involved in lipopolysaccharide (LPS) biosynthesis, indicating a likely function for GmACP3 in LPS production. By overexpression in Escherichia coli, about 50% holo-GmACP3 and 50% apo-GmACP3 were obtained. Apo-GmACP3 exhibited slow precipitation and non-monomeric behavior by 15NNMRrelaxation measurements. Addition of 4'-phosphopantetheine (4'-PP) via enzymatic conversion by E. coli holo-ACP synthase resulted in stable >95% holo-GmACP3 that was characterized as monomeric by 15N relaxation measurements and had no indication of conformational exchange. We have determined a high-resolution solution structure of holo-GmACP3 by standard NMR methods, including refinement with two sets of NH residual dipolar couplings, allowing for a detailed structural analysis of the interactions between 4'-PP and GmACP3. Whereas the overall four helix bundle topology is similar to previously solved ACP structures, this structure has unique characteristics, including an ordered 4'-PP conformation that places the thiol at the entrance to a central hydrophobic cavity near a conserved hydrogen-bonded Trp-His pair. These residues are part of a conservedWDSLxH/N motif found in GmACP3 and its orthologs. The helix locations and the large hydrophobic cavity are more similar tomediumand long-chain acyl-ACPs than to other apo- and holo-ACP structures. Taken together, structural characterization along with bioinformatic analysis of nearby genes suggests that GmACP3 is involved in lipid A acylation, possibly by atypical long-chain hydroxy fatty acids, and potentially is involved in synthesis of secondary metabolites.

  18. A Time Scheduling Model of Logistics Service Supply Chain Based on the Customer Order Decoupling Point: A Perspective from the Constant Service Operation Time

    PubMed Central

    Yang, Yi; Xu, Haitao; Liu, Xiaoyan; Wang, Yijia; Liang, Zhicheng

    2014-01-01

    In mass customization logistics service, reasonable scheduling of the logistics service supply chain (LSSC), especially time scheduling, is benefit to increase its competitiveness. Therefore, the effect of a customer order decoupling point (CODP) on the time scheduling performance should be considered. To minimize the total order operation cost of the LSSC, minimize the difference between the expected and actual time of completing the service orders, and maximize the satisfaction of functional logistics service providers, this study establishes an LSSC time scheduling model based on the CODP. Matlab 7.8 software is used in the numerical analysis for a specific example. Results show that the order completion time of the LSSC can be delayed or be ahead of schedule but cannot be infinitely advanced or infinitely delayed. Obtaining the optimal comprehensive performance can be effective if the expected order completion time is appropriately delayed. The increase in supply chain comprehensive performance caused by the increase in the relationship coefficient of logistics service integrator (LSI) is limited. The relative concern degree of LSI on cost and service delivery punctuality leads to not only changes in CODP but also to those in the scheduling performance of the LSSC. PMID:24715818

  19. A time scheduling model of logistics service supply chain based on the customer order decoupling point: a perspective from the constant service operation time.

    PubMed

    Liu, Weihua; Yang, Yi; Xu, Haitao; Liu, Xiaoyan; Wang, Yijia; Liang, Zhicheng

    2014-01-01

    In mass customization logistics service, reasonable scheduling of the logistics service supply chain (LSSC), especially time scheduling, is benefit to increase its competitiveness. Therefore, the effect of a customer order decoupling point (CODP) on the time scheduling performance should be considered. To minimize the total order operation cost of the LSSC, minimize the difference between the expected and actual time of completing the service orders, and maximize the satisfaction of functional logistics service providers, this study establishes an LSSC time scheduling model based on the CODP. Matlab 7.8 software is used in the numerical analysis for a specific example. Results show that the order completion time of the LSSC can be delayed or be ahead of schedule but cannot be infinitely advanced or infinitely delayed. Obtaining the optimal comprehensive performance can be effective if the expected order completion time is appropriately delayed. The increase in supply chain comprehensive performance caused by the increase in the relationship coefficient of logistics service integrator (LSI) is limited. The relative concern degree of LSI on cost and service delivery punctuality leads to not only changes in CODP but also to those in the scheduling performance of the LSSC. PMID:24715818

  20. Insight into Coenzyme A cofactor binding and the mechanism of acyl-transfer in an acylating aldehyde dehydrogenase from Clostridium phytofermentans

    PubMed Central

    Tuck, Laura R.; Altenbach, Kirsten; Ang, Thiau Fu; Crawshaw, Adam D.; Campopiano, Dominic J.; Clarke, David J.; Marles-Wright, Jon

    2016-01-01

    The breakdown of fucose and rhamnose released from plant cell walls by the cellulolytic soil bacterium Clostridium phytofermentans produces toxic aldehyde intermediates. To enable growth on these carbon sources, the pathway for the breakdown of fucose and rhamnose is encapsulated within a bacterial microcompartment (BMC). These proteinaceous organelles sequester the toxic aldehyde intermediates and allow the efficient action of acylating aldehyde dehydrogenase enzymes to produce an acyl-CoA that is ultimately used in substrate-level phosphorylation to produce ATP. Here we analyse the kinetics of the aldehyde dehydrogenase enzyme from the fucose/rhamnose utilisation BMC with different short-chain fatty aldehydes and show that it has activity against substrates with up to six carbon atoms, with optimal activity against propionaldehyde. We have also determined the X-ray crystal structure of this enzyme in complex with CoA and show that the adenine nucleotide of this cofactor is bound in a distinct pocket to the same group in NAD+. This work is the first report of the structure of CoA bound to an aldehyde dehydrogenase enzyme and our crystallographic model provides important insight into the differences within the active site that distinguish the acylating from non-acylating aldehyde dehydrogenase enzymes. PMID:26899032

  1. Insight into Coenzyme A cofactor binding and the mechanism of acyl-transfer in an acylating aldehyde dehydrogenase from Clostridium phytofermentans.

    PubMed

    Tuck, Laura R; Altenbach, Kirsten; Ang, Thiau Fu; Crawshaw, Adam D; Campopiano, Dominic J; Clarke, David J; Marles-Wright, Jon

    2016-01-01

    The breakdown of fucose and rhamnose released from plant cell walls by the cellulolytic soil bacterium Clostridium phytofermentans produces toxic aldehyde intermediates. To enable growth on these carbon sources, the pathway for the breakdown of fucose and rhamnose is encapsulated within a bacterial microcompartment (BMC). These proteinaceous organelles sequester the toxic aldehyde intermediates and allow the efficient action of acylating aldehyde dehydrogenase enzymes to produce an acyl-CoA that is ultimately used in substrate-level phosphorylation to produce ATP. Here we analyse the kinetics of the aldehyde dehydrogenase enzyme from the fucose/rhamnose utilisation BMC with different short-chain fatty aldehydes and show that it has activity against substrates with up to six carbon atoms, with optimal activity against propionaldehyde. We have also determined the X-ray crystal structure of this enzyme in complex with CoA and show that the adenine nucleotide of this cofactor is bound in a distinct pocket to the same group in NAD(+). This work is the first report of the structure of CoA bound to an aldehyde dehydrogenase enzyme and our crystallographic model provides important insight into the differences within the active site that distinguish the acylating from non-acylating aldehyde dehydrogenase enzymes. PMID:26899032

  2. Vortex chains due to nonpairwise interactions and field-induced phase transitions between states with different broken symmetry in superconductors with competing order parameters

    NASA Astrophysics Data System (ADS)

    Garaud, Julien; Babaev, Egor

    2015-01-01

    We study superconductors with two order components and phase separation driven by intercomponent density-density interaction, focusing on the phase where only one condensate has nonzero ground-state density and a competing order parameter exists only in vortex cores. We demonstrate there that multibody intervortex interactions can be strongly nonpairwise, leading to some unusual vortex patterns in an external field, such as vortex pairs and vortex chains. We demonstrate that in an external magnetic field such a system undergoes a field-driven phase transition from (broken) U (1 ) to (broken) U (1 )×U (1 ) symmetries when a subdominant order parameter in the vortex cores acquires global coherence. Observation of these characteristic ordering patterns in surface probes may signal the presence of a subdominant condensate in the vortex core.

  3. Plant Cytosolic Acyl-CoA-Binding Proteins.

    PubMed

    Ye, Zi-Wei; Chye, Mee-Len

    2016-01-01

    A gene family encoding six members of acyl-CoA-binding proteins (ACBP) exists in Arabidopsis and they are designated as AtACBP1-AtACBP6. They have been observed to play pivotal roles in plant lipid metabolism, consistent to the abilities of recombinant AtACBP in binding different medium- and long-chain acyl-CoA esters in vitro. While AtACBP1 and AtACBP2 are membrane-associated proteins with ankyrin repeats and AtACBP3 contains a signaling peptide for targeting to the apoplast, AtACBP4, AtACBP5 and AtACBP6 represent the cytosolic forms in the AtACBP family. They were verified to be subcellularly localized in the cytosol using diverse experimental methods, including cell fractionation followed by western blot analysis, immunoelectron microscopy and confocal laser-scanning microscopy using autofluorescence-tagged fusions. AtACBP4 (73.2 kDa) and AtACBP5 (70.1 kDa) are the largest, while AtACBP6 (10.4 kDa) is the smallest. Their binding affinities to oleoyl-CoA esters suggested that they can potentially transfer oleoyl-CoA esters from the plastids to the endoplasmic reticulum, facilitating the subsequent biosynthesis of non-plastidial membrane lipids in Arabidopsis. Recent studies on ACBP, extended from a dicot (Arabidopsis) to a monocot, revealed that six ACBP are also encoded in rice (Oryza sativa). Interestingly, three small rice ACBP (OsACBP1, OsACBP2 and OsACBP3) are present in the cytosol in comparison to one (AtACBP6) in Arabidopsis. In this review, the combinatory and distinct roles of the cytosolic AtACBP are discussed, including their functions in pollen and seed development, light-dependent regulation and substrate affinities to acyl-CoA esters. PMID:26662549

  4. Monogalactosyldiacylglycerol biosynthesis by direct acyl transfer in Anabaene variabilis

    SciTech Connect

    Chen, H.H.; Wickrema, A.; Jaworski, J.

    1987-04-01

    The authors previously reported the direct acylation of monogalactosyldiacylglycerol (MGDG) by an enzyme in the membranes of the cyanobacterium Anabaena variabilis. The enzyme requires acyl-acyl carrier protein (acyl-ACP) as substrate, but had no other additional cofactor requirements. Palmitoyl-, stearoyl- and oleoyl-ACP were all effective substrates. The A. variabilis membranes also had a hydrolase activity which metabolized the acyl-ACP to yield free fatty acid and ACP. Possible mechanisms for the acylation reaction include either acyl exchange with existing MGDG or direct acyl transfer to a lyso-MGDG, with concomitant release of free ACP. The mechanism of this reaction has been resolved using a double labelled (/sup 14/C)acyl-(/sup 14/)ACP substrate prepared with E. coli acyl-ACP synthetase. Following incubation with the enzyme, the unreacted (/sup 14/)acyl-(/sup 14/)ACP was isolated and the (/sup 14/)acyl/(/sup 14/)ACP ratio determined. Comparison of this ratio to that of the original substrate indicated no change and eliminated acyl exchange as a possible mechanism. Therefore, the direct acylation of lyso-MGDG is the proposed mechanism for this enzyme.

  5. Anatomy of a simple acyl intermediate in enzyme catalysis: combined biophysical and modeling studies on ornithine acetyl transferase.

    PubMed

    Iqbal, Aman; Clifton, Ian J; Bagonis, Maria; Kershaw, Nadia J; Domene, Carmen; Claridge, Timothy D W; Wharton, Christopher W; Schofield, Christopher J

    2009-01-21

    Acyl-enzyme complexes are intermediates in reactions catalyzed by many hydrolases and related enzymes which employ nucleophilic catalysis. However, most of the reported structural data on acyl-enzyme complexes has been acquired under noncatalytic conditions. Recent IR analyses have indicated that some acyl-enzyme complexes may be more flexible than most crystallographic analyses have implied. OAT2 is a member of the N-terminal nucleophile (Ntn) hydrolase enzyme superfamily and catalyzes the reversible transfer of an acetyl group between the alpha-amino groups of ornithine and glutamate in a mechanism proposed to involve an acyl-enzyme complex. We have carried out biophysical analyses on ornithine acetyl transferase (OAT2), both in solution and in the crystalline state. Mass spectrometric studies identified Thr-181 as the residue acetylated during OAT2 catalysis; (13)C NMR analyses implied the presence of an acyl-enzyme complex in solution. Crystallization of OAT2 in the presence of N-alpha-acetyl-L-glutamate led to a structure in which Thr-181 was acetylated; the carbonyl oxygen of the acyl-enzyme complex was located in an oxyanion hole and positioned to hydrogen bond with the backbone amide NH of Gly-112 and the alcohol of Thr-111. While the crystallographic analyses revealed only one structure, IR spectroscopy demonstrated the presence of two distinct acyl-enzyme complex structures with carbonyl stretching frequencies at 1691 and 1701 cm(-1). Modeling studies implied two possible acyl-enzyme complex structures, one of which correlates with that observed in the crystal structure and with the 1691 cm(-1) IR absorption. The second acyl-enzyme complex structure, which has only a single oxyanion hole hydrogen bond, is proposed to give rise to the 1701 cm(-1) IR absorption. The two acyl-enzyme complex structures can interconvert by movement of the Thr-111 side-chain alcohol hydrogen away from the oxyanion hole to hydrogen bond with the backbone carbonyl of the acylated

  6. Microbial Tailoring of Acyl Peptidic Siderophores

    PubMed Central

    2015-01-01

    Marine bacteria produce an abundance of suites of acylated siderophores characterized by a unique, species-dependent headgroup that binds iron(III) and one of a series of fatty acid appendages. Marinobacter sp. DS40M6 produces a suite of seven acylated marinobactins, with fatty acids ranging from saturated and unsaturated C12–C18 fatty acids. In the present study, we report that in the late log phase of growth, the fatty acids are hydrolyzed by an amide hydrolase producing the peptidic marinobactin headgroup. Halomonas aquamarina str. DS40M3, another marine bacterium isolated originally from the same sample of open ocean water as Marinobacter sp. DS40M6, produces the acyl aquachelins, also as a suite composed of a peptidic headgroup distinct from that of the marinobactins. In contrast to the acyl marinobactins, hydrolysis of the suite of acyl aquachelins is not detected, even when H. aquamarina str. DS40M3 is grown into the stationary phase. The Marinobacter cell-free extract containing the acyl amide hydrolase is active toward exogenous acyl-peptidic siderophores (e.g., aquachelin C, loihichelin C, as well as octanoyl homoserine lactone used in quorum sensing). Further, when H. aquamarina str. DS40M3 is cultured together with Marinobacter sp. DS40M6, the fatty acids of both suites of siderophores are hydrolyzed, and the aquachelin headgroup is also produced. The present study demonstrates that coculturing bacteria leads to metabolically tailored metabolites compared to growth in a single pure culture, which is interesting given the importance of siderophore-mediated iron acquisition for bacterial growth and that Marinobacter sp. DS40M6 and H. aquamarina str. DS40M3 were isolated from the same sample of seawater. PMID:24735218

  7. Microbial tailoring of acyl peptidic siderophores.

    PubMed

    Gauglitz, Julia M; Iinishi, Akira; Ito, Yusai; Butler, Alison

    2014-04-29

    Marine bacteria produce an abundance of suites of acylated siderophores characterized by a unique, species-dependent headgroup that binds iron(III) and one of a series of fatty acid appendages. Marinobacter sp. DS40M6 produces a suite of seven acylated marinobactins, with fatty acids ranging from saturated and unsaturated C12-C18 fatty acids. In the present study, we report that in the late log phase of growth, the fatty acids are hydrolyzed by an amide hydrolase producing the peptidic marinobactin headgroup. Halomonas aquamarina str. DS40M3, another marine bacterium isolated originally from the same sample of open ocean water as Marinobacter sp. DS40M6, produces the acyl aquachelins, also as a suite composed of a peptidic headgroup distinct from that of the marinobactins. In contrast to the acyl marinobactins, hydrolysis of the suite of acyl aquachelins is not detected, even when H. aquamarina str. DS40M3 is grown into the stationary phase. The Marinobacter cell-free extract containing the acyl amide hydrolase is active toward exogenous acyl-peptidic siderophores (e.g., aquachelin C, loihichelin C, as well as octanoyl homoserine lactone used in quorum sensing). Further, when H. aquamarina str. DS40M3 is cultured together with Marinobacter sp. DS40M6, the fatty acids of both suites of siderophores are hydrolyzed, and the aquachelin headgroup is also produced. The present study demonstrates that coculturing bacteria leads to metabolically tailored metabolites compared to growth in a single pure culture, which is interesting given the importance of siderophore-mediated iron acquisition for bacterial growth and that Marinobacter sp. DS40M6 and H. aquamarina str. DS40M3 were isolated from the same sample of seawater. PMID:24735218

  8. Use of acyl phosphonates for the synthesis of inulin esters and their use as emulsion stabilizing agents.

    PubMed

    Rogge, Tina M; Stevens, Christian V; Colpaert, Anton; Levecke, Bart; Booten, Karl

    2007-02-01

    Inulin, the polydisperse polyfructose, extracted from chicory, was modified via esterification with acyl phosphonates. The grafting of an acyl chain onto the inulin backbone under different conditions led to a highly efficient synthesis of a series of inulin esters, with interesting tensioactive properties. The derivatives were evaluated in oil-in-water (O/W) emulsions with isoparaffinic oil, Isopar M. Therefore, a 2% (w/v) aqueous solution of inulin-based surfactant was used in 50/50 O/W emulsions, in nonelectrolyte, and in electrolyte media, using 1 M MgSO4. Longer acyl chains, e.g., dodecanoyl (C12), hexadecanoyl (C16), and octadecanoyl (C18), with degrees of substitution lower than 0.5, gave rise to the highest emulsion stabilities against coalescence. PMID:17291072

  9. Membrane Topology and Transient Acylation of Toxoplasma gondii Glycosylphosphatidylinositols

    PubMed Central

    Kimmel, Jürgen; Smith, Terry K.; Azzouz, Nahid; Gerold, Peter; Seeber, Frank; Lingelbach, Klaus; Dubremetz, Jean-François; Schwarz, Ralph T.

    2006-01-01

    Using hypotonically permeabilized Toxoplasma gondii tachyzoites, we investigated the topology of the free glycosylphosphatidylinositols (GPIs) within the endoplasmic reticulum (ER) membrane. The morphology and permeability of parasites were checked by electron microscopy and release of a cytosolic protein. The membrane integrity of organelles (ER and rhoptries) was checked by protease protection assays. In initial experiments, GPI biosynthetic intermediates were labeled with UDP-[6-3H]GlcNAc in permeabilized parasites, and the transmembrane distribution of the radiolabeled lipids was probed with phosphatidylinositol-specific phospholipase C (PI-PLC). A new early intermediate with an acyl modification on the inositol was identified, indicating that inositol acylation also occurs in T. gondii. A significant portion of the early GPI intermediates (GlcN-PI and GlcNAc-PI) could be hydrolyzed following PI-PLC treatment, indicating that these glycolipids are predominantly present in the cytoplasmic leaflet of the ER. Permeabilized T. gondii parasites labeled with either GDP-[2-3H]mannose or UDP-[6-3H]glucose showed that the more mannosylated and side chain (Glc-GalNAc)-modified GPI intermediates are also preferentially localized in the cytoplasmic leaflet of the ER. PMID:16896225

  10. The optimal retailer's ordering policies with trade credit financing and limited storage capacity in the supply chain system

    NASA Astrophysics Data System (ADS)

    Yen, Ghi-Feng; Chung, Kun-Jen; Chen, Tzung-Ching

    2012-11-01

    The traditional economic order quantity model assumes that the retailer's storage capacity is unlimited. However, as we all know, the capacity of any warehouse is limited. In practice, there usually exist various factors that induce the decision-maker of the inventory system to order more items than can be held in his/her own warehouse. Therefore, for the decision-maker, it is very practical to determine whether or not to rent other warehouses. In this article, we try to incorporate two levels of trade credit and two separate warehouses (own warehouse and rented warehouse) to establish a new inventory model to help the decision-maker to make the decision. Four theorems are provided to determine the optimal cycle time to generalise some existing articles. Finally, the sensitivity analysis is executed to investigate the effects of the various parameters on ordering policies and annual costs of the inventory system.

  11. The Liganding of Glycolipid Transfer Protein Is Controlled by Glycolipid Acyl Structure

    PubMed Central

    Kanack, Alex T; Lu, Min; Abagyan, Ruben; Brown, Rhoderick E; Patel, Dinshaw J

    2006-01-01

    Glycosphingolipids (GSLs) play major roles in cellular growth and development. Mammalian glycolipid transfer proteins (GLTPs) are potential regulators of cell processes mediated by GSLs and display a unique architecture among lipid binding/transfer proteins. The GLTP fold represents a novel membrane targeting/interaction domain among peripheral proteins. Here we report crystal structures of human GLTP bound to GSLs of diverse acyl chain length, unsaturation, and sugar composition. Structural comparisons show a highly conserved anchoring of galactosyl- and lactosyl-amide headgroups by the GLTP recognition center. By contrast, acyl chain chemical structure and occupancy of the hydrophobic tunnel dictate partitioning between sphingosine-in and newly-observed sphingosine-out ligand-binding modes. The structural insights, combined with computed interaction propensity distributions, suggest a concerted sequence of events mediated by GLTP conformational changes during GSL transfer to and/or from membranes, as well as during GSL presentation and/or transfer to other proteins. PMID:17105344

  12. Cloning, characterization, and expression analysis of acyl-acyl carrier protein (ACP)-thioesterase B from seeds of Chinese Spicehush (Lindera communis).

    PubMed

    Dong, Shubin; Huang, Jiacong; Li, Yannan; Zhang, Jing; Lin, Shanzhi; Zhang, Zhixiang

    2014-05-25

    Acyl-acyl carrier protein (ACP) thioesterases (TE EC 3.1.2.14) are fatty acid biosynthesis key enzymes that determine fatty acid carbon chain length in most plant tissues. A full-length cDNA corresponding to one of the fatty acyl-ACP thioesterase (Fat) genes, designated LcFatB, was isolated from developing Lindera communis seeds using PCR and RACE with degenerate primers based on conserved sequences of multiple TE gene sequences obtained from GenBank. The 1788 bp cDNA had an open reading frame (ORF) of 1260 bp encoding a protein of 419 amino acids. The deduced amino acid sequence showed 61-73% identity to proteins in the FatB class of plant thioesterases. Real-time quantitative PCR analysis revealed that LcFatB was expressed in all tissues of L. communis, with the highest expression in the developing seeds 75days after flowering. Recombinant pET-MLcFatB was constructed using the pET-30 a vector and transformed into Escherichia coli BL21(DE3)△FadE, a strain that deleted the acyl-CoA dehydrogenase (FadE). SDS-PAGE analysis of proteins isolated from pET-MLcFatB E. coli cells after induction with IPTG revealed a protein band at ~40.5kDa, corresponding to the predicted size of LcFatB mature protein. The decanoic acid and lauric acid contents of the pET-MLcFatB transformant were increased significantly. These findings suggest that an LcFatB gene from a non-traditional oil-seed tree could be used to function as a saturated acyl-ACP thioesterase and could potentially be used to modify the fatty acid composition of seed oil from L. communis or other species through transgenic approaches. PMID:24631366

  13. Downregulation of Carnitine Acyl-Carnitine Translocase by miRNAs 132 and 212 Amplifies Glucose-Stimulated Insulin Secretion

    PubMed Central

    Soni, Mufaddal S.; Rabaglia, Mary E.; Bhatnagar, Sushant; Shang, Jin; Ilkayeva, Olga; Mynatt, Randall; Zhou, Yun-Ping; Schadt, Eric E.; Thornberry, Nancy A.; Muoio, Deborah M.; Keller, Mark P.

    2014-01-01

    We previously demonstrated that micro-RNAs (miRNAs) 132 and 212 are differentially upregulated in response to obesity in two mouse strains that differ in their susceptibility to obesity-induced diabetes. Here we show the overexpression of miRNAs 132 and 212 enhances insulin secretion (IS) in response to glucose and other secretagogues including nonfuel stimuli. We determined that carnitine acyl-carnitine translocase (CACT; Slc25a20) is a direct target of these miRNAs. CACT is responsible for transporting long-chain acyl-carnitines into the mitochondria for β-oxidation. Small interfering RNA–mediated knockdown of CACT in β-cells led to the accumulation of fatty acyl-carnitines and enhanced IS. The addition of long-chain fatty acyl-carnitines promoted IS from rat insulinoma β-cells (INS-1) as well as primary mouse islets. The effect on INS-1 cells was augmented in response to suppression of CACT. A nonhydrolyzable ether analog of palmitoyl-carnitine stimulated IS, showing that β-oxidation of palmitoyl-carnitine is not required for its stimulation of IS. These studies establish a link between miRNA-dependent regulation of CACT and fatty acyl-carnitine–mediated regulation of IS. PMID:24969106

  14. The monounsaturated acyl- and alkyl- moieties of wax esters and their distribution in commercial orange roughy (Hoplostethus atlanticus) oil.

    PubMed

    Body, D R; Johnson, C B; Shaw, G J

    1985-10-01

    Wax esters were isolated from commercial orange roughy (Hoplostethus atlanticus) oil by column chromatography and fractionated by argentation thin layer chromatography. Following transesterification, the resultant fatty acid methyl esters and fatty alcohols were analyzed by gas chromatography. Both acyl- and alkyl-moieties were mainly of the monoene structure within the 16:1-22:1 range. After derivatization, the positions of the double bonds of even numbered fatty acid and fatty alcohol isomers were located by chromatography-mass spectrometry and compared. Results of these positional analyses indicate that the primary desaturation reactions takes place in the delta 9 position of pre-existing (C14 to C24) acyl chains. It is proposed that acyl components from 18:1 are subjected to chain elongation to form a mixture of 24:1 isomers as the final product. Apart from the 24:1 acyl moiety of the wax esters, in which the double bond was almost exclusively in the delta 15 position, de novo biosynthetic reactions on acids and alcohols appear to yield related acyl- and alkyl-moieties of resynthesized wax esters. PMID:4058265

  15. High-Order Tunable Filters Based on a Chain of Coupled Crystalline Whispering Gallery-Mode Resonators

    NASA Technical Reports Server (NTRS)

    Savchenkov, Anatoliy A.; Ilchenko, Vladimir S.; Matsko, Andrey B.; Maleki, Lute

    2005-01-01

    We demonstrate experimentally a tunable third-order optical filter fabricated from the three voltage-controlled lithium niobate whispering gallery-mode resonators. The filter operates at 1550 nm with 30-MHz bandwidth and can be electrooptically tuned by 12 GHz in the linear regime with approximately 80-MHz/V tuning rate. With this filter, we have demonstrated 6-dB fiber-to-fiber insertion loss and 30-ns tuning speed, limited by the resonator buildup time.

  16. Discovery of acyl guanidine tryptophan hydroxylase-1 inhibitors.

    PubMed

    Goldberg, Daniel R; De Lombaert, Stéphane; Aiello, Robert; Bourassa, Patricia; Barucci, Nicole; Zhang, Qing; Paralkar, Vishwas; Stein, Adam J; Valentine, Jim; Zavadoski, William

    2016-06-15

    An increasing number of diseases have been linked to a dysfunctional peripheral serotonin system. Given that tryptophan hydroxylase 1 (TPH1) is the rate limiting enzyme in the biosynthesis off serotonin, it represents an attractive target to regulate peripheral serotonin. Following up to our first disclosure, we report a new chemotype of TPH1 inhibitors where-by the more common central planar heterocycle has been replaced with an open-chain, acyl guanidine surrogate. Through our work, we found that compounds of this nature provide highly potent TPH1 inhibitors with favorable physicochemical properties that were effective in reducing murine intestinal 5-HT in vivo. Furthermore, we obtained a high resolution (1.90Å) X-ray structure crystal structure of one of these inhibitors (compound 51) that elucidated the active conformation along with revealing a dimeric form of TPH1 for the first time. PMID:27146606

  17. Acyl silicates and acyl aluminates as activated intermediates in peptide formation on clays

    NASA Technical Reports Server (NTRS)

    White, D. H.; Kennedy, R. M.; Macklin, J.

    1984-01-01

    Glycine reacts with heating on dried clays and other minerals to give peptides in much better yield than in the absence of mineral. This reaction was proposed to occur by way of an activated intermediate such as an acyl silicate or acyl aluminate analogous to acyl phosphates involved in several biochemical reactions including peptide bond synthesis. The proposed mechanism has been confirmed by trapping the intermediate, as well as by direct spectroscopic observation of a related intermediate. The reaction of amino acids on periodically dried mineral surfaces represents a widespead, geologically realistic setting for prebiotic peptide formation via in situ activation.

  18. Membrane binding of an acyl-lactoferricin B antimicrobial peptide from solid-state NMR experiments and molecular dynamics simulations

    PubMed Central

    Romo, Tod D.; Bradney, Laura A.; Greathouse, Denise V.; Grossfield, Alan

    2011-01-01

    One approach to the growing health problem of antibiotic resistant bacteria is the development of antimicrobial peptides (AMPs) as alternative treatments. The mechanism by which these AMPs selectively attack the bacterial membrane is not well understood, but is believed to depend on differences in membrane lipid composition. N-acylation of the small amidated hexapeptide, RRWQWR-NH2 (LfB6) derived from the 25 amino acid bovine lactoferricin (LfB25) can be an effective means to improve its antimicrobial properties. Here, we investigate the interactions of C6-LfB6, N-acylated with a 6 carbon fatty acid, with model lipid bilayers with two distinct compositions: 3:1 POPE:POPG (negatively charged) and POPC (zwitterionic). Results from solid-state 2H and 31P NMR experiments are compared with those from an ensemble of all-atom molecular dynamics simulations running in aggregate more than 8.6 microseconds. 2H NMR spectra reveal no change in the lipid acyl chain order when C6-LfB6 is bound to the negatively charged membrane and only a slight decrease in order when it is bound to the zwitterionic membrane. 31P NMR spectra show no significant perturbation of the phosphate headgroups of either lipid system in the presence of C6-LfB6. Molecular dynamics simulations show that for the negatively charged membrane, the peptide’s arginines drive the initial association with the membrane, followed by attachment of the tryptophans at the membrane-water interface, and finally by the insertion of the C6 tails deep into the bilayer. In contrast, the C6 tail leads the association with the zwitterionic membrane, with the tryptophans and arginines associating with the membrane-water interface in roughly the same amount of time. We find similar patterns in the order parameters from our simulations. Moreover, we find in the simulations that the C6 tail can insert 1–2 Å more deeply into the zwitterionic membrane and can exist in a wider range of angles than in the negatively charged

  19. Effect of solution concentration on the structured order and optical properties of short-chain polyene biomolecules

    NASA Astrophysics Data System (ADS)

    Ouyang, Shunli; Sun, Chenglin; Zhou, Mi; Li, Dongfei; Wang, Weiwei; Qu, Guannan; Li, Zuowei; Gao, Shuqin; Yang, Jiange

    2010-09-01

    We have measured the Raman spectra and UV-Vis absorption spectra of linear polyene biomolecules (β-carotene and lycopene) in CS2 at low concentrations (10-6-10-10 mol/L). With decreasing concentration, all the carbon-carbon vibrations form a coherent mode in ordered β-carotene and lycopene due to extended π-conjugation that gives strong electron-phonon coupling, which leads to an anomalous experimental phenomenon. We observed an extremely high Raman scattering cross section( RSCS) and the Raman activities in β-carotene and lycopene are characterized by intensive overtones and combinations. Further, the UV-Vis absorption bands become narrower.

  20. Effect of increase in orientational order of lipid chains and head group spacing on non steroidal anti-inflammatory drug induced membrane fusion.

    PubMed

    Roy, Sutapa Mondal; Bansode, Amol S; Sarkar, Munna

    2010-12-21

    Membrane fusion is a key event in many biological processes. The fusion process, both in vivo and in vitro, is induced by different agents which include mainly proteins and peptides. For protein- and peptide-mediated membrane fusion, conformational reorganization serves as a driving force. Small drug molecules do not share this advantage; hence, drug induced membrane fusion occurring in absence of any other fusogenic agent and at physiologically relevant concentration of the drugs is a very rare event. To date, only three drugs, namely, meloxicam (Mx), piroxicam (Px), and tenoxicam (Tx), belonging to the oxicam group of non steroidal anti-inflammatory drugs (NSAIDs), have been shown by us to induce fusion at very low drug to lipid ratio without the aid of any other fusogenic agent. In our continued effort to understand the interplay of different physical and chemical parameters of both the participating drugs and the membrane on the mechanism of this drug induced membrane fusion, we present here the effect of increase in orientational order of the lipid chains and increase in head group spacing. This is achieved by studying the effect of low concentration cholesterol (<10 mol %) at temperatures above the chain-melting transition. Low concentration cholesterol (<10 mol %), above the gel to fluid transition temperature, is mainly known to increase orientational order of the lipid chains and increase head group spacing. To isolate the effect of these parameters, small unilameller vesicles (SUVs) formed by dimyristoylphosphatidylcholine (DMPC) with an average diameter of 50-60 nm were used as simple model membranes. Fluorescence assays were used to probe the time dependence of lipid mixing, content mixing, and leakage and also used to determine the partitioning of the drugs in the membrane bilayer. Differential scanning calorimetry (DSC) was used to study the effect of drugs in the presence of cholesterol on the chain-melting temperature which reflects the fluidization

  1. Nash and integrated solutions in a just-in-time seller-buyer supply chain with buyer's ordering cost reductions

    NASA Astrophysics Data System (ADS)

    Lou, Kuo-Ren; Wang, Lu

    2016-05-01

    The seller frequently offers the buyer trade credit to settle the purchase amount. From the seller's prospective, granting trade credit increases not only the opportunity cost (i.e., the interest loss on the buyer's purchase amount during the credit period) but also the default risk (i.e., the rate that the buyer will be unable to pay off his/her debt obligations). On the other hand, granting trade credit increases sales volume and revenue. Consequently, trade credit is an important strategy to increase seller's profitability. In this paper, we assume that the seller uses trade credit and number of shipments in a production run as decision variables to maximise his/her profit, while the buyer determines his/her replenishment cycle time and capital investment as decision variables to reduce his/her ordering cost and achieve his/her maximum profit. We then derive non-cooperative Nash solution and cooperative integrated solution in a just-in-time inventory system, in which granting trade credit increases not only the demand but also the opportunity cost and default risk, and the relationship between the capital investment and the ordering cost reduction is logarithmic. Then, we use a software to solve and compare these two distinct solutions. Finally, we use sensitivity analysis to obtain some managerial insights.

  2. Quantum fidelity, string order parameter, and topological quantum phase transition in a spin-1/2 dimerized and frustrated Heisenberg chain

    NASA Astrophysics Data System (ADS)

    Liu, Jin Hua; Wang, Hai Tao

    2015-10-01

    Topological quantum phase transitions are numerically investigated in a spin-1/2 dimerized and frustrated Heisenberg chain by using infinite matrix product state representation with the infinite time evolving block decimation method. Quantum fidelity approach is employed to detect the degenerate ground states and quantum phase transitions. By calculating the long-range string order parameters, we find two topological Haldane phases characterized by two long-range string orders. Also, continuous and discontinuous behaviors of von Neumann entropy show that phase transitions between two topological Haldane phases are topologically continuous and discontinuous quantum phase transitions. For the topologically continuous phase transition, the central charge at the critical point is obtained as c = 1, which means that the topologically continuous quantum phase transition belongs to the Gaussian universality class.

  3. Free amino and imino-bridged centres attached to organic chains bonded to structurally ordered silica for dye removal from aqueous solution.

    PubMed

    Rehman, Fozia; Volpe, Pedro L O; Airoldi, Claudio

    2014-01-15

    Ordered mesoporous SBA-15 type silica was synthesized by sol gel polymerization and reacted with 3-aminopropyltriethoxysilane (AP) or triethylenetetramine (TE), to attach pendant chains or bridging molecules, with basic centres. The materials were characterized by elemental analysis, infrared spectroscopy, and nuclear magnetic resonance in the solid state, X-ray diffractometry, scanning and transmission electron microscopy. The nitrogen sorption/desorption data for SBA-15 and the organofunctionalized SBA-15AP and SBA-15TE silicas resulted in IV type isotherms with hysteresis loops of the H1 type, surface areas of 800; 213 and 457 m(2) g(-1) and average pore diameters of 8.0; 3.2 and 6.8 nm, respectively. The ordered structural features of the mesoporous silica remained preserved after post-functionalization with pendant and bridged organic chains. Sorption data for organofunctionalized silicas gave highly selective sorption capacities for anionic water soluble Reactive Blue dye, with 0.064 and 0.072 mmol g(-1). Negligible sorption was observed with the unmodified mesoporous silica. The results suggest that organofunctionalized silica can be a simple, efficient, inexpensive and suitable method for the effective and selective removal of anionic organic dye pollutants from aqueous solutions. PMID:24374243

  4. Decoupled phase of frustrated spin-(1)/(2) antiferromagnetic chains with and without long-range order in the ground state

    NASA Astrophysics Data System (ADS)

    Kumar, Manoranjan; Soos, Z. G.

    2013-10-01

    The quantum phases of one-dimensional spin s=1/2 chains are discussed for models with two parameters, frustrating exchange g=J2>0 between second neighbors and normalized nonfrustrating power-law exchange with exponent α and distance dependence r-α. The ground state (GS) at g=0 has a long-range order (LRO) for α<2 and long-range spin fluctuations for α>2. The models conserve total spin S=SA+SB, have singlet GS for any g, α≥0 and decouple at 1/g=0 to linear Heisenberg antiferromagnets on sublattices A and B of odd- and even-numbered sites. Exact diagonalization of finite chains gives the sublattice spin , the magnetic gap Em to the lowest triplet state, and the excitation Eσ to the lowest singlet with opposite inversion symmetry to the GS. An analytical model that conserves sublattice spin has a first-order quantum transition at gc=1/4ln2 from a GS with perfect LRO to a decoupled phase with SA=SB=0 for g≥4/π2 and no correlation between spins in different sublattices. The model with α=1 has a first-order transition to a decoupled phase that closely resembles the analytical model. The bond order wave (BOW) phase and continuous quantum phase transitions of finite models with α≥2 are discussed in terms of GS degeneracy where Eσ(g)=0, excited state degeneracy where Eσ(g)=Em(g), and . The decoupled phase at large frustration has nondegenerate GS for any exponent α and excited states related to sublattice excitations.

  5. Compartmentalized Acyl-CoA Metabolism in Skeletal Muscle Regulates Systemic Glucose Homeostasis

    PubMed Central

    Li, Lei O.; Grevengoed, Trisha J.; Paul, David S.; Ilkayeva, Olga; Koves, Timothy R.; Pascual, Florencia; Newgard, Christopher B.; Muoio, Deborah M.

    2015-01-01

    The impaired capacity of skeletal muscle to switch between the oxidation of fatty acid (FA) and glucose is linked to disordered metabolic homeostasis. To understand how muscle FA oxidation affects systemic glucose, we studied mice with a skeletal muscle–specific deficiency of long-chain acyl-CoA synthetase (ACSL)1. ACSL1 deficiency caused a 91% loss of ACSL-specific activity and a 60–85% decrease in muscle FA oxidation. Acsl1M−/− mice were more insulin sensitive, and, during an overnight fast, their respiratory exchange ratio was higher, indicating greater glucose use. During endurance exercise, Acsl1M−/− mice ran only 48% as far as controls. At the time that Acsl1M−/− mice were exhausted but control mice continued to run, liver and muscle glycogen and triacylglycerol stores were similar in both genotypes; however, plasma glucose concentrations in Acsl1M−/− mice were ∼40 mg/dL, whereas glucose concentrations in controls were ∼90 mg/dL. Excess use of glucose and the likely use of amino acids for fuel within muscle depleted glucose reserves and diminished substrate availability for hepatic gluconeogenesis. Surprisingly, the content of muscle acyl-CoA at exhaustion was markedly elevated, indicating that acyl-CoAs synthesized by other ACSL isoforms were not available for β-oxidation. This compartmentalization of acyl-CoAs resulted in both an excessive glucose requirement and severely compromised systemic glucose homeostasis. PMID:25071025

  6. Prolyl oligopeptidase inhibition by N-acyl-pro-pyrrolidine-type molecules.

    PubMed

    Kánai, Károly; Arányi, Péter; Böcskei, Zsolt; Ferenczy, György; Harmat, Veronika; Simon, Kálmán; Bátori, Sándor; Náray-Szabo, Gábor; Hermecz, István

    2008-12-11

    Three novel, N-acyl-pro-pyrrolidine-type, inhibitors of prolyl oligopeptidase (POP) with nanomolar activities were synthesized and their binding analyzed to the host enzyme in the light of X-ray diffraction and molecular modeling studies. We were interested in the alteration in the binding affinity at the S3 site as a function of the properties of the N-terminal group of the inhibitors. Our studies revealed that, for inhibitors with flat aromatic terminal groups, the optimal length of the linker chain is three C-C bonds, but this increases to four C-C bonds if there is a bulky group in the terminal position. Molecular dynamics calculations indicate that this is due to the better fit into the binding pocket. A 4-fold enhancement of the inhibitor activity upon replacement of the 4-CH2 group of the proline ring by CF2 is a consequence of a weak hydrogen bond formed between the fluorine atom and the hydroxy group of Tyr473 of the host enzyme. There is notably good agreement between the calculated and experimental free energies of binding; the average error in the IC50 values is around 1 order of magnitude. PMID:19006380

  7. Kinetic studies on the intramolecular acyl migration of beta-1-O-acyl glucuronides: application to the glucuronides of (R)- and (S)-ketoprofen, (R)- and (S)-hydroxy-ketoprofen metabolites, and tolmetin by 1H-NMR spectroscopy.

    PubMed

    Skordi, E; Wilson, I D; Lindon, J C; Nicholson, J K

    2005-07-01

    Conjugation of carboxylate drugs with D-glucuronic acid is of considerable interest because of the inherent reactivity of the resulting beta-1-O-acyl glucuronides. These conjugates can degrade by spontaneous hydrolysis and internal acyl migration. beta-1-O-acyl glucuronides and their acyl migration products can also react covalently with macromolecules with potential toxicological consequences. The spontaneous degradation of the diastereoisomeric beta-1-O-acyl glucuronide metabolites of the racemic drug ketoprofen, two of its ring-hydroxylated metabolites and of tolmetin beta-1-O-acyl glucuronide was investigated by (1)H-NMR spectroscopy in buffer solutions, at pH 7.4 and 37 degrees C. A plot of the logarithm of the peak integrals against time revealed first-order kinetics. Degradation rates and half-lives were calculated for each glucuronide using first-order reaction equations. Tolmetin glucuronide had the fastest degradation rate, whilst all of the ketoprofen-related glucuronides had similar degradation rates. The degradation of the diastereoisomeric glucuronides was stereoselective, with the rate for the (S)-isomer always slower compared with the (R)-isomer by approximately a factor of 2. PMID:16316930

  8. Protease-catalyzed peptide synthesis using inverse substrates: the influence of reaction conditions on the trypsin acyl transfer efficiency.

    PubMed

    Schellenberger, V; Jakubke, H D; Zapevalova, N P; Mitin, Y V

    1991-06-01

    Benzyloxycarbonyl-L-alanine p-guanidinophenyl ester behaves as a trypsin "inverse substrate," i.e., a cationic center is included in the leaving group instead of being in the acyl moiety. Using this substrate as an acyl donor, trypsin catalyzes the synthesis of peptide bonds that cannot be split by this enzyme. An optimal acyl transfer efficiency was achieved between pH 8 and 9 at 30 degrees C.The addition of as much as 50% cosolvent was shown to be of minor influence on the acyl transfer efficiency, whereas the reaction velocity decreases by more than one order of magnitude. The efficiency of H-Leu-NH(2) and H-Val-NH(2) in deacylation is almost the same for "inverse" and normal type substrates. PMID:18600704

  9. Antiferromagnetic spin chain behavior and a transition to 3D magnetic order in Cu(D,L-alanine)2: Roles of H-bonds

    NASA Astrophysics Data System (ADS)

    Calvo, Rafael; Sartoris, Rosana P.; Calvo, Hernán L.; Chagas, Edson F.; Rapp, Raul E.

    2016-05-01

    We study the spin chain behavior, a transition to 3D magnetic order and the magnitudes of the exchange interactions for the metal-amino acid complex Cu(D,L-alanine)2•H2O, a model compound to investigate exchange couplings supported by chemical paths characteristic of biomolecules. Thermal and magnetic data were obtained as a function of temperature (T) and magnetic field (B0). The magnetic contribution to the specific heat, measured between 0.48 and 30 K, displays above 1.8 K a 1D spin-chain behavior that can be fitted with an intrachain antiferromagnetic (AFM) exchange coupling constant 2J0=(-2.12±0.08) cm-1 (defined as ℋex(i,i+1) = -2J0SiṡSi+1), between neighbor coppers at 4.49 Å along chains connected by non-covalent and H-bonds. We also observe a narrow specific heat peak at 0.89 K indicating a phase transition to a 3D magnetically ordered phase. Magnetization curves at fixed T = 2, 4 and 7 K with B0 between 0 and 9 T, and at T between 2 and 300 K with several fixed values of B0 were globally fitted by an intrachain AFM exchange coupling constant 2J0=(-2.27±0.02) cm-1 and g = 2.091±0.005. Interchain interactions J1 between coppers in neighbor chains connected through long chemical paths with total length of 9.51 Å cannot be estimated from magnetization curves. However, observation of the phase transition in the specific heat data allows estimating the range 0.1≤|2J1|≤0.4 cm-1, covering the predictions of various approximations. We analyze the magnitudes of 2J0 and 2J1 in terms of the structure of the corresponding chemical paths. The main contribution in supporting the intrachain interaction is assigned to H-bonds while the interchain interactions are supported by paths containing H-bonds and carboxylate bridges, with the role of the H-bonds being predominant. We compare the obtained intrachain coupling with studies of compounds showing similar behavior and discuss the validity of the approximations allowing to calculate the interchain

  10. High acyl gellan as an emulsion stabilizer.

    PubMed

    Vilela, Joice Aline Pires; da Cunha, Rosiane Lopes

    2016-03-30

    High acyl gellan (0.01-0.2% w/w) was used as stabilizer in oil in water emulsions containing 30% (w/w) of sunflower oil and prepared under different process conditions. Stable emulsions to phase separation could be obtained using high acyl gellan (HA) content above 0.05% (w/w), while low acyl gellan (LA) prepared at the same conditions could not stabilize emulsions. Emulsions properties depended on the process used to mix the oil and gellan dispersion since high pressure homogenization favored stabilization while very high energy density applied by ultrasound led to systems destabilization. Emulsions prepared using high pressure homogenization showed zeta potential values ranging from -50 up to -59 mV, suggesting that electrostatic repulsion could be contributing to the systems stability. Rheological properties of continuous phase were also responsible for emulsions stabilization, since HA gellan dispersions showed high viscosity and gel-like behavior. The high viscosity of the continuous phase could be associated to the presence of high acyl gellan microgels/aggregates. Disentanglement of these aggregates performed by ultrasound strongly decreased the viscosity and consequently affected the emulsions behavior, reducing the stability to phase separation. PMID:26794954

  11. Cloning and functional expression of an acyl-ACP thioesterase FatB type from Diploknema (Madhuca) butyracea seeds in Escherichia coli.

    PubMed

    Jha, J K; Maiti, M K; Bhattacharjee, A; Basu, A; Sen, P C; Sen, S K

    2006-01-01

    A cDNA of fatty acyl-acyl carrier protein (ACP) thioesterase (Fat) from developing seed of Madhuca butyracea has been cloned. The deduced amino acid sequence of the cDNA corresponding to the mature polypeptide showed 30-40% and 60-75% identity to the reported FatA and FatB class of plant thioesterases, respectively. This gene, MbFatB, is present as a single copy in M. butyracea genome and the MbFatB protein was detected clearly in seed tissues of this plant but not in that of Indian mustard (Brassica juncea). Heterologous expression of the MbFatB gene driven by different promoters in E. coli wild type and fatty acid beta-oxidation mutant (fadD88) strains resulted production of the recombinant protein with various fusion tags either as biologically inactive (insoluble) or functionally active forms. Expression of functionally active recombinant MbFatB in E. coli affected bacterial growth and cell morphology as well as changed the fatty acid profiles of the membrane lipid and the culture supernatant. Alteration of the fatty acid composition was directed predominantly towards palmitate and to a lesser extent myristate and oleate due to acyl chain termination activity of plant thioesterase in bacteria. Thus, this new MbFatB gene isolated from a non-traditional oil-seed tree can be used in future for transgenic development of oil-seed Brassica, a widely cultivated crop that expresses predominantly oleoyl-ACP thioesterase (FatA) in its seed tissue and has high amount of unwanted erucic acid in edible oil in order to alter the fatty acid profile in a desirable way. PMID:17092734

  12. Hypernetted-chain investigation of the random first-order transition of a Lennard-Jones liquid to an ideal glass.

    PubMed

    Bomont, Jean-Marc; Hansen, Jean-Pierre; Pastore, Giorgio

    2015-10-01

    The structural and thermodynamic behavior of a deeply supercooled Lennard-Jones liquid, and its random first-order transition (RFOT) to an ideal glass is investigated, using a system of two weakly coupled replicas and the hypernetted chain integral equation for the pair structure of this symmetric binary system. A systematic search in the density-temperature plane points to the existence of two glass branches below a density-dependent threshold temperature. The branch of lower free energy exhibits a rapid growth of the structural overlap order parameter upon cooling and may be identified with the ideal glass phase conjectured by several authors for both spin and structural glasses. The RFOT, signaled by a sharp discontinuity of the order parameter, is predicted to be weakly first order from a thermodynamic viewpoint. The transition temperature T(cr) increases rapidly with density and approximately obeys a scaling relation valid for a reference system of particles interacting via a purely repulsive 1/r(18) potential. PMID:26565249

  13. Commensurate and incommensurate magnetic order in spin-1 chains stacked on the triangular lattice in Li2NiW2O8

    NASA Astrophysics Data System (ADS)

    Ranjith, K. M.; Nath, R.; Majumder, M.; Kasinathan, D.; Skoulatos, M.; Keller, L.; Skourski, Y.; Baenitz, M.; Tsirlin, A. A.

    2016-07-01

    We report the thermodynamic properties, magnetic ground state, and microscopic magnetic model of the spin-1 frustrated antiferromagnet Li2NiW2O8 , showing successive transitions at TN 1≃18 K and TN 2≃12.5 K in zero field. Nuclear magnetic resonance and neutron diffraction reveal collinear and commensurate magnetic order with the propagation vector k =(1/2 ,0 ,1/2 ) below TN 2. The ordered moment of 1.8 μB at 1.5 K is directed along [0.89 (9 ),-0.10 (5 ),-0.49 (6 )] and matches the magnetic easy axis of spin-1 Ni2 + ions, which is determined by the scissor-like distortion of the NiO6 octahedra. Incommensurate magnetic order, presumably of spin-density-wave type, is observed in the region between TN 2 and TN 1. Density-functional band-structure calculations put forward a three-dimensional spin lattice with spin-1 chains running along the [01 1 ¯] direction and stacked on a spatially anisotropic triangular lattice in the a b plane. We show that the collinear magnetic order in Li2NiW2O8 is incompatible with the triangular lattice geometry and thus driven by a pronounced easy-axis single-ion anisotropy of Ni2 +.

  14. Structural Basis for Substrate Specificity in Adenosylcobalamin-dependent Isobutyryl-CoA Mutase and Related Acyl-CoA Mutases.

    PubMed

    Jost, Marco; Born, David A; Cracan, Valentin; Banerjee, Ruma; Drennan, Catherine L

    2015-11-01

    Acyl-CoA mutases are a growing class of adenosylcobalamin-dependent radical enzymes that perform challenging carbon skeleton rearrangements in primary and secondary metabolism. Members of this class of enzymes must precisely control substrate positioning to prevent oxidative interception of radical intermediates during catalysis. Our understanding of substrate specificity and catalysis in acyl-CoA mutases, however, is incomplete. Here, we present crystal structures of IcmF, a natural fusion protein variant of isobutyryl-CoA mutase, in complex with the adenosylcobalamin cofactor and four different acyl-CoA substrates. These structures demonstrate how the active site is designed to accommodate the aliphatic acyl chains of each substrate. The structures suggest that a conformational change of the 5'-deoxyadenosyl group from C2'-endo to C3'-endo could contribute to initiation of catalysis. Furthermore, detailed bioinformatic analyses guided by our structural findings identify critical determinants of acyl-CoA mutase substrate specificity and predict new acyl-CoA mutase-catalyzed reactions. These results expand our understanding of the substrate specificity and the catalytic scope of acyl-CoA mutases and could benefit engineering efforts for biotechnological applications ranging from production of biofuels and commercial products to hydrocarbon remediation. PMID:26318610

  15. Effect of alkyl chain length on the conformation and order of simple ionic surfactants adsorbed at the D{sub 2}O/CCl{sub 4} interface as studied by sum-frequency vibrational spectroscopy

    SciTech Connect

    Conboy, J.C.; Messmer, M.C.; Richmond, G.L.

    1998-11-10

    The conformational order of three alkanesulfonates, sodium hexanesulfonate (HS), sodium undecanesulfonate (UDS), and sodium dodecanesulfonate (DDS), adsorbed at the D{sub 2}O/CCl{sub 4} interface are examined in detail by sum-frequency vibrational spectroscopy. An increase in surfactant concentration at the interface results in the reduction of gauche defects in the hydrocarbon chains as determined from the intensity ratio of the methyl to methylene symmetric stretch vibrational modes. The degree of disorder in the alkyl chains varies greatly with alkyl chain length. The alkyl chain of HS displays the fewest gauche defects while DDS and UDS display more disorder in their hydrocarbon chains at similar surface concentrations. This observation is interpreted as a reduction in the possible number of gauche conformations for the shorter alkyl chain.

  16. Antiferromagnetic ordering in spin-chain multiferroic Gd{sub 2}BaNiO{sub 5} studied by electronic spin resonance

    SciTech Connect

    Guo, Y. M.; Ruan, M. Y.; Cheng, J. J.; Sun, Y. C.; Ouyang, Z. W. Xia, Z. C.; Rao, G. H.

    2015-06-14

    High-field electron spin resonance (ESR) has been employed to study the antiferromagnetic (AFM) ordering state (T < T{sub N} = 55 K) of spin-chain multiferroic Gd{sub 2}BaNiO{sub 5}. The spin reorientation at T{sub SR} = 24 K is well characterized by the temperature-dependent ESR spectra. The magnetization data evidence a field-induced spin-flop transition at 2 K. The frequency-field relationship of the ESR data can be explained by conventional AFM resonance theory with uniaxial anisotropy, in good agreement with magnetization data. Related discussion on zero-field spin gap is presented.

  17. Levels of acyl-coenzyme A synthetase 5 in urothelial cells and corresponding neoplasias reflect cellular differentiation.

    PubMed

    Gaisa, Nadine T; Reinartz, Andrea; Schneider, Ursula; Klaus, Christina; Heidenreich, Axel; Jakse, Gerhard; Kaemmerer, Elke; Klinkhammer, Barbara Mara; Knuechel, Ruth; Gassler, Nikolaus

    2013-03-01

    Metabolic components like fatty acids and acyl-Coenzyme A (acyl-CoA) thioesters have been implicated in the pathogenesis of various tumours. The activation of fatty acids to acyl-CoAs is catalysed by long chain acyl-CoA synthetases (ACSLs), and impairment of ACSL expression levels has been associated with tumourigenesis and progression. Since ACSLs have never been investigated in bladder tissues, the study aims to characterize ACSL expression and acyl-CoA synthesis in normal and neoplastic bladder tissues, as well as cell lines. ACSL isoforms 1, 3, 4 and 5 and synthesis of acyl-CoAs were analysed using qRT-PCR, western blot analysis, immunohistochemistry and lipid mass spectrometry. In normal urothelium, expression of ACSL1, 3, 4 and 5, with highest levels of ACSL isoform 5 was found. However, ACSL5 expression was reduced in corresponding neoplastic tissues and urothelial cell lines depending on the grade of cellular differentiation. Anti-ACSL5 immunostainings showed expression in normal urothelium and a gradual loss of ACSL5 protein via pre-invasive lesions to invasive carcinomas. High expression of ACSL5 correlated with increased α-galactosidase activity and positive Uroplakin III staining in tumours. In contrast, synthesis of acyl-CoAs was enhanced in neoplastic bladder tissues compared to normal urothelium, and reflected an increase with respect to cellular differentiation. These results confirm an expression of ACSLs, especially isoform 5, in human urothelium, prove enzymatic/lipidomic changes in bladder cancer tissues, and suggest an involvement of ACSL5 in cellular maturation and/or senescence with possible effects onto induction of tumour formation or progression. Further work may identify responsible pathway alterations, and attempting to re-balance the metabolic equilibrium of the urothelium may offer a further opportunity for tumour treatment and prevention. PMID:23348389

  18. Characterization of soluble acyl-ACP desaturases from Camelina sativa, Macadamia tetraphylla and Dolichandra unguis-cati.

    PubMed

    Rodríguez, Manuel Fernando Rodríguez; Sánchez-García, Alicia; Salas, Joaquín J; Garcés, Rafael; Martínez-Force, Enrique

    2015-04-15

    Acyl-acyl carrier protein (ACP) desaturases (EC 1.14.19.2) are soluble enzymes that catalyse the insertion of a double bond into saturated fatty acid bound in saturated acyl chains bound to ACP in higher plants, producing cis-monounsaturated fatty acids. Three types of soluble acyl-ACP desaturases have been described: Δ(9)-acyl-ACP, Δ(6)-acyl-ACP and Δ(4)-acyl-ACP desaturases, which differ in the substrate specificity and the position in which the double bond is introduced. In the present work, Camelina sativa (CsSAD), Macadamia tetraphylla (MtSAD) and Dolichandra unguis-cati (DuSAD) desaturases were cloned, sequenced and characterized. Single copies of CsSAD, MtSAD and DuSAD with three, one and two different alleles, respectively, were found. The corresponding mature proteins were heterologously expressed in Escherichia coli for biochemical characterization in protein extracts. The recombinant CsSAD enzyme showed 300-fold higher specificity towards 18:0-ACP than 16:0-ACP. Similar profile exhibited MtSAD although the differences in the specificity were lower, around 170-fold higher for 18:0-ACP than 16:0-ACP. Furthermore, DuSAD presented a profile showing preference towards 16:0-ACP against 18:0-ACP, around twice more, being so a Δ(9) palmitoyl-ACP desaturase. Also, we reported the expression profile of CsSAD, which showed the highest levels of expression in expanding tissues that typically are very active in lipid biosynthesis such as developing seed endosperm. Moreover, the possibility to express a new desaturase in C. sativa (oilseed crop that store high levels of oil and is easy to transform) to create a new line rich in short monounsaturated fatty acid is discussed. PMID:25765361

  19. Ising-like chain magnetism, Arrhenius magnetic relaxation, and case against 3D magnetic ordering in β-manganese phthalocyanine (C₃₂H₁₆MnN₈).

    PubMed

    Wang, Zhengjun; Seehra, Mohindar S

    2016-04-01

    Previous magnetic studies in the organic semiconductor β-manganese phthalocyanine (β-MnPc) have reported it to be a canted ferromagnet below T(C)  ≈  8.6 K. However, the recent result of the lack of a λ-type anomaly in the specific heat versus temperature data near the quoted T(C) has questioned the presence of long-range 3-dimensional (3D) magnetic ordering in this system. In this paper, detailed measurements and analysis of the temperature (2 K-300 K) and magnetic field (up to 90 kOe) dependence of the dc and ac magnetic susceptibilities in a powder sample of β-MnPc leads us to conclude that 3D long-range magnetic ordering is absent in this material. This is supported by the Arrott plots and the lack of a peak in the ac susceptibilities, χ' and χ″, near the quoted T(C). Instead, the system can be best described as an Ising-like chain magnet with Arrhenius relaxation of the magnetization governed by an intra-layer ferromagnetic exchange constant J/k(B)  =  2.6 K and the single ion anisotropy energy parameter |D|/k(B)  =  8.3 K. The absence of 3D long range order is consistent with the measured |D|/  >  J. PMID:26954989

  20. Ising-like chain magnetism, Arrhenius magnetic relaxation, and case against 3D magnetic ordering in β-manganese phthalocyanine (C32H16MnN8)

    NASA Astrophysics Data System (ADS)

    Wang, Zhengjun; Seehra, Mohindar S.

    2016-04-01

    Previous magnetic studies in the organic semiconductor β-manganese phthalocyanine (β-MnPc) have reported it to be a canted ferromagnet below T C  ≈  8.6 K. However, the recent result of the lack of a λ-type anomaly in the specific heat versus temperature data near the quoted T C has questioned the presence of long-range 3-dimensional (3D) magnetic ordering in this system. In this paper, detailed measurements and analysis of the temperature (2 K-300 K) and magnetic field (up to 90 kOe) dependence of the dc and ac magnetic susceptibilities in a powder sample of β-MnPc leads us to conclude that 3D long-range magnetic ordering is absent in this material. This is supported by the Arrott plots and the lack of a peak in the ac susceptibilities, χ‧ and χ″, near the quoted T C. Instead, the system can be best described as an Ising-like chain magnet with Arrhenius relaxation of the magnetization governed by an intra-layer ferromagnetic exchange constant J/k B  =  2.6 K and the single ion anisotropy energy parameter |D|/k B  =  8.3 K. The absence of 3D long range order is consistent with the measured \\mid D\\mid   >  J.

  1. Synthesis, calorimetric studies, and crystal structures of N, O-diacylethanolamines with matched chains[S

    PubMed Central

    Kamlekar, Ravi Kanth; Tarafdar, Pradip K.; Swamy, Musti J.

    2010-01-01

    Recent studies show that N-, O-diacylethanolamines (DAEs) can be derived by the O-acylation of N-acylethanolamines (NAEs) under physiological conditions. Because the content of NAEs in a variety of organisms increases in response to stress, it is likely that DAEs may also be present in biomembranes. In view of this, a homologous series of DAEs with matched acyl chains (n = 10–20) have been synthesized and characterized. Transition enthalpies and entropies obtained from differential scanning calorimetry show that dry DAEs with even and odd acyl chains independently exhibit linear dependence on the chainlength. Linear least-squares analyses yielded incremental values contributed by each methylene group to the transition enthalpy and entropy and the corresponding end contributions. N-, O-Didecanoylethanolamine (DDEA), N-, O-dilauroylethanolamine (DLEA), and N-, O-dimyristoylethanolamine (DMEA) crystallized in the orthorhombic space group Pbc21 with four symmetry-related molecules in the unit cell. Single-crystal X-ray diffraction studies show that DDEA, DLEA, and DMEA are isostructural and adopt an L-shaped structure with the N-acyl chain and the central ethanolamine moiety being essentially identical to the structure of N-acylethanolamines, whereas the O-acyl chain is linear with all-trans conformation. In all three DAEs, the lipid molecules are organized in a bilayer fashion wherein the N-acyl and O-acyl chains from adjacent layers oppose each other. PMID:19597189

  2. Enzymatic Acylation of Anthocyanin Isolated from Black Rice with Methyl Aromatic Acid Ester as Donor: Stability of the Acylated Derivatives.

    PubMed

    Yan, Zheng; Li, Chunyang; Zhang, Lixia; Liu, Qin; Ou, Shiyi; Zeng, Xiaoxiong

    2016-02-10

    The enzymatic acylation of anthocyanin from black rice with aromatic acid methyl esters as acyl donors and Candida antarctica lipase B was carried out under reduced pressure. The highest conversion of 91% was obtained with benzoic acid methyl ester as acyl donor; cyanidin 3-(6″-benzoyl)-glucoside, cyanidin 3-(6″-salicyloyl)-glucoside, and cyanidin 3-(6″-cinnamoyl)-glucoside were successfully synthesized. This is the first report on the enzymatic acylation of anthocyanin from black rice with methyl aromatic esters as acyl donors and lipase as biocatalyst. Furthermore, the acylation with aromatic carboxylic acids enhanced both the thermostability and light resistivity of anthocyanin. In particular, cyanidin 3-(6″-cinnamoyl)-glucoside was the most stable among the three acylated anthocyanins synthesized. PMID:26766135

  3. The pharmacokinetics of naproxen, its metabolite O-desmethylnaproxen, and their acyl glucuronides in humans. Effect of cimetidine.

    PubMed Central

    Vree, T B; Van Den Biggelaar-Martea, M; Verwey-Van Wissen, C P; Vree, M L; Guelen, P J

    1993-01-01

    1. The pharmacokinetics of 500 mg naproxen given orally were described in 10 subjects using a direct h.p.l.c. analysis of the acyl glucuronide conjugates of naproxen and its metabolite O-desmethylnaproxen. 2. The mean elimination half-life of naproxen was 24.7 +/- 6.4 h (range 7 to 36 h). 3. Naproxen acyl glucuronide accounted for 50.8 +/- 7.3% of the dose recovered in the urine, its isomerised conjugate isoglucuronide for 6.5 +/- 2.0%, O-desmethylnaproxen acyl glucuronide for 14.3 +/- 3.4%, and its isoglucuronide for 5.5 +/- 1.3%. Naproxen and O-desmethylnaproxen were excreted in negligible amounts (< 1%). 4. Even though the urine pH of the subjects was kept acid in order to stabilize the acyl glucuronides, isomerisation took place in blood. 5. The extents of plasma binding of the unconjugated compounds were 98% (naproxen) and 100% (O-desmethylnaproxen), while naproxen acyl glucuronide binding was 92%; that of its isomer isoglucuronide 66%. O-desmethylnaproxen acyl glucuronide was 72% bound and its isoglucuronide was 42% bound. 6. Cimetidine (400 mg twice daily) decreased the t1/2 of naproxen by 39-60% (mean 47.3 +/- 11.5%; P = 0.0014) from 24.7 +/- 6.4 h to 13.2 +/- 1.0 h. It increased (10%) the urinary recovery of naproxen acyl glucuronide (P = 0.0492). The urinary recoveries of naproxen isoglucuronide and O-desmethylnaproxen acyl glucuronide remained unchanged. PMID:8512758

  4. The pharmacokinetics of naproxen, its metabolite O-desmethylnaproxen, and their acyl glucuronides in humans. Effect of cimetidine.

    PubMed

    Vree, T B; Van Den Biggelaar-Martea, M; Verwey-Van Wissen, C P; Vree, M L; Guelen, P J

    1993-05-01

    1. The pharmacokinetics of 500 mg naproxen given orally were described in 10 subjects using a direct h.p.l.c. analysis of the acyl glucuronide conjugates of naproxen and its metabolite O-desmethylnaproxen. 2. The mean elimination half-life of naproxen was 24.7 +/- 6.4 h (range 7 to 36 h). 3. Naproxen acyl glucuronide accounted for 50.8 +/- 7.3% of the dose recovered in the urine, its isomerised conjugate isoglucuronide for 6.5 +/- 2.0%, O-desmethylnaproxen acyl glucuronide for 14.3 +/- 3.4%, and its isoglucuronide for 5.5 +/- 1.3%. Naproxen and O-desmethylnaproxen were excreted in negligible amounts (< 1%). 4. Even though the urine pH of the subjects was kept acid in order to stabilize the acyl glucuronides, isomerisation took place in blood. 5. The extents of plasma binding of the unconjugated compounds were 98% (naproxen) and 100% (O-desmethylnaproxen), while naproxen acyl glucuronide binding was 92%; that of its isomer isoglucuronide 66%. O-desmethylnaproxen acyl glucuronide was 72% bound and its isoglucuronide was 42% bound. 6. Cimetidine (400 mg twice daily) decreased the t1/2 of naproxen by 39-60% (mean 47.3 +/- 11.5%; P = 0.0014) from 24.7 +/- 6.4 h to 13.2 +/- 1.0 h. It increased (10%) the urinary recovery of naproxen acyl glucuronide (P = 0.0492). The urinary recoveries of naproxen isoglucuronide and O-desmethylnaproxen acyl glucuronide remained unchanged. PMID:8512758

  5. Structure of armadillo ACBP: a new member of the acyl-CoA-binding protein family

    SciTech Connect

    Costabel, Marcelo D.; Ermácora, Mario R.; Santomé, José A.; Alzari, Pedro M.; Guérin, Diego M. A.

    2006-10-01

    The X-ray structure of the tetragonal form of apo acyl-CoA-binding protein (ACBP) from the Harderian gland of the South American armadillo Chaetophractus villosus has been solved. The X-ray structure of the tetragonal form of apo acyl-CoA-binding protein (ACBP) from the Harderian gland of the South American armadillo Chaetophractus villosus has been solved. ACBP is a carrier for activated long-chain fatty acids and has been associated with many aspects of lipid metabolism. Its secondary structure is highly similar to that of the corresponding form of bovine ACBP and exhibits the unique flattened α-helical bundle (up–down–down–up) motif reported for animal, yeast and insect ACBPs. Conformational differences are located in loops and turns, although these structural differences do not suffice to account for features that could be related to the unusual biochemistry and lipid metabolism of the Harderian gland.

  6. [Antibacterial Activity of Alkylated and Acylated Derivatives of Low-Molecular Weight Chitosan].

    PubMed

    Shagdarova, B Ts; Il'ina, A V; Varlamov, V P

    2016-01-01

    A number of alkylated (quaternized) and acylated derivatives of low-molecular weight chitosan were obtained. The structure and composition of the compounds were confirmed by the results of IR and PMR spectroscopy, as well as conductometric titration. The effect of the acyl substituent and the degree of substitution of N-(2-hydroxy-3-trimethylammonium) with the propyl fragment appended to amino groups of the C2 atom of polymer chains on antibacterial activity against typical representatives of gram-positive and gram-negative microorganisms (Staphylococcus epidermidis and Escherichia coli) was studied. The highest activity was in the case of N-[(2-hydroxy-3-trimethylammonium)propyl]chitosan chloride with the maximal substitution (98%). The minimal inhibitory concentration of the derivative was 0.48 µg/mL and 3.90 µg/mL for S. epidermis and E. coli, respectively. PMID:27266254

  7. Ab initio study on the transition state of acylation step of trypsin catalysis.

    PubMed

    Kubodera, H; Nakagawa, S; Umeyama, H

    1990-03-01

    The transition state of acylation step of trypsin catalysis was determined by molecular orbital calculations. The calculations were carried out at the RHF-LCAO-SCF approximation level with double zeta basis set (plus polarization functions). The role of His57 residue in the acylation step of the catalytic reaction of trypsin was analysed from a quantum mechanical point of view. The influences of surrounding residues, such as oxyanion hole and Asp102-, and the electrostatic effect of the other regions of the enzyme were also studied. His57 was proved to capture the proton from Ser195 side chain terminus with its lone pair and to transfer it to substrate with electrostatic assistance of Asp102- and oxyanion hole. PMID:2165153

  8. Endogenous N-acyl taurines regulate skin wound healing.

    PubMed

    Sasso, Oscar; Pontis, Silvia; Armirotti, Andrea; Cardinali, Giorgia; Kovacs, Daniela; Migliore, Marco; Summa, Maria; Moreno-Sanz, Guillermo; Picardo, Mauro; Piomelli, Daniele

    2016-07-26

    The intracellular serine amidase, fatty acid amide hydrolase (FAAH), degrades a heterogeneous family of lipid-derived bioactive molecules that include amides of long-chain fatty acids with taurine [N-acyl-taurines (NATs)]. The physiological functions of the NATs are unknown. Here we show that genetic or pharmacological disruption of FAAH activity accelerates skin wound healing in mice and stimulates motogenesis of human keratinocytes and differentiation of human fibroblasts in primary cultures. Using untargeted and targeted lipidomics strategies, we identify two long-chain saturated NATs-N-tetracosanoyl-taurine [NAT(24:0)] and N-eicosanoyl-taurine [NAT(20:0)]-as primary substrates for FAAH in mouse skin, and show that the levels of these substances sharply decrease at the margins of a freshly inflicted wound to increase again as healing begins. Additionally, we demonstrate that local administration of synthetic NATs accelerates wound closure in mice and stimulates repair-associated responses in primary cultures of human keratinocytes and fibroblasts, through a mechanism that involves tyrosine phosphorylation of the epidermal growth factor receptor and an increase in intracellular calcium levels, under the permissive control of transient receptor potential vanilloid-1 receptors. The results point to FAAH-regulated NAT signaling as an unprecedented lipid-based mechanism of wound-healing control in mammalian skin, which might be targeted for chronic wound therapy. PMID:27412859

  9. Purification and characterization of fatty acyl-acyl carrier protein synthetase from Vibrio harveyi.

    PubMed Central

    Fice, D; Shen, Z; Byers, D M

    1993-01-01

    A Vibrio harveyi enzyme which catalyzes the ATP-dependent ligation of fatty acids to acyl carrier protein (ACP) has been purified 6,000-fold to apparent homogeneity by anion-exchange, gel filtration, and ACP-Sepharose affinity chromatography. Purified acyl-ACP synthetase migrated as a single 62-kDa band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and as an 80-kDa protein by gel filtration under reducing conditions. Activity of the purified enzyme was lost within hours in the absence of glycerol and low concentrations of Triton X-100. Acyl-ACP synthetase exhibited Kms for myristic acid, ACP, and ATP of 7 microM, 18 microM, and 0.3 mM, respectively. The enzyme was specific for adenine-containing nucleotides, and AMP was the product of the reaction. No covalent acyl-enzyme intermediate was observed. Enzyme activity was stimulated up to 50% by iodoacetamide but inhibited > 80% by N-ethylmaleimide: inhibition by the latter was prevented by ATP and ACP but not myristic acid. Dithiothreitol and sulfhydryl-directed reagents also influenced enzyme size, activity, and elution pattern on anion-exchange resins. The function of acyl-ACP synthetase has not been established, but it may be related to the capacity of V. harveyi to elongate exogenous fatty acids by an ACP-dependent mechanism. Images PMID:8384617

  10. Phase Behavior and Nanoscale Structure of Phospholipid Membranes Incorporated with Acylated C14-Peptides

    PubMed Central

    Pedersen, Tina B.; Kaasgaard, Thomas; Jensen, Morten Ø.; Frokjaer, Sven; Mouritsen, Ole G.; Jørgensen, Kent

    2005-01-01

    The thermotropic phase behavior and lateral structure of dipalmitoylphosphatidylcholine (DPPC) lipid bilayers containing an acylated peptide has been characterized by differential scanning calorimetry (DSC) on vesicles and atomic force microscopy (AFM) on mica-supported bilayers. The acylated peptide, which is a synthetic decapeptide N-terminally linked to a C14 acyl chain (C14-peptide), is incorporated into DPPC bilayers in amounts ranging from 0–20 mol %. The calorimetric scans of the two-component system demonstrate a distinct influence of the C14-peptide on the lipid bilayer thermodynamics. This is manifested as a concentration-dependent downshift of both the main phase transition and the pretransition. In addition, the main phase transition peak is significantly broadened, indicating phase coexistence. In the AFM imaging scans we found that the C14-peptide, when added to supported gel phase DPPC bilayers, inserts preferentially into preexisting defect regions and has a noticeable influence on the organization of the surrounding lipids. The presence of the C14-peptide gives rise to a laterally heterogeneous bilayer structure with coexisting lipid domains characterized by a 10 Å height difference. The AFM images also show that the appearance of the ripple phase of the DPPC lipid bilayers is unaffected by the C14-peptide. The experimental results are supported by molecular dynamics simulations, which show that the C14-peptide has a disordering effect on the lipid acyl chains and causes a lateral expansion of the lipid bilayer. These effects are most pronounced for gel-like bilayer structures and support the observed downshift in the phase-transition temperature. Moreover, the molecular dynamics data indicate a tendency of a tryptophan residue in the peptide sequence to position itself in the bilayer headgroup region. PMID:16100273

  11. Speeding up spin-component-scaled third-order pertubation theory with the chain of spheres approximation: the COSX-SCS-MP3 method

    NASA Astrophysics Data System (ADS)

    Izsák, Róbert; Neese, Frank

    2013-07-01

    The 'chain of spheres' approximation, developed earlier for the efficient evaluation of the self-consistent field exchange term, is introduced here into the evaluation of the external exchange term of higher order correlation methods. Its performance is studied in the specific case of the spin-component-scaled third-order Møller--Plesset perturbation (SCS-MP3) theory. The results indicate that the approximation performs excellently in terms of both computer time and achievable accuracy. Significant speedups over a conventional method are obtained for larger systems and basis sets. Owing to this development, SCS-MP3 calculations on molecules of the size of penicillin (42 atoms) with a polarised triple-zeta basis set can be performed in ∼3 hours using 16 cores of an Intel Xeon E7-8837 processor with a 2.67 GHz clock speed, which represents a speedup by a factor of 8-9 compared to the previously most efficient algorithm. Thus, the increased accuracy offered by SCS-MP3 can now be explored for at least medium-sized molecules.

  12. Solution Structure of 4′-Phosphopantetheine - GmACP3 from Geobacter metallireducens: A Specialized Acyl Carrier Protein with Atypical Structural Features and a Putative Role in Lipopolysaccharide Biosynthesis†

    PubMed Central

    Ramelot, Theresa A.; Smola, Matthew J.; Lee, Hsiau-Wei; Ciccosanti, Colleen; Hamilton, Keith; Acton, Thomas B.; Xiao, Rong; Everett, John K.; Prestegard, James H.; Montelione, Gaetano T.; Kennedy, Michael A.

    2011-01-01

    GmACP3 from Geobacter metallireducens is a specialized acyl carrier protein (ACP) whose gene, gmet_2339, is located near genes encoding many proteins involved in lipopolysaccharide (LPS) biosynthesis, indicating a likely function for GmACP3 in LPS production. By overexpression in Escherichia coli, about 50% holo-GmACP3 and 50% apo-GmACP3 were obtained. Apo-GmACP3 exhibited slow precipitation and non-monomeric behavior by 15N NMR relaxation measurements. Addition of 4′-phosphopantetheine (4′-PP) via enzymatic conversion by E. coli holo-ACP synthase, resulted in stable >95% holo-GmACP3 that was characterized as monomeric by 15N relaxation measurements and had no indication of conformational exchange. We have determined a high-resolution solution structure of holo-GmACP3 by standard NMR methods, including refinement with two sets of NH residual dipolar couplings, allowing for a detailed structural analysis of the interactions between 4′-PP and GmACP3. Whereas the overall four helix bundle topology is similar to previously solved ACP structures, this structure has unique characteristics, including an ordered 4′-PP conformation that places the thiol at the entrance to a central hydrophobic cavity near a conserved hydrogen-bonded Trp-His pair. These residues are part of a conserved WDSLxH/N motif found in GmACP3 and it’s orthologs. The helix locations and the large hydrophobic cavity are more similar to medium- and long-chain acyl-ACPs than to other apo- and holo-ACP structures. Taken together, structural characterization along with bioinformatic analysis of nearby genes suggest that GmACP3 is involved in lipid A acylation, possibly by atypical long-chain hydroxy fatty acids, and potentially involved in synthesis of secondary metabolites. PMID:21235239

  13. Head-group acylation of monogalactosyldiacylglycerol is a common stress response, and the acyl-galactose acyl composition varies with the plant species and applied stress

    PubMed Central

    Vu, Hieu Sy; Roth, Mary R.; Tamura, Pamela; Samarakoon, Thilani; Shiva, Sunitha; Honey, Samuel; Lowe, Kaleb; Schmelz, Eric A.; Williams, Todd D.; Welti, Ruth

    2014-01-01

    Formation of galactose-acylated monogalactosyldiacylglycerols has been shown to be induced by leaf homogenization, mechanical wounding, avirulent bacterial infection, and thawing after snap-freezing. Here, lipidomic analysis using mass spectrometry showed that galactose-acylated monogalactosyldiacylglycerols, formed in wheat (Triticum aestivum) and tomato (Solanum lycopersicum) leaves upon wounding, have acyl-galactose profiles that differ from those of wounded Arabidopsis thaliana, indicating that different plant species accumulate different acyl-galactose components in response to the same stress. Additionally, the composition of the acyl-galactose component of Arabidopsis acMGDG depends on the stress treatment. After sub-lethal freezing treatment, acMGDG contained mainly non-oxidized fatty acids esterified to galactose, whereas mostly oxidized fatty acids accumulated on galactose after wounding or bacterial infection. Compositional data are consistent with acMGDG being formed in vivo by transacylation with fatty acids from digalactosyldiacylglycerols. Oxophytodienoic acid, an oxidized fatty acid, was more concentrated on the galactosyl ring of acylated monogalactosyldiacylglycerols than in galactolipids in general. Also, oxidized fatty acid-containing acylated monogalactosyldiacylglycerols increased cumulatively when wounded Arabidopsis leaves were wounded again. These findings suggest that, in Arabidopsis, the pool of galactose-acylated monogalactosyldiacylglycerols may serve to sequester oxidized fatty acids during stress responses. PMID:24286212

  14. Acyl Silicates and Acyl Aluminates as Activated Intermediates in Peptide Formation on Clays

    NASA Astrophysics Data System (ADS)

    White, David H.; Kennedy, Robert M.; Macklin, John

    1984-12-01

    Glycine reacts with heating on dried clays and other minerals to give peptides in much better yield than in the absence of mineral. This reaction was proposed to occur by way of an activated intermediate such as an acyl silicate or acyl aluminate (i.e., the anhydride of a carboxylic acid with Si-OH or Al-OH), analogous to acyl phosphates involved in several biochemical reactions including peptide bond synthesis. We confirmed the proposed mechanism by trapping the intermediate, as well as by direct spectroscopic observation of a related intermediate. The reaction of amino acids on periodically dried mineral surfaces represents a widespread, geologically realistic setting for prebiotic peptide formation via in situ activation.

  15. Fatty Acid Export from the Chloroplast. Molecular Characterization of a Major Plastidial Acyl-Coenzyme A Synthetase from Arabidopsis1

    PubMed Central

    Schnurr, Judy A.; Shockey, Jay M.; de Boer, Gert-Jan; Browse, John A.

    2002-01-01

    Acyl-coenzyme A (CoA) synthetases (ACSs, EC 6.2.1.3) catalyze the formation of fatty acyl-CoAs from free fatty acid, ATP, and CoA. Essentially all de novo fatty acid synthesis occurs in the plastid. Fatty acids destined for membrane glycerolipid and triacylglycerol synthesis in the endoplasmic reticulum must be first activated to acyl-CoAs via an ACS. Within a family of nine ACS genes from Arabidopsis, we identified a chloroplast isoform, LACS9. LACS9 is highly expressed in developing seeds and young rosette leaves. Both in vitro chloroplast import assays and transient expression of a green fluorescent protein fusion indicated that the LACS9 protein is localized in the plastid envelope. A T-DNA knockout mutant (lacs9-1) was identified by reverse genetics and these mutant plants were indistinguishable from wild type in growth and appearance. Analysis of leaf lipids provided no evidence for compromised export of acyl groups from chloroplasts. However, direct assays demonstrated that lacs9-1 plants contained only 10% of the chloroplast long-chain ACS activity found for wild type. The residual long-chain ACS activity in mutant chloroplasts was comparable with calculated rates of fatty acid synthesis. Although another isozyme contributes to the activation of fatty acids during their export from the chloroplast, LACS9 is a major chloroplast ACS. PMID:12177483

  16. The fruit ripening-related gene FaAAT2 encodes an acyl transferase involved in strawberry aroma biogenesis.

    PubMed

    Cumplido-Laso, Guadalupe; Medina-Puche, Laura; Moyano, Enriqueta; Hoffmann, Thomas; Sinz, Quirin; Ring, Ludwig; Studart-Wittkowski, Claudia; Caballero, José Luis; Schwab, Wilfried; Muñoz-Blanco, Juan; Blanco-Portales, Rosario

    2012-06-01

    Short-chain esters contribute to the blend of volatiles that define the strawberry aroma. The last step in their biosynthesis involves an alcohol acyltransferase that catalyses the esterification of an acyl moiety of acyl-CoA with an alcohol. This study identified a novel strawberry alcohol acyltransferase gene (FaAAT2) whose expression pattern during fruit receptacle growth and ripening is in accordance with the production of esters throughout strawberry fruit ripening. The full-length FaAAT2 cDNA was cloned and expressed in Escherichia coli and its activity was analysed with acyl-CoA and alcohol substrates. The semi-purified FaAAT2 enzyme had activity with C1-C8 straight-chain alcohols and aromatic alcohols in the presence of acetyl-CoA. Cinnamyl alcohol was the most efficient acyl acceptor. When FaAAT2 expression was transiently downregulated in the fruit receptacle by agroinfiltration, the volatile ester production was significantly reduced in strawberry fruit. The results suggest that FaAAT2 plays a significant role in the production of esters that contribute to the final strawberry fruit flavour. PMID:22563120

  17. Interactions of a very long chain fatty acid with model membranes and serum albumin. Implications for the pathogenesis of adrenoleukodystrophy.

    PubMed Central

    Ho, J K; Moser, H; Kishimoto, Y; Hamilton, J A

    1995-01-01

    Adrenoleukodystrophy (ALD) is an inherited disorder of fatty acid metabolism marked by accumulation of very long chain saturated fatty acids (VLCFA), especially the 26-carbon acid, hexacosanoic acid (HA), in membranes and tissues. We have studied interactions of 13C-enriched HA with model membranes (phospholipid bilayer vesicles) and bovine serum albumin (BSA) by 13C NMR spectroscopy to compare properties of HA with those of typical dietary fatty acids. In phospholipid bilayers the carboxyl group of HA is localized in the aqueous interface, with an apparent pKa (7.4) similar to other fatty acids; the acyl chain must then penetrate very deeply into the membrane. Desorption of HA from vesicles (t1+2 = 3 h) is orders of magnitude slower than shorter chain fatty acids. In mixtures of vesicles and BSA, HA partitions much more favorably to phospholipid bilayers than typical fatty acids. BSA binds a maximum of only 1 mole of HA at one binding site. Calorimetric experiments show strong perturbations of acyl chains of phospholipids by HA. We predict that disruptive effects of VLCFA on cell membrane structure and function may explain the neurological manifestations of ALD patients. These effects will be further amplified by slow desorption of VLCFA from membranes and by the ineffective binding to serum albumin. PMID:7657817

  18. Unique plasma metabolomic signatures of individuals with inherited disorders of long-chain fatty acid oxidation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Blood and urine acylcarnitine profiles are commonly used to diagnose long-chain fatty acid oxidation disorders (FAOD: i.e., long-chain hydroxy-acyl-CoA dehydrogenase [LCHAD] and carnitine palmitoyltransferase 2 [CPT2] deficiency), but the global metabolic impact of long-chain FAOD has not been repor...

  19. Engineering Yarrowia lipolytica for production of medium-chain fatty acids.

    PubMed

    Rutter, Charles D; Zhang, Shuyan; Rao, Christopher V

    2015-09-01

    Lipids are naturally derived products that offer an attractive, renewable alternative to petroleum-based hydrocarbons. While naturally produced long-chain fatty acids can replace some petroleum analogs, medium-chain fatty acid would more closely match the desired physical and chemical properties of currently employed petroleum products. In this study, we engineered Yarrowia lipolytica, an oleaginous yeast that naturally produces lipids at high titers, to produce medium-chain fatty acids. Five different acyl-acyl carrier protein (ACP) thioesterases with specificity for medium-chain acyl-ACP molecules were expressed in Y. lipolytica, resulting in formation of either decanoic or octanoic acid. These novel fatty acid products were found to comprise up to 40 % of the total cell lipids. Furthermore, the reduction in chain length resulted in a twofold increase in specific lipid productivity in these engineered strains. The medium-chain fatty acids were found to be incorporated into all lipid classes. PMID:26129951

  20. Quantum phase transitions and string orders in the spin-1/2 Heisenberg-Ising alternating chain with Dzyaloshinskii-Moriya interaction.

    PubMed

    Liu, Guang-Hua; You, Wen-Long; Li, Wei; Su, Gang

    2015-04-29

    Quantum phase transitions (QPTs) and the ground-state phase diagram of the spin-1/2 Heisenberg-Ising alternating chain (HIAC) with uniform Dzyaloshinskii-Moriya (DM) interaction are investigated by a matrix-product-state (MPS) method. By calculating the odd- and even-string order parameters, we recognize two kinds of Haldane phases, i.e. the odd- and even-Haldane phases. Furthermore, doubly degenerate entanglement spectra on odd and even bonds are observed in odd- and even-Haldane phases, respectively. A rich phase diagram including four different phases, i.e. an antiferromagnetic (AF), AF stripe, odd- and even-Haldane phases, is obtained. These phases are found to be separated by continuous QPTs: the topological QPT between the odd- and even-Haldane phases is verified to be continuous and corresponds to conformal field theory with central charge c = 1; while the rest of the phase transitions in the phase diagram are found to be c = 1/2. We also revisit, with our MPS method, the exactly solvable case of HIAC model with DM interactions only on odd bonds and find that the even-Haldane phase disappears, but the other three phases, i.e. the AF, AF stripe and odd-Haldane phases, still remain in the phase diagram. We exhibit the evolution of the even-Haldane phase by tuning the DM interactions on the even bonds gradually. PMID:25817273

  1. Quantum phase transitions and string orders in the spin-1/2 Heisenberg-Ising alternating chain with Dzyaloshinskii-Moriya interaction

    NASA Astrophysics Data System (ADS)

    Liu, Guang-Hua; You, Wen-Long; Li, Wei; Su, Gang

    2015-04-01

    Quantum phase transitions (QPTs) and the ground-state phase diagram of the spin-1/2 Heisenberg-Ising alternating chain (HIAC) with uniform Dzyaloshinskii-Moriya (DM) interaction are investigated by a matrix-product-state (MPS) method. By calculating the odd- and even-string order parameters, we recognize two kinds of Haldane phases, i.e. the odd- and even-Haldane phases. Furthermore, doubly degenerate entanglement spectra on odd and even bonds are observed in odd- and even-Haldane phases, respectively. A rich phase diagram including four different phases, i.e. an antiferromagnetic (AF), AF stripe, odd- and even-Haldane phases, is obtained. These phases are found to be separated by continuous QPTs: the topological QPT between the odd- and even-Haldane phases is verified to be continuous and corresponds to conformal field theory with central charge c = 1 while the rest of the phase transitions in the phase diagram are found to be c = 1/2. We also revisit, with our MPS method, the exactly solvable case of HIAC model with DM interactions only on odd bonds and find that the even-Haldane phase disappears, but the other three phases, i.e. the AF, AF stripe and odd-Haldane phases, still remain in the phase diagram. We exhibit the evolution of the even-Haldane phase by tuning the DM interactions on the even bonds gradually.

  2. Coexisting charge and magnetic orders in the dimer-chain iridate B a5AlI r2O11

    NASA Astrophysics Data System (ADS)

    Terzic, J.; Wang, J. C.; Ye, Feng; Song, W. H.; Yuan, S. J.; Aswartham, S.; DeLong, L. E.; Streltsov, S. V.; Khomskii, D. I.; Cao, G.

    2015-06-01

    We have synthesized and studied single-crystal B a5AlI r2O11 that features dimer chains of two inequivalent octahedra occupied by tetravalent I r4 +(5 d5) and pentavalent I r5 +(5 d4) ions, respectively. B a5AlI r2O11 is a Mott insulator that undergoes a subtle structural phase transition near TS=210 K and a magnetic transition at TM=4.5 K ; the latter transition is surprisingly resistant to applied magnetic fields μoH ≤12 T but more sensitive to modest applied pressure (d TM/d p ≈+0 .61 K /GPa ). All results indicate that the phase transition at TS signals an enhanced charge order that induces electrical dipoles and strong dielectric response near TS. It is clear that the strong covalency and spin-orbit interaction (SOI) suppress double exchange in Ir dimers and stabilize a novel magnetic state that is neither S =3 /2 nor J =1 /2 , but rather lies in an "intermediate" regime between these two states. The novel behavior of B a5AlI r2O11 therefore provides unique insights into the physics of SOI along with strong covalency in competition with double-exchange interactions of comparable strength.

  3. Modulation of FadR binding capacity for acyl-CoA fatty acids through structure-guided mutagenesis.

    PubMed

    Bacik, John-Paul; Yeager, Chris M; Twary, Scott N; Martí-Arbona, Ricardo

    2015-10-01

    FadR is a versatile global regulator in Escherichia coli that controls fatty acid metabolism and thereby modulates the ability of this bacterium to grow using fatty acids or acetate as the sole carbon source. FadR regulates fatty acid metabolism in response to intra-cellular concentrations of acyl-CoA lipids. The ability of FadR to bind acyl-CoA fatty acids is thus of significant interest for the engineering of biosynthetic pathways for the production of lipid-based biofuels and commodity chemicals. Based on the available crystal structure of E. coli bound to myristoyl-CoA, we predicted amino acid positions within the effector binding pocket that would alter the ability of FadR to bind acyl-CoA fatty acids without affecting DNA binding. We utilized fluorescence polarization to characterize the in vitro binding properties of wild type and mutant FadR. We found that a Leu102Ala mutant enhanced binding of the effector, likely by increasing the size of the binding pocket for the acyl moiety of the molecule. Conversely, the elimination of the guanidine side chain (Arg213Ala and Arg213Met mutants) of the CoA moiety binding site severely diminished the ability of FadR to bind the acyl-CoA effector. These results demonstrate the ability to fine tune FadR binding capacity. The validation of an efficient method to fully characterize all the binding events involved in the specific activity (effector and DNA operator binding) of FadR has allowed us to increase our understanding of the role of specific amino acids in the binding and recognition of acyl-CoA fatty acids and will greatly facilitate efforts aimed at engineering tunable FadR regulators for synthetic biology. PMID:26385696

  4. Modulation of FadR Binding Capacity for Acyl-CoA Fatty Acids Through Structure-Guided Mutagenesis

    DOE PAGESBeta

    Bacik, John-Paul; Yeager, Chris M.; Twary, Scott N.; Martí-Arbona, Ricardo

    2015-09-18

    FadR is a versatile global regulator in Escherichia coli that controls fatty acid metabolism and thereby modulates the ability of this bacterium to grow using fatty acids or acetate as the sole carbon source. FadR regulates fatty acid metabolism in response to intra-cellular concentrations of acyl-CoA lipids. The ability of FadR to bind acyl-CoA fatty acids is hence of significant interest for the engineering of biosynthetic pathways for the production of lipid-based biofuels and commodity chemicals. Based on the available crystal structure of E. coli bound to myristoyl- CoA, we predicted amino acid positions within the effector binding pocket thatmore » would alter the ability of FadR to bind acyl-CoA fatty acids without affecting DNA binding. We utilized fluorescence polarization to characterize the in-vitro binding properties of wild type and mutant FadR. We found that a Leu102Ala mutant enhanced binding of the effector, likely by increasing the size of the binding pocket for the acyl moiety of the molecule. Conversely, the elimination of the guanidine side chain (Arg213Ala and Arg213Met mutants) of the CoA moiety binding site severely diminished the ability of FadR to bind the acyl-CoA effector. These results demonstrate the ability to fine tune FadR binding capacity. The validation of an efficient method to fully characterize all the binding events involved in the specific activity (effector and DNA operator binding) of FadR has allowed us to increase our understanding of the role of specific amino acids in the binding and recognition of acyl-CoA fatty acids and will greatly facilitate efforts aimed at engineering tunable FadR regulators for synthetic biology.« less

  5. Modulation of FadR Binding Capacity for Acyl-CoA Fatty Acids Through Structure-Guided Mutagenesis

    SciTech Connect

    Bacik, John-Paul; Yeager, Chris M.; Twary, Scott N.; Martí-Arbona, Ricardo

    2015-09-18

    FadR is a versatile global regulator in Escherichia coli that controls fatty acid metabolism and thereby modulates the ability of this bacterium to grow using fatty acids or acetate as the sole carbon source. FadR regulates fatty acid metabolism in response to intra-cellular concentrations of acyl-CoA lipids. The ability of FadR to bind acyl-CoA fatty acids is hence of significant interest for the engineering of biosynthetic pathways for the production of lipid-based biofuels and commodity chemicals. Based on the available crystal structure of E. coli bound to myristoyl- CoA, we predicted amino acid positions within the effector binding pocket that would alter the ability of FadR to bind acyl-CoA fatty acids without affecting DNA binding. We utilized fluorescence polarization to characterize the in-vitro binding properties of wild type and mutant FadR. We found that a Leu102Ala mutant enhanced binding of the effector, likely by increasing the size of the binding pocket for the acyl moiety of the molecule. Conversely, the elimination of the guanidine side chain (Arg213Ala and Arg213Met mutants) of the CoA moiety binding site severely diminished the ability of FadR to bind the acyl-CoA effector. These results demonstrate the ability to fine tune FadR binding capacity. The validation of an efficient method to fully characterize all the binding events involved in the specific activity (effector and DNA operator binding) of FadR has allowed us to increase our understanding of the role of specific amino acids in the binding and recognition of acyl-CoA fatty acids and will greatly facilitate efforts aimed at engineering tunable FadR regulators for synthetic biology.

  6. Ion channel regulation by protein S-acylation

    PubMed Central

    2014-01-01

    Protein S-acylation, the reversible covalent fatty-acid modification of cysteine residues, has emerged as a dynamic posttranslational modification (PTM) that controls the diversity, life cycle, and physiological function of numerous ligand- and voltage-gated ion channels. S-acylation is enzymatically mediated by a diverse family of acyltransferases (zDHHCs) and is reversed by acylthioesterases. However, for most ion channels, the dynamics and subcellular localization at which S-acylation and deacylation cycles occur are not known. S-acylation can control the two fundamental determinants of ion channel function: (1) the number of channels resident in a membrane and (2) the activity of the channel at the membrane. It controls the former by regulating channel trafficking and the latter by controlling channel kinetics and modulation by other PTMs. Ion channel function may be modulated by S-acylation of both pore-forming and regulatory subunits as well as through control of adapter, signaling, and scaffolding proteins in ion channel complexes. Importantly, cross-talk of S-acylation with other PTMs of both cysteine residues by themselves and neighboring sites of phosphorylation is an emerging concept in the control of ion channel physiology. In this review, I discuss the fundamentals of protein S-acylation and the tools available to investigate ion channel S-acylation. The mechanisms and role of S-acylation in controlling diverse stages of the ion channel life cycle and its effect on ion channel function are highlighted. Finally, I discuss future goals and challenges for the field to understand both the mechanistic basis for S-acylation control of ion channels and the functional consequence and implications for understanding the physiological function of ion channel S-acylation in health and disease. PMID:24821965

  7. The Research on Integrated Strategy of Supply Chain Information Systems in the Automobile Industry Based on Order-To-Delivery Mode

    NASA Astrophysics Data System (ADS)

    Li, Ming; Gan, Lianzhen; He, Xuefeng

    The automotive industry there are different degrees of impairment of many companies supply chain IT strategy. In this paper, in which the automotive industry supply chain management business cooperation between enterprises loose, poor exchange of information leading to the presence or delays in product customization, supply of raw materials, material control, production planning and control, sales and service and a fast response propose a series of typical problems of scientific and rational supply chain information integration strategy. The strategy through the development system integration platform, improve internal ERP system, implementation of supply chain management and other methods. Put some protection principles in the information process, to ensure the correct implementation of supply chain IT strategy, and ultimately achieve collaborative business development concept and enhance the automotive industry as a whole level of information.

  8. Synthesis, Surface Active Properties and Cytotoxicity of Sodium N-Acyl Prolines.

    PubMed

    Sreenu, Madhumanchi; Narayana Prasad, Rachapudi Badari; Sujitha, Pombala; Kumar, Chityal Ganesh

    2015-01-01

    Sodium N-acyl prolines (NaNAPro) were synthesized using mixture of fatty acids obtained from coconut, palm, karanja, Sterculia foetida and high oleic sunflower oils via Schotten-Baumann reaction in 58-75% yields to study the synergetic effect of mixture of hydrophobic fatty acyl functionalities like saturation, unsaturation and cyclopropene fatty acids with different chain lengths and aliphatic hetero cyclic proline head group on their surface and cytotoxicity activities. The products were characterized by chromatographic and spectral techniques. The synthesized products were evaluated for their surface active properties such as surface tension, wetting power, foaming characteristics, emulsion stability, calcium tolerance, critical micelle concentration (CMC) and thermodynamic properties. The results revealed that all the products exhibited superior surface active properties like CMC, calcium tolerance and emulsion stability as compared to the standard surfactant, sodium lauryl sulphate (SLS). In addition, palm, Sterculia foetida and high oleic sunflower fatty N-acyl prolines exhibited promising cytotoxicity against different tumor cell lines. PMID:26521810

  9. Cloning of a palmitoyl-acyl carrier protein thioesterase from oil palm.

    PubMed

    Othman, A; Lazarus, C; Fraser, T; Stobart, K

    2000-12-01

    A palmitoyl-acyl carrier protein (ACP) thioesterase cDNA clone was isolated from an oil palm cDNA library. The cDNA was expressed in Escherichia coli as a glutathione S-transferase fusion protein and a crude bacterial extract was assayed for acyl-CoA-hydrolysing activity. The recombinant enzyme was able to hydrolyse medium- and long-chain acyl-CoAs. Northern-blot analysis showed a high level of gene expression in leaf, flower and 15-, 17- and 18-week mesocarp tissues. Low-level gene expression was detected in germinated seedlings and 8- and 12-week mesocarp tissues, but no transcript was detected in any kernel tissues. Southern-blot analysis indicated the presence of a single gene and we have also isolated a genomic clone using the cDNA as a probe. Two genomic fragments were subcloned and a 7 kb contiguous stretch of the oil palm genome was sequenced. Comparison of this sequence with the cDNA sequence identified a putative 93 amino acid transit peptide, most of which is missing from the cDNA. The coding region of the gene consisted of seven exons and six introns. PMID:11171146

  10. Arabidopsis cytosolic acyl-CoA-binding proteins ACBP4, ACBP5 and ACBP6 have overlapping but distinct roles in seed development

    PubMed Central

    Hsiao, An-Shan; Haslam, Richard P.; Michaelson, Louise V.; Liao, Pan; Chen, Qin-Fang; Sooriyaarachchi, Sanjeewani; Mowbray, Sherry L.; Napier, Johnathan A.; Tanner, Julian A.; Chye, Mee-Len

    2014-01-01

    Eukaryotic cytosolic ACBPs (acyl-CoA-binding proteins) bind acyl-CoA esters and maintain a cytosolic acyl-CoA pool, but the thermodynamics of their protein–lipid interactions and physiological relevance in plants are not well understood. Arabidopsis has three cytosolic ACBPs which have been identified as AtACBP4, AtACBP5 and AtACBP6, and microarray data indicated that all of them are expressed in seeds; AtACBP4 is expressed in early embryogenesis, whereas AtACBP5 is expressed later. ITC (isothermal titration calorimetry) in combination with transgenic Arabidopsis lines were used to investigate the roles of these three ACBPs from Arabidopsis thaliana. The dissociation constants, stoichiometry and enthalpy change of AtACBP interactions with various acyl-CoA esters were determined using ITC. Strong binding of recombinant (r) AtACBP6 with long-chain acyl-CoA (C16- to C18-CoA) esters was observed with dissociation constants in the nanomolar range. However, the affinity of rAtACBP4 and rAtACBP5 to these acyl-CoA esters was much weaker (dissociation constants in the micromolar range), suggesting that they interact with acyl-CoA esters differently from rAtACBP6. When transgenic Arabidopsis expressing AtACBP6pro::GUS was generated, strong GUS (β-glucuronidase) expression in cotyledonary-staged embryos and seedlings prompted us to measure the acyl-CoA contents of the acbp6 mutant. This mutant accumulated higher levels of C18:1-CoA and C18:1- and C18:2-CoAs in cotyledonary-staged embryos and seedlings, respectively, in comparison with the wild type. The acbp4acbp5acbp6 mutant showed the lightest seed weight and highest sensitivity to abscisic acid during germination, suggesting their physiological functions in seeds. PMID:25423293

  11. Efficient production of di- and tri-acylated mannosylerythritol lipids as glycolipid biosurfactants by Pseudozyma parantarctica JCM 11752(T).

    PubMed

    Morita, Tomotake; Konishi, Masaaki; Fukuoka, Tokuma; Imura, Tomohiro; Sakai, Hideki; Kitamoto, Dai

    2008-01-01

    Mannosylerythritol lipids (MELs) are one of the most promising biosurfactants known, because of their multifunctionality and biocompatibility. In order to attain an efficient production of MELs, Pseudozyma parantarctica JCM 11752(T), which is a newly identified strain of the genus, was examined for the productivity of MELs at different culture conditions. The yeast strain showed significant cell growth and production of di-acylated MELs even at 36 degrees C. In contrast, on conventional high-level MEL producers including P. rugulosa, the MEL yield considerably decreased with an increase of the cultivation temperature at over 30 degrees C. On P. parantarctica, soybean oil and sodium nitrate were the best carbon and nitrogen sources, respectively. Under the optimal conditions on a shake-flask culture at 34 degrees C, the amount of di-acylated MELs reached over 100 g/L by intermittent feeding of only soybean oil. Interestingly, the yeast strain produced tri-acylated MELs as well as di-acylated ones when grown on the medium containing higher soybean oil concentrations than 8% (vol/vol). The production of tri-acylated MELs was significantly accelerated at between 34 and 36 degrees C. With 20 % (vol/vol) of soybean oil at 34 degrees C, the yield of tri-acylated MELs reached 22.7 g/L. The extracellular lipase activity considerably depended on the culture temperature, and became the maximum at 34 degrees C; this would bring the accelerated production of tri-acylated MELs. Accordingly, the present strain of P. parantarctica provided high efficiency in MEL production at elevated temperatures compared to conventional MEL producers, and would thus be highly advantageous for the commercial production of the promising biosurfactants. PMID:18781056

  12. Chlorsulfuron modifies biosynthesis of acyl Acid substituents of sucrose esters secreted by tobacco trichomes.

    PubMed

    Kandra, L; Wagner, G J

    1990-11-01

    Sucrose esters and duvatrienediol diterpenes are principal constituents formed in and secreted outside head cells of trichomes occurring on surfaces of Nicotiana tabacum. Using trichome-bearing epidermal peels prepared from midveins of N. tabacum cv T.I. 1068 leaves, we found that chlorsulfuron reduced and modified radiolabeling of sucrose ester acyl acids derived from branched-chain amino acid metabolism. The herbicide did not effect formation and exudation of diterpenes which are products of isoprenoid metabolism. Treatment with 1.0 micromolar chlorsulfuron affected 8.5- and 6.3-fold reductions in radiolabeling of methylvaleryl and methylbutyryl groups of sucrose esters, respectively, and concomitant increases of 9- and 9.8-fold in radiolabeling of straight chain valeryl and butyryl groups, respectively. These results and others indicate that inhibition of acetolactate synthase causes an accumulation of 2-oxo-butyric acid that is utilized by enzymes common to Leu biosynthesis to form 2-oxo-valeric acid. Coenzyme A (CoA) activation of this keto acid gives rise to butyryl CoA, which is utilized to form butyryl containing sucrose esters. Alternatively, reutilization of 2-oxo-valeric acid by the same enzymes followed by CoA activation leads to valeryl containing sucrose esters. We propose that in trichome secretory cells synthase, isomerase and dehydrogenase enzymes which catalyze Leu synthesis/degredation in most tissues, convert iso-branched, anteiso-branched and straight-chain keto acids in the formation of sucrose ester acyl groups. PMID:16667871

  13. Chlorsulfuron Modifies Biosynthesis of Acyl Acid Substituents of Sucrose Esters Secreted by Tobacco Trichomes

    PubMed Central

    Kandra, Lili; Wagner, George J.

    1990-01-01

    Sucrose esters and duvatrienediol diterpenes are principal constituents formed in and secreted outside head cells of trichomes occurring on surfaces of Nicotiana tabacum. Using trichome-bearing epidermal peels prepared from midveins of N. tabacum cv T.I. 1068 leaves, we found that chlorsulfuron reduced and modified radiolabeling of sucrose ester acyl acids derived from branched-chain amino acid metabolism. The herbicide did not effect formation and exudation of diterpenes which are products of isoprenoid metabolism. Treatment with 1.0 micromolar chlorsulfuron affected 8.5- and 6.3-fold reductions in radiolabeling of methylvaleryl and methylbutyryl groups of sucrose esters, respectively, and concomitant increases of 9- and 9.8-fold in radiolabeling of straight chain valeryl and butyryl groups, respectively. These results and others indicate that inhibition of acetolactate synthase causes an accumulation of 2-oxo-butyric acid that is utilized by enzymes common to Leu biosynthesis to form 2-oxo-valeric acid. Coenzyme A (CoA) activation of this keto acid gives rise to butyryl CoA, which is utilized to form butyryl containing sucrose esters. Alternatively, reutilization of 2-oxo-valeric acid by the same enzymes followed by CoA activation leads to valeryl containing sucrose esters. We propose that in trichome secretory cells synthase, isomerase and dehydrogenase enzymes which catalyze Leu synthesis/degredation in most tissues, convert iso-branched, anteiso-branched and straight-chain keto acids in the formation of sucrose ester acyl groups. PMID:16667871

  14. Characterization of Novel Acyl Coenzyme A Dehydrogenases Involved in Bacterial Steroid Degradation

    PubMed Central

    Ruprecht, Amanda; Maddox, Jaymie; Stirling, Alexander J.; Visaggio, Nicole

    2015-01-01

    ABSTRACT The acyl coenzyme A (acyl-CoA) dehydrogenases (ACADs) FadE34 and CasC, encoded by the cholesterol and cholate gene clusters of Mycobacterium tuberculosis and Rhodococcus jostii RHA1, respectively, were successfully purified. Both enzymes differ from previously characterized ACADs in that they contain two fused acyl-CoA dehydrogenase domains in a single polypeptide. Site-specific mutagenesis showed that only the C-terminal ACAD domain contains the catalytic glutamate base required for enzyme activity, while the N-terminal ACAD domain contains an arginine required for ionic interactions with the pyrophosphate of the flavin adenine dinucleotide (FAD) cofactor. Therefore, the two ACAD domains must associate to form a single active site. FadE34 and CasC were not active toward the 3-carbon side chain steroid metabolite 3-oxo-23,24-bisnorchol-4-en-22-oyl-CoA (4BNC-CoA) but were active toward steroid CoA esters containing 5-carbon side chains. CasC has similar specificity constants for cholyl-CoA, deoxycholyl-CoA, and 3β-hydroxy-5-cholen-24-oyl-CoA, while FadE34 has a preference for the last compound, which has a ring structure similar to that of cholesterol metabolites. Knockout of the casC gene in R. jostii RHA1 resulted in a reduced growth on cholate as a sole carbon source and accumulation of a 5-carbon side chain cholate metabolite. FadE34 and CasC represent unique members of ACADs with primary structures and substrate specificities that are distinct from those of previously characterized ACADs. IMPORTANCE We report here the identification and characterization of acyl-CoA dehydrogenases (ACADs) involved in the metabolism of 5-carbon side chains of cholesterol and cholate. The two homologous enzymes FadE34 and CasC, from M. tuberculosis and Rhodococcus jostii RHA1, respectively, contain two ACAD domains per polypeptide, and we show that these two domains interact to form a single active site. FadE34 and CasC are therefore representatives of a new class of

  15. Synthesis and characterization of some acyl thiourea derivatives of chitosan and their biocidal activities.

    PubMed

    Elkholy, Said S; Salem, Hend A; Eweis, Mohamed; Elsabee, Maher Z

    2014-09-01

    Three acyl derivatives of chitosan (CS) with different side chains were synthesized and their structures were characterized. Their swelling behavior was investigated. The antifungal behavior of these chitosan derivatives was investigated in vitro on the mycelial growth, sporulation and germination of conidia or sclerotia of the sugar-beet pathogens, Rhizoctonia solani K"uhn (AG2-2) and Sclerotium rolfsii Sacc. All the prepared derivatives had a significant inhibiting effect on the different stages of development on the germination of conidia or sclerotia of all the investigated fungi. In the absence of chitosan and its derivative, R. solani exhibited the fastest growth of the fungi studied. PMID:25002014

  16. Arabidopsis membrane-associated acyl-CoA-binding protein ACBP1 is involved in stem cuticle formation

    PubMed Central

    Xue, Yan; Xiao, Shi; Kim, Juyoung; Lung, Shiu-Cheung; Chen, Liang; Tanner, Julian A.; Suh, Mi Chung; Chye, Mee-Len

    2014-01-01

    The membrane-anchored Arabidopsis thaliana ACYL-COA-BINDING PROTEIN1 (AtACBP1) plays important roles in embryogenesis and abiotic stress responses, and interacts with long-chain (LC) acyl-CoA esters. Here, AtACBP1 function in stem cuticle formation was investigated. Transgenic Arabidopsis transformed with an AtACBP1pro::GUS construct revealed β-glucuronidase (GUS) expression on the stem (but not leaf) surface, suggesting a specific role in stem cuticle formation. Isothermal titration calorimetry results revealed that (His)6-tagged recombinant AtACBP1 interacts with LC acyl-CoA esters (18:1-, 18:2-, and 18:3-CoAs) and very-long-chain (VLC) acyl-CoA esters (24:0-, 25:0-, and 26:0-CoAs). VLC fatty acids have been previously demonstrated to act as precursors in wax biosynthesis. Gas chromatography (GC)–flame ionization detector (FID) and GC–mass spectrometry (MS) analyses revealed that an acbp1 mutant showed a reduction in stem and leaf cuticular wax and stem cutin monomer composition in comparison with the wild type (Col-0). Consequently, the acbp1 mutant showed fewer wax crystals on the stem surface in scanning electron microscopy and an irregular stem cuticle layer in transmission electron microscopy in comparison with the wild type. Also, the mutant stems consistently showed a decline in expression of cuticular wax and cutin biosynthetic genes in comparison with the wild type, and the mutant leaves were more susceptible to infection by the necrotrophic pathogen Botrytis cinerea. Taken together, these findings suggest that AtACBP1 participates in Arabidopsis stem cuticle formation by trafficking VLC acyl-CoAs. PMID:25053648

  17. Characterization of the acyl substrate binding pocket of acetyl-CoA synthetase.

    PubMed

    Ingram-Smith, Cheryl; Woods, Barrett I; Smith, Kerry S

    2006-09-26

    AMP-forming acetyl-CoA synthetase [ACS; acetate:CoA ligase (AMP-forming), EC 6.2.1.1] catalyzes the activation of acetate to acetyl-CoA in a two-step reaction. This enzyme is a member of the adenylate-forming enzyme superfamily that includes firefly luciferase, nonribosomal peptide synthetases, and acyl- and aryl-CoA synthetases/ligases. Although the structures of several superfamily members demonstrate that these enzymes have a similar fold and domain structure, the low sequence conservation and diversity of the substrates utilized have limited the utility of these structures in understanding substrate binding in more distantly related enzymes in this superfamily. The crystal structures of the Salmonella enterica ACS and Saccharomyces cerevisiae ACS1 have allowed a directed approach to investigating substrate binding and catalysis in ACS. In the S. enterica ACS structure, the propyl group of adenosine 5'-propylphosphate, which mimics the acyl-adenylate intermediate, lies in a hydrophobic pocket. Modeling of the Methanothermobacter thermautotrophicus Z245 ACS (MT-ACS1) on the S. cerevisiae ACS structure showed similar active site architecture, and alignment of the amino acid sequences of proven ACSs indicates that the four residues that compose the putative acetate binding pocket are well conserved. These four residues, Ile312, Thr313, Val388, and Trp416 of MT-ACS1, were targeted for alteration, and our results support that they do indeed form the acetate binding pocket and that alterations at these positions significantly alter the enzyme's affinity for acetate as well as the range of acyl substrates that can be utilized. In particular, Trp416 appears to be the primary determinant for acyl chain length that can be accommodated in the binding site. PMID:16981708

  18. Fluorescent metal-organic polymers of zinc and cadmium from hydrothermal in situ acylation reaction.

    PubMed

    Yu, Xiao-Yang; Ye, Ling; Zhang, Xiao; Cui, Xiao-Bing; Zhang, Jian-Po; Xu, Ji-Qing; Hou, Qin; Wang, Tie-Gang

    2010-11-28

    A series of metal-organic complexes based on d(10) metals and the ligand H(4)bbh (H(4)bbh = benzene-1, 2, 4, 5-biformhydrazide), formed through hydrothermal in situ acylate reaction of H(4)bta (H(4)bta = benzene-1, 2, 4, 5-tetracarboxylic acid) with hydrazine hydrate (N(2)H(4)·H(2)O), have been prepared and structurally characterized by single-crystal X-ray diffraction. Compounds [Zn(μ(2)-H(2)bbh)(phen)(H(2)O)](2) (1) (phen = 1, 10-phenanthroline) and [Zn(μ(2)-H(2)bbh)(2, 2'-bpy)](2) (2) (2, 2'-bpy = 2, 2'-bipyridine) are both dinuclear complexes in which bridging ligands H(2)bbh(2-) display different μ(2)- coordination modes. [Zn(μ(2)-H(2)bbh)(1/2)(μ(2)-H(2)bbh)(1/2)(H(2)O)](n) (3) exhibits a two-dimensional (2-D) layer structure containing simultaneously two kinds of different coordination modes of H(2)bbh(2-): μ(2)-bidentate and μ(4)-tetradentate. [Cd(μ(3)-H(2)bbh)(phen)](n) (4) consists of one-dimensional (1-D) double-metal chains. The crystal structures of these compounds are stabilized by hydrogen bonds and π···π interactions, forming three-dimensional supramolecular networks. All of the compounds were characterized by IR, UV-vis spectra and elemental analysis and they show good fluorescence properties in the solid state at room temperature. In order to understand the emission mechanism, we carried out TDDFT calculations on the excited electronic states of compound 2. PMID:20886135

  19. Modification of seed oil content and acyl composition in the brassicaceae by expression of a yeast sn-2 acyltransferase gene.

    PubMed Central

    Zou, J; Katavic, V; Giblin, E M; Barton, D L; MacKenzie, S L; Keller, W A; Hu, X; Taylor, D C

    1997-01-01

    A putative yeast sn-2 acyltransferase gene (SLC1-1), reportedly a variant acyltransferase that suppresses a genetic defect in sphingolipid long-chain base biosynthesis, has been expressed in a yeast SLC deletion strain. The SLC1-1 gene product was shown in vitro to encode an sn-2 acyltransferase capable of acylating sn-1 oleoyl-lysophosphatidic acid, using a range of acyl-CoA thioesters, including 18:1-, 22:1-, and 24:0-CoAs. The SLC1-1 gene was introduced into Arabidopsis and a high erucic acid-containing Brassica napus cv Hero under the control of a constitutive (tandem cauliflower mosaic virus 35S) promoter. The resulting transgenic plants showed substantial increases of 8 to 48% in seed oil content (expressed on the basis of seed dry weight) and increases in both overall proportions and amounts of very-long-chain fatty acids in seed triacylglycerols (TAGs). Furthermore, the proportion of very-long-chain fatty acids found at the sn-2 position of TAGs was increased, and homogenates prepared from developing seeds of transformed plants exhibited elevated lysophosphatidic acid acyltransferase (EC 2.3.1.51) activity. Thus, the yeast sn-2 acyltransferase has been shown to encode a protein that can exhibit lysophosphatidic acid acyltransferase activity and that can be used to change total fatty acid content and composition as well as to alter the stereospecific acyl distribution of fatty acids in seed TAGs. PMID:9212466

  20. Acyl peptidic siderophores: structures, biosyntheses and post-assembly modifications.

    PubMed

    Kem, Michelle P; Butler, Alison

    2015-06-01

    Acyl peptidic siderophores are produced by a variety of bacteria and possess unique amphiphilic properties. Amphiphilic siderophores are generally produced in a suite where the iron(III)-binding headgroup remains constant while the fatty acid appendage varies by length and functionality. Acyl peptidic siderophores are commonly synthesized by non-ribosomal peptide synthetases; however, the method of peptide acylation during biosynthesis can vary between siderophores. Following biosynthesis, acyl siderophores can be further modified enzymatically to produce a more hydrophilic compound, which retains its ferric chelating abilities as demonstrated by pyoverdine from Pseudomonas aeruginosa and the marinobactins from certain Marinobacter species. Siderophore hydrophobicity can also be altered through photolysis of the ferric complex of certain β-hydroxyaspartic acid-containing acyl peptidic siderophores. PMID:25677460

  1. Lysine fatty acylation promotes lysosomal targeting of TNF-α

    PubMed Central

    Jiang, Hong; Zhang, Xiaoyu; Lin, Hening

    2016-01-01

    Tumor necrosis factor-α (TNF-α) is a proinflammation cytokine secreted by various cells. Understanding its secretive pathway is important to understand the biological functions of TNF-α and diseases associated with TNF-α. TNF-α is one of the first proteins known be modified by lysine fatty acylation (e.g. myristoylation). We previously demonstrated that SIRT6, a member of the mammalian sirtuin family of enzymes, can remove the fatty acyl modification on TNF-α and promote its secretion. However, the mechanistic details about how lysine fatty acylation regulates TNF-α secretion have been unknown. Here we present experimental data supporting that lysine fatty acylation promotes lysosomal targeting of TNF-α. The result is an important first step toward understanding the biological functions of lysine fatty acylation. PMID:27079798

  2. Vertebrate fatty acyl desaturase with Δ4 activity

    PubMed Central

    Li, Yuanyou; Monroig, Oscar; Zhang, Liang; Wang, Shuqi; Zheng, Xiaozhong; Dick, James R.; You, Cuihong; Tocher, Douglas R.

    2010-01-01

    Biosynthesis of the highly biologically active long-chain polyunsaturated fatty acids, arachidonic (ARA), eicosapentaenoic (EPA), and docosahexaenoic (DHA) acids, in vertebrates requires the introduction of up to three double bonds catalyzed by fatty acyl desaturases (Fad). Synthesis of ARA is achieved by Δ6 desaturation of 18∶2n - 6 to produce 18∶3n - 6 that is elongated to 20∶3n - 6 followed by Δ5 desaturation. Synthesis of EPA from 18∶3n - 3 requires the same enzymes and pathway as for ARA, but DHA synthesis reportedly requires two further elongations, a second Δ6 desaturation and a peroxisomal chain shortening step. This paper describes cDNAs, fad1 and fad2, isolated from the herbivorous, marine teleost fish (Siganus canaliculatus) with high similarity to mammalian Fad proteins. Functional characterization of the cDNAs by heterologous expression in the yeast Saccharomyces cerevisiae showed that Fad1 was a bifunctional Δ6/Δ5 Fad. Previously, functional dual specificity in vertebrates had been demonstrated for a zebrafish Danio rerio Fad and baboon Fad, so the present report suggests bifunctionality may be more widespread in vertebrates. However, Fad2 conferred on the yeast the ability to convert 22∶5n - 3 to DHA indicating that this S. canaliculatus gene encoded an enzyme having Δ4 Fad activity. This is a unique report of a Fad with Δ4 activity in any vertebrate species and indicates that there are two possible mechanisms for DHA biosynthesis, a direct route involving elongation of EPA to 22∶5n - 3 followed by Δ4 desaturation, as well as the more complicated pathway as described above. PMID:20826444

  3. Chromatin higher-order structure: two-start double superhelix formed by zig-zag shaped nucleosome chain with folded linker DNA.

    PubMed

    Osipova, T N; Karpova, E V; Vorob'ev, V I

    1990-08-01

    Hydrodynamic properties of chromatins differing in linker DNA length and in transcriptional activity have been studied by the method of sedimentation velocity. Oligonucleosomes of different chain length were isolated from chromatins of pigeon brain cortical neurones, rat thymus and sea urchin sperm characterized by nucleosome DNA repeat length of 165, 198 and 248 base pairs respectively. The hydrodynamic behaviour of oligonucleosomes in the dependence on the number of nucleosomes in the chain and on the ionic strength has been analysed on the basis of cylinder model. The data obtained allows one to calculate the main structural parameters of the oligonucleosomal chain: its mass per unit length, the hydrodynamic diameter of the chain, the length of the chain per nucleosome and DNA packing ratio. It is shown that hydrodynamic behaviour of nucleosome oligomers from all types of chromatins investigated at low ionic strength can be well described by the model of three-dimensional zig-zag chain with similar diameter and length of the chain per nucleosome, DNA packing ratio growing with the increase of linker DNA length. It can be achieved by unfolding the short linker DNA in neurone chromatin and by coiling the long linker DNA of sea urchin sperm chromatin into a loop. With the increase of ionic strength zig-zag shaped nucleosomal chain is condensed into a two-start double superhelix with closely arranged nucleosomes and linker DNA loops packed inside the superhelix. The suggested model is in good agreement with available experimental data and overcomes a number of difficulties which arise for the solenoid model and other models of the 30-nm chromatin fibril. PMID:2275789

  4. Decarboxylation of malonyl-(acyl carrier protein) by 3-oxoacyl-(acyl carrier protein) synthases in plant fatty acid biosynthesis.

    PubMed Central

    Winter, E; Brummel, M; Schuch, R; Spener, F

    1997-01-01

    In order to identify regulatory steps in fatty acid biosynthesis, the influence of intermediate 3-oxoacyl-(acyl carrier proteins) (3-oxoacyl-ACPs) and end-product acyl-ACPs of the fatty acid synthase reaction on the condensation reaction was investigated in vitro, using total fatty acid synthase preparations and purified 3-oxoacyl-ACP synthases (KASs; EC 2.3.1.41) from Cuphea lanceolata seeds. KAS I and II in the fatty acid synthase preparations were assayed for the elongation of octanoyl- and hexadecanoyl-ACP respectively, and the accumulation of the corresponding condensation product 3-oxoacyl-ACP was studied by modulating the content of the reducing equivalentS NADH and NADPH. Complete omission of reducing equivalents resulted with either KAS in the abnormal synthesis of acetyl-ACP from malonyl-ACP by a decarboxylation reaction. Supplementation with NADPH or NADH, separately or in combination with recombinant 3-oxoacyl-ACP reductase (EC 1.1.1.100), led to a decrease in the amount of acetyl-ACP and a simultaneous increase in elongation products. This demonstrates that the accumulation of 3-oxoacyl-ACP inhibits the condensation reaction on the one hand, and induces the decarboxylation of malonyl-ACP on the other. By carrying out similar experiments with purified enzymes, this decarboxylation was attributed to the action of KAS. Our data point to a regulatory mechanism for the degradation of malonyl-ACP in plants which is activated by the accumulation of the fatty acid synthase intermediate 3-oxoacyl-ACP. PMID:9020860

  5. Structural characterization of acyl-CoA oxidases reveals a direct link between pheromone biosynthesis and metabolic state in Caenorhabditis elegans.

    PubMed

    Zhang, Xinxing; Li, Kunhua; Jones, Rachel A; Bruner, Steven D; Butcher, Rebecca A

    2016-09-01

    Caenorhabditis elegans secretes ascarosides as pheromones to communicate with other worms and to coordinate the development and behavior of the population. Peroxisomal β-oxidation cycles shorten the side chains of ascaroside precursors to produce the short-chain ascaroside pheromones. Acyl-CoA oxidases, which catalyze the first step in these β-oxidation cycles, have different side chain-length specificities and enable C. elegans to regulate the production of specific ascaroside pheromones. Here, we determine the crystal structure of the acyl-CoA oxidase 1 (ACOX-1) homodimer and the ACOX-2 homodimer bound to its substrate. Our results provide a molecular basis for the substrate specificities of the acyl-CoA oxidases and reveal why some of these enzymes have a very broad substrate range, whereas others are quite specific. Our results also enable predictions to be made for the roles of uncharacterized acyl-CoA oxidases in C. elegans and in other nematode species. Remarkably, we show that most of the C. elegans acyl-CoA oxidases that participate in ascaroside biosynthesis contain a conserved ATP-binding pocket that lies at the dimer interface, and we identify key residues in this binding pocket. ATP binding induces a structural change that is associated with tighter binding of the FAD cofactor. Mutations that disrupt ATP binding reduce FAD binding and reduce enzyme activity. Thus, ATP may serve as a regulator of acyl-CoA oxidase activity, thereby directly linking ascaroside biosynthesis to ATP concentration and metabolic state. PMID:27551084

  6. Temperature-Dependence of Lipid A Acyl Structure in Psychrobacter cryohalolentis and Arctic Isolates of Colwellia hornerae and Colwellia piezophila.

    PubMed

    Sweet, Charles R; Watson, Rebecca E; Landis, Corinne A; Smith, Joseph P

    2015-08-01

    Lipid A is a fundamental Gram-negative outer membrane component and the essential element of lipopolysaccharide (endotoxin), a potent immunostimulatory molecule. This work describes the metabolic adaptation of the lipid A acyl structure by Psychrobacter cryohalolentis at various temperatures in its facultative psychrophilic growth range, as characterized by MALDI-TOF MS and FAME GC-MS. It also presents the first elucidation of lipid A structure from the Colwellia genus, describing lipid A from strains of Colwellia hornerae and Colwellia piezophila, which were isolated as primary cultures from Arctic fast sea ice and identified by 16S rDNA sequencing. The Colwellia strains are obligate psychrophiles, with a growth range restricted to 15 °C or less. As such, these organisms have less need for fluidity adaptation in the acyl moiety of the outer membrane, and they do not display alterations in lipid A based on growth temperature. Both Psychrobacter and Colwellia make use of extensive single-methylene variation in the size of their lipid A molecules. Such single-carbon variations in acyl size were thought to be restricted to psychrotolerant (facultative) species, but its presence in these Colwellia species shows that odd-chain acyl units and a single-carbon variation in lipid A structure are present in obligate psychrophiles, as well. PMID:26264000

  7. Temperature-Dependence of Lipid A Acyl Structure in Psychrobacter cryohalolentis and Arctic Isolates of Colwellia hornerae and Colwellia piezophila

    PubMed Central

    Sweet, Charles R.; Watson, Rebecca E.; Landis, Corinne A.; Smith, Joseph P.

    2015-01-01

    Lipid A is a fundamental Gram-negative outer membrane component and the essential element of lipopolysaccharide (endotoxin), a potent immunostimulatory molecule. This work describes the metabolic adaptation of the lipid A acyl structure by Psychrobacter cryohalolentis at various temperatures in its facultative psychrophilic growth range, as characterized by MALDI-TOF MS and FAME GC-MS. It also presents the first elucidation of lipid A structure from the Colwellia genus, describing lipid A from strains of Colwellia hornerae and Colwellia piezophila, which were isolated as primary cultures from Arctic fast sea ice and identified by 16S rDNA sequencing. The Colwellia strains are obligate psychrophiles, with a growth range restricted to 15 °C or less. As such, these organisms have less need for fluidity adaptation in the acyl moiety of the outer membrane, and they do not display alterations in lipid A based on growth temperature. Both Psychrobacter and Colwellia make use of extensive single-methylene variation in the size of their lipid A molecules. Such single-carbon variations in acyl size were thought to be restricted to psychrotolerant (facultative) species, but its presence in these Colwellia species shows that odd-chain acyl units and a single-carbon variation in lipid A structure are present in obligate psychrophiles, as well. PMID:26264000

  8. Friedel-Craft acylation of ar-himachalene: synthesis of acyl-ar-himachalene and a new acyl-hydroperoxide.

    PubMed

    Hossini, Issam; Harrad, Mohamed Anoir; Ait Ali, Mustapha; El Firdoussi, Larbi; Karim, Abdallah; Valerga, Pedro; Puerta, M Carmen

    2011-01-01

    Friedel-Craft acylation at 100 °C of 2,5,9,9-tetramethyl-6,7,8,9-tetrahydro-5H-benzocycloheptene [ar-himachalene], a sesquiterpenic hydrocarbon obtained by catalytic dehydrogenation of α-, β- and γ-himachalenes, produces a mixture of two compounds: (3,5,5,9-tetramethyl-6,7,8,9-tetrahydro-5H-benzocyclohepten-2-yl)-ethanone (2, in 69% yield), with a conserved reactant backbone, and 3, with a different skeleton, in 21% yield. The crystal structure of 3 reveals it to be 1-(8-ethyl-8-hydroperoxy-3,5,5-trimethyl-5,6,7,8-tetrahydronaphthalen-2-yl)-ethanone. In this compound O-H…O bonds form dimers. These hydrogen-bonds, in conjunction with weaker C-H…O interactions, form a more extended supramolecular arrangement in the crystal. PMID:21760570

  9. Enhanced cellular uptake of short polyarginine peptides through fatty acylation and cyclization.

    PubMed

    Oh, Donghoon; Nasrolahi Shirazi, Amir; Northup, Kevin; Sullivan, Brian; Tiwari, Rakesh Kumar; Bisoffi, Marco; Parang, Keykavous

    2014-08-01

    Many of the reported arginine-rich cell-penetrating peptides (CPPs) for the enhanced delivery of drugs are linear peptides composed of more than seven arginine residues to retain the cell penetration properties. Herein, we synthesized a class of nine polyarginine peptides containing 5 and 6 arginines, namely, R5 and R6. We further explored the effect of acylation with long chain fatty acids (i.e., octanoic acid, dodecanoic acid, and hexadecanoic acid) and cyclization on the cell penetrating properties of the peptides. The fluorescence-labeled acylated cyclic peptide dodecanoyl-[R5] and linear peptide dodecanoyl-(R5) showed approximately 13.7- and 10.2-fold higher cellular uptake than that of control 5,6-carboxyfluorescein, respectively. The mechanism of the peptide internalization into cells was found to be energy-dependent endocytosis. Dodecanoyl-[R5] and dodecanoyl-[R6] enhanced the intracellular uptake of a fluorescence-labeled cell-impermeable negatively charged phosphopeptide (F'-GpYEEI) in human ovarian cancer cells (SK-OV-3) by 3.4-fold and 5.5-fold, respectively, as shown by flow cytometry. The cellular uptake of F'-GpYEEI in the presence of hexadecanoyl-[R5] was 9.3- and 6.0-fold higher than that in the presence of octanoyl-[R5] and dodecanoyl-[R5], respectively. Dodecanoyl-[R5] enhanced the cellular uptake of the phosphopeptide by 1.4-2.5-fold higher than the corresponding linear peptide dodecanoyl-(R5) and those of representative CPPs, such as hepta-arginine (CR7) and TAT peptide. These results showed that a combination of acylation by long chain fatty acids and cyclization on short arginine-containing peptides can improve their cell-penetrating property, possibly through efficient interaction of rigid positively charged R and hydrophobic dodecanoyl moiety with the corresponding residues in the cell membrane phospholipids. PMID:24978295

  10. Structure of 3-oxoacyl-(acyl-carrier protein) synthase II from Thermus thermophilus HB8

    SciTech Connect

    Bagautdinov, Bagautdin Ukita, Yoko; Miyano, Masashi; Kunishima, Naoki

    2008-05-01

    The crystal structure of 3-oxoacyl-(acyl-carrier protein) synthase II from T. thermophilus HB8 has been determined at 2.0 Å resolution and compared with the structures of β-keto-ACP synthases from other sources. The β-ketoacyl-(acyl carrier protein) synthases (β-keto-ACP synthases; KAS) catalyse the addition of two-carbon units to the growing acyl chain during the elongation phase of fatty-acid synthesis. As key regulators of bacterial fatty-acid synthesis, they are promising targets for the development of new antibacterial agents. The crystal structure of 3-oxoacyl-ACP synthase II from Thermus thermophilus HB8 (TtKAS II) has been solved by molecular replacement and refined at 2.0 Å resolution. The crystal is orthorhombic, space group P2{sub 1}2{sub 1}2, with unit-cell parameters a = 72.07, b = 185.57, c = 62.52 Å, and contains one homodimer in the asymmetric unit. The subunits adopt the well known α-β-α-β-α thiolase fold that is common to ACP synthases. The structural and sequence similarities of TtKAS II to KAS I and KAS II enzymes of known structure from other sources support the hypothesis of comparable enzymatic activity. The dimeric state of TtKAS II is important to create each fatty-acid-binding pocket. Closer examination of KAS structures reveals that compared with other KAS structures in the apo form, the active site of TtKAS II is more accessible because of the ‘open’ conformation of the Phe396 side chain.

  11. Palladium-Catalyzed Environmentally Benign Acylation.

    PubMed

    Suchand, Basuli; Satyanarayana, Gedu

    2016-08-01

    Recent trends in research have gained an orientation toward developing efficient strategies using innocuous reagents. The earlier reported transition-metal-catalyzed carbonylations involved either toxic carbon monoxide (CO) gas as carbonylating agent or functional-group-assisted ortho sp(2) C-H activation (i.e., ortho acylation) or carbonylation by activation of the carbonyl group (i.e., via the formation of enamines). Contradicting these methods, here we describe an environmentally benign process, [Pd]-catalyzed direct carbonylation starting from simple and commercially available iodo arenes and aldehydes, for the synthesis of a wide variety of ketones. Moreover, this method comprises direct coupling of iodoarenes with aldehydes without activation of the carbonyl and also without directing group assistance. Significantly, the strategy was successfully applied to the synthesis n-butylphthalide and pitofenone. PMID:27377566

  12. Fusion Peptide from Influenza Hemagglutinin Increases Membrane Surface Order: An Electron-Spin Resonance Study

    PubMed Central

    Ge, Mingtao; Freed, Jack H.

    2009-01-01

    Abstract A spin-labeling study of interactions of a fusion peptide from the hemagglutinin of the influenza virus, wt20, and a fusion-inactive mutant ΔG1 with dimyristoylphosphatidylcholine (DMPC) and 1-palmitoyl-2-oleoyl-phosphatdylcholine bilayers was performed. We found that upon binding of wt20, the ordering of headgroups and the ordering of acyl chains near the headgroup increased significantly, in a manner consistent with a cooperative phenomenon. However, changes in the order at the end of the acyl chains were negligible. The ordering effect of wt20 on the headgroup was much stronger at pH 5 than at pH 7. No effect of ΔG1 binding on the order of bilayers was evident. We also found that 1-palmitoyl-2-hydroxyl phosphatidylcholine, a membrane-fusion inhibitor, decreased the ordering of DMPC headgroups, whereas arachidonic acid, a membrane-fusion promoter, increased the ordering of DMPC headgroups. These results suggest that increases in headgroup ordering may be important for membrane fusion. We propose that upon binding of wt20, which is known to affect only the outer leaflet of the bilayer, this outer leaflet becomes more ordered, and thus more solid-like. Then the coupling between the hardened outer leaflet and the softer inner leaflet generates bending stresses in the bilayer, which tend to increase the negative curvature of the bilayer. We suggest that the increased ordering in the headgroup region enhances dipolar interactions and lowers electrostatic energy, which may provide an energy source for membrane fusion. Possible roles of bending stresses in promoting membrane fusion are discussed. PMID:19527651

  13. Magnetic ordering in the frustrated J1 - J2 Ising chain candidate BaNd2O4

    SciTech Connect

    Aczel, Adam A.; Li, Ling; Garlea, Vasile O.; Yan, Jiaqiang; Weickert, Franziska; Jaime, M.; Maiorov, B.; Movshovich, R.; Civale, L.; Keppens, V.; Mandrus, D.

    2014-10-06

    The AR2O4 family (R = rare earth) has recently been attracting interest as a new series of frustrated magnets, with the magnetic R atoms forming zigzag chains running along the c axis. In this paper, we have investigated polycrystalline BaNd2O4 with a combination of magnetization, heat-capacity, and neutron powder diffraction measurements. Magnetic Bragg peaks are observed below TN = 1.7 K, and they can be indexed with a propagation vector of k = (0,1/2,1/2). The signal from magnetic diffraction is well described by long-range ordering of only one of the two types of Nd zigzag chains, with collinear up-up-down-down intrachain spin configurations (double Néel state). Furthermore, low-temperature magnetization and heat-capacity measurements reveal two magnetic-field-induced spin transitions at 2.75 and 4 T for T = 0.46 K. The high-field phase is paramagnetic, while the intermediate-field state may arise from a spin transition of the long-range ordered Nd chains. Finally, one possible candidate for the field-induced ordered state corresponds to an up-up-down intrachain spin configuration, as predicted for a classical J1-J2 Ising chain with a double Néel ground state in zero field.

  14. Recognition of acyl carrier proteins by ketoreductases in assembly line polyketide synthases.

    PubMed

    Ostrowski, Matthew P; Cane, David E; Khosla, Chaitan

    2016-07-01

    Ketoreductases (KRs) are the most widespread tailoring domains found in individual modules of assembly line polyketide synthases (PKSs), and are responsible for controlling the configurations of both the α-methyl and β-hydroxyl stereogenic centers in the growing polyketide chain. Because they recognize substrates that are covalently bound to acyl carrier proteins (ACPs) within the same PKS module, we sought to quantify the extent to which protein-protein recognition contributes to the turnover of these oxidoreductive enzymes using stand-alone domains from the 6-deoxyerythronolide B synthase (DEBS). Reduced 2-methyl-3-hydroxyacyl-ACP substrates derived from two enantiomeric acyl chains and four distinct ACP domains were synthesized and presented to four distinct KR domains. Two KRs, from DEBS modules 2 and 5, displayed little preference for oxidation of substrates tethered to their cognate ACP domains over those attached to the other ACP domains tested. In contrast, the KR from DEBS module 1 showed an ~10-50-fold preference for substrate attached to its native ACP domain, whereas the KR from DEBS module 6 actually displayed an ~10-fold preference for the ACP from DEBS module 5. Our findings suggest that recognition of the ACP by a KR domain is unlikely to affect the rate of native assembly line polyketide biosynthesis. In some cases, however, unfavorable KR-ACP interactions may suppress the rate of substrate processing when KR domains are swapped to construct hybrid PKS modules. PMID:27118242

  15. Structure of 3-oxoacyl-(acyl-carrier protein) synthase II from Thermus thermophilus HB8

    PubMed Central

    Bagautdinov, Bagautdin; Ukita, Yoko; Miyano, Masashi; Kunishima, Naoki

    2008-01-01

    The β-ketoacyl-(acyl carrier protein) synthases (β-keto-ACP synthases; KAS) catalyse the addition of two-carbon units to the growing acyl chain during the elongation phase of fatty-acid synthesis. As key regulators of bacterial fatty-acid synthesis, they are promising targets for the development of new antibacterial agents. The crystal structure of 3-oxoacyl-ACP synthase II from Thermus thermophilus HB8 (TtKAS II) has been solved by molecular replacement and refined at 2.0 Å resolution. The crystal is orthorhombic, space group P21212, with unit-cell parameters a = 72.07, b = 185.57, c = 62.52 Å, and contains one homodimer in the asymmetric unit. The subunits adopt the well known α-β-α-β-α thiolase fold that is common to ACP synthases. The structural and sequence similarities of TtKAS II to KAS I and KAS II enzymes of known structure from other sources support the hypothesis of comparable enzymatic activity. The dimeric state of TtKAS II is important to create each fatty-acid-binding pocket. Closer examination of KAS structures reveals that compared with other KAS structures in the apo form, the active site of TtKAS II is more accessible because of the ‘open’ conformation of the Phe396 side chain. PMID:18453702

  16. Structure of 3-oxoacyl-(acyl-carrier protein) synthase II from Thermus thermophilus HB8.

    PubMed

    Bagautdinov, Bagautdin; Ukita, Yoko; Miyano, Masashi; Kunishima, Naoki

    2008-05-01

    The beta-ketoacyl-(acyl carrier protein) synthases (beta-keto-ACP synthases; KAS) catalyse the addition of two-carbon units to the growing acyl chain during the elongation phase of fatty-acid synthesis. As key regulators of bacterial fatty-acid synthesis, they are promising targets for the development of new antibacterial agents. The crystal structure of 3-oxoacyl-ACP synthase II from Thermus thermophilus HB8 (TtKAS II) has been solved by molecular replacement and refined at 2.0 A resolution. The crystal is orthorhombic, space group P2(1)2(1)2, with unit-cell parameters a = 72.07, b = 185.57, c = 62.52 A, and contains one homodimer in the asymmetric unit. The subunits adopt the well known alpha-beta-alpha-beta-alpha thiolase fold that is common to ACP synthases. The structural and sequence similarities of TtKAS II to KAS I and KAS II enzymes of known structure from other sources support the hypothesis of comparable enzymatic activity. The dimeric state of TtKAS II is important to create each fatty-acid-binding pocket. Closer examination of KAS structures reveals that compared with other KAS structures in the apo form, the active site of TtKAS II is more accessible because of the ;open' conformation of the Phe396 side chain. PMID:18453702

  17. Direct Acylation of Carrier Proteins with Functionalized β-Lactones

    PubMed Central

    Amoroso, Jon W.; Borketey, Lawrence S.; Prasad, Gitanjeli

    2014-01-01

    As the key component of many biosynthetic assemblies, acyl-carrier proteins offer a robust entry point for introduction of small molecule probes and pathway intermediates. Current labeling strategies primarily rely on modifications to the phosphopantetheine cofactor or its biosynthetic precursors followed by attachment to the apo form of a given carrier protein. As a greatly simplified alternative, direct and selective acylation of holo-acyl-carrier proteins using readily accessible β-lactones as electrophilic partners for the phosphopantetheine-thiol has been demonstrated. PMID:20433156

  18. Role of acyl carrier protein isoforms in plant lipid metabolism

    SciTech Connect

    Not Available

    1990-01-01

    Although acyl carrier protein (ACP) is the best studied protein in plant fatty acid biosynthesis, the in vivo forms of ACPs and their steady state pools have not been examined previously in either seed or leaf. Information about the relative pool sizes of free ACP and its acyl-ACP intermediates is essential for understanding regulation of de novo fatty acid biosynthesis in plants. In this study we utilized antibodies directed against spinach ACP as a sensitive assay to analyze the acyl groups while they were still covalently attached to ACPs. 4 refs., 4 figs.

  19. First- and Second-Order Phase Transitions between the Uniform and FFLO Excitonic States in the Three-Chain Hubbard Model for Ta2NiSe5

    NASA Astrophysics Data System (ADS)

    Domon, Kaoru; Yamada, Takemi; Ōno, Yoshiaki

    2016-06-01

    We examine the free energy and the thermodynamic properties in the three-chain Hubbard model for Ta2NiSe5 to clarify the phase transitions between the uniform and the FFLO excitonic states which are expected to be observed in Ta2NiSe5 under high pressure.

  20. Probing the Mechanism of the Mycobacterium tuberculosis [beta]-Ketoacyl-Acyl Carrier Protein Synthase III mtFabH: Factors Influencing Catalysis and Substrate Specificity

    SciTech Connect

    Brown, Alistair K.; Sridharan, Sudharsan; Kremer, Laurent; Lindenberg, Sandra; Dover, Lynn G.; Sacchettini, James C.; Besra, Gurdyal S.

    2010-11-30

    Mycolic acids are the dominant feature of the Mycobacterium tuberculosis cell wall. These {alpha}-alkyl, {beta}-hydroxy fatty acids are formed by the condensation of two fatty acids, a long meromycolic acid and a shorter C{sub 24}-C{sub 26} fatty acid. The component fatty acids are produced via a combination of type I and II fatty acid synthases (FAS) with FAS-I products being elongated by FAS-II toward meromycolic acids. The {beta}-ketoacyl-acyl carrier protein (ACP) synthase III encoded by mtfabH (mtFabH) links FAS-I and FAS-II, catalyzing the condensation of FAS-I-derived acyl-CoAs with malonyl-acyl carrier protein (ACP). The acyl-CoA chain length specificity of mtFabH was assessed in vitro; the enzyme extended longer, physiologically relevant acyl-CoA primers when paired with AcpM, its natural partner, than with Escherichia coli ACP. The ability of the enzyme to use E. coli ACP suggests that a similar mode of binding is likely with both ACPs, yet it is clear that unique factors inherent to AcpM modulate the substrate specificity of mtFabH. Mutation of proposed key mtFabH residues was used to define their catalytic roles. Substitution of supposed acyl-CoA binding residues reduced transacylation, with double substitutions totally abrogating activity. Mutation of Arg{sup 46} revealed its more critical role in malonyl-AcpM decarboxylation than in the acyl-CoA binding role. Interestingly, this effect was suppressed intragenically by Arg{sup 161} {yields} Ala substitution. Our structural studies suggested that His{sup 258}, previously implicated in malonyl-ACP decarboxylation, also acts as an anchor point for a network of water molecules that we propose promotes deprotonation and transacylation of Cys{sup 122}.

  1. Anti-Tumor Effects of Novel 5-O-Acyl Plumbagins Based on the Inhibition of Mammalian DNA Replicative Polymerase Activity

    PubMed Central

    Kawamura, Moe; Kuriyama, Isoko; Maruo, Sayako; Kuramochi, Kouji; Tsubaki, Kazunori; Yoshida, Hiromi; Mizushina, Yoshiyuki

    2014-01-01

    We previously found that vitamin K3 (menadione, 2-methyl-1,4-naphthoquinone) inhibits the activity of human mitochondrial DNA polymerase γ (pol γ). In this study, we focused on plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone), and chemically synthesized novel plumbagins conjugated with C2:0 to C22:6 fatty acids (5-O-acyl plumbagins). These chemically modified plumbagins enhanced mammalian pol inhibition and their cytotoxic activity. Plumbagin conjugated with chains consisting of more than C18-unsaturated fatty acids strongly inhibited the activities of calf pol α and human pol γ. Plumbagin conjugated with oleic acid (C18:1-acyl plumbagin) showed the strongest suppression of human colon carcinoma (HCT116) cell proliferation among the ten synthesized 5-O-acyl plumbagins. The inhibitory activity on pol α, a DNA replicative pol, by these compounds showed high correlation with their cancer cell proliferation suppressive activity. C18:1-Acyl plumbagin selectively inhibited the activities of mammalian pol species, but did not influence the activities of other pols and DNA metabolic enzymes tested. This compound inhibited the proliferation of various human cancer cell lines, and was the cytotoxic inhibitor showing strongest inhibition towards HT-29 colon cancer cells (LD50 = 2.9 µM) among the nine cell lines tested. In an in vivo anti-tumor assay conducted on nude mice bearing solid tumors of HT-29 cells, C18:1-acyl plumbagin was shown to be a promising tumor suppressor. These data indicate that novel 5-O-acyl plumbagins act as anti-cancer agents based on mammalian DNA replicative pol α inhibition. Moreover, the results suggest that acylation of plumbagin is an effective chemical modification to improve the anti-cancer activity of vitamin K3 derivatives, such as plumbagin. PMID:24520419

  2. Characterization and cloning of a stearoyl/oleoyl specific fatty acyl-acyl carrier protein thioesterase from the seeds of Madhuca longifolia (latifolia).

    PubMed

    Ghosh, Santosh K; Bhattacharjee, Ashish; Jha, Jyoti K; Mondal, Ashis K; Maiti, Mrinal K; Basu, Asitava; Ghosh, Dolly; Ghosh, Sudhamoy; Sen, Soumitra K

    2007-12-01

    Deposition of oleate, stearate and palmitate at the later stages of seed development in Mahua (Madhuca longifolia (latifolia)), a tropical non-conventional oil seed plant, has been found to be the characteristic feature of the regulatory mechanism that produces the saturated fatty acid rich Mahua seed fat (commonly known as Mowrah fat). Although, the content of palmitate has been observed to be higher than that of stearate at the initial stages of seed development, it goes down when the stearate and oleate contents consistently rise till maturity. The present study was undertaken in order to identify the kind of acyl-ACP thioesterase(s) that drives the characteristic composition of signature fatty acids (oleate 37%, palmitate 25%, stearate 23%, linoleate 12.5%) in its seed oil at maturity. The relative Fat activities in the crude protein extracts of the matured seeds towards three thioester substrates (oleoyl-, stearoyl- and palmitoyl-ACP) have been found to be present in the following respective ratio 100:31:8. Upon further purification of the crude extract, the search revealed the presence of two partially purified thioesterases: a long-chain oleoyl preferring house-keeping LC-Fat and a novel stearoyl-oleoyl preferring SO-Fat. The characteristic accumulation of oleate and linoleate in the M. latifolia seed fat is believed to be primarily due to the thioesterase activity of the LC-Fat or MlFatA. On the other hand, the SO-Fat showed almost equal substrate specificity towards stearoyl- and oleoyl-ACP, when its activity towards palmitoyl-ACP compared to stearoyl-ACP was only about 12%. An RT-PCR based technique for cloning of a DNA fragment from the mRNA pool of the developing seed followed by nucleotide sequencing resulted in the identification of a FatB type of thioesterase gene (MlFatB). This gene was found to exist as a single copy in the mother plant genome. Ectopic expression of this MlFatB gene product in E. coli strain fadD88 further proved that it induced a

  3. Structure of YciA from Haemophilus influenzae (HI0827), a Hexameric Broad Specificity Acyl-Coenzyme A Thioesterase

    SciTech Connect

    Willis, Mark A.; Zhuang, Zhihao; Song, Feng; Howard, Andrew; Dunaway-Mariano, Debra; Herzberg, Osnat

    2008-04-02

    The crystal structure of HI0827 from Haemophilus influenzae Rd KW20, initially annotated 'hypothetical protein' in sequence databases, exhibits an acyl-coenzyme A (acyl-CoA) thioesterase 'hot dog' fold with a trimer of dimers oligomeric association, a novel assembly for this enzyme family. In studies described in the preceding paper [Zhuang, Z., Song, F., Zhao, H., Li, L., Cao, J., Eisenstein, E., Herzberg, O., and Dunaway-Mariano, D. (2008) Biochemistry 47, 2789-2796], HI0827 is shown to be an acyl-CoA thioesterase that acts on a wide range of acyl-CoA compounds. Two substrate binding sites are located across the dimer interface. The binding sites are occupied by two CoA molecules, one with full occupancy and the second only partially occupied. The CoA molecules, acquired from HI0827-expressing Escherichia coli cells, remained tightly bound to the enzyme through the protein purification steps. The difference in CoA occupancies indicates a different substrate affinity for each of the binding sites, which in turn implies that the enzyme might be subject to allosteric regulation. Mutagenesis studies have shown that the replacement of the putative catalytic carboxylate Asp44 with an alanine residue abolishes activity. The impact of this mutation is seen in the crystal structure of D44A HI0827. Whereas the overall fold and assembly of the mutant protein are the same as those of the wild-type enzyme, the CoA ligands are absent. The dimer interface is perturbed, and the channel that accommodates the thioester acyl chain is more open and wider than that observed in the wild-type enzyme. A model of intact substrate bound to wild-type HI0827 provides a structural rationale for the broad substrate range.

  4. Immunomodulatory N-acyl Dopamine Glycosides from the Icelandic Marine Sponge Myxilla incrustans Collected at a Hydrothermal Vent Site.

    PubMed

    Einarsdottir, Eydis; Liu, Hong-Bing; Freysdottir, Jona; Gotfredsen, Charlotte Held; Omarsdottir, Sesselja

    2016-06-01

    A chemical investigation of the sponge (Porifera) Myxilla incrustans collected from the unique submarine hydrothermal vent site Strytan, North of Iceland, revealed a novel family of closely related N-acyl dopamine glycosides. Three new compounds, myxillin A (1), B (2) and C (3), were isolated and structurally elucidated using several analytical techniques, such as HR-MS, 1D and 2D NMR spectroscopy. Myxillin A (1) and B (2)were shown to be structurally similar, composed of a dopamine moiety, but differ in the acyl chain length and saturation. The myxillin C (3) has a dehydrotyrosine moiety composing the same acyl chain and glycosylation as myxillin B (2). Myxillins A (1) and C (3) were tested for immunomodulating activity in an in vitro dendritic cell model. Dendritic cells matured and stimulated in the presence of myxillin A (1) secreted lower levels of IL-12p40, whilst dendritic cells matured and stimulated in the presence of myxillin C (3) secreted lower levels of IL-10 compared with dendritic cells matured and stimulated in the presence of the solvent alone. These opposing results indicate that the structural differences in the aromatic ring part of the molecules could have an impact on the immunological effects of dendritic cells. These molecules could, therefore, prove to be important in preventing inflammatory diseases on the one hand, and inducing a response to fight tumors and/or pathogens on the other hand. Further studies will be needed to confirm these potential uses. PMID:27135626

  5. The halo-substituent effect on Pseudomonas cepacia lipase-mediated regioselective acylation of nucleosides: A comparative investigation.

    PubMed

    Wang, Zhao-Yu; Bi, Yan-Hong; Yang, Rong-Ling; Duan, Zhang-Qun; Nie, Ling-Hong; Li, Xiang-Qian; Zong, Min-Hua; Wu, Jie

    2015-10-20

    In this work, comparative experiments were explored to investigate the substrate specificity of Pseudomonas cepacia lipase in regioselective acylation of nucleosides carrying various substituents (such as the H, F, Cl, Br, I) at 2'- and 5-positions. Experimental data indicated that the catalytic performance of the enzyme depended very much on the halo-substituents in nucleosides. The increased bulk of 2'-substituents in ribose moiety of the nucleoside might contribute to the improved 3'-regioselectivity (90-98%, nucleosides a-d) in enzymatic decanoylation, while the enhancement of regioselectivity (93-99%) in 3'-O-acylated nucleosides e-h could be attributable to the increasing hydrophobicity of the halogen atoms at 5-positions. With regard to the chain-length selectivity, P. cepacia lipase displayed the highest 3'-regioselectivity toward the longer chain (C14) as compared to shorter (C6 and C10) ones. The position, orientation and property of the substituent, specific structure of the lipase's active site, and acyl structure could account for the diverse results. PMID:26325198

  6. A carbon-13 nuclear magnetic resonance spectroscopic study of inter-proton pair order parameters: a new approach to study order and dynamics in phospholipid membrane systems.

    PubMed

    Urbina, J A; Moreno, B; Arnold, W; Taron, C H; Orlean, P; Oldfield, E

    1998-09-01

    We report a simple new nuclear magnetic resonance (NMR) spectroscopic method to investigate order and dynamics in phospholipids in which inter-proton pair order parameters are derived by using high resolution 13C cross-polarization/magic angle spinning (CP/MAS) NMR combined with 1H dipolar echo preparation. The resulting two-dimensional NMR spectra permit determination of the motionally averaged interpair second moment for protons attached to each resolved 13C site, from which the corresponding interpair order parameters can be deducted. A spin-lock mixing pulse before cross-polarization enables the detection of spin diffusion amongst the different regions of the lipid molecules. The method was applied to a variety of model membrane systems, including 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)/sterol and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/sterol model membranes. The results agree well with previous studies using specifically deuterium labeled or predeuterated phospholipid molecules. It was also found that efficient spin diffusion takes place within the phospholipid acyl chains, and between the glycerol backbone and choline headgroup of these molecules. The experiment was also applied to biosynthetically 13C-labeled ergosterol incorporated into phosphatidylcholine bilayers. These results indicate highly restricted motions of both the sterol nucleus and the aliphatic side chain, and efficient spin exchange between these structurally dissimilar regions of the sterol molecule. Finally, studies were carried out in the lamellar liquid crystalline (L alpha) and inverted hexagonal (HII) phases of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE). These results indicated that phosphatidylethanolamine lamellar phases are more ordered than the equivalent phases of phosphatidylcholines. In the HII (inverted hexagonal) phase, despite the increased translational freedom, there is highly constrained packing of the lipid molecules, particularly in

  7. Enhanced free fatty acid production by codon-optimized Lactococcus lactis acyl-ACP thioesterase gene expression in Escherichia coli using crude glycerol.

    PubMed

    Lee, Sunhee; Park, Soohyun; Park, Chulhwan; Pack, Seung Pil; Lee, Jinwon

    2014-12-01

    Fatty acid production and composition are determined by the type of acyl-acyl carrier protein thioesterases (acyl-ACP TEs) expressed in Escherichia coli. Bacterial acyl-ACP TEs from Lactococcus lactis (SGJS47), Enterococcus faecalis (SGJS49), and Burkholderia cepacia (SGJS50) were codon-optimized and expressed in E. coli for enhanced fatty acid production. Samples were extracted at the lag, log, and stationary phases of cell growth, and gene expression levels of the codon optimized acy-ACP TEs as well as fatty acid production were monitored. At 24h after initiation of gene expression, the OPLlTE expression level and fatty acid production in SGJS47 increased up to 15.8-fold and 3.2-fold compared to the control and other recombinant strains, respectively. Additionally, in SGJS47, improvement in free fatty acid (FFA) composition, high-specificity production of short-chain fatty acids (C8, C10) and unsaturated fatty acids (C16:1) was achieved in crude glycerol medium condition. Compared with control strain, the percentage of FFAs (C8 and C10) was enhanced by approximately 16- to 21-fold, C16:1 FFA ratio increased approximately 18-fold. Observation of codon-optimized acyl-ACP TE genes expression level in E. coli may be useful for understanding mechanisms towards improving fatty acid production. Engineered strains have the potential to overproduce specific FFAs and thereby reduce the cost of fatty acid production by using industrially inexpensive carbon sources. PMID:25442943

  8. Chemoselective O-acylation of hydroxyamino acids and amino alcohols under acidic reaction conditions: History, scope and applications.

    PubMed

    Kristensen, Tor E

    2015-01-01

    Amino acids, whether natural, semisynthetic or synthetic, are among the most important and useful chiral building blocks available for organic chemical synthesis. In principle, they can function as inexpensive, chiral and densely functionalized starting materials. On the other hand, the use of amino acid starting materials routinely necessitates protective group chemistry, and in reality, large-scale preparations of even the simplest side-chain derivatives of many amino acids often become annoyingly strenuous due to the necessity of employing protecting groups, on one or more of the amino acid functionalities, during the synthetic sequence. However, in the case of hydroxyamino acids such as hydroxyproline, serine, threonine, tyrosine and 3,4-dihydroxyphenylalanine (DOPA), many O-acyl side-chain derivatives are directly accessible via a particularly expedient and scalable method not commonly applied until recently. Direct acylation of unprotected hydroxyamino acids with acyl halides or carboxylic anhydrides under appropriately acidic reaction conditions renders possible chemoselective O-acylation, furnishing the corresponding side-chain esters directly, on multigram-scale, in a single step, and without chromatographic purification. Assuming a certain degree of stability under acidic reaction conditions, the method is also applicable for a number of related compounds, such as various amino alcohols and the thiol-functional amino acid cysteine. While the basic methodology underlying this approach has been known for decades, it has evolved through recent developments connected to amino acid-derived chiral organocatalysts to become a more widely recognized procedure for large-scale preparation of many useful side-chain derivatives of hydroxyamino acids and related compounds. Such derivatives are useful in peptide chemistry and drug development, as amino acid amphiphiles for asymmetric catalysis, and as amino acid acrylic precursors for preparation of catalytically

  9. Chemoselective O-acylation of hydroxyamino acids and amino alcohols under acidic reaction conditions: History, scope and applications

    PubMed Central

    2015-01-01

    Summary Amino acids, whether natural, semisynthetic or synthetic, are among the most important and useful chiral building blocks available for organic chemical synthesis. In principle, they can function as inexpensive, chiral and densely functionalized starting materials. On the other hand, the use of amino acid starting materials routinely necessitates protective group chemistry, and in reality, large-scale preparations of even the simplest side-chain derivatives of many amino acids often become annoyingly strenuous due to the necessity of employing protecting groups, on one or more of the amino acid functionalities, during the synthetic sequence. However, in the case of hydroxyamino acids such as hydroxyproline, serine, threonine, tyrosine and 3,4-dihydroxyphenylalanine (DOPA), many O-acyl side-chain derivatives are directly accessible via a particularly expedient and scalable method not commonly applied until recently. Direct acylation of unprotected hydroxyamino acids with acyl halides or carboxylic anhydrides under appropriately acidic reaction conditions renders possible chemoselective O-acylation, furnishing the corresponding side-chain esters directly, on multigram-scale, in a single step, and without chromatographic purification. Assuming a certain degree of stability under acidic reaction conditions, the method is also applicable for a number of related compounds, such as various amino alcohols and the thiol-functional amino acid cysteine. While the basic methodology underlying this approach has been known for decades, it has evolved through recent developments connected to amino acid-derived chiral organocatalysts to become a more widely recognized procedure for large-scale preparation of many useful side-chain derivatives of hydroxyamino acids and related compounds. Such derivatives are useful in peptide chemistry and drug development, as amino acid amphiphiles for asymmetric catalysis, and as amino acid acrylic precursors for preparation of

  10. Carbapenems and SHV-1 β-Lactamase Form Different Acyl-Enzyme Populations in Crystals and Solution

    PubMed Central

    Kalp, Matthew; Carey, Paul R.

    2009-01-01

    The reactions between single crystals of the SHV-1 β-lactamase enzyme and the carbapenems, meropenem, imipenem and ertapenem, have been studied by Raman microscopy. Aided by quantum mechanical calculations, major populations of two acyl-enzyme species, a labile Δ2-pyrroline and a more tightly bound Δ1-pyrroline, have been identified for all three compounds. These isomers differ only in the position of the double bond about the carbapenem nucleus. This discovery is consonant with X-ray crystallographic findings that also identified two populations for meropenem bound in SHV-1: one with the acyl C=O group in the oxyanion hole and the second with the acyl group rotated 180 degrees compared to its expected position [Nukaga, M., Bethel, C. R., Thomson, J. M., Hujer, A. M., Distler, A. M., Anderson, V. E., Knox, J. R., and Bonomo, R. A. (2008) Journal of the American Chemical Society]. When crystals of the Δ1 and Δ2 containing acyl-enzymes were exposed to solutions with no carbapenem, rapid deacylation of the Δ2 species was observed by kinetic Raman experiments. However, no change in the Δ1 population was observed over 1 hour, the effective lifetime of the crystal. These observations lead to the hypothesis that the stable Δ1 species is due to the form seen by X-ray with the acyl carbonyl outside the oxyanion hole, while the Δ2 species corresponds to the form with the carbonyl inside the oxyanion hole. Soak-in and soak-out Raman experiments also demonstrated that tautomeric exchange between the Δ1 and Δ2 forms does not occur on the crystalline enzyme. When meropenem or ertapenem were reacted with SHV-1 in solution, the Raman difference spectra demonstrated that only a major population corresponding to the Δ1 acyl-enzyme could be detected. The 1003 cm-1 mode of the phenyl ring positioned on the C3 side chain of ertapenem acts as an effective internal Raman intensity standard and the ratio of its intensity to that of the 1600 cm-1 feature of Δ1 provides an

  11. LC-quadrupole/Orbitrap high-resolution mass spectrometry enables stable isotope-resolved simultaneous quantification and ¹³C-isotopic labeling of acyl-coenzyme A thioesters.

    PubMed

    Frey, Alexander J; Feldman, Daniel R; Trefely, Sophie; Worth, Andrew J; Basu, Sankha S; Snyder, Nathaniel W

    2016-05-01

    Acyl-coenzyme A (acyl-CoA) thioesters are evolutionarily conserved, compartmentalized, and energetically activated substrates for biochemical reactions. The ubiquitous involvement of acyl-CoA thioesters in metabolism, including the tricarboxylic acid cycle, fatty acid metabolism, amino acid degradation, and cholesterol metabolism highlights the broad applicability of applied measurements of acyl-CoA thioesters. However, quantitation of acyl-CoA levels provides only one dimension of metabolic information and a more complete description of metabolism requires the relative contribution of different precursors to individual substrates and pathways. Using two distinct stable isotope labeling approaches, acyl-CoA thioesters can be labeled with either a fixed [(13)C3(15)N1] label derived from pantothenate into the CoA moiety or via variable [(13)C] labeling into the acyl chain from metabolic precursors. Liquid chromatography-hybrid quadrupole/Orbitrap high-resolution mass spectrometry using parallel reaction monitoring, but not single ion monitoring, allowed the simultaneous quantitation of acyl-CoA thioesters by stable isotope dilution using the [(13)C3(15)N1] label and measurement of the incorporation of labeled carbon atoms derived from [(13)C6]-glucose, [(13)C5(15)N2]-glutamine, and [(13)C3]-propionate. As a proof of principle, we applied this method to human B cell lymphoma (WSU-DLCL2) cells in culture to precisely describe the relative pool size and enrichment of isotopic tracers into acetyl-, succinyl-, and propionyl-CoA. This method will allow highly precise, multiplexed, and stable isotope-resolved determination of metabolism to refine metabolic models, characterize novel metabolism, and test modulators of metabolic pathways involving acyl-CoA thioesters. PMID:26968563

  12. Sonochemical enzyme-catalyzed regioselective acylation of flavonoid glycosides.

    PubMed

    Ziaullah; Rupasinghe, H P Vasantha

    2016-04-01

    This work compares a highly efficient and alternative method of sonication-assisted lipase catalyzed acylation of quercetin-3-O-glucoside and phloretin-2'-glucoside, using Candida antarctica lipase B (Novozyme 435(®)), with a range of fatty acids. In this study, sonication-assisted irradiation coupled with stirring has been found to be more efficient and economical than conventional reaction conditions. Sonication-assisted acylation accelerated the reactions and reduced the time required by 4-5 folds. PMID:26829593

  13. Trichome-derived O-acyl sugars are a first meal for caterpillars that tags them for predation

    PubMed Central

    Weinhold, Alexander; Baldwin, Ian Thomas

    2011-01-01

    Plant glandular trichomes exude secondary metabolites with defensive functions, but these epidermal protuberances are surprisingly the first meal of Lepidopteran herbivores on Nicotiana attenuata. O-acyl sugars, the most abundant metabolite of glandular trichomes, impart a distinct volatile profile to the body and frass of larvae that feed on them. The headspace composition of Manduca sexta larvae is dominated by the branched chain aliphatic acids hydrolyzed from ingested O-acyl sugars, which waxes and wanes rapidly with trichome ingestion. In native habitats a ground-hunting predator, the omnivorous ant Pogonomyrmex rugosus, but not the big-eyed bug Geocoris spp., use these volatile aliphatic acids to locate their prey. PMID:21518882

  14. Primary structure of a cerulenin-binding. beta. -ketoacyl-(acyl carrier protein) synthase from barley chloroplasts

    SciTech Connect

    Siggaard-Andersen, M.; Kauppinen, S. ); von Wettstein-Knowles, P. Univ. of Copenhagen )

    1991-05-15

    The radioactively labeled {beta}-ketoacyl thioester synthase inhibitor ({sup 3}H)cerulenin was used to tag three dimeric barley chloroplast proteins ({alpha}{alpha}, {alpha}{beta}, and {beta}{beta}) from the stromal fraction. Oligonucleotides corresponding to amino acid sequences obtained from the purified proteins were used to generate with the polymerase chain reaction a probe for cDNAs encoding the {beta} subunit. cDNA sequencing revealed an open reading frame for 462 residues comprising the mature protein and a 35-amino acid transit peptide. The deduced amino acid sequence of the mature protein is homologous to the {beta}-ketoacyl-(acyl carrier protein) (ACP) synthase I (3-oxoacyl-ACP synthase; acyl-ACP:malonyl-ACP C-acyltransferase (decarboxylating), EC 2.3.1.41) of Escherichia coli. Under analogous experimental conditions ({sup 3}H)cerulenin tagged a single dimeric protein from spinach chloroplasts.

  15. Trichome-derived O-acyl sugars are a first meal for caterpillars that tags them for predation.

    PubMed

    Weinhold, Alexander; Baldwin, Ian Thomas

    2011-05-10

    Plant glandular trichomes exude secondary metabolites with defensive functions, but these epidermal protuberances are surprisingly the first meal of Lepidopteran herbivores on Nicotiana attenuata. O-acyl sugars, the most abundant metabolite of glandular trichomes, impart a distinct volatile profile to the body and frass of larvae that feed on them. The headspace composition of Manduca sexta larvae is dominated by the branched chain aliphatic acids hydrolyzed from ingested O-acyl sugars, which waxes and wanes rapidly with trichome ingestion. In native habitats a ground-hunting predator, the omnivorous ant Pogonomyrmex rugosus, but not the big-eyed bug Geocoris spp., use these volatile aliphatic acids to locate their prey. PMID:21518882

  16. Branched Chain Amino Acid Metabolism in the Biosynthesis of Lycopersicon pennellii Glucose Esters 1

    PubMed Central

    Walters, Donald S.; Steffens, John C.

    1990-01-01

    Lycopersicon pennellii Corr. (D'Arcy) an insect-resistant, wild tomato possesses high densities of glandular trichomes which exude a mixture of 2,3,4-tri-O-acylated glucose esters that function as a physical impediment and feeding deterrent to small arthropod pests. The acyl moieties are branched C4 and C5 acids, and branched and straight chain C10, C11, and C12 acids. The structure of the branched acyl constituents suggests that the branched chain amino acid biosynthetic pathway participates in their biosynthesis. [14C]Valine and deuterated branched chain amino acids (and their oxo-acid derivatives) were incorporated into branched C4 and C5 acid groups of glucose esters by a process of transamination, oxidative decarboxylation and subsequent acylation. C4 and C5 branched acids were elongated by two carbon units to produce the branched C10-C12 groups. Norvaline, norleucine, allylglycine, and methionine also were processed into acyl moieties and secreted from the trichomes as glucose esters. Changes in the acyl composition of the glucose esters following sulfonylurea herbicide administration support the participation of acetohydroxyacid synthetase and the other enzymes of branched amino acid biosynthesis in the production of glucose esters. PMID:16667654

  17. Order and dynamics in mixtures of membrane glucolipids from Acholeplasma laidlawii studied by sup 2 H NMR

    SciTech Connect

    Eriksson, P.O.; Rilfors, L.; Lundberg, A.; Lindblom, G.; Wieslander, A. )

    1991-05-21

    The two dominant glucolipids in Acholeplasma laidlawii, viz., 1,2-diacyl-3-O-({alpha}-D-glucopyranosyl)-sn-glycerol (MGlcDG) and 1,2-diacyl-3-O-({alpha}-D-glucopyranosyl-(1{yields}2)-O-{alpha}-D-glucopyranosyl)-sn-glycerol (DGlcDG), have markedly different phase behavior. MGlcDG has an ability to form nonlamellar phases, whereas DGlcDG only forms lamellar phases. For maintenance of a stable lipid bilayer, the polar headgroup composition in A. laidlawii is metabolically regulated in vivo, in response to changes in the growth conditions. To investigate the mechanism behind the lipid regulation the authors have here studied bilayers of mixtures of unsaturated MGlcDG and DGlcDG, containing a small fraction of biosynthetically incorporated per-deuterated palmitic acid, with {sup 2}H NMR. The order-parameter profile of the acyl chains and an apparent transverse spin relaxation rate (R{sub 2}) were determined from dePaked quadrupole-echo spectra. The variation of order with lipid composition is rationalized from simple packing constraints. The relaxation data indicate the presence of slow reorientational motions, such as collective bilayer fluctuations and/or lipid lateral diffusion over a curved bilayer surface. The variation of acyl-chain order and bilayer curvature and/or fluctuations with sample composition are discussed in relation to the tendency of MGlcDG to form nonlamellar phases in vitro and in relation to the lipid regulation in vivo.

  18. "One-Pot" Approach to 8-Acylated 2-Quinolinones via Palladium-Catalyzed Regioselective Acylation of Quinoline N-Oxides.

    PubMed

    Chen, Xiaopei; Cui, Xiuling; Wu, Yangjie

    2016-05-20

    A "one-pot" facile and efficient protocol for 8-acylated 2-quinolinones has been developed through palladium-catalyzed acylation of quinoline N-oxides, which proceeds with high selectivity at the C8-position. The desired products were isolated in up to 95% yield and good functional group tolerance. A palladacycle was isolated from the catalytic process and proposed as a key intermediate. PMID:27153298

  19. Possible Role of Different Yeast and Plant Lysophospholipid:Acyl-CoA Acyltransferases (LPLATs) in Acyl Remodelling of Phospholipids.

    PubMed

    Jasieniecka-Gazarkiewicz, Katarzyna; Demski, Kamil; Lager, Ida; Stymne, Sten; Banaś, Antoni

    2016-01-01

    Recent results have suggested that plant lysophosphatidylcholine:acyl-coenzyme A acyltransferases (LPCATs) can operate in reverse in vivo and thereby catalyse an acyl exchange between the acyl-coenzyme A (CoA) pool and the phosphatidylcholine. We have investigated the abilities of Arabidopsis AtLPCAT2, Arabidopsis lysophosphatidylethanolamine acyltransferase (LPEAT2), S. cerevisiae lysophospholipid acyltransferase (Ale1) and S. cerevisiae lysophosphatidic acid acyltransferase (SLC1) to acylate lysoPtdCho, lysoPtdEtn and lysoPtdOH and act reversibly on the products of the acylation; the PtdCho, PtdEtn and PtdOH. The tested LPLATs were expressed in an S. cervisiae ale1 strain and enzyme activities were assessed in assays using microsomal preparations of the different transformants. The results show that, despite high activity towards lysoPtdCho, lysoPtdEtn and lysoPtdOH by the ALE1, its capacities to operate reversibly on the products of the acylation were very low. Slc1 readily acylated lysoPtdOH, lysoPtdCho and lysoPtdEtn but showed no reversibility towards PtdCho, very little reversibility towards PtdEtn and very high reversibility towards PtdOH. LPEAT2 showed the highest levels of reversibility towards PtdCho and PtdEtn of all LPLATs tested but low ability to operate reversibly on PtdOH. AtLPCAT2 showed good reversible activity towards PtdCho and PtdEtn and very low reversibility towards PtdOH. Thus, it appears that some of the LPLATs have developed properties that, to a much higher degree than other LPLATs, promote the reverse reaction during the same assay conditions and with the same phospholipid. The results also show that the capacity of reversibility can be specific for a particular phospholipid, albeit the lysophospholipid derivatives of other phospholipids serve as good acyl acceptors for the forward reaction of the enzyme. PMID:26643989

  20. Purification and biochemical characterization of the Mycobacterium tuberculosis beta-ketoacyl-acyl carrier protein synthases KasA and KasB.

    PubMed

    Schaeffer, M L; Agnihotri, G; Volker, C; Kallender, H; Brennan, P J; Lonsdale, J T

    2001-12-14

    Mycolic acids are vital components of the Mycobacterium tuberculosis cell wall, and enzymes involved in their formation represent attractive targets for the discovery of novel anti-tuberculosis agents. Biosynthesis of the fatty acyl chains of mycolic acids involves two fatty acid synthetic systems, the multifunctional polypeptide fatty acid synthase I (FASI), which performs de novo fatty acid synthesis, and the dissociated FASII system, which consists of monofunctional enzymes, and acyl carrier protein (ACP) and elongates FASI products to long chain mycolic acid precursors. In this study, we present the initial characterization of purified KasA and KasB, two beta-ketoacyl-ACP synthase (KAS) enzymes of the M. tuberculosis FASII system. KasA and KasB were expressed in E. coli and purified by affinity chromatography. Both enzymes showed activity typical of bacterial KASs, condensing an acyl-ACP with malonyl-ACP. Consistent with the proposed role of FASII in mycolic acid synthesis, analysis of various acyl-ACP substrates indicated KasA and KasB had higher specificity for long chain acyl-ACPs containing at least 16 carbons. Activity of KasA and KasB increased with use of M. tuberculosis AcpM, suggesting that structural differences between AcpM and E. coli ACP may affect their recognition by the enzymes. Both enzymes were sensitive to KAS inhibitors cerulenin and thiolactomycin. These results represent important steps in characterizing KasA and KasB as targets for antimycobacterial drug discovery. PMID:11600501

  1. Two Isostructural Coordination Polymers Showing Diverse Magnetic Behaviors: Weak Coupling (Ni(II)) and an Ordered Array of Single-Chain Magnets (Co(II)).

    PubMed

    Chen, Min; Zhao, Hui; Sañudo, E Carolina; Liu, Chun-Sen; Du, Miao

    2016-04-18

    Two isomorphic 3-D complexes with the formulas [M3(TPTA) (OH)2(H2O)4]n (M = Ni for 1 and Co for 2; H4TPTA = [1,1':4',1″-terphenyl]-2',3,3″,5'-tetracarboxylic acid) have been synthesized and magnetically characterized. Complexes 1 (Ni(II)) and 2 (Co(II)) have the same 1-D rod-shaped inorganic SBUs but exhibit significantly different magnetic properties. Complex 2(Co(II)) is a 3-D arrangement of a 1-D Co(II) single-chain magnet (SCM), while complex 1(Ni(II)) exhibits weak coupling. PMID:27022765

  2. Chemically Modified N-Acylated Hyaluronan Fragments Modulate Proinflammatory Cytokine Production by Stimulated Human Macrophages*

    PubMed Central

    Babasola, Oladunni; Rees-Milton, Karen J.; Bebe, Siziwe; Wang, Jiaxi; Anastassiades, Tassos P.

    2014-01-01

    Low molecular mass hyaluronans are known to induce inflammation. To determine the role of the acetyl groups of low molecular mass hyaluronan in stimulating the production of proinflammatory cytokines, partial N-deacetylation was carried out by hydrazinolysis. This resulted in 19.7 ± 3.5% free NH2 functional groups, which were then acylated by reacting with an acyl anhydride, including acetic anhydride. Hydrazinolysis resulted in bond cleavage of the hyaluronan chain causing a reduction of the molecular mass to 30–214 kDa. The total NH2 and N-acetyl moieties in the reacetylated hyaluronan were 0% and 98.7 ± 1.5% respectively, whereas for butyrylated hyaluronan, the total NH2, N-acetyl, and N-butyryl moieties were 0, 82.2 ± 4.6, and 22.7 ± 3.8%, respectively, based on 1H NMR. We studied the effect of these polymers on cytokine production by cultured human macrophages (THP-1 cells). The reacetylated hyaluronan stimulated proinflammatory cytokine production to levels similar to LPS, whereas partially deacetylated hyaluronan had no stimulatory effect, indicating the critical role of the N-acetyl groups in the stimulation of proinflammatory cytokine production. Butyrylated hyaluronan significantly reduced the stimulatory effect on cytokine production by the reacetylated hyaluronan or LPS but had no stimulatory effect of its own. The other partially N-acylated hyaluronan derivatives tested showed smaller stimulatory effects than reacetylated hyaluronan. Antibody and antagonist experiments suggest that the acetylated and partially butyrylated lower molecular mass hyaluronans exert their effects through the TLR-4 receptor system. Selectively N-butyrylated lower molecular mass hyaluronan shows promise as an example of a novel semisynthetic anti-inflammatory molecule. PMID:25053413

  3. Monogalactosyldiacylglycerol biosynthesis by direct acyl transfer in Anabaena variabilis. [Anabaena variabilis

    SciTech Connect

    Chen, H.H.; Wickrema, A.; Jaworski, J.

    1987-05-01

    The authors previously reported the direct acylation of monogalactosyldiacylglycerol (MGDG) by an enzyme in the membranes of the cyanobacterium (Anabaena variabilis. The enzyme requires acyl-acyl carrier protein (acyl-ACP) as substrate, but had no other additional cofactor requirements. Palmitoyl-, stearoyl- and oleoyl-ACP were all effective substrates. The A. variabilis membranes also had a hydrolase activity which metabolized the acyl-ACP to yield free fatty acid and ACP. Possible mechanisms for the acylation reaction include either acyl exchange with existing MGDG or direct acyl transfer to a lyso-MGDG, with concomitant release of free ACP. The mechanism of this reaction has been resolved using a double labelled (/sup 14/C)acyl-(/sup 14/C)ACP substrate prepared with E. coli acyl-ACP synthetase. Following incubation with the enzyme, the unreacted (/sup 14/C)acyl-(/sup 14/C)ACP was isolated and the (/sup 14/C)acyl/(/sup 14/C)ACP ratio determined. Comparison of this ratio to that of the original substrate indicated no change and eliminated acyl exchange as a possible mechanism. Therefore, the direct acylation of lyso-MGDG is the proposed mechanism for this enzyme. The reaction is apparently specific for MGDG synthesis, as other glycolipids and phospholipids were not labelled during incubations.

  4. Regioselective Acylation of Diols and Triols: The Cyanide Effect.

    PubMed

    Peng, Peng; Linseis, Michael; Winter, Rainer F; Schmidt, Richard R

    2016-05-11

    Central topics of carbohydrate chemistry embrace structural modifications of carbohydrates and oligosaccharide synthesis. Both require regioselectively protected building blocks that are mainly available via indirect multistep procedures. Hence, direct protection methods targeting a specific hydroxy group are demanded. Dual hydrogen bonding will eventually differentiate between differently positioned hydroxy groups. As cyanide is capable of various kinds of hydrogen bonding and as it is a quite strong sterically nondemanding base, regioselective O-acylations should be possible at low temperatures even at sterically congested positions, thus permitting formation and also isolation of the kinetic product. Indeed, 1,2-cis-diols, having an equatorial and an axial hydroxy group, benzoyl cyanide or acetyl cyanide as an acylating agent, and DMAP as a catalyst yield at -78 °C the thermodynamically unfavorable axial O-acylation product; acyl migration is not observed under these conditions. This phenomenon was substantiated with 3,4-O-unproteced galacto- and fucopyranosides and 2,3-O-unprotected mannopyranosides. Even for 3,4,6-O-unprotected galactopyranosides as triols, axial 4-O-acylation is appreciably faster than O-acylation of the primary 6-hydroxy group. The importance of hydrogen bonding for this unusual regioselectivity could be confirmed by NMR studies and DFT calculations, which indicate favorable hydrogen bonding of cyanide to the most acidic axial hydroxy group supported by hydrogen bonding of the equatorial hydroxy group to the axial oxygen. Thus, the "cyanide effect" is due to dual hydrogen bonding of the axial hydroxy group which enhances the nucleophilicity of the respective oxygen atom, permitting an even faster reaction for diols than for mono-ols. In contrast, fluoride as a counterion favors dual hydrogen bonding to both hydroxy groups leading to equatorial O-acylation. PMID:27104625

  5. Blunted Suppression of Acyl-Ghrelin in Response to Fructose Ingestion in Obese Adolescents: the Role of Insulin Resistance

    PubMed Central

    Van Name, Michelle; Giannini, Cosimo; Santoro, Nicola; Jastreboff, Ania; Kubat, Jessica; Li, Fangyong; Kursawe, Romy; Savoye, Mary; Duran, Elvira; Dziura, James; Sinha, Rajita; Sherwin, Robert; Cline, Gary; Caprio, Sonia

    2015-01-01

    Objective Fructose consumption has risen alongside obesity and diabetes. Gut hormones involved in hunger and satiety (ghrelin and PYY) may respond differently to fructose compared to glucose ingestion. We evaluated the effects of glucose and fructose ingestion on ghrelin and PYY in lean and obese adolescents with differing insulin sensitivity. Methods Adolescents were divided into lean (n=14), obese insulin sensitive (n=12) (OIS), and obese insulin resistant (n=15) (OIR). In a double-blind, cross-over design, subjects drank 75g of glucose or fructose in random order, serum was obtained every 10 minutes for 60 minutes. Results Baseline acyl-ghrelin was highest in lean and lowest in OIR (p=0.02). After glucose ingestion acyl-ghrelin decreased similarly in lean and OIS, but appeared lower in OIR (vs lean p=0.03). Suppression differences were more pronounced after fructose (lean vs. OIS p=0.008, lean vs. OIR p<0.001). OIS became significantly hungrier after fructose (p=0.015). PYY was not significantly different at baseline, varied minimally after glucose, and rose after fructose. Conclusion Compared to lean, OIS adolescents have impaired acyl-ghrelin responses to fructose but not glucose, whereas OIR adolescents have blunted responses to both. Diminished suppression of acyl-ghrelin in childhood obesity, particularly if accompanied by insulin resistance, may promote hunger and overeating. PMID:25645909

  6. Transgenic rice seed expressing flavonoid biosynthetic genes accumulate glycosylated and/or acylated flavonoids in protein bodies.

    PubMed

    Ogo, Yuko; Mori, Tetsuya; Nakabayashi, Ryo; Saito, Kazuki; Takaiwa, Fumio

    2016-01-01

    Plant-specialized (or secondary) metabolites represent an important source of high-value chemicals. In order to generate a new production platform for these metabolites, an attempt was made to produce flavonoids in rice seeds. Metabolome analysis of these transgenic rice seeds using liquid chromatography-photodiode array-quadrupole time-of-flight mass spectrometry was performed. A total of 4392 peaks were detected in both transgenic and non-transgenic rice, 20-40% of which were only detected in transgenic rice. Among these, 82 flavonoids, including 37 flavonols, 11 isoflavones, and 34 flavones, were chemically assigned. Most of the flavonols and isoflavones were O-glycosylated, while many flavones were O-glycosylated and/or C-glycosylated. Several flavonoids were acylated with malonyl, feruloyl, acetyl, and coumaroyl groups. These glycosylated/acylated flavonoids are thought to have been biosynthesized by endogenous rice enzymes using newly synthesized flavonoids whose biosynthesis was catalysed by exogenous enzymes. The subcellular localization of the flavonoids differed depending on the class of aglycone and the glycosylation/acylation pattern. Therefore, flavonoids with the intended aglycones were efficiently produced in rice seeds via the exogenous enzymes introduced, while the flavonoids were variously glycosylated/acylated by endogenous enzymes. The results suggest that rice seeds are useful not only as a production platform for plant-specialized metabolites such as flavonoids but also as a tool for expanding the diversity of flavonoid structures, providing novel, physiologically active substances. PMID:26438413

  7. Transgenic rice seed expressing flavonoid biosynthetic genes accumulate glycosylated and/or acylated flavonoids in protein bodies

    PubMed Central

    Ogo, Yuko; Mori, Tetsuya; Nakabayashi, Ryo; Saito, Kazuki; Takaiwa, Fumio

    2016-01-01

    Plant-specialized (or secondary) metabolites represent an important source of high-value chemicals. In order to generate a new production platform for these metabolites, an attempt was made to produce flavonoids in rice seeds. Metabolome analysis of these transgenic rice seeds using liquid chromatography-photodiode array-quadrupole time-of-flight mass spectrometry was performed. A total of 4392 peaks were detected in both transgenic and non-transgenic rice, 20–40% of which were only detected in transgenic rice. Among these, 82 flavonoids, including 37 flavonols, 11 isoflavones, and 34 flavones, were chemically assigned. Most of the flavonols and isoflavones were O-glycosylated, while many flavones were O-glycosylated and/or C-glycosylated. Several flavonoids were acylated with malonyl, feruloyl, acetyl, and coumaroyl groups. These glycosylated/acylated flavonoids are thought to have been biosynthesized by endogenous rice enzymes using newly synthesized flavonoids whose biosynthesis was catalysed by exogenous enzymes. The subcellular localization of the flavonoids differed depending on the class of aglycone and the glycosylation/acylation pattern. Therefore, flavonoids with the intended aglycones were efficiently produced in rice seeds via the exogenous enzymes introduced, while the flavonoids were variously glycosylated/acylated by endogenous enzymes. The results suggest that rice seeds are useful not only as a production platform for plant-specialized metabolites such as flavonoids but also as a tool for expanding the diversity of flavonoid structures, providing novel, physiologically active substances. PMID:26438413

  8. Head-group acylation of monogalactosyldiacylglycerol is a common stress response, but the acyl-galactose acyl composition varies with the plant species and applied stress

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Head group acylation of monogalactosyldiacylglycerol is a plant lipid modification occurring during bacterial infection. Little is known about the range of stresses that induce this lipid modification, the molecular species induced, and the function of the modification. Lipidomic analysis using trip...

  9. Polarizabilities and second hyperpolarizabilities of hydrogen chains using the spin-component-scaled Møller-Plesset second-order method

    NASA Astrophysics Data System (ADS)

    Champagne, Benoît; Kirtman, Bernard

    Static longitudinal polarizabilities (α) and second hyperpolarizabilities (γ) of model H2 chains have been calculated at different ab initio levels to address the performance of the recently proposed spin-component-scaled MP2 (SCS-MP2) method (Grimme, J. Chem Phys 2003, 118, 9095). For both α and γ, the SCS-MP2 method improves over the MP2 results in comparison with reference values evaluated at the CCSD(T) level. Differences from the reference are in the range of 4-6% for α and 1-4% for γ. In the case of γ, the SCS-MP2 scheme improves not only over MP2 but also MP4 and CCSD. Further studies are needed on π-conjugated systems to evaluate the generality of these results.

  10. Investigation of some characteristics of polyhydroxy milkweed triglycerides and their acylated derivatives in relation to lubricity.

    PubMed

    Harry-O'kuru, Rogers E; Biresaw, Girma; Cermak, Steven C; Gordon, Sherald H; Vermillion, Karl

    2011-05-11

    Most industrial lubricants are derived from nonrenewable petroleum-based sources. As useful as these lubricants are, their unintended consequences are the pollution of the Earth's environment as a result of the slow degradation of the spent materials. Native seed oils, on the other hand, are renewable and are also biodegradable in the environment, but these oils often suffer a drawback in having lower thermal stability and a shorter shelf life because of the intrinsic -C═C- unsaturation in their structures. This drawback can be overcome, yet the inherent biodegradative property retained, by appropriate derivatization of the oil. Pursuant to this, this study investigated derivatized polyhydroxy milkweed oil to assess its suitability as lubricant. The milkweed plant is a member of the Asclepiadaceae, a family with many genera including the common milkweeds, Asclepias syriaca L., Asclepias speciosa L., Asclepias tuberosa L., etc. The seeds of these species contain mainly C-18 triglycerides that are highly unsaturated, 92%. The olefinic character of this oil has been chemically modified by generating polyhydroxy triglycerides (HMWO) that show high viscosity and excellent moisturizing characteristics. In this work, HMWO have been chemically modified by esterifying their hydroxyl groups with acyl groups of various chain lengths (C2-C5). The results of investigation into the effect of the acyl derivatives' chemical structure on kinematic and dynamic viscosity, oxidation stability, cold-flow (pour point, cloud point) properties, coefficient of friction, wear, and elastohydrodynamic film thickness are discussed. PMID:21428293

  11. Proton conductance and fatty acyl composition of liver mitochondria correlates with body mass in birds.

    PubMed Central

    Brand, Martin D; Turner, Nigel; Ocloo, Augustine; Else, Paul L; Hulbert, A J

    2003-01-01

    The proton conductance of isolated liver mitochondria correlates significantly with body mass in mammals, but not in ectotherms. To establish whether the correlation in mammals is general for endotherms or m