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Sample records for acyl chain tilt

  1. Fatty Acyl Chains of Mycobacterium marinum Lipooligosaccharides

    PubMed Central

    Rombouts, Yoann; Alibaud, Laeticia; Carrère-Kremer, Séverine; Maes, Emmanuel; Tokarski, Caroline; Elass, Elisabeth; Kremer, Laurent; Guérardel, Yann

    2011-01-01

    We have recently established the fine structure of the glycan backbone of lipooligosaccharides (LOS-I to LOS-IV) isolated from Mycobacterium marinum, a close relative of Mycobacterium tuberculosis. These studies culminated with the description of an unusual terminal N-acylated monosaccharide that confers important biological functions to LOS-IV, such as macrophage activation, that may be relevant to granuloma formation. It was, however, also suggested that the lipid moiety was required for LOSs to exert their immunomodulatory activity. Herein, using highly purified LOSs from M. marinum, we have determined through a combination of mass spectrometric and NMR techniques, the structure and localization of the fatty acids composing the lipid moiety. The occurrence of two distinct polymethyl-branched fatty acids presenting specific localizations is consistent with the presence of two highly related polyketide synthases (Pks5 and Pks5.1) in M. marinum and presumably involved in the synthesis of these fatty acyl chains. In addition, a bioinformatic search permitted us to identify a set of enzymes potentially involved in the biosynthesis or transfer of these lipids to the LOS trehalose unit. These include MMAR_2343, a member of the Pap (polyketide-associated protein) family, that acylates trehalose-based glycolipids in M. marinum. The participation of MMAR_2343 to LOS assembly was demonstrated using a M. marinum mutant carrying a transposon insertion in the MMAR_2343 gene. Disruption of MMAR_2343 resulted in a severe LOS breakdown, indicating that MMAR_2343, hereafter designated PapA4, fulfills the requirements for LOS acylation and assembly. PMID:21803773

  2. Sphingomyelin interfacial behavior: the impact of changing acyl chain composition.

    PubMed Central

    Li, X M; Smaby, J M; Momsen, M M; Brockman, H L; Brown, R E

    2000-01-01

    Sphingomyelins (SMs) containing homogeneous acyl chains with 12, 14, 16, 18, 24, or 26 carbons were synthesized and characterized using an automated Langmuir-type film balance. Surface pressure was monitored as a function of lipid molecular area at constant temperatures between 10 degrees C and 30 degrees C. SM containing lauroyl (12:0) acyl chains displayed only liquid-expanded behavior. Increasing the length of the saturated acyl chain (e.g., 14:0, 16:0, or 18:0) resulted in liquid-expanded to condensed two-dimensional phase transitions at many temperatures in the 10-30 degrees C range. Similar behavior was observed for SMs with lignoceroyl (24:0) or (cerotoyl) 26:0 acyl chains, but isotherms showed only condensed behavior at 10 and 15 degrees C. Insights into the physico-mechanical in-plane interactions occurring within the different SM phases and accompanying changes in SM phase state were provided by analyzing the interfacial area compressibility moduli. At similar surface pressures, SM fluid phases were less compressible than those of phosphatidylcholines with similar chain structures. The area per molecule and compressibility of SM condensed phases depended upon the length of the saturated acyl chain and upon spreading temperature. Spreading of SMs with very long saturated acyl chains at temperatures 30-35 degrees below T(m) resulted in condensed films with lower in-plane compressibilities, but consistently larger cross-sectional molecular areas than the condensed phases achieved by spreading at temperatures only 10-20 degrees below T(m). This behavior is discussed in terms of the enhancement of SM lateral aggregation by temperature reduction, a common approach used during domain isolation from biomembranes. PMID:10733971

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

    PubMed

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

    2016-08-08

    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).

  4. Characterization of Lipid A Variants by Energy-Resolved Mass Spectrometry: Impact of Acyl Chains

    NASA Astrophysics Data System (ADS)

    Crittenden, Christopher M.; Akin, Lucas D.; Morrison, Lindsay J.; Trent, M. Stephen; Brodbelt, Jennifer S.

    2016-12-01

    Lipid A molecules consist of a diglucosamine sugar core with a number of appended acyl chains that vary in their length and connectivity. Because of the challenging nature of characterizing these molecules and differentiating between isomeric species, an energy-resolved MS/MS strategy was undertaken to track the fragmentation trends and map genealogies of product ions originating from consecutive cleavages of acyl chains. Generalizations were developed based on the number and locations of the primary and secondary acyl chains as well as variations in preferential cleavages arising from the location of the phosphate groups. Secondary acyl chain cleavage occurs most readily for lipid A species at the 3' position, followed by primary acyl chain fragmentation at both the 3' and 3 positions. In the instances of bisphosphorylated lipid A variants, phosphate loss occurs readily in conjunction with the most favorable primary and secondary acyl chain cleavages.

  5. A Cerulenin Insensitive Short Chain 3-Ketoacyl-Acyl Carrier Protein Synthase in Spinacia oleracea Leaves

    PubMed Central

    Jaworski, Jan G.; Clough, Richard C.; Barnum, Susan R.

    1989-01-01

    A cerulenin insensitive 3-ketoacyl-acyl carrier protein synthase has been assayed in extracts of spinach (Spinacia oleracea) leaf. The enzyme was active in the 40 to 80% ammonium sulfate precipitate of whole leaf homogenates and catalyzed the synthesis of acetoacetyl-acyl carrier protein. This condensation reaction was five-fold faster than acetyl-CoA:acyl carrier protein transacylase, and the initial rates of acyl-acyl carrier protein synthesis were independent of the presence of cerulenin. In the presence of fatty acid synthase cofactors and 100 micromolar cerulenin, the principal fatty acid product of de novo synthesis was butyric and hexanoic acids. Using conformationally sensitive native polyacrylamide gel electrophoresis for separation, malonyl-, acetyl-, butyryl-, hexanoyl, and long chain acyl-acyl carrier proteins could be detected by immunoblotting and autoradiography. In the presence of 100 micromolar cerulenin, the accumulation of butyryl- and hexanoyl-acyl carrier protein was observed, with no detectable long chain acyl-acyl carrier proteins or fatty acids being produced. In the absence of cerulenin, the long chain acyl-acyl carrier proteins also accumulated. Images Figure 2 Figure 3 PMID:16666765

  6. 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.

  7. Defluoridation potential of jute fibers grafted with fatty acyl chain

    NASA Astrophysics Data System (ADS)

    Manna, Suvendu; Saha, Prosenjit; Roy, Debasis; Sen, Ramkrishna; Adhikari, Basudam

    2015-11-01

    Waterborne fluoride is usually removed from water by coagulation, adsorption, ion exchange, electro dialysis or reverse osmosis. These processes are often effective over narrow pH ranges, release ions considered hazardous to human health or produce large volumes of toxic sludge that are difficult to handle and dispose. Although plant matters have been shown to remove waterborne fluoride, they suffer from poor removal efficiency. Following from the insight that interaction between microbial carbohydrate biopolymers and anionic surfaces is often facilitated by lipids, an attempt has been made to enhance fluoride adsorption efficiency of jute by grafting the lignocellulosic fiber with fatty acyl chains found in vegetable oils. Fluoride removal efficiency of grafted jute was found to be comparable or higher than those of alternative defluoridation processes. Infrared and X-ray photoelectron spectroscopic evidence indicated that hydrogen bonding, protonation and C-F bonding were responsible for fluoride accumulation on grafted jute. Adsorption based on grafted jute fibers appears to be an economical, sustainable and eco-friendly alternative technique for removing waterborne fluoride.

  8. The dependence of lipid asymmetry upon phosphatidylcholine acyl chain structure[S

    PubMed Central

    Son, Mijin; London, Erwin

    2013-01-01

    Lipid asymmetry, the difference in inner and outer leaflet lipid composition, is an important feature of biomembranes. By utilizing our recently developed MβCD-catalyzed exchange method, the effect of lipid acyl chain structure upon the ability to form asymmetric membranes was investigated. Using this approach, SM was efficiently introduced into the outer leaflet of vesicles containing various phosphatidylcholines (PC), but whether the resulting vesicles were asymmetric (SM outside/PC inside) depended upon PC acyl chain structure. Vesicles exhibited asymmetry using PC with two monounsaturated chains of >14 carbons; PC with one saturated and one unsaturated chain; and PC with phytanoyl chains. Vesicles were most weakly asymmetric using PC with two 14 carbon monounsaturated chains or with two polyunsaturated chains. To define the origin of this behavior, transverse diffusion (flip-flop) of lipids in vesicles containing various PCs was compared. A correlation between asymmetry and transverse diffusion was observed, with slower transverse diffusion in vesicles containing PCs that supported lipid asymmetry. Thus, asymmetric vesicles can be prepared using a wide range of acyl chain structures, but fast transverse diffusion destroys lipid asymmetry. These properties may constrain acyl chain structure in asymmetric natural membranes to avoid short or overly polyunsaturated acyl chains. PMID:23093551

  9. Revised nomenclature for the mammalian long-chain acyl-CoA synthetase gene family.

    PubMed

    Mashek, Douglas G; Bornfeldt, Karin E; Coleman, Rosalind A; Berger, Johannes; Bernlohr, David A; Black, Paul; DiRusso, Concetta C; Farber, Steven A; Guo, Wen; Hashimoto, Naohiro; Khodiyar, Varsha; Kuypers, Frans A; Maltais, Lois J; Nebert, Daniel W; Renieri, Alessandra; Schaffer, Jean E; Stahl, Andreas; Watkins, Paul A; Vasiliou, Vasilis; Yamamoto, Tokuo T

    2004-10-01

    By consensus, the acyl-CoA synthetase (ACS) community, with the advice of the human and mouse genome nomenclature committees, has revised the nomenclature for the mammalian long-chain acyl-CoA synthetases. ACS is the family root name, and the human and mouse genes for the long-chain ACSs are termed ACSL1,3-6 and Acsl1,3-6, respectively. Splice variants of ACSL3, -4, -5, and -6 are cataloged. Suggestions for naming other family members and for the nonmammalian acyl-CoA synthetases are made.

  10. Altered ceramide acyl chain length and ceramide synthase gene expression in Parkinson’s disease.

    PubMed

    Abbott, Sarah K; Li, Hongyun; Muñoz, Sonia Sanz; Knoch, Bianca; Batterham, Marijka; Murphy, Karen E; Halliday, Glenda M; Garner, Brett

    2014-04-01

    Genetic studies have provided increasing evidence that ceramide homeostasis plays a role in neurodegenerative diseases including Parkinson’s disease (PD). It is known that the relative amounts of different ceramide molecular species, as defined by their fatty acyl chain length, regulate ceramide function in lipid membranes and in signaling pathways. In the present study we used a comprehensive sphingolipidomic case-control approach to determine the effects of PD on ceramide composition in postmortem brain tissue from the anterior cingulate cortex (a region with significant PD pathology) and the occipital cortex (spared in PD), also assessing mRNA expression of the major ceramide synthase genes that regulate ceramide acyl chain composition in the same tissue using quantitative PCR. In PD anterior cingulate cortex but not occipital cortex, total ceramide and sphingomyelin levels were reduced from control levels by 53% (P < 0.001) and 42% (P < 0.001), respectively. Of the 13 ceramide and 15 sphingomyelin molecular lipid species identified and quantified, there was a significant shift in the ceramide acyl chain composition toward shorter acyl chain length in the PD anterior cingulate cortex. This PD-associated change in ceramide acyl chain composition was accompanied by an upregulation of ceramide synthase-1 gene expression, which we consider may represent a response to reduced ceramide levels. These data suggest a significant shift in ceramide function in lipid membranes and signaling pathways occurs in regions with PD pathology. Identifying the regulatory mechanisms precipitating this change may provide novel targets for future therapeutics.

  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. 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

  14. 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 ...

  15. Acyl chain conformations in phospholipid bilayers: a comparative study of docosahexaenoic acid and saturated fatty acids.

    PubMed

    Feller, Scott E

    2008-05-01

    A variety of experimental methods indicate unique biophysical properties of membranes containing the highly polyunsaturated omega-3 fatty acid, docosahexaenoic acid (DHA). In the following we review the atomically detailed picture of DHA acyl chains structure and dynamics that has emerged from computational studies of this system in our lab. A comprehensive approach, beginning with ab-initio quantum chemical studies of model compounds representing segments of DHA and ending with large scale classical molecular dynamics simulations of DHA-containing bilayers, is described with particular attention paid to contrasting the properties of DHA with those of saturated fatty acids. Connection with experiment is made primarily through comparison with Nuclear Magnetic Resonance (NMR) studies, particularly those that probe details of the chain structure and dynamics. Our computational results suggest that low torsional energy barriers, comparable to kT at physiological conditions, for the rotatable bonds in the DHA chain are the key to the differences observed between polyunsaturated and saturated acyl chains.

  16. Cationic amphiphiles with fatty acyl chain asymmetry of coconut oil deliver genes selectively to mouse lung.

    PubMed

    Chandrashekhar, Voshavar; Srujan, Marepally; Prabhakar, Rairala; Reddy, Rakesh C; Sreedhar, Bojja; Rentam, Kiran K R; Kanjilal, Sanjit; Chaudhuri, Arabinda

    2011-03-16

    Recent structure-activity studies have revealed a dramatic influence of hydrophobic chain asymmetry in enhancing gene delivery efficacies of synthetic cationic amphiphiles (Nantz, M. H. et al. Mol. Pharmaceutics2010, 7, 786-794; Koynova, R. et al. Mol. Pharmaceutics2009, 6, 951-958). The present findings demonstrate for the first time that such a transfection enhancing influence of asymmetric hydrocarbon chains observed in pure synthetic cationic amphiphiles also works for cationic amphiphiles designed with natural, asymmetric fatty acyl chains of a food-grade oil. Herein, we demonstrate that cationic amphiphiles designed with the natural fatty acyl chain asymmetry of food-grade coconut oil are less cytotoxic and deliver genes selectively to mouse lung. Despite lauroyl chains being the major fatty acyl chains of coconut oil, both the in vitro and In vivo gene transfer efficiencies of such cationic amphiphiles were found to be remarkably superior (>4-fold) to those of their pure dilauroyl analogue. Mechanistic studies involving the technique of fluorescence resonance energy transfer (FRET) revealed higher biomembrane fusibility of the cationic liposomes of the coconut amphiphiles than that of the symmetric dilauroyl analogue. AFM study revealed pronounced fusogenic nonlamellar structures of the liposomes of coconut amphiphiles. Findings in the FRET and cellular uptake study, taken together, support the notion that the higher cellular uptake resulting from the more fusogenic nature of the liposomes of coconut amphiphiles 1 are likely to play a dominant role in making the coconut amphiphiles transfection competent.

  17. Role of long-chain fatty acyl-CoA esters in the regulation of metabolism and in cell signalling.

    PubMed Central

    Faergeman, N J; Knudsen, J

    1997-01-01

    The intracellular concentration of free unbound acyl-CoA esters is tightly controlled by feedback inhibition of the acyl-CoA synthetase and is buffered by specific acyl-CoA binding proteins. Excessive increases in the concentration are expected to be prevented by conversion into acylcarnitines or by hydrolysis by acyl-CoA hydrolases. Under normal physiological conditions the free cytosolic concentration of acyl-CoA esters will be in the low nanomolar range, and it is unlikely to exceed 200 nM under the most extreme conditions. The fact that acetyl-CoA carboxylase is active during fatty acid synthesis (Ki for acyl-CoA is 5 nM) indicates strongly that the free cytosolic acyl-CoA concentration is below 5 nM under these conditions. Only a limited number of the reported experiments on the effects of acyl-CoA on cellular functions and enzymes have been carried out at low physiological concentrations in the presence of the appropriate acyl-CoA-buffering binding proteins. Re-evaluation of many of the reported effects is therefore urgently required. However, the observations that the ryanodine-senstitive Ca2+-release channel is regulated by long-chain acyl-CoA esters in the presence of a molar excess of acyl-CoA binding protein and that acetyl-CoA carboxylase, the AMP kinase kinase and the Escherichia coli transcription factor FadR are affected by low nanomolar concentrations of acyl-CoA indicate that long-chain acyl-CoA esters can act as regulatory molecules in vivo. This view is further supported by the observation that fatty acids do not repress expression of acetyl-CoA carboxylase or Delta9-desaturase in yeast deficient in acyl-CoA synthetase. PMID:9173866

  18. Comparison of the lipid acyl chain dynamics between small and large unilamellar vesicles.

    PubMed Central

    Lepore, L S; Ellena, J F; Cafiso, D S

    1992-01-01

    13C NMR spin-lattice relaxation (T1) rates and 13C-1H nuclear Overhauser effects (NOEs) were measured in an identical fashion in two lipid preparations having dramatically different curvatures. The T1 times that were obtained at four magnetic field strengths were fit along with the NOEs to simple models for lipid molecular dynamics. The results indicate that phospholipid chain ordering and dynamics are virtually identical in small and large unilamellar vesicles at the time scales sampled by these 13C-NMR studies. The order parameters and reorientational correlation times that characterize the amplitudes and rates of internal acyl chain motions were equal within experimental error for the methylene segments in the middle of the chains. The only significant differences in order parameters and correlation times between the two vesicle types were small and appeared at the ends of the acyl chains. At the carbonyl end the order was slightly higher in small vesicles than large vesicles, and at the methyl end the order was slightly lower for small vesicles. This indicates that in the more planar systems the acyl chains exhibit a slightly flatter order profile than in more highly curved membranes. The use of the same experimental approach in both small and large vesicle systems provided a more reliable and accurate assessment of the effect of curvature on molecular order than has been previously obtained. PMID:1504247

  19. Measurement of chain tilt angle in fully hydrated bilayers of gel phase lecithins.

    PubMed Central

    Tristram-Nagle, S; Zhang, R; Suter, R M; Worthington, C R; Sun, W J; Nagle, J F

    1993-01-01

    The tilt angle theta tilt of the hydrocarbon chains has been determined for fully hydrated gel phase of a series of saturated lecithins. Oriented samples were prepared on glass substrates and hydrated with supersaturated water vapor. Evidence for full hydration was the same intensity pattern of the low angle lamellar peaks and the same lamellar repeat D as unoriented multilamellar vesicles. Tilting the sample permitted observation of all the wide angle arcs necessary to verify the theoretical diffraction pattern corresponding to tilting of the chains towards nearest neighbors. The length of the scattering unit corresponds to two hydrocarbon chains, requiring each bilayer to scatter coherently rather than each monolayer. For DPPC, theta tilt was determined to be 32.0 +/- 0.5 degrees at 19 degrees C, slightly larger than previous direct determinations and considerably smaller than the value required by recent gravimetric measurements. This new value allows more accurate determinations of a variety of structural parameters, such as area per lipid molecule, A = 47.2 +/- 0.5 A2, and number of water molecules of hydration, nw = 11.8 +/- 0.7. As the chain length n of the lipids was increased from 16 to 20 carbons, the parameters A and nw remained constant, suggesting that the headgroup packing is at its excluded volume limit for this range. However, theta tilt increased by 3 degrees and the chain area Ac decreased by 0.5 A2. This behavior is explained in terms of a competition between a bulk free energy term and a finite or end effect term. Images FIGURE 6 FIGURE 7 PMID:8494973

  20. A severe genotype with favourable outcome in very long chain acyl-CoA dehydrogenase deficiency

    PubMed Central

    Touma, E; Rashed, M; Vianey-Saban, C; Sakr, A; Divry, P; Gregersen, N; Andresen, B

    2001-01-01

    A patient with very long chain acyl-CoA dehydrogenase (VLCAD) deficiency is reported. He had a severe neonatal presentation and cardiomyopathy. He was found to be homozygous for a severe mutation with no residual enzyme activity. Tandem mass spectrometry on dried blood spots revealed increased long chain acylcarnitines. VLCAD enzyme activity was severely decreased to 2% of control levels. Dietary management consisted of skimmed milk supplemented with medium chain triglycerides and L-carnitine. Outcome was good and there was no acute recurrence.

 PMID:11124787

  1. 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.

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

    DOE PAGES

    Xia, Yan; Li, Ming; Charubin, Kamil; ...

    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

  3. A specific acyl-ACP thioesterase implicated in medium-chain fatty acid production in immature cotyledons of Umbellularia californica.

    PubMed

    Pollard, M R; Anderson, L; Fan, C; Hawkins, D J; Davies, H M

    1991-02-01

    Umbellularia californica (California Bay) seeds accumulate 10:0 and 12:0 as principal reserve fatty acyl groups. An in vitro fatty acid synthesis system from the developing cotyledons produces chiefly 10:0 and 12:0, in approximately the same proportions as the intact tissue. The kinetics of acyl thioester and free fatty acid formation in this system suggest that a medium-chain specific acyl-acyl-carrier protein (ACP) hydrolysis mechanism is responsible for the preponderance of medium-chain products. A crude extract of the developing cotyledons exhibits hydrolytic activity toward acyl-ACPs, with marked preference for 12:0-ACP and 18:1-ACP in the test series 6:0, 8:0, 10:0, 11:0, 12:0, 14:0, 16:0, and 18:1-ACPs. Partial purification of the 12:0-ACP hydrolytic activity has resulted in its separation from the 18:1-ACP hydrolase(s) and the 12:0-coenzyme A hydrolase(s) that are also present, thereby demonstrating its specificity for the 12-carbon acyl chain length and the ACP derivative. During cotyledon development, as the proportion of medium-chain to other fatty acyl groups increases, the extractable yield of this activity also increases substantially. Collectively these results suggest a role for this 12-ACP thioesterase in medium-chain production in vivo.

  4. Syntheses of Papyracillic Acids: Application of the Tandem Chain Extension-Acylation Reaction

    PubMed Central

    Mazzone, Jennifer R.; Zercher, Charles K.

    2012-01-01

    A synthetic approach to the papyracillic acid family of natural products has been developed. The spiroacetal core is rapidly assembled through an unprecedented zinc carbenoid-mediated tandem chain extension-acylation reaction. Subsequent functional group manipulation provided access to papyracillic acid B and 4-epi-papyracillic acid C. The successful preparation of these molecules resulted in the clarification of structural assignments of members of this family of natural products. PMID:23013246

  5. Effect of salicylic acid and diclofenac on the medium-chain and long-chain acyl-CoA formation in the liver and brain of mouse.

    PubMed

    Kasuya, Fumiyo; Kazumi, Maya; Tatsuki, Takao; Suzuki, Risa

    2009-07-01

    Medium-chain and long-chain acyl-CoA esters are key metabolites in fatty acid metabolism. Effects of salicylic acid on the in vivo formation of acyl-CoAs in mouse liver and brain were investigated. Further, inhibition of the medium-chain and long-chain acyl-CoA synthetases by salicylic acid and diclofenac was determined in mouse liver and brain mitochondria. Acyl-CoA esters were analyzed by liquid chromatography-tandem mass spectrometry. The amounts of medium-chain acyl-CoAs (C(6), C(8) and C(10)) were less than long-chain acyl-CoAs (C(16:0), C(18:0), C(18:1) and C(20:4)) in both liver and brain. The administration of salicylic acid decreased the levels of both the medium-chain (C(6), C(8) and C(10)) and long-chain acyl-CoAs (C(16:0), C(18:0), C(18:1) and C(20:4)) in liver. In brain, however, only long-chain acyl-CoAs were decreased. The level of salicylyl-CoA detected in brain was about 12% of that in liver. Salicylic acid had a strong inhibitory activity (IC(50) = 0.1 mm) for the liver mitochondrial formation of hexanoyl-CoA from hexanoic acid, whereas diclofenac was weak (IC(50) = 4.4 mm). In contrast, diclofenac (IC(50) = 1.4 mm) inhibited the liver mitochondrial long-chain acyl-CoA synthetases more potently than salicylic acid (IC(50) = 25.5 mm). Similar inhibitory activities for the acyl-CoA synthetases were obtained in the case of the brain and liver mitochondria, except for the weak inhibition of brain medium-chain acyl-CoA synthetases by salicylic acid (IC(50) = 1.8 mm). These findings suggest that salicylic acid and diclofenac exhibit different mechanisms of inhibition of fatty acid metabolism depending on the length of the acyl chain and tissues, and they may contribute to the further understanding of the toxic effects associated with these drugs.

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

    PubMed Central

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

    2015-01-01

    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 liver but not in adipose tissue or skeletal muscle in 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 [3H]-palmitate were also abrogated in hepatocytes 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 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

  7. Characterization of acyl chain position in unsaturated phosphatidylcholines using differential mobility-mass spectrometry[S

    PubMed Central

    Maccarone, Alan T.; Duldig, Jackson; Mitchell, Todd W.; Blanksby, Stephen J.; Duchoslav, Eva; Campbell, J. Larry

    2014-01-01

    Glycerophospholipids (GPs) that differ in the relative position of the two fatty acyl chains on the glycerol backbone (i.e., sn-positional isomers) can have distinct physicochemical properties. The unambiguous assignment of acyl chain position to an individual GP represents a significant analytical challenge. Here we describe a workflow where phosphatidylcholines (PCs) are subjected to ESI for characterization by a combination of differential mobility spectrometry and MS (DMS-MS). When infused as a mixture, ions formed from silver adduction of each phospholipid isomer {e.g., [PC (16:0/18:1) + Ag]+ and [PC (18:1/16:0) + Ag]+} are transmitted through the DMS device at discrete compensation voltages. Varying their relative amounts allows facile and unambiguous assignment of the sn-positions of the fatty acyl chains for each isomer. Integration of the well-resolved ion populations provides a rapid method (< 3 min) for relative quantification of these lipid isomers. The DMS-MS results show excellent agreement with established, but time-consuming, enzymatic approaches and also provide superior accuracy to methods that rely on MS alone. The advantages of this DMS-MS method in identification and quantification of GP isomer populations is demonstrated by direct analysis of complex biological extracts without any prior fractionation. PMID:24939921

  8. Alteration of the specificity and regulation of fatty acid synthesis of Escherichia coli by expression of a plant medium-chain acyl-acyl carrier protein thioesterase.

    PubMed

    Voelker, T A; Davies, H M

    1994-12-01

    The expression of a plant (Umbellularia californica) medium-chain acyl-acyl carrier protein (ACP) thioesterase (BTE) cDNA in Escherichia coli results in a very high level of extractable medium-chain-specific hydrolytic activity but causes only a minor accumulation of medium-chain fatty acids. BTE's full impact on the bacterial fatty acid synthase is apparent only after expression in a strain deficient in fatty acid degradation, in which BTE increases the total fatty acid output of the bacterial cultures fourfold. Laurate (12:0), normally a minor fatty acid component of E. coli, becomes predominant, is secreted into the medium, and can accumulate to a level comparable to the total dry weight of the bacteria. Also, large quantities of 12:1, 14:0, and 14:1 are made. At the end of exponential growth, the pathway of saturated fatty acids is almost 100% diverted by BTE to the production of free medium-chain fatty acids, starving the cells for saturated acyl-ACP substrates for lipid biosynthesis. This results in drastic changes in membrane lipid composition from predominantly 16:0 to 18:1. The continued hydrolysis of medium-chain ACPs by the BTE causes the bacterial fatty acid synthase to produce fatty acids even when membrane production has ceased in stationary phase, which shows that the fatty acid synthesis rate can be uncoupled from phospholipid biosynthesis and suggests that acyl-ACP intermediates might normally act as feedback inhibitors for fatty acid synthase. As the fatty acid synthesis is increasingly diverted to medium chains with the onset of stationary phase, the rate of C12 production increases relative to C14 production. This observation is consistent with activity of the BTE on free acyl-ACP pools, as opposed to its interaction with fatty acid synthase-bound substrates.

  9. 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

  10. Accumulation of medium-chain, saturated fatty acyl moieties in seed oils of transgenic Camelina sativa.

    PubMed

    Hu, Zhaohui; Wu, Qian; Dalal, Jyoti; Vasani, Naresh; Lopez, Harry O; Sederoff, Heike W; Qu, Rongda

    2017-01-01

    With its high seed oil content, the mustard family plant Camelina sativa has gained attention as a potential biofuel source. As a bioenergy crop, camelina has many advantages. It grows on marginal land with low demand for water and fertilizer, has a relatively short life cycle, and is stress tolerant. As most other crop seed oils, camelina seed triacylglycerols (TAGs) consist of mostly long, unsaturated fatty acyl moieties, which is not desirable for biofuel processing. In our efforts to produce shorter, saturated chain fatty acyl moieties in camelina seed oil for conversion to jet fuel, a 12:0-acyl-carrier thioesterase gene, UcFATB1, from California bay (Umbellularia californica Nutt.) was expressed in camelina seeds. Up to 40% of short chain laurate (C12:0) and myristate (C14:0) were present in TAGs of the seed oil of the transgenics. The total oil content and germination rate of the transgenic seeds were not affected. Analysis of positions of these two fatty acyl moieties in TAGs indicated that they were present at the sn-1 and sn-3 positions, but not sn-2, on the TAGs. Suppression of the camelina KASII genes by RNAi constructs led to higher accumulation of palmitate (C16:0), from 7.5% up to 28.5%, and further reduction of longer, unsaturated fatty acids in seed TAGs. Co-transformation of camelina with both constructs resulted in enhanced accumulation of all three medium-chain, saturated fatty acids in camelina seed oils. Our results show that a California bay gene can be successfully used to modify the oil composition in camelina seed and present a new biological alternative for jet fuel production.

  11. Accumulation of medium-chain, saturated fatty acyl moieties in seed oils of transgenic Camelina sativa

    PubMed Central

    Dalal, Jyoti; Vasani, Naresh; Lopez, Harry O.; Sederoff, Heike W.

    2017-01-01

    With its high seed oil content, the mustard family plant Camelina sativa has gained attention as a potential biofuel source. As a bioenergy crop, camelina has many advantages. It grows on marginal land with low demand for water and fertilizer, has a relatively short life cycle, and is stress tolerant. As most other crop seed oils, camelina seed triacylglycerols (TAGs) consist of mostly long, unsaturated fatty acyl moieties, which is not desirable for biofuel processing. In our efforts to produce shorter, saturated chain fatty acyl moieties in camelina seed oil for conversion to jet fuel, a 12:0-acyl-carrier thioesterase gene, UcFATB1, from California bay (Umbellularia californica Nutt.) was expressed in camelina seeds. Up to 40% of short chain laurate (C12:0) and myristate (C14:0) were present in TAGs of the seed oil of the transgenics. The total oil content and germination rate of the transgenic seeds were not affected. Analysis of positions of these two fatty acyl moieties in TAGs indicated that they were present at the sn-1 and sn-3 positions, but not sn-2, on the TAGs. Suppression of the camelina KASII genes by RNAi constructs led to higher accumulation of palmitate (C16:0), from 7.5% up to 28.5%, and further reduction of longer, unsaturated fatty acids in seed TAGs. Co-transformation of camelina with both constructs resulted in enhanced accumulation of all three medium-chain, saturated fatty acids in camelina seed oils. Our results show that a California bay gene can be successfully used to modify the oil composition in camelina seed and present a new biological alternative for jet fuel production. PMID:28212406

  12. 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

  13. Medium-chain acyl-CoA dehydrogenase deficiency in children with non-ketotic hypoglycemia and low carnitine levels.

    PubMed

    Stanley, C A; Hale, D E; Coates, P M; Hall, C L; Corkey, B E; Yang, W; Kelley, R I; Gonzales, E L; Williamson, J R; Baker, L

    1983-11-01

    Three children in two families presented in early childhood with episodes of illness associated with fasting which resembled Reye's syndrome: coma, hypoglycemia, hyperammonemia, and fatty liver. One child died with cerebral edema during an episode. Clinical studies revealed an absence of ketosis on fasting (plasma beta-hydroxybutyrate less than 0.4 mmole/liter) despite elevated levels of free fatty acids (2.6-4.2 mmole/liter) which suggested that hepatic fatty acid oxidation was impaired. Urinary dicarboxylic acids were elevated during illness or fasting. Total carnitine levels were low in plasma (18-25 mumole/liter), liver (200-500 nmole/g), and muscle (500-800 nmole/g); however, treatment with L-carnitine failed to correct the defect in ketogenesis. Studies on ketone production from fatty acid substrates by liver tissue in vitro showed normal rates from short-chain fatty acids, but very low rates from all medium and long-chain fatty acid substrates. These results suggested that the defect was in the mid-portion of the intramitochondrial beta-oxidation pathway at the medium-chain acyl-CoA dehydrogenase step. A new assay for the electron transfer flavoprotein-linked acyl-CoA dehydrogenases was used to test this hypothesis. This assay follows the decrease in electron transfer flavoprotein fluorescence as it is reduced by acyl-CoA-acyl-CoA dehydrogenase complex. Results with octanoyl-CoA as substrate indicated that patients had less than 2.5% normal activity of medium-chain acyl-CoA dehydrogenase. The activities of short-chain and isovaleryl acyl-CoA dehydrogenases were normal; the activity of long-chain acyl-CoA dehydrogenase was one-third normal. These results define a previously unrecognized inherited metabolic disorder of fatty acid oxidation due to deficiency of medium-chain acyl-CoA dehydrogenase.

  14. Structural identification of skin ceramides containing ω-hydroxy acyl chains using mass spectrometry.

    PubMed

    Wu, Zhexue; Shon, Jong Cheol; Kim, Jong Yei; Cho, Yunhi; Liu, Kwang-Hyeon

    2016-10-01

    The stratum corneum (SC) acts as a barrier that protects organisms against the environment and from transepidermal water loss. It consists of corneocytes embedded in a matrix of lipid metabolites (ceramides, cholesterol, and free fatty acids). Of these lipids, ceramides are sphingolipids consisting of sphingoid bases, linked to fatty acyl chains. Typical fatty acid acyl chains are composed of α-hydroxy fatty acids (A), esterified ω-hydroxy fatty acids (EO), non-hydroxy fatty acids (N), and ω-hydroxy fatty acids (O). Of these, O-type ceramides are ester-linked via their ω-hydroxyl group to proteins in the cornified envelope and can be released and extracted following mild alkaline hydrolysis. Tandem mass spectrometry (MS/MS) analysis of O-type ceramides using chip-based direct infusion nanoelectrospray-ion trap mass spectrometry generated the characteristic fragmentation pattern of both acyl and sphingoid units, suggesting that this method could be applied to the structural identification of O-type ceramides. Based on the MS/MS fragmentation patterns of O-type ceramides, comprehensive fragmentation schemes are proposed. In addition, we have also developed a method for identifying and profiling O-type ceramides in the mouse and guinea pig SC. This information may be used to identify O-type ceramides in the SC of animal skin.

  15. Characterization of a novel long-chain acyl-CoA thioesterase from Alcaligenes faecalis.

    PubMed

    Shahi, Puja; Kumar, Ish; Sharma, Ritu; Sanger, Shefali; Jolly, Ravinder S

    2006-06-01

    A novel long-chain acyl-CoA thioesterase from Alcaligenes faecalis has been isolated and characterized. The protein was extracted from the cells with 1 m NaCl, which required 1.5-fold, single-step purification to yield near-homogeneous preparations. In solution, the protein exists as homomeric aggregates, of mean diameter 21.6 nm, consisting of 22-kDa subunits. MS/MS data for peptides obtained by trypsin digestion of the thiosterase did not match any peptide from Escherichia coli thioesterases or any other thioesterases in the database. The thioesterase was associated exclusively with the surface of cells as revealed by ultrastructural studies using electron microscopy and immunogold labeling. It hydrolyzed saturated and unsaturated fatty acyl-CoAs of C12 to C18 chain length with Vmax and Km of 3.58-9.73 micromol x min(-1) x (mg protein)(-1) and 2.66-4.11 microm, respectively. A catalytically important histidine residue is implicated in the active site of the enzyme. The thioesterase was active and stable over a wide range of temperature and pH. Maximum activity was observed at 65 degrees C and pH 10.5, and varied between 60% and 80% at temperatures of 25-70 degrees C and pH 6.5-10. The thioesterase also hydrolyzed p-nitrophenyl esters of C2 to C12 chain length, but substrate competition experiments demonstrated that the long-chain acyl-CoAs are better substrates for thioesterase than p-nitrophenyl esters. When assayed at 37 and 20 degrees C, the affinity and catalytic efficiency of the thioesterase for palmitoleoyl-CoA and cis-vaccenoyl-CoA were reduced approximately twofold at the lower temperature, but remained largely unaltered for palmitoyl-CoA.

  16. 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.

  17. 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.

  18. Acyl-CoA dehydrogenase 9 (ACAD 9) is the long-chain acyl-CoA dehydrogenase in human embryonic and fetal brain.

    PubMed

    Oey, N A; Ruiter, J P N; Ijlst, L; Attie-Bitach, T; Vekemans, M; Wanders, R J A; Wijburg, F A

    2006-07-21

    We recently reported the expression and activity of several fatty acid oxidation enzymes in human embryonic and fetal tissues including brain and spinal cord. Liver and heart showed expression of both very long-chain acyl-CoA dehydrogenase (VLCAD) and long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) mRNA. However, while mRNA expression of LCHAD could be clearly detected in the retina and spinal cord, expression of VLCAD mRNA was low to undetectable in these tissues. Nevertheless, abundant acyl-CoA dehydrogenase (ACAD) activity was detected with palmitoyl-CoA as substrate in fetal central nervous tissue. These conflicting data suggested the presence of a different long-chain ACAD in human embryonic and fetal brain. In this study, using in situ hybridization as well as enzymatic studies, we identified acyl-CoA dehydrogenase 9 (ACAD 9) as the long-chain ACAD in human embryonic and fetal central nervous tissue. Until now, no clinical signs and symptoms of central nervous system involvement have been reported in VLCAD deficiency. A novel long-chain FAO defect, i.e., ACAD 9 deficiency with only central nervous system involvement, could, if not lethal during intra uterine development, easily escape proper diagnosis, since probably no classical signs and symptoms of FAO deficiency will be observed. Screening for ACAD 9 deficiency in patients with undefined neurological symptoms and/or impairment in neurological development of unknown origin is necessary to establish if ACAD 9 deficiency exists as a separate disease entity.

  19. Continuous recording of long-chain acyl-coenzyme a synthetase activity using fluorescently labeled bovine serum albumin.

    PubMed

    Demant, E J; Nystrøm, B T

    2001-08-01

    The fluorescence-based long-chain fatty acid probe BSA-HCA (bovine serum albumin labeled with 7-hydroxycoumarin-4-acetic acid) is shown to respond to binding of long-chain acyl-CoA thioesters by quenching of the 450 nm fluorescence emission. As determined by spectrofluorometric titration, binding affinities for palmitoyl-, stearoyl-, and oleoyl-CoA (Kd = 0.2-0.4 microM) are 5-10 times lower than those for the corresponding nonesterified fatty acids. In the presence of detergent (Chaps, Triton X-100, n-octylglucoside) above the critical micelle concentration, acyl-CoA partitions from BSA-HCA and into the detergent micelles. This allows BSA-HCA to be used as a fluorescent probe for continuous recording of fatty acid concentrations in detergent solution with little interference from acyl-CoA. Using a calibration of the fluorescence signal with fatty acids in the C14 to C20 chain-length range, fatty acid consumption by Pseudomonas fragi and rat liver microsomal acyl-CoA synthetase activities are measured down to 0.05 microM/min with a data sampling rate of 10 points per second. This new method provides a very promising spectrofluorometric approach to the study of acyl-CoA synthetase reaction kinetics at physiologically relevant (nM) aqueous phase concentrations of fatty acid substrates and at a time resolution that cannot be obtained in isotopic sampling or enzyme-coupled assays.

  20. Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency: diagnosis by acylcarnitine analysis in blood.

    PubMed Central

    Van Hove, J L; Zhang, W; Kahler, S G; Roe, C R; Chen, Y T; Terada, N; Chace, D H; Iafolla, A K; Ding, J H; Millington, D S

    1993-01-01

    Medium-chain acyl-coenzyme A dehydrogenase (MCAD) deficiency is a disorder of fatty acid catabolism, with autosomal recessive inheritance. The disease is characterized by episodic illness associated with potentially fatal hypoglycemia and has a relatively high frequency. A rapid and reliable method for the diagnosis of MCAD deficiency is highly desirable. Analysis of specific acylcarnitines was performed by isotope-dilution tandem mass spectrometry on plasma or whole blood samples from 62 patients with MCAD deficiency. Acylcarnitines were also analyzed in 42 unaffected relatives of patients with MCAD deficiency and in other groups of patients having elevated plasma C8 acylcarnitine, consisting of 32 receiving valproic acid, 9 receiving medium-chain triglyceride supplement, 4 having multiple acyl-coenzyme A dehydrogenase deficiency, and 8 others with various etiologies. Criteria for the unequivocal diagnosis of MCAD deficiency by acylcarnitine analysis are an elevated C8-acylcarnitine concentration (> 0.3 microM), a ratio of C8/C10 acylcarnitines of > 5, and lack of elevated species of chain length > C10. These criteria were not influenced by clinical state, carnitine treatment, or underlying genetic mutation, and no false-positive or false-negative results were obtained. The same criteria were also successfully applied to profiles from neonatal blood spots retrieved from the original Guthrie cards of eight patients. Diagnosis of MCAD deficiency can therefore be made reliably through the analysis of acylcarnitines in blood, including presymptomatic neonatal recognition. Tandem mass spectrometry is a convenient method for fast and accurate determination of all relevant acylcarnitine species. PMID:8488845

  1. Functional reconstitution of the Mycobacterium tuberculosis long-chain acyl-CoA carboxylase from multiple acyl-CoA subunits.

    PubMed

    Bazet Lyonnet, Bernardo; Diacovich, Lautaro; Gago, Gabriela; Spina, Lucie; Bardou, Fabienne; Lemassu, Anne; Quémard, Annaïk; Gramajo, Hugo

    2017-02-21

    Mycobacterium tuberculosis produces a large number of structurally diverse lipids that have been implicated in the pathogenicity, persistence and antibiotic resistance of this organism. Most building blocks involved in the biosynthesis of all these lipids are generated by acyl-CoA carboxylases (ACCase) whose subunit composition and physiological roles have not yet been clearly established. A rather controversial data in the literature refers to the exact protein composition and substrate specificity of the enzyme complex that produces the long-chain α-carboxy-acyl-CoAs; one of the substrates involved in the last step of condensation mediated by the polyketide synthase Pks13 to synthesize mature mycolic acids. Here we have successfully reconstituted the so called long-chain acyl-CoA carboxylase complex (LCC) from its purified components: the α-subunit AccA3, the ε-subunit AccE5 and the two β-subunits AccD4 and AccD5, and demonstrated that the four subunits are essential for its LCC activity. Furthermore, we also showed by substrate competition experiments and the use of a specific inhibitor of the AccD5 subunit, that its role in the carboxylation of the long acyl-CoAs, as part of the LCC complex, was structural rather than catalytic. Moreover, AccD5 was also able to carboxylate its natural substrates, acetyl-CoA and propionyl-CoA, in the context of the LCC enzyme complex. Thus, the supercomplex formed by these four subunits has the potential to generate the main substrates, malonyl-CoA, methylmalonyl-CoA and α-carboxy-C24-26 -CoA, used as condensing units for the biosynthesis of all the lipids present in this pathogen. This article is protected by copyright. All rights reserved.

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

    PubMed Central

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

    2006-01-01

    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. PMID:16511283

  3. Ceramide acyl chain length markedly influences miscibility with palmitoyl sphingomyelin in bilayer membranes.

    PubMed

    Westerlund, Bodil; Grandell, Pia-Maria; Isaksson, Y Jenny E; Slotte, J Peter

    2010-07-01

    Ceramides are precursors of major sphingolipids and can be important cellular effectors. The biological effects of ceramides have been suggested to stem from their biophysical effects on membrane structure affecting the lateral and transbilayer organization of other membrane components. In this study we investigated the effect of acyl chain composition in ceramides (C4-C24:1) on their miscibility with N-palmitoyl-sphingomyelin (PSM) using differential scanning calorimetry. We found that short-chain (C4 and C8) ceramides induced phase separation and lowered the T (m) and enthalpy of the PSM endotherm. We conclude that short-chain ceramides were more miscible in the fluid-phase than in the gel-phase PSM bilayers. Long-chain ceramides induced apparent heterogeneity in the bilayers. The main PSM endotherm decreased in cooperativity and enthalpy with increasing ceramide concentration. New ceramide-enriched components could be seen in the thermograms at all ceramide concentrations above X (Cer) = 0.05. These broad components had higher T (m) values than pure PSM. C24:1 ceramide exhibited complex behavior in the PSM bilayers. The miscibility of C24:1 ceramide with PSM at low (X (Cer) = 0.05-0.10) concentrations was exceptionally good according to the cooperativity of the transition. At higher concentrations, multiple components were detected, which might have arisen from interdigitated gel-phases formed by this very asymmetric ceramide. The results of this study indicate that short-chain and long-chain ceramides have very different effects on the sphingomyelin bilayers. There also seems to be a correlation between their miscibility in binary systems and the effect of ceramides of different hydrophobic length on sphingomyelin-rich domains in multicomponent membranes.

  4. Lipid transfer between phosphatidylcholine vesicles and human erythrocytes: exponential decrease in rate with increasing acyl chain length.

    PubMed

    Ferrell, J E; Lee, K J; Huestis, W H

    1985-06-04

    The rate of phospholipid transfer from sonicated phospholipid vesicles to human erythrocytes has been studied as a function of membrane concentration and lipid acyl chain composition. Phospholipid transfer exhibits saturable first-order kinetics with respect to both cell and vesicle membrane concentrations. This kinetic behavior is consistent either with transfer during transient contact between cell and vesicle surfaces (but only if the fraction of the cell surface susceptible to such interaction is small) or with transfer of monomers through the aqueous phase. The acyl chain composition of the transferred phospholipid affects the transfer kinetics profoundly; for homologous saturated phosphatidylcholines, the rate of transfer decreases exponentially with increasing acyl chain length. This behavior is consistent with passage of phospholipid monomers through a polar phase, which might be the bulk aqueous phase( as in the monomer transfer model) or the hydrated head-group regions of a cell-vesicle complex (transient collision model). Collisional transfer also predicts that intercell transfer of phospholipids should be slow compared to cell-vesicle transfer, as surface charge and steric effects should prevent close apposition of donor and acceptor membranes. This is not found; dilauroylphosphatidylcholine transfers rapidly between red cells. Thus, the observed relationship between acyl chain length and intermembrane phospholipid transfer rates likely reflects the energetics of monomer transfer through the aqueous phase.

  5. Genomic analysis of branched chain fatty acid and acyl sugar production in Solanum pennellii and Nicotiana benthamiana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Acyl sugars are extracellular epidermal lipids that are exuded from glandular trichomes and coat the aerial organs of many species in the Solanaceae. These highly viscous surfactants, which often contain branched-chain fatty acids (BCFA), play an important defensive role against pest and insects. ...

  6. Unsaturated acyl chains dramatically enhanced cellular uptake by direct translocation of a minimalist oligo-arginine lipopeptide.

    PubMed

    Swiecicki, J-M; Di Pisa, M; Lippi, F; Chwetzoff, S; Mansuy, C; Trugnan, G; Chassaing, G; Lavielle, S; Burlina, F

    2015-10-07

    The recurring issue with cell penetrating peptides is how to increase direct translocation vs. endocytosis, to avoid premature degradation. Acylation by a cis unsaturated chain (C22:6) of a short cationic peptide provides a new rational design to favour diffuse cytosolic and dense Golgi localisations.

  7. ACX3, a Novel Medium-Chain Acyl-Coenzyme A Oxidase from Arabidopsis

    PubMed Central

    Froman, Byron E.; Edwards, Patricia C.; Bursch, Adam G.; Dehesh, Katayoon

    2000-01-01

    In a database search for homologs of acyl-coenzyme A oxidases (ACX) in Arabidopsis, we identified a partial genomic sequence encoding an apparently novel member of this gene family. Using this sequence information we then isolated the corresponding full-length cDNA from etiolated Arabidopsis cotyledons and have characterized the encoded recombinant protein. The polypeptide contains 675 amino acids. The 34 residues at the amino terminus have sequence similarity to the peroxisomal targeting signal 2 of glyoxysomal proteins, including the R-[I/Q/L]-X5-HL-XL-X15-22-C consensus sequence, suggesting a possible microsomal localization. Affinity purification of the encoded recombinant protein expressed in Escherichia coli followed by enzymatic assay, showed that this enzyme is active on C8:0- to C14:0-coenzyme A with maximal activity on C12:0-coenzyme A, indicating that it has medium-chain-specific activity. These data indicate that the protein reported here is different from previously characterized classes of ACX1, ACX2, and short-chain ACX (SACX), both in sequence and substrate chain-length specificity profile. We therefore, designate this new gene AtACX3. The temporal and spatial expression patterns of AtACX3 during development and in various tissues were similar to those of the AtSACX and other genes expressed in glyoxysomes. Currently available database information indicates that AtACX3 is present as a single copy gene. PMID:10859203

  8. 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.

  9. Determination of individual long-chain fatty acyl-CoA esters in heart and skeletal muscle.

    PubMed

    Molaparast-Saless, F; Shrago, E; Spennetta, T L; Donatello, S; Kneeland, L M; Nellis, S H; Liedtke, A J

    1988-05-01

    A method has been developed for determination of individual long-chain fatty acyl-CoA esters from heart and skeletal muscle using high performance liquid chromatography (HPLC). The esters were extracted from freeze-clamped tissue of pig and rat hearts and rat skeletal muscle for analysis on a radially compressed C18 5mu reverse-phase column. Nine peaks in the extract with carbon chain lengths from C12 to C20 that subsequently disappeared on alkaline hydrolysis were identified. The major acyl-CoA peaks were 14:1, 18:2, 16:0 and 18:1 and additionally in rat heart 18:0. Total long-chain acyl-CoA esters obtained by summation of the individual molecular species was 11.34 +/- 1.48 nmol/g wet wt. pig heart; 14.51 +/- 2.11 nmol/g wet wt. in rat heart, and 4.35 +/- 0.71 nmol/g wet wt. in rat skeletal muscle. These values were approximately 132% of those obtained using a separate procedure that measured total CoA by HPLC after alkaline hydrolysis of the esters. The described method demonstrates the quantitation of individual acyl-CoA species in muscle tissue. Therefore, it has a number of advantages in that it permits information to be obtained on the individual molecular species under various nutritional and metabolic conditions.

  10. Purification and Characterization of a Novel Pumpkin Short-Chain Acyl-Coenzyme A Oxidase with Structural Similarity to Acyl-Coenzyme A Dehydrogenases

    PubMed Central

    De Bellis, Luigi; Gonzali, Silvia; Alpi, Amedeo; Hayashi, Hiroshi; Hayashi, Makoto; Nishimura, Mikio

    2000-01-01

    A novel pumpkin (Cucurbita pepo) short-chain acyl-coenzyme A (CoA) oxidase (ACOX) was purified to homogeneity by hydrophobic-interaction, hydroxyapatite, affinity, and anion-exchange chromatography. The purified enzyme is a tetrameric protein, consisting of apparently identical 47-kD subunits. The protein structure of this oxidase differs from other plant and mammalian ACOXs, but is similar to the protein structure of mammalian mitochondrial acyl-CoA dehydrogenase (ACDH) and the recently identified plant mitochondrial ACDH. Subcellular organelle separation by sucrose density gradient centrifugation revealed that the enzyme is localized in glyoxysomes, whereas no immunoreactive bands of similar molecular weight were detected in mitochondrial fractions. The enzyme selectively catalyzes the oxidation of CoA esters of fatty acids with 4 to 10 carbon atoms, and exhibits the highest activity on C-6 fatty acids. Apparently, the enzyme has no activity on CoA esters of branched-chain or dicarboxylic fatty acids. The enzyme is slightly inhibited by high concentrations of substrate and it is not inhibited by Triton X-100 at concentrations up to 0.5% (v/v). The characteristics of this novel ACOX enzyme are discussed in relation to other ACOXs and ACDHs. PMID:10806249

  11. Effect of ceramide acyl chain length on skin permeability and thermotropic phase behavior of model stratum corneum lipid membranes.

    PubMed

    Janůšová, Barbora; Zbytovská, Jarmila; Lorenc, Petr; Vavrysová, Helena; Palát, Karel; Hrabálek, Alexandr; Vávrová, Kateřina

    2011-03-01

    Stratum corneum ceramides play an essential role in the barrier properties of skin. However, their structure-activity relationships are poorly understood. We investigated the effects of acyl chain length in the non-hydroxy acyl sphingosine type (NS) ceramides on the skin permeability and their thermotropic phase behavior. Neither the long- to medium-chain ceramides (8-24 C) nor free sphingosine produced any changes of the skin barrier function. In contrast, the short-chain ceramides decreased skin electrical impedance and increased skin permeability for two marker drugs, theophylline and indomethacin, with maxima in the 4-6C acyl ceramides. The thermotropic phase behavior of pure ceramides and model stratum corneum lipid membranes composed of ceramide/lignoceric acid/cholesterol/cholesterol sulfate was studied by differential scanning calorimetry and infrared spectroscopy. Differences in thermotropic phase behavior of these lipids were found: those ceramides that had the greatest impact on the skin barrier properties displayed the lowest phase transitions and formed the least dense model stratum corneum lipid membranes at 32°C. In conclusion, the long hydrophobic chains in the NS-type ceramides are essential for maintaining the skin barrier function. However, this ability is not shared by their short-chain counterparts despite their having the same polar head structure and hydrogen bonding ability.

  12. Acyl chain preference and inhibitor identification of Moraxella catarrhalis LpxA: Insight through crystal structure and computational studies.

    PubMed

    Pratap, Shivendra; Kesari, Pooja; Yadav, Ravi; Dev, Aditya; Narwal, Manju; Kumar, Pravindra

    2017-03-01

    Lipopolysaccharide (LPS) is an important surface component and a potential virulence factor in the pathogenesis of Gram-negative bacteria. UDP-N-acetylglucosamine acyltransferase (LpxA) enzyme catalyzes the first reaction of LPS biosynthesis, reversible transfer of R-3-hydroxy-acyl moiety from donor R-3-hydroxy-acyl-acyl carrier protein to the 3' hydroxyl position of UDP-N-acetyl-glucosamine. LpxA enzyme's essentiality in bacterial survival and absence of any homologous protein in humans makes it a promising target for anti-bacterial drug development. Herein, we present the crystal structure of Moraxella catarrhalis LpxA (McLpxA). We propose that L171 is responsible for limiting the acyl chain length in McLpxA to 10C or 12C. The study reveals the plausible interactions between the highly conserved clusters of basic residues at the C-terminal end of McLpxA and acidic residues of acyl carrier protein (ACP). Furthermore, the crystal structure of McLpxA was used to screen potential inhibitors from NCI open database using various computational approaches viz. pharmacophore mapping, virtual screening and molecular docking. Molecules Mol212032, Mol609399 and Mol152546 showed best binding affinity with McLpxA among all screened molecules. These molecules mimic the substrate-LpxA binding interactions.

  13. Retrospective study of the medium-chain acyl-CoA dehydrogenase deficiency in Portugal.

    PubMed

    Ventura, F V; Leandro, P; Luz, A; Rivera, I A; Silva, M F B; Ramos, R; Rocha, H; Lopes, A; Fonseca, H; Gaspar, A; Diogo, L; Martins, E; Leão-Teles, E; Vilarinho, L; Tavares de Almeida, I

    2014-06-01

    Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is the commonest genetic defect of mitochondrial fatty acid β-oxidation. About 60% of MCADD patients are homozygous for the c.985A>G (p.Lys329Glu) mutation in the ACADM gene (G985 allele). Herein, we present the first report on the molecular and biochemical spectrum of Portuguese MCADD population. From the 109 patients studied, 83 were diagnosed after inclusion of MCADD in the national newborn screening, 8 following the onset of symptoms and 18 through segregation studies. Gypsy ancestry was identified in 85/109 patients. The G985 allele was found in homozygosity in 102/109 patients, in compound heterozygosity in 6/109 and was absent in one patient. Segregation studies in the Gypsy families showed that 93/123 relatives were carriers of the G985 allele, suggesting its high prevalence in this ethnic group. Additionally, three new substitutions-c.218A>G (p.Tyr73Cys), c.503A>T (p.Asp168Val) and c.1205G>T (p.Gly402Val)-were identified. Despite the particularity of the MCADD population investigated, the G985 allele was found in linkage disequilibrium with H1(112) haplotype. Furthermore, two novel haplotypes, H5(212) and H6(122) were revealed.

  14. Medium chain acyl-CoA dehydrogenase deficiency detected among Hispanics by New Jersey newborn screening.

    PubMed

    Anderson, Sharon; Botti, Christina; Li, Bo; Millonig, James H; Lyon, Elaine; Millson, Alison; Karabin, Suzanne S M; Brooks, Susan Sklower

    2012-09-01

    In the follow-up of New Jersey newborn screens suggestive of medium chain acyl-CoA dehydrogenase deficiency (MCADD) during a 30-month period, we identified five patients of Hispanic American ethnicity. With information provided by the New Jersey Department of Health and Human Services Newborn Screening program we calculated an overall cumulative incidence of approximately 7.20/100,000 for MCADD; 7.58/100,000 among Hispanic Americans and 7.08/100,000 among non-Hispanic Americans. Among the five Hispanic American infants who screened positive, a common variant (c.443G>A [p.R148K]) was identified which accounted for 30% of the alleles; c.799G>A (p.G267R) and c.985A>G (p.K329E) each accounted for an additional 20%; and a novel variant c.302G>A (p.G101E) was identified in one patient. Although treated prospectively during interim illnesses to prevent unwanted sequelae; till date, none of the patients carrying the c.443G>A variant have been symptomatic.

  15. 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).

  16. Enzymatic Transesterification of Kraft Lignin with Long Acyl Chains in Ionic Liquids.

    PubMed

    Hulin, Lise; Husson, Eric; Bonnet, Jean-Pierre; Stevanovic, Tatjana; Sarazin, Catherine

    2015-09-09

    Valorization of lignin is essential for the economic viability of the biorefinery concept. For example, the enhancement of lignin hydrophobicity by chemical esterification is known to improve its miscibility in apolar polyolefin matrices, thereby helping the production of bio-based composites. To this end and due to its many reactive hydroxyl groups, lignin is a challenging macromolecular substrate for biocatalyzed esterification in non-conventional media. The present work describes for the first time the lipase-catalyzed transesterification of Kraft lignin in ionic liquids (ILs). Three lipases, three 1-butyl-3-methylimidazolium based ILs and ethyl oleate as long chain acyl donor were selected. Best results were obtained with a hydrophilic/hydrophobic binary IL system (1-butyl-3-methylimidazolium trifluoromethanesulfonate/1-butyl-3-methylimidazolium hexafluoro- phosphate, 1/1 v/v) and the immobilized lipase B from Candida antarctica (CALB) that afforded a promising transesterification yield (ca. 30%). Similar performances were achieved by using 1-butyl-3-methylimidazolium hexafluorophosphate as a coating agent for CALB rather than as a co-solvent in 1-butyl-3-methylimidazolium trifluoromethane-sulfonate thus limiting the use of hydrophobic IL. Structural characterization of lignin oleate was performed by spectroscopic studies (FTIR and ¹H-NMR). The synthesized lignin oleate exhibited interesting thermal and textural properties, different from those of the original Kraft lignin.

  17. 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.

  18. Enhanced production of branched-chain fatty acids by replacing β-ketoacyl-(acyl-carrier-protein) synthase III (FabH).

    PubMed

    Jiang, Wen; Jiang, Yanfang; Bentley, Gayle J; Liu, Di; Xiao, Yi; Zhang, Fuzhong

    2015-08-01

    Branched-chain fatty acids (BCFAs) are important precursors for the production of advanced biofuels with improved cold-flow properties. Previous efforts in engineering type II fatty acid synthase (FAS) for BCFA production suffered from low titers and/or the co-production of a large amount of straight-chain fatty acids (SCFAs), making it nearly impossible for further conversion of BCFAs to branched biofuels. Synthesis of both SCFAs and BCFAs requires FabH, the only β-ketoacyl-(acyl-carrier-protein) synthase in Escherichia coli that catalyzes the initial condensation reaction between malonyl-ACP and a short-chain acyl-CoA. In this study, we demonstrated that replacement of the acetyl-CoA-specific E. coli FabH with a branched-chain-acyl-CoA-specific FabH directed the flux to the synthesis of BCFAs, resulting in a significant enhancement in BCFA titer compared to a strain containing both acetyl-CoA- and branched-chain-acyl-CoA-specific FabHs. We further demonstrated that the composition of BCFAs can be tuned by engineering the upstream pathway to control the supply of different branched-chain acyl-CoAs, leading to the production either even-chain-iso-, odd-chain-iso-, or odd-chain-anteiso-BCFAs separately. Overall, the top-performing strain from this study produced BCFAs at 126 mg/L, comprising 52% of the total free fatty acids.

  19. Screening for medium chain acyl-CoA dehydrogenase deficiency using electrospray ionisation tandem mass spectrometry

    PubMed Central

    Clayton, P.; Doig, M.; Ghafari, S.; Meaney, C.; Taylor, C.; Leonard, J.; Morris, M.; Johnson, A.

    1998-01-01

    OBJECTIVE—To establish criteria for the diagnosis of medium chain acyl-CoA dehydrogenase (MCAD) deficiency in the UK population using a method in which carnitine species eluted from blood spots are butylated and analysed by electrospray ionisation tandem mass spectrometry (ESI-MS/MS).
DESIGN—Four groups were studied: (1) 35 children, aged 4 days to 16.2 years, with proven MCAD deficiency (mostly homozygous for the A985G mutation, none receiving carnitine supplements); (2) 2168control children; (3) 482 neonates; and (4) 15 MCAD heterozygotes.
RESULTS—All patients with MCAD deficiency had an octanoylcarnitine concentration ([C8-Cn]) > 0.38 µM and no accumulation of carnitine species > C10 or < C6. Among the patients with MCAD deficiency, the [C8-Cn] was significantly lower in children > 10 weeks old and in children with carnitine depletion (free carnitine < 20 µM). Neonatal blood spots from patients with MCAD deficiency had a [C8-Cn] > 1.5 µM, whereas in heterozygotes and other normal neonates the [C8-Cn] was < 1.0 µM. In contrast, the blood spot [C8-Cn] in eight of 27 patients with MCAD deficiency > 10 weeks old fell within the same range as five of 15 MCAD heterozygotes (0.38-1.0 µM). However, the free carnitine concentrations were reduced (< 20 µM) in the patients with MCAD deficiency but normal in the heterozygotes.
CONCLUSIONS—Criteria for the diagnosis of MCAD deficiency using ESI-MS/MS must take account of age and carnitine depletion. If screening is undertaken at 7-10 days, the number of false positive and negative results should be negligible. Because there have been no instances of death or neurological damage following diagnosis of MCAD deficiency in our patient group, a strong case can be made for neonatal screening for MCAD deficiency in the UK.

 PMID:9797589

  20. Unusual Heme Iron-Lipid Acyl Chain Coordination in Escherichia coli Flavohemoglobin

    PubMed Central

    D'Angelo, Paola; Lucarelli, Debora; della Longa, Stefano; Benfatto, Maurizio; Hazemann, Jean Louis; Feis, Alessandro; Smulevich, Giulietta; Ilari, Andrea; Bonamore, Alessandra; Boffi, Alberto

    2004-01-01

    Escherichia coli flavohemoglobin is endowed with the notable property of binding specifically unsaturated and/or cyclopropanated fatty acids both as free acids or incorporated into a phospholipid molecule. Unsaturated or cyclopropanated fatty acid binding to the ferric heme results in a spectral change observed in the visible absorption, resonance Raman, extended x-ray absorption fine spectroscopy (EXAFS), and x-ray absorption near edge spectroscopy (XANES) spectra. Resonance Raman spectra, measured on the flavohemoglobin heme domain, demonstrate that the lipid (linoleic acid or total lipid extracts)-induced spectral signals correspond to a transition from a five-coordinated (typical of the ligand-free protein) to a hexacoordinated, high spin heme iron. EXAFS and XANES measurements have been carried out both on the lipid-free and on the lipid-bound protein to assign the nature of ligand in the sixth coordination position of the ferric heme iron. EXAFS data analysis is consistent with the presence of a couple of atoms in the sixth coordination position at 2.7 Å in the lipid-bound derivative (bonding interaction), whereas a contribution at 3.54 Å (nonbonding interaction) can be singled out in the lipid-free protein. This last contribution is assigned to the CD1 carbon atoms of the distal LeuE11, in full agreement with crystallographic data on the lipid-free protein at 1.6 Å resolution obtained in the present work. Thus, the contributions at 2.7 Å distance from the heme iron are assigned to a couple of carbon atoms of the lipid acyl chain, possibly corresponding to the unsaturated carbons of the linoleic acid. PMID:15189885

  1. Ceramides with a pentadecasphingosine chain and short acyls have strong permeabilization effects on skin and model lipid membranes.

    PubMed

    Školová, Barbora; Janůšová, Barbora; Vávrová, Kateřina

    2016-02-01

    The composition and organization of stratum corneum lipids play an essential role in skin barrier function. Ceramides represent essential components of this lipid matrix; however, the importance of the individual structural features in ceramides is not fully understood. To probe the structure-permeability relationships in ceramides, we prepared analogs of N-lignoceroylsphingosine with shortened sphingosine (15 and 12 carbons) and acyl chains (2, 4 and 6 carbons) and studied their behavior in skin and in model lipid membranes. Ceramide analogs with pentadecasphingosine (15C) chains were more barrier-perturbing than 12C- and 18C-sphingosine ceramides; the greatest effects were found with 4 to 6C acyls (up to 15 times higher skin permeability compared to an untreated control and up to 79 times higher permeability of model stratum corneum lipid membranes compared to native very long-chain ceramides). Infrared spectroscopy using deuterated lipids and X-ray powder diffraction showed surprisingly similar behavior of the short ceramide membranes in terms of lipid chain order and packing, phase transitions and domain formation. The high- and low-permeability membranes differed in their amide I band shape and lamellar organization. These skin and membrane permeabilization properties of some short ceramides may be explored, for example, for the rational design of permeation enhancers for transdermal drug delivery.

  2. Acyl chain length and saturation modulate interleaflet coupling in asymmetric bilayers: effects on dynamics and structural order.

    PubMed

    Chiantia, Salvatore; London, Erwin

    2012-12-05

    A long-standing question about membrane structure and function is the degree to which the physical properties of the inner and outer leaflets of a bilayer are coupled to one another. Using our recently developed methods to prepare asymmetric vesicles, coupling was investigated for vesicles containing phosphatidylcholine (PC) in the inner leaflet and sphingomyelin (SM) in the outer leaflet. The coupling of both lateral diffusion and membrane order was monitored as a function of PC and SM acyl chain structure. The presence in the outer leaflet of brain SM, which decreased outer-leaflet lateral diffusion, had little effect upon lateral diffusion in inner leaflets composed of dioleoyl PC (i.e., diffusion was only weakly coupled in the two leaflets) but did greatly reduce lateral diffusion in inner leaflets composed of PC with one saturated and one oleoyl acyl chain (i.e., diffusion was strongly coupled in these cases). In addition, reduced outer-leaflet diffusion upon introduction of outer-leaflet milk SM or a synthetic C24:0 SM, both of which have long interdigitating acyl chains, also greatly reduce diffusion of inner leaflets composed of dioleoyl PC, indicative of strong coupling. Strikingly, several assays showed that the ordering of the outer leaflet induced by the presence of SM was not reflected in increased lipid order in the inner leaflet, i.e., there was no detectable coupling between inner and outer leaflet membrane order. We propose a model for how lateral diffusion can be coupled in opposite leaflets and discuss how this might impact membrane function.

  3. α-Ketoheterocycle Inhibitors of Fatty Acid Amide Hydrolase: Exploration of Conformational Constraints in the Acyl Side Chain

    PubMed Central

    Duncan, Katharine K.; Otrubova, Katerina; Boger, Dale L.

    2014-01-01

    A series of α-ketooxazoles containing heteroatoms embedded within conformational constraints in the C2 acyl side chain of 2 (OL-135) were synthesized and evaluated as inhibitors of fatty acid amide hydrolase (FAAH). The studies reveal that the installation of a heteroatom (O) in the conformational constraint is achievable, although the potency of these novel derivatives is reduced slightly relative to 2 and the analogous 1,2,3,4-tetrahydronaphthalene series. Interestingly, both enantiomers (R and S) of the candidate inhibitors bearing a chiral center adjacent to the electrophilic carbonyl were found to effectively inhibit FAAH. PMID:24690529

  4. 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

  5. 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

  6. Pre-exercise medium-chain triglyceride application prevents acylcarnitine accumulation in skeletal muscle from very-long-chain acyl-CoA-dehydrogenase-deficient mice.

    PubMed

    Primassin, Sonja; Tucci, Sara; Herebian, Diran; Seibt, Annette; Hoffmann, Lars; ter Veld, Frank; Spiekerkoetter, Ute

    2010-06-01

    Dietary modification with medium-chain triglyceride (MCT) supplementation is one crucial way of treating children with long-chain fatty acid oxidation disorders. Recently, supplementation prior to exercise has been reported to prevent muscular pain and rhabdomyolysis. Systematic studies to determine when MCT supplementation is most beneficial have not yet been undertaken. We studied the effects of an MCT-based diet compared with MCT administration only prior to exercise in very-long-chain acyl-CoA dehydrogenase (VLCAD) knockout (KO) mice. VLCAD KO mice were fed an MCT-based diet in same amounts as normal mouse diet containing long-chain triglycerides (LCT) and were exercised on a treadmill. Mice fed a normal LCT diet received MCT only prior to exercise. Acylcarnitine concentration, free carnitine concentration, and acyl-coenzyme A (CoA) oxidation capacity in skeletal muscle as well as hepatic lipid accumulation were determined. Long-chain acylcarnitines significantly increased in VLCAD-deficient skeletal muscle with an MCT diet compared with an LCT diet with MCT bolus prior to exercise, whereas an MCT bolus treatment significantly decreased long-chain acylcarnitines after exercise compared with an LCT diet. C8-carnitine was significantly increased in skeletal muscle after MCT bolus treatment and exercise compared with LCT and long-term MCT treatment. Increased hepatic lipid accumulation was observed in long-term MCT-treated KO mice. MCT seems most beneficial when given in a single dose directly prior to exercise to prevent acylcarnitine accumulation. In contrast, continuous MCT treatment produces a higher skeletal muscle content of long-chain acylcarnitines after exercise and increases hepatic lipid storage in VLCAD KO mice.

  7. 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

  8. Clear correlation of genotype with disease phenotype in very-long-chain acyl-CoA dehydrogenase deficiency.

    PubMed Central

    Andresen, B S; Olpin, S; Poorthuis, B J; Scholte, H R; Vianey-Saban, C; Wanders, R; Ijlst, L; Morris, A; Pourfarzam, M; Bartlett, K; Baumgartner, E R; deKlerk, J B; Schroeder, L D; Corydon, T J; Lund, H; Winter, V; Bross, P; Bolund, L; Gregersen, N

    1999-01-01

    Very-long-chain acyl-CoA dehydrogenase (VLCAD) catalyzes the initial rate-limiting step in mitochondrial fatty acid beta-oxidation. VLCAD deficiency is clinically heterogenous, with three major phenotypes: a severe childhood form, with early onset, high mortality, and high incidence of cardiomyopathy; a milder childhood form, with later onset, usually with hypoketotic hypoglycemia as the main presenting feature, low mortality, and rare cardiomyopathy; and an adult form, with isolated skeletal muscle involvement, rhabdomyolysis, and myoglobinuria, usually triggered by exercise or fasting. To examine whether these different phenotypes are due to differences in the VLCAD genotype, we investigated 58 different mutations in 55 unrelated patients representing all known clinical phenotypes and correlated the mutation type with the clinical phenotype. Our results show a clear relationship between the nature of the mutation and the severity of disease. Patients with the severe childhood phenotype have mutations that result in no residual enzyme activity, whereas patients with the milder childhood and adult phenotypes have mutations that may result in residual enzyme activity. This clear genotype-phenotype relationship is in sharp contrast to what has been observed in medium-chain acyl-CoA dehydrogenase deficiency, in which no correlation between genotype and phenotype can be established. PMID:9973285

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

    PubMed

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

    2016-03-18

    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.

  10. Enrichment of hydroxylated C24- and C26-acyl-chain sphingolipids mediates PIN2 apical sorting at trans-Golgi network subdomains

    PubMed Central

    Wattelet-Boyer, Valérie; Brocard, Lysiane; Jonsson, Kristoffer; Esnay, Nicolas; Joubès, Jérôme; Domergue, Frédéric; Mongrand, Sébastien; Raikhel, Natasha; Bhalerao, Rishikesh P.; Moreau, Patrick; Boutté, Yohann

    2016-01-01

    The post-Golgi compartment trans-Golgi Network (TGN) is a central hub divided into multiple subdomains hosting distinct trafficking pathways, including polar delivery to apical membrane. Lipids such as sphingolipids and sterols have been implicated in polar trafficking from the TGN but the underlying mechanisms linking lipid composition to functional polar sorting at TGN subdomains remain unknown. Here we demonstrate that sphingolipids with α-hydroxylated acyl-chains of at least 24 carbon atoms are enriched in secretory vesicle subdomains of the TGN and are critical for de novo polar secretory sorting of the auxin carrier PIN2 to apical membrane of Arabidopsis root epithelial cells. We show that sphingolipid acyl-chain length influences the morphology and interconnections of TGN-associated secretory vesicles. Our results uncover that the sphingolipids acyl-chain length links lipid composition of TGN subdomains with polar secretory trafficking of PIN2 to apical membrane of polarized epithelial cells. PMID:27681606

  11. Differential effects of cholesterol on acyl chain order in erythrocyte membranes as a function of depth from the surface. An electron paramagnetic resonance (EPR) spin label study.

    PubMed

    Cassera, M B; Silber, A M; Gennaro, A M

    2002-10-16

    The purpose of this work is to analyze the effects of cholesterol modulation on acyl chain ordering in the membrane of human erythrocytes as a function of depth from the surface. Partial cholesterol depletion was achieved by incubation of erythrocytes with liposomes containing saturated phospholipids, or with methyl-beta-cyclodextrin (MbetaCD). Cholesterol enrichment was achieved by incubation with liposomes formed by phospholipids/cholesterol, or with the complex MbetaCD/cholesterol. Acyl chain order was studied with electron paramagnetic resonance spectroscopy (EPR) using spin labels that sense the lipid bilayer at different depths. It is shown that the increase in cholesterol stiffens acyl chains but decreases the interaction among lipid headgroups, while cholesterol depletion causes the opposite behavior. It is likely that the observed cholesterol effects are related to those stabilizing the cholesterol-rich detergent-insoluble membrane domains (rafts), recently shown to exist in erythrocytes.

  12. Carbon and Acyl Chain Flux during Stress-induced Triglyceride Accumulation by Stable Isotopic Labeling of the Polar Microalga Coccomyxa subellipsoidea C169.

    PubMed

    Allen, James W; DiRusso, Concetta C; Black, Paul N

    2017-01-06

    Deriving biofuels and other lipoid products from algae is a promising future technology directly addressing global issues of atmospheric CO2 balance. To better understand the metabolism of triglyceride synthesis in algae, we examined their metabolic origins in the model species, Coccomyxa subellipsoidea C169, using stable isotopic labeling. Labeling patterns arising from [U-(13)C]glucose, (13)CO2, or D2O supplementation were analyzed by GC-MS and/or LC-MS over time courses during nitrogen starvation to address the roles of catabolic carbon recycling, acyl chain redistribution, and de novo fatty acid (FA) synthesis during the expansion of the lipid bodies. The metabolic origin of stress-induced triglyceride was found to be a continuous 8:2 ratio between de novo synthesized FA and acyl chain transfer from pre-stressed membrane lipids with little input from lipid remodeling. Membrane lipids were continually synthesized with associated acyl chain editing during nitrogen stress, in contrast to an overall decrease in total membrane lipid. The incorporation rates of de novo synthesized FA into lipid classes were measured over a time course of nitrogen starvation. The synthesis of triglycerides, phospholipids, and galactolipids followed a two-stage pattern where nitrogen starvation resulted in a 2.5-fold increase followed by a gradual decline. Acyl chain flux into membrane lipids was dominant in the first stage followed by triglycerides. These data indicate that the level of metabolic control that determines acyl chain flux between membrane lipids and triglycerides during nitrogen stress relies primarily on the Kennedy pathway and de novo FA synthesis with limited, defined input from acyl editing reactions.

  13. 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

  14. 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

    2016-03-11

    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.

  15. 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

    2016-08-09

    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.

  16. 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

  17. Medium-chain triglycerides impair lipid metabolism and induce hepatic steatosis in very long-chain acyl-CoA dehydrogenase (VLCAD)-deficient mice.

    PubMed

    Tucci, Sara; Primassin, Sonja; Ter Veld, Frank; Spiekerkoetter, Ute

    2010-09-01

    A medium-chain-triglyceride (MCT)-based diet is mainstay of treatment in very-long-chain acyl-CoA dehydrogenase deficiency (VLCADD), a long-chain fatty acid beta-oxidation defect. Beneficial effects have been reported with an MCT-bolus prior to exercise. Little is known about the impact of a long-term MCT diet on hepatic lipid metabolism. Here we investigate the effects of MCT-supplementation on liver and blood lipids in the murine model of VLCADD. Wild-type (WT) and VLCAD-knock-out (KO) mice were fed (1) a long-chain triglyceride (LCT)-diet over 5weeks, (2) an MCT diet over 5 weeks and (3) an LCT diet plus MCT-bolus. Blood and liver lipid content were determined. Expression of genes regulating lipogenesis was analyzed by RT-PCR. Under the LCT diet, VLCAD-KO mice accumulated significantly higher blood cholesterol concentrations compared to WT mice. The MCT-diet induced severe hepatic steatosis, significantly higher serum free fatty acids and impaired hepatic lipid mobilization in VLCAD-KO mice. Expression at mRNA level of hepatic lipogenic genes was up-regulated. The long-term MCT diet stimulates lipogenesis and impairs hepatic lipid metabolism in VLCAD-KO mice. These results suggest a critical reconsideration of a long-term MCT-modified diet in human VLCADD. In contrast, MCT in situations of increased energy demand appears to be a safer treatment alternative.

  18. 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 ...

  19. 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 ...

  20. Protoxenicins A and B, Cytotoxic Long-Chain Acylated Xenicanes from the Soft Coral Protodendron repens.

    PubMed

    Urda, Carlos; Fernández, Rogelio; Pérez, Marta; Rodríguez, Jaime; Jiménez, Carlos; Cuevas, Carmen

    2017-03-24

    Two new xenicanes, named protoxenicins A (1) and B (2), were isolated from an organic extract of the soft coral Protodendron repens, collected off the coast of Okuza (Tanzania), being the first chemical study of an organism belonging to this genus. Their planar structures were determined by 1D and 2D NMR and HRESIMS techniques, while the relative configurations were elucidated by comparison of their chemical shifts and coupling constants with the literature values of their congeners, as well as by ROESY experiments, chemical derivatization, and molecular mechanics calculations. This is the first report of a xenicin acylated with a long saturated fatty acid. Furthermore, the absolute configuration of the stereogenic centers of the cyclononane ring and at C-1 in 1 was determined by Mosher's method. Protoxenicin B (2) is present in solution as a mixture of two conformers in a 2:1 ratio deduced by (1)H NMR. Both xenicanes display significant cytotoxic activity against a panel of different tumor cell lines.

  1. Characterization of carnitine and fatty acid metabolism in the long-chain acyl-CoA dehydrogenase-deficient mouse

    PubMed Central

    van Vlies, Naomi; Tian, Liqun; Overmars, Henk; Bootsma, Albert H.; Kulik, Willem; Wanders, Ronald J. A.; Wood, Philip A.; Vaz, Frédéric M.

    2004-01-01

    In the present paper, we describe a novel method which enables the analysis of tissue acylcarnitines and carnitine biosynthesis intermediates in the same sample. This method was used to investigate the carnitine and fatty acid metabolism in wild-type and LCAD−/− (long-chain acyl-CoA dehydrogenase-deficient) mice. In agreement with previous results in plasma and bile, we found accumulation of the characteristic C14:1-acylcarnitine in all investigated tissues from LCAD−/− mice. Surprisingly, quantitatively relevant levels of 3-hydroxyacylcarnitines were found to be present in heart, muscle and brain in wild-type mice, suggesting that, in these tissues, long-chain 3-hydroxyacyl-CoA dehydrogenase is rate-limiting for mitochondrial β-oxidation. The 3-hydroxyacylcarnitines were absent in LCAD−/− tissues, indicating that, in this situation, the β-oxidation flux is limited by the LCAD deficiency. A profound deficiency of acetylcarnitine was observed in LCAD−/− hearts, which most likely corresponds with low cardiac levels of acetyl-CoA. Since there was no carnitine deficiency and only a marginal elevation of potentially cardiotoxic acylcarnitines, we conclude from these data that the cardiomyopathy in the LCAD−/− mouse is caused primarily by a severe energy deficiency in the heart, stressing the important role of LCAD in cardiac fatty acid metabolism in the mouse. PMID:15535801

  2. 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

  3. Hepatic expression of long-chain acyl-CoA synthetase 3 is upregulated in hyperlipidemic hamsters.

    PubMed

    Wu, Minhao; Liu, Haiyan; Chen, Wei; Fujimoto, Yasuyuki; Liu, Jingwen

    2009-11-01

    Members of the mammalian long-chain acyl-CoA synthetase (ACSL) family are key enzymes for cellular fatty acid metabolism that catalyze the initial step in activation of long-chain fatty acids. However, the specificity of individual isoforms of ACSL to the lipid metabolic process is not well studied. In addition, the regulation of expression of individual ACSL isoforms under hyperlipidemic conditions is largely unknown. We cloned the hamster ACSL3 cDNA coding region and generated specific antibodies recognizing the ACSL3 protein. We next observed the changes in ACSL3 mRNA and protein expression in hamsters fed a standard chow diet or a high fat and high cholesterol (HFHC) diet. HFHC feeding significantly increased ACSL3 mRNA and protein expression in liver and to a lesser extent in muscle but not in adipose, brain, heart, or testis. Additionally, ACSL3 mRNA abundance was differentially regulated by the nutritional status in different tissues with liver, muscle, and adipose being the most sensitive tissues. Importantly, the hepatic ACSL3 mRNA expression pattern in response to fasting and refeeding in hyperlipidemic hamsters differed from that observed in normal chow-fed hamsters. Together, these results provide the first in vivo evidence of altered regulation of hepatic ACSL3 expression under hyperlipidemic conditions and suggest important regulatory roles for this enzyme in lipid metabolism.

  4. 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.

  5. Anesthetic agents in patients with very long-chain acyl-coenzyme A dehydrogenase deficiency: a literature review.

    PubMed

    Redshaw, Charlotte; Stewart, Catherine

    2014-11-01

    Very long-chain acyl-coenzyme A dehydrongenase deficiency (VLCADD) is a rare disorder of fatty acid metabolism that renders sufferers susceptible to hypoglycemia, liver failure, cardiomyopathy, and rhabdomyolysis. The literature about the management of these patients is hugely conflicting, suggesting that both propofol and volatile anesthesia should be avoided. We have reviewed the literature and have concluded that the source papers do not support the statements that volatile anesthetic agents are unsafe. The reports on rhabdomyolysis secondary to anesthesia appear to be due to inadequate supply of carbohydrate not volatile agents. Catabolism must be avoided with minimal fasting, glucose infusions based on age and weight, and attenuation of emotional and physical stress. General anesthesia appears to be protective of stress-induced catabolism and may offer benefits in children and anxious patients over regional anesthesia. Propofol has not been demonstrated to be harmful in VLCADD but is presented in an emulsion containing very long-chain fatty acids which can cause organ lipidosis and itself can inhibit mitochondrial fatty acid metabolism. It is therefore not recommended. Suxamethonium-induced myalgia may mimic symptoms of rhabdomyolysis and cause raised CK therefore should be avoided. Opioids, NSAIDS, regional anesthesia, and local anesthetic techniques have all been used without complication.

  6. Sunflower (Helianthus annuus) long-chain acyl-coenzyme A synthetases expressed at high levels in developing seeds.

    PubMed

    Aznar-Moreno, Jose A; Venegas Calerón, Mónica; Martínez-Force, Enrique; Garcés, Rafael; Mullen, Robert; Gidda, Satinder K; Salas, Joaquín J

    2014-03-01

    Long chain fatty acid synthetases (LACSs) activate the fatty acid chains produced by plastidial de novo biosynthesis to generate acyl-CoA derivatives, important intermediates in lipid metabolism. Oilseeds, like sunflower, accumulate high levels of triacylglycerols (TAGs) in their seeds to nourish the embryo during germination. This requires that sunflower seed endosperm supports very active glycerolipid synthesis during development. Sunflower seed plastids produce large amounts of fatty acids, which must be activated through the action of LACSs, in order to be incorporated into TAGs. We cloned two different LACS genes from developing sunflower endosperm, HaLACS1 and HaLACS2, which displayed sequence homology with Arabidopsis LACS9 and LACS8 genes, respectively. These genes were expressed at high levels in developing seeds and exhibited distinct subcellular distributions. We generated constructs in which these proteins were fused to green fluorescent protein and performed transient expression experiments in tobacco cells. The HaLACS1 protein associated with the external envelope of tobacco chloroplasts, whereas HaLACS2 was strongly bound to the endoplasmic reticulum. Finally, both proteins were overexpressed in Escherichia coli and recovered as active enzymes in the bacterial membranes. Both enzymes displayed similar substrate specificities, with a very high preference for oleic acid and weaker activity toward stearic acid. On the basis of our findings, we discuss the role of these enzymes in sunflower oil synthesis.

  7. 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

  8. Only One of the Five Ralstonia solanacearum Long-Chain 3-Ketoacyl-Acyl Carrier Protein Synthase Homologues Functions in Fatty Acid Synthesis

    PubMed Central

    Cheng, Juanli; Ma, Jincheng; Lin, Jinshui; Fan, Zhen-Chuan; Cronan, John E.

    2012-01-01

    Ralstonia solanacearum, a major phytopathogenic bacterium, causes a bacterial wilt disease in diverse plants. Although fatty acid analyses of total membranes of R. solanacearum showed that they contain primarily palmitic (C16:0), palmitoleic (C16:1) and cis-vaccenic (C18:1) acids, little is known regarding R. solanacearum fatty acid synthesis. The R. solanacearum GMI1000 genome is unusual in that it contains four genes (fabF1, fabF2, fabF3, and fabF4) annotated as encoding 3-ketoacyl-acyl carrier protein synthase II homologues and one gene (fabB) annotated as encoding 3-ketoacyl-acyl carrier protein synthase I. We have analyzed this puzzling apparent redundancy and found that only one of these genes, fabF1, encoded a long-chain 3-ketoacyl-acyl carrier protein synthase, whereas the other homologues did not play roles in R. solanacearum fatty acid synthesis. Mutant strains lacking fabF1 are nonviable, and thus, FabF1 is essential for R. solanacearum fatty acid biosynthesis. Moreover, R. solanacearum FabF1 has the activities of both 3-ketoacyl-acyl carrier protein synthase II and 3-ketoacyl-acyl carrier protein synthase I. PMID:22194290

  9. Only one of the five Ralstonia solanacearum long-chain 3-ketoacyl-acyl carrier protein synthase homologues functions in fatty acid synthesis.

    PubMed

    Cheng, Juanli; Ma, Jincheng; Lin, Jinshui; Fan, Zhen-Chuan; Cronan, John E; Wang, Haihong

    2012-03-01

    Ralstonia solanacearum, a major phytopathogenic bacterium, causes a bacterial wilt disease in diverse plants. Although fatty acid analyses of total membranes of R. solanacearum showed that they contain primarily palmitic (C(16:0)), palmitoleic (C(16:1)) and cis-vaccenic (C(18:1)) acids, little is known regarding R. solanacearum fatty acid synthesis. The R. solanacearum GMI1000 genome is unusual in that it contains four genes (fabF1, fabF2, fabF3, and fabF4) annotated as encoding 3-ketoacyl-acyl carrier protein synthase II homologues and one gene (fabB) annotated as encoding 3-ketoacyl-acyl carrier protein synthase I. We have analyzed this puzzling apparent redundancy and found that only one of these genes, fabF1, encoded a long-chain 3-ketoacyl-acyl carrier protein synthase, whereas the other homologues did not play roles in R. solanacearum fatty acid synthesis. Mutant strains lacking fabF1 are nonviable, and thus, FabF1 is essential for R. solanacearum fatty acid biosynthesis. Moreover, R. solanacearum FabF1 has the activities of both 3-ketoacyl-acyl carrier protein synthase II and 3-ketoacyl-acyl carrier protein synthase I.

  10. 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.

    PubMed

    Vandevoorde, Séverine; Saha, Bijali; Mahadevan, Anu; Razdan, Raj K; Pertwee, Roger G; Martin, Billy R; Fowler, Christopher J

    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 (IC50 values in the range 5.1-8.2 microM), whereas the two compounds with a single unsaturated bond were less potent (IC50 values 19 and 21 microM). 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 IC50 values of 12 and 32 microM, respectively. The 22-carbon chain analogue of 1-AG was also potent (IC50 value 4.5 microM). 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.

  11. 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.

  12. Interfacial interactions of ceramide with dimyristoylphosphatidylcholine: impact of the N-acyl chain.

    PubMed

    Holopainen, J M; Brockman, H L; Brown, R E; Kinnunen, P K

    2001-02-01

    The mixing behavior of dimyristoylphosphatidylcholine (DMPC) with either N-palmitoyl-sphingosine (C16:0-ceramide) or N-nervonoyl-sphingosine (C24:1-ceramide) was examined using monomolecular films. While DMPC forms highly elastic liquid-expanded monolayers, both neat C16:0-ceramide and C24:1-ceramide yield stable solid condensed monomolecular films with small areas and low interfacial elasticity. Compression isotherms of mixed C16:0-ceramide/DMPC films exhibit an apparent condensation upon increasing X(cer16:0) at all surface pressures. The average area isobars, coupled with the lack of a liquid-expanded to condensed phase transition as X(cer16:0) is increased, are indicative of immiscibility of the lipids at all surface pressures. In contrast, isobars for C24:1-ceramide/DMPC mixtures show surface pressure-dependent apparent condensation or expansion and surface pressure-area isotherms show a composition and surface pressure-dependent phase transition. This suggests miscibility, albeit non-ideal, of C24:1-ceramide and DMPC in both liquid and condensed surface phases. The above could be verified by fluorescence microscopy of the monolayers and measurements of surface potential, which revealed distinctly different domain morphologies and surface potential values for the DMPC/C16:0- and DMPC/C24:1-ceramide monolayers. Taken together, whereas C16:0-ceramide and DMPC form immiscible pseudo-compounds, C24:1-ceramide and DMPC are partially miscible in both the liquid-expanded and condensed phases, and a composition and lateral pressure-dependent two-phase region is evident between the liquid-expanded and condensed regimes. Our results provide novel understanding of the regulation of membrane properties by ceramides and raise the possibility that ceramides with different acyl groups could serve very different functions in cells, relating to their different physicochemical properties.

  13. Interfacial interactions of ceramide with dimyristoylphosphatidylcholine: impact of the N-acyl chain.

    PubMed Central

    Holopainen, J M; Brockman, H L; Brown, R E; Kinnunen, P K

    2001-01-01

    The mixing behavior of dimyristoylphosphatidylcholine (DMPC) with either N-palmitoyl-sphingosine (C16:0-ceramide) or N-nervonoyl-sphingosine (C24:1-ceramide) was examined using monomolecular films. While DMPC forms highly elastic liquid-expanded monolayers, both neat C16:0-ceramide and C24:1-ceramide yield stable solid condensed monomolecular films with small areas and low interfacial elasticity. Compression isotherms of mixed C16:0-ceramide/DMPC films exhibit an apparent condensation upon increasing X(cer16:0) at all surface pressures. The average area isobars, coupled with the lack of a liquid-expanded to condensed phase transition as X(cer16:0) is increased, are indicative of immiscibility of the lipids at all surface pressures. In contrast, isobars for C24:1-ceramide/DMPC mixtures show surface pressure-dependent apparent condensation or expansion and surface pressure-area isotherms show a composition and surface pressure-dependent phase transition. This suggests miscibility, albeit non-ideal, of C24:1-ceramide and DMPC in both liquid and condensed surface phases. The above could be verified by fluorescence microscopy of the monolayers and measurements of surface potential, which revealed distinctly different domain morphologies and surface potential values for the DMPC/C16:0- and DMPC/C24:1-ceramide monolayers. Taken together, whereas C16:0-ceramide and DMPC form immiscible pseudo-compounds, C24:1-ceramide and DMPC are partially miscible in both the liquid-expanded and condensed phases, and a composition and lateral pressure-dependent two-phase region is evident between the liquid-expanded and condensed regimes. Our results provide novel understanding of the regulation of membrane properties by ceramides and raise the possibility that ceramides with different acyl groups could serve very different functions in cells, relating to their different physicochemical properties. PMID:11159444

  14. Arabidopsis CER8 encodes LONG-CHAIN ACYL-COA SYNTHETASE 1 (LACS1) that has overlapping functions with LACS2 in plant wax and cutin synthesis.

    PubMed

    Lü, Shiyou; Song, Tao; Kosma, Dylan K; Parsons, Eugene P; Rowland, Owen; Jenks, Matthew A

    2009-08-01

    Plant cuticle is an extracellular lipid-based matrix of cutin and waxes, which covers aerial organs and protects them from many forms of environmental stress. We report here the characterization of CER8/LACS1, one of nine Arabidopsis long-chain acyl-CoA synthetases thought to activate acyl chains. Mutations in LACS1 reduced the amount of wax in all chemical classes on the stem and leaf, except in the very long-chain fatty acid (VLCFA) class wherein acids longer than 24 carbons (C(24)) were elevated more than 155%. The C(16) cutin monomers on lacs1 were reduced by 37% and 22%, whereas the C(18) monomers were increased by 28% and 20% on stem and leaf, respectively. Amounts of wax and cutin on a lacs1-1 lacs2-3 double mutant were much lower than on either parent, and lacs1-1 lacs2-3 had much higher cuticular permeability than either parent. These additive effects indicate that LACS1 and LACS2 have overlapping functions in both wax and cutin synthesis. We demonstrated that LACS1 has synthetase activity for VLCFAs C(20)-C(30), with highest activity for C(30) acids. LACS1 thus appears to function as a very long-chain acyl-CoA synthetase in wax metabolism. Since C(16) but not C(18) cutin monomers are reduced in lacs1, and C(16) acids are the next most preferred acid (behind C(30)) by LACS1 in our assays, LACS1 also appears to be important for the incorporation of C(16) monomers into cutin polyester. As such, LACS1 defines a functionally novel acyl-CoA synthetase that preferentially modifies both VLCFAs for wax synthesis and long-chain (C(16)) fatty acids for cutin synthesis.

  15. Elevated Temperature Enhances Short to Medium Chain Acyl Homoserine Lactone Production by Black Band Disease Associated Vibrios.

    PubMed

    Bhedi, Chinmayee D; Prevatte, Carson W; Lookadoo, Maggie S; Waikel, Patricia A; Gillevet, Patrick M; Sikaroodi, Masoumeh; Campagna, Shawn R; Richardson, Laurie L

    2017-01-29

    Black band disease (BBD) of corals is a horizontally migrating, pathogenic, polymicrobial mat community which is active above a temperature threshold of 27.5°C on the reef. Bacterial isolates from BBD, the surface mucopolysaccharide layer (SML) of healthy corals, and SML of healthy areas of BBD infected corals were tested for production of short to medium chain acyl homoserine lactones (AHLs) using the Chromobacterium violaceum CV026 reporter strain. Of 110 bacterial isolates tested, 19 produced AHLs and 15 of these were from BBD. Eight AHLs were identified using LC-MS/MS, with 3OHC4 the most commonly produced, followed by C6. AHL-producing isolates exposed to three temperatures (24°, 27°, 30°C) revealed that production of three AHLs (3OHC4, 3OHC5, and 3OHC6) significantly increased at 30°C when compared to 24°C. 16S rRNA gene sequencing revealed that all of the AHL producing BBD isolates were vibrios. Metagenomic data of BBD communities showed the presence of AHL (and autoinducer-2) genes, many of which are known to be associated with vibrios. These findings suggest that quorum sensing may be involved in BBD pathobiology and community structure due to enhanced production of quorum sensing signal molecules (AHLs) above the temperature threshold of this globally distributed coral disease.

  16. 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

  17. 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.

  18. Functional effects of different medium-chain acyl-CoA dehydrogenase genotypes and identification of asymptomatic variants.

    PubMed

    Sturm, Marga; Herebian, Diran; Mueller, Martina; Laryea, Maurice D; Spiekerkoetter, Ute

    2012-01-01

    Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency (OMIM 201450) is the most common inherited disorder of fatty acid metabolism presenting with hypoglycaemia, hepatopathy and Reye-like symptoms during catabolism. In the past, the majority of patients carried the prevalent c.985A>G mutation in the ACADM gene. Since the introduction of newborn screening many other mutations with unknown clinical relevance have been identified in asymptomatic newborns. In order to identify functional effects of these mutant genotypes we correlated residual MCAD (OMIM 607008) activities as measured by octanoyl-CoA oxidation in lymphocytes with both genotype and relevant medical reports in 65 newborns harbouring mutant alleles. We identified true disease-causing mutations with residual activities of 0 to 20%. In individuals carrying the c.199T>C or c.127G>A mutation on one allele, residual activities were much higher and in the range of heterozygotes (31%-60%). Therefore, both mutations cannot clearly be associated with a clinical phenotype. This demonstrates a correlation between the octanoyl-CoA oxidation rate in lymphocytes and the clinical outcome. With newborn screening, the natural course of disease is difficult to assess. The octanoyl-CoA oxidation rate, therefore, allows a risk assessment at birth and the identification of new ACADM genotypes associated with asymptomatic disease variants.

  19. 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.

  20. 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.

  1. Genetic association of long-chain acyl-CoA synthetase 1 variants with fasting glucose, diabetes, and subclinical atherosclerosis[S

    PubMed Central

    Manichaikul, Ani; Wang, Xin-Qun; Zhao, Wei; Wojczynski, Mary K.; Siebenthall, Kyle; Stamatoyannopoulos, John A.; Saleheen, Danish; Borecki, Ingrid B.; Reilly, Muredach P.; Rich, Stephen S.; Bornfeldt, Karin E.

    2016-01-01

    Long-chain acyl-CoA synthetase 1 (ACSL1) converts free fatty acids into acyl-CoAs. Mouse studies have revealed that ACSL1 channels acyl-CoAs to β-oxidation, thereby reducing glucose utilization, and is required for diabetes-accelerated atherosclerosis. The role of ACSL1 in humans is unknown. We therefore examined common variants in the human ACSL1 locus by genetic association studies for fasting glucose, diabetes status, and preclinical atherosclerosis by using the MAGIC and DIAGRAM consortia; followed by analyses in participants from the Multi-Ethnic Study of Atherosclerosis, the Penn-T2D consortium, and a meta-analysis of subclinical atherosclerosis in African Americans; and finally, expression quantitative trait locus analysis and identification of DNase I hypersensitive sites (DHS). The results show that three SNPs in ACSL1 (rs7681334, rs735949, and rs4862423) are associated with fasting glucose or diabetes status in these large (>200,000 subjects) data sets. Furthermore, rs4862423 is associated with subclinical atherosclerosis and coincides with a DHS highly accessible in human heart. SNP rs735949 is in strong linkage disequilibrium with rs745805, significantly associated with ACSL1 levels in skin, suggesting tissue-specific regulatory mechanisms. This study provides evidence in humans of ACSL1 SNPs associated with fasting glucose, diabetes, and subclinical atherosclerosis and suggests links among these traits and acyl-CoA synthesis. PMID:26711138

  2. Multiple erythroid isoforms of human long-chain acyl-CoA synthetases are produced by switch of the fatty acid gate domains

    PubMed Central

    Soupene, Eric; Kuypers, Frans A

    2006-01-01

    Background The formation of acyl-CoA by the action of acyl-CoA synthetases plays a crucial role in membrane lipid turnover, including the plasma membrane of erythrocytes. In human, five Acyl-CoA Synthetase Long-chain (ACSL) genes have been identified with as many as 3 different transcript variants for each. Results Acyl-CoA Synthetase Long-chain member 6 (ACSL6) is responsible for activation of long-chain fatty acids in erythrocytes. Two additional transcript variants were also isolated from brain and testis. We report the expression in reticulocytes of two new variants and of the one isolated from brain. All three represented different spliced variants of a mutually exclusive exon pair. They encode a slightly different short motif which contains a conserved structural domain, the fatty acid Gate domain. The motifs differ in the presence of either the aromatic residue phenylalanine (Phe) or tyrosine (Tyr). Based on homology, two new isoforms for the closely related ACSL1 were predicted and characterized. One represented a switch of the Phe- to the Tyr-Gate domain motif, the other resulted from the exclusion of both. Swapping of this motif also appears to be common in all mammalian ACSL member 1 and 6 homologs. Conclusion We propose that a Phe to Tyr substitution or deletion of the Gate domain, is the structural reason for the conserved alternative splicing that affects these motifs. Our findings support our hypothesis that this region is structurally important to define the activity of these enzymes. PMID:16834775

  3. Successful Treatment of Cardiomyopathy due to Very Long-Chain Acyl-CoA Dehydrogenase Deficiency: First Case Report from Oman with Literature Review

    PubMed Central

    Sharef, Sharef Waadallah; Al-Senaidi, Khalfan; Joshi, Surendra Nath

    2013-01-01

    Very long-chain acyl-CoA dehydrogenase deficiency (MIM 201475) is a severe defect of mitochondrial energy production from oxidation of very long-chain fatty acids. This inherited metabolic disorder often presents in early neonatal period with episodes of symptomatic hypoglycemia usually responding well to intravenous glucose infusion. These babies are often discharged without establishment of diagnosis but return by 2-5 months of age with severe and progressive cardiac failure due to hypertrophic cardiomyopathy with or without hepatic failure and steatosis. An early diagnosis and treatment with high concentration medium chain triglycerides based feeding formula can be life saving in such patients. Here, we report the first diagnosed and treated case of Very long-chain acyl-CoA dehydrogenase deficiency in Oman. This infant developed heart failure with left ventricular dilation, hypertrophy and pericardial effusion at the age of 7 weeks. Prompt diagnosis and subsequent intervention with medium chain triglycerides-based formula resulted in a reversal of severe clinical symptoms with significant improvement of cardiac status. This treatment also ensured normal growth and neurodevelopment. It is stressed that the disease must be recognized by the pediatricians and cardiologists since the disease can be identified by Tandem Mass Spectrometry; therefore, it should be considered to be included in expanded newborn screening program, allowing early diagnosis and intervention in order to ensure better outcome and prevent complications. PMID:24044064

  4. Suppression of long chain acyl-CoA synthetase 3 decreases hepatic de novo fatty acid synthesis through decreased transcriptional activity.

    PubMed

    Bu, So Young; Mashek, Mara T; Mashek, Douglas G

    2009-10-30

    Long chain acyl-CoA synthetases (ACSL) and fatty acid transport proteins (FATP) activate fatty acids to acyl-CoAs in the initial step of fatty acid metabolism. Numerous isoforms of ACSL and FATP exist with different tissue distribution patterns, intracellular locations, and substrate preferences, suggesting that each isoform has distinct functions in channeling fatty acids into different metabolic pathways. Because fatty acids, acyl-CoAs, and downstream lipid metabolites regulate various transcription factors that control hepatic energy metabolism, we hypothesized that ACSL or FATP isoforms differentially regulate hepatic gene expression. Using small interference RNA (siRNA), we knocked down each liver-specific ACSL and FATP isoform in rat primary hepatocyte cultures and subsequently analyzed reporter gene activity of numerous transcription factors and performed quantitative mRNA analysis of their target genes. Compared with control cells, which were transfected with control siRNA, knockdown of acyl-CoA synthetase 3 (ACSL3) significantly decreased reporter gene activity of several lipogenic transcription factors such as peroxisome proliferator activation receptor-gamma, carbohydrate-responsive element-binding protein, sterol regulatory element-binding protein-1c, and liver X receptor-alpha and the expression of their target genes. These findings were further supported by metabolic labeling studies that showed [1-(14)C]acetate incorporation into lipid extracts was decreased in cells treated with ACSL3 siRNAs and that ACSL3 expression is up-regulated in ob/ob mice and mice fed a high sucrose diet. ACSL3 knockdown decreased total acyl-CoA synthetase activity without substantially altering the expression of other ACSL isoforms. In summary, these results identify a novel role for ACSL3 in mediating transcriptional control of hepatic lipogenesis.

  5. PPARδ activation induces hepatic long-chain acyl-CoA synthetase 4 expression in vivo and in vitro

    PubMed Central

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

    2017-01-01

    The arachidonic acid preferred long-chain acyl-CoA synthetase 4 (ACSL4) is a key enzyme for fatty acid metabolism in various metabolic tissues. In this study, we utilized hamsters fed a normal chow diet, a high-fat diet or a high cholesterol and high fat diet (HCHFD) as animal models to explore novel transcriptional regulatory mechanisms for ACSL4 expression under hyperlipidemic conditions. Through cloning hamster ACSL4 homolog and tissue profiling ACSL4 mRNA and protein expressions we observed a selective upregulation of ACSL4 in testis and liver of HCHFD fed animals. Examination of transcriptional activators of the ACSL family revealed an increased hepatic expression of PPARδ but not PPARα in HCHFD fed hamsters. To explore a role of PPARδ in dietary cholesterol-mediated upregulation of ACSL4, we administered a PPARδ specific agonist L165041 to normolipidemic and dyslipidemic hamsters. We observed significant increases of hepatic ACSL4 mRNA and protein levels in all L165041-treated hamsters as compared to control animals. The induction of ACSL4 expression by L165041 in liver tissue in vivo was recapitulated in human primary hepatocytes and hepatocytes isolated from hamster and mouse. Moreover, employing the approach of adenovirus-mediated gene knockdown, we showed that depletion of PPARδ in hamster hepatocytes specifically reduced ACSL4 expression. Finally, utilizing HepG2 as a model system, we demonstrate that PPARδ activation leads to increased ACSL4 promoter activity, mRNA and protein expression, and consequently higher arachidonoyl-CoA synthetase activity. Taken together, we have discovered a novel PPARδ-mediated regulatory mechanism for ACSL4 expression in liver tissue and cultured hepatic cells. PMID:25645621

  6. PPARδ activation induces hepatic long-chain acyl-CoA synthetase 4 expression in vivo and in vitro.

    PubMed

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

    2015-05-01

    The arachidonic acid preferred long-chain acyl-CoA synthetase 4 (ACSL4) is a key enzyme for fatty acid metabolism in various metabolic tissues. In this study, we utilized hamsters fed a normal chow diet, a high-fat diet or a high cholesterol and high fat diet (HCHFD) as animal models to explore novel transcriptional regulatory mechanisms for ACSL4 expression under hyperlipidemic conditions. Through cloning hamster ACSL4 homolog and tissue profiling ACSL4 mRNA and protein expressions we observed a selective upregulation of ACSL4 in testis and liver of HCHFD fed animals. Examination of transcriptional activators of the ACSL family revealed an increased hepatic expression of PPARδ but not PPARα in HCHFD fed hamsters. To explore a role of PPARδ in dietary cholesterol-mediated upregulation of ACSL4, we administered a PPARδ specific agonist L165041 to normolipidemic and dyslipidemic hamsters. We observed significant increases of hepatic ACSL4 mRNA and protein levels in all L165041-treated hamsters as compared to control animals. The induction of ACSL4 expression by L165041 in liver tissue in vivo was recapitulated in human primary hepatocytes and hepatocytes isolated from hamster and mouse. Moreover, employing the approach of adenovirus-mediated gene knockdown, we showed that depletion of PPARδ in hamster hepatocytes specifically reduced ACSL4 expression. Finally, utilizing HepG2 as a model system, we demonstrate that PPARδ activation leads to increased ACSL4 promoter activity, mRNA and protein expression, and consequently higher arachidonoyl-CoA synthetase activity. Taken together, we have discovered a novel PPARδ-mediated regulatory mechanism for ACSL4 expression in liver tissue and cultured hepatic cells.

  7. 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/.

  8. 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.

  9. Isolation of a Saccharomyces cerevisiae long chain fatty acyl:CoA synthetase gene (FAA1) and assessment of its role in protein N- myristoylation

    PubMed Central

    1992-01-01

    Regulation of myristoylCoA pools in Saccharomyces cerevisiae plays an important role in modulating the activity of myristoylCoA:protein N- myristoyltransferase (NMT), an essential enzyme with an ordered Bi Bi reaction that catalyzes the transfer of myristate from myristoylCoA to greater than or equal to 12 cellular proteins. At least two pathways are available for generating myristoylCoA: de novo synthesis by the multifunctional, multisubunit fatty acid synthetase complex (FAS) and activation of exogenous myristate by acylCoA synthetase. The FAA1 (fatty acid activation) gene has been isolated by genetic complementation of a faal mutant. This single copy gene, which maps to the right arm of chromosome XV, specifies a long chain acylCoA synthetase of 700 amino acids. Analyses of strains containing NMT1 and a faal null mutation indicated that FAA1 is not essential for vegetative growth when an active de novo pathway for fatty acid synthesis is present. The role of FAA1 in cellular lipid metabolism and protein N-myristoylation was therefore assessed in strains subjected to biochemical or genetic blockade of FAS. At 36 degrees C, FAA1 is required for the utilization of exogenous myristate by NMT and for the synthesis of several phospholipid species. This requirement is not apparent at 24 or 30 degrees C, suggesting that S. cerevisiae contains another acylCoA synthetase activity whose chain length and/or temperature optima may differ from Faalp. PMID:1572893

  10. 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.

  11. Long-term Correction of Very Long-chain Acyl-CoA Dehydrogenase Deficiency in Mice Using AAV9 Gene Therapy

    PubMed Central

    Keeler, Allison M; Conlon, Thomas; Walter, Glenn; Zeng, Huadong; Shaffer, Scott A; Dungtao, Fu; Erger, Kirsten; Cossette, Travis; Tang, Qiushi; Mueller, Christian; Flotte, Terence R

    2012-01-01

    Very long-chain acyl-coA dehydrogenase (VLCAD) is the rate-limiting step in mitochondrial fatty acid oxidation. VLCAD-deficient mice and patients clinical symptoms stem from not only an energy deficiency but also long-chain metabolite accumulations. VLCAD-deficient mice were treated systemically with 1 × 1012 vector genomes of recombinant adeno-associated virus 9 (rAAV9)-VLCAD. Biochemical correction was observed in vector-treated mice beginning 2 weeks postinjection, as characterized by a significant drop in long-chain fatty acyl accumulates in whole blood after an overnight fast. Changes persisted through the termination point around 20 weeks postinjection. Magnetic resonance spectroscopy (MRS) and tandem mass spectrometry (MS/MS) revealed normalization of intramuscular lipids in treated animals. Correction was not observed in liver tissue extracts, but cardiac muscle extracts showed significant reduction of long-chain metabolites. Disease-specific phenotypes were characterized, including thermoregulation and maintenance of euglycemia after a fasting cold challenge. Internal body temperatures of untreated VLCAD−/− mice dropped below 20 °C and the mice became lethargic, requiring euthanasia. In contrast, all rAAV9-treated VLCAD−/− mice and the wild-type controls maintained body temperatures. rAAV9-treated VLCAD−/− mice maintained euglycemia, whereas untreated VLCAD−/− mice suffered hypoglycemia following a fasting cold challenge. These promising results suggest rAAV9 gene therapy as a potential treatment for VLCAD deficiency in humans. PMID:22395529

  12. Identification of Middle Chain Fatty Acyl-CoA Ligase Responsible for the Biosynthesis of 2-Alkylmalonyl-CoAs for Polyketide Extender Unit*

    PubMed Central

    Miyazawa, Takeshi; Takahashi, Shunji; Kawata, Akihiro; Panthee, Suresh; Hayashi, Teruo; Shimizu, Takeshi; Nogawa, Toshihiko; Osada, Hiroyuki

    2015-01-01

    Understanding the biosynthetic mechanism of the atypical polyketide extender unit is important for the development of bioactive natural products. Reveromycin (RM) derivatives produced by Streptomyces sp. SN-593 possess several aliphatic extender units. Here, we studied the molecular basis of 2-alkylmalonyl-CoA formation by analyzing the revR and revS genes, which form a transcriptional unit with the revT gene, a crotonyl-CoA carboxylase/reductase homolog. We mainly focused on the uncharacterized adenylate-forming enzyme (RevS). revS gene disruption resulted in the reduction of all RM derivatives, whereas reintroduction of the gene restored the yield of RMs. Although RevS was classified in the fatty acyl-AMP ligase clade based on phylogenetic analysis, biochemical characterization revealed that the enzyme catalyzed the middle chain fatty acyl-CoA ligase (FACL) but not the fatty acyl-AMP ligase activity, suggesting the molecular evolution for acyl-CoA biosynthesis. Moreover, we examined the in vitro conversion of fatty acid into 2-alkylmalonyl-CoA using purified RevS and RevT. The coupling reaction showed efficient conversion of hexenoic acid into butylmalonyl-CoA. RevS efficiently catalyzed C8–C10 middle chain FACL activity; therefore, we speculated that the acyl-CoA precursor was truncated via β-oxidation and converted into (E)-2-enoyl-CoA, a RevT substrate. To determine whether the β-oxidation process is involved between the RevS and RevT reaction, we performed the feeding experiment using [1,2,3,4-13C]octanoic acid. 13C NMR analysis clearly demonstrated incorporation of the [3,4-13C]octanoic acid moiety into the structure of RM-A. Our results provide insight into the role of uncharacterized RevS homologs that may catalyze middle chain FACL to produce a unique polyketide extender unit. PMID:26378232

  13. [A two-year-old infant with a myopathic form of very-long-chain Acyl-CoA dehydrogenase deficiency].

    PubMed

    Ito, Yasushi; Nakano, Kazutoshi; Shishikura, Keiko; Suzuki, Haruko; Iida, Norihisa; Sasaki, Nobutaka; Kimura, Masahiko; Hasegawa, Yuki; Yamaguchi, Seiji; Osawa, Makiko

    2003-11-01

    A two-year-three-month old girl was hospitalized for detailed examination following repeated hyper-creatine kinasemia and cervical muscle cramps induced by pyrexia and persistent hypertonicity of the cervical muscles. Physical examination showed mild hypotonia but no muscle weakness. Induction of symptoms by continuous cervical muscular exercise and the appearance of dicarboxylic aciduria during the fasting test indicated a disorder of fatty acid oxidation. Free fatty acid and acyl carnitine analyses using dried blood spots, and acyl-CoA dehydrogenase activity assays using cultured skin fibroblasts established a diagnosis of very-long-chain acyl-CoA dehydrogenase (VLCAD) deficiency. Currently VLCAD deficiency has been divided into three phenotypes; a severe childhood form, a milder childhood form, and an adult form. However, we suggest that the severe and milder childhood forms would be better described as a systemic form, and the adult form and our infant case as a myopathic form. An early onset of the myopathic form within the first year of life, as well as its diagnosis in early infancy, has never been described in the literature.

  14. Newborn screening for medium-chain acyl-CoA dehydrogenase deficiency: regional experience and high incidence of carnitine deficiency

    PubMed Central

    2013-01-01

    Background Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is the most common inherited defect in the mitochondrial fatty acid oxidation pathway, resulting in significant morbidity and mortality in undiagnosed patients. Newborn screening (NBS) has considerably improved MCADD outcome, but the risk of complication remains in some patients. The aim of this study was to evaluate the relationship between genotype, biochemical parameters and clinical data at diagnosis and during follow-up, in order to optimize monitoring of these patients. Methods We carried out a multicenter study in southwest Europe, of MCADD patients detected by NBS. Evaluated NBS data included free carnitine (C0) and the acylcarnitines C8, C10, C10:1 together with C8/C2 and C8/C10 ratios, clinical presentation parameters and genotype, in 45 patients. Follow-up data included C0 levels, duration of carnitine supplementation and occurrence of metabolic crises. Results C8/C2 ratio and C8 were the most accurate biomarkers of MCADD in NBS. We found a high number of patients homozygous for the prevalent c.985A > G mutation (75%). Moreover, in these patients C8, C8/C10 and C8/C2 were higher than in patients with other genotypes, while median value of C0 was significantly lower (23 μmol/L vs 36 μmol/L). The average follow-up period was 43 months. To keep carnitine levels within the normal range, carnitine supplementation was required in 82% of patients, and for a longer period in patients homozygotes for the c.985A>G mutation than in patients with other genotypes (average 31 vs 18 months). Even with treatment, median C0 levels remained lower in homozygous patients than in those with other genotypes (14 μmol/L vs 22 μmol/L). Two patients died and another three suffered a metabolic crisis, all of whom were homozygous for the c.985 A>G mutation. Conclusions Our data show a direct association between homozygosity for c.985A>G and lower carnitine values at diagnosis, and a higher dose of carnitine

  15. Loss of long-chain acyl-CoA synthetase isoform 1 impairs cardiac autophagy and mitochondrial structure through mechanistic target of rapamycin complex 1 activation

    PubMed Central

    Grevengoed, Trisha J.; Cooper, Daniel E.; Young, Pamela A.; Ellis, Jessica M.; Coleman, Rosalind A.

    2015-01-01

    Because hearts with a temporally induced knockout of acyl-CoA synthetase 1 (Acsl1T−/−) are virtually unable to oxidize fatty acids, glucose use increases 8-fold to compensate. This metabolic switch activates mechanistic target of rapamycin complex 1 (mTORC1), which initiates growth by increasing protein and RNA synthesis and fatty acid metabolism, while decreasing autophagy. Compared with controls, Acsl1T−/− hearts contained 3 times more mitochondria with abnormal structure and displayed a 35–43% lower respiratory function. To study the effects of mTORC1 activation on mitochondrial structure and function, mTORC1 was inhibited by treating Acsl1T−/− and littermate control mice with rapamycin or vehicle alone for 2 wk. Rapamycin treatment normalized mitochondrial structure, number, and the maximal respiration rate in Acsl1T−/− hearts, but did not improve ADP-stimulated oxygen consumption, which was likely caused by the 33–51% lower ATP synthase activity present in both vehicle- and rapamycin-treated Acsl1T−/− hearts. The turnover of microtubule associated protein light chain 3b in Acsl1T−/− hearts was 88% lower than controls, indicating a diminished rate of autophagy. Rapamycin treatment increased autophagy to a rate that was 3.1-fold higher than in controls, allowing the formation of autophagolysosomes and the clearance of damaged mitochondria. Thus, long-chain acyl-CoA synthetase isoform 1 (ACSL1) deficiency in the heart activated mTORC1, thereby inhibiting autophagy and increasing the number of damaged mitochondria.—Grevengoed, T. J., Cooper, D. E., Young, P. A., Ellis, J. M., Coleman, R. A. Loss of long-chain acyl-CoA synthetase isoform 1 impairs cardiac autophagy and mitochondrial structure through mechanistic target of rapamycin complex 1 activation. PMID:26220174

  16. 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

    2015-11-06

    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.

  17. 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.

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

    PubMed Central

    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.

    2015-01-01

    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

  19. Cardiac failure in very long chain acyl-CoA dehydrogenase deficiency requiring extracorporeal membrane oxygenation (ECMO) treatment: A case report and review of the literature.

    PubMed

    Katz, Sharon; Landau, Yuval; Pode-Shakked, Ben; Pessach, Itai M; Rubinshtein, Marina; Anikster, Yair; Salem, Yishay; Paret, Gideon

    2017-03-01

    Fatty acid oxidation (FAO) defects often present with multi-system involvement, including several life-threatening cardiac manifestations, such as cardiomyopathy, pericardial effusion and arrhythmias. We report herein a fatal case of cardiac dysfunction and rapid-onset tamponade following an acute illness in a neonate with molecularly proven very long chain acyl-CoA dehydrogenase (VLCAD) deficiency (harboring the known del799_802 mutation), requiring 15 days of extracorporeal membrane oxygenation (ECMO) treatment. As data regarding the use of ECMO in FAO defects in general, and VLCAD in particular, are scarce, we review the literature and discuss insights from in vitro models and several successful reported cases.

  20. Familial very long chain acyl-CoA dehydrogenase deficiency as a cause of neonatal sudden infant death: improved survival by prompt diagnosis.

    PubMed

    Scalais, Emmanuel; Bottu, Jean; Wanders, Ronald J A; Ferdinandusse, Sacha; Waterham, Hans R; De Meirleir, Linda

    2015-01-01

    In neonates, very long chain acyl-CoA dehydrogenase (VLCAD) deficiency is often characterized by cardiomyopathy, hepatic encephalopathy, or severe hypoketotic hypoglycemia, or a combination thereof. The purpose of this study was to further elucidate a familial VLCAD deficiency in three patients, two of whom died in the neonatal period. We report on a family with VLCAD deficiency. Acyl-carnitine profiles were obtained from dried blood spot and/or from oxidation of (13) C-palmitate by cultured skin fibroblasts. In the index patient, VLCAD deficiency was ascertained by enzyme activity measurement in fibroblasts and by molecular analysis of ACADVL. At 30 hr of life, the proband was diagnosed with hypoglycemia (1.77 mmol/L), rhabdomyolysis (CK: 12966 IU/L) and hyperlactacidemia (10.6 mmol/L). Acylcarnitine profile performed at 31 hr of life was consistent with VLCAD deficiency and confirmed by cultured skin fibroblast enzyme activity measurement. Molecular analysis of ACADVL revealed a homozygous splice-site mutation (1077 + 2T>C). The acyl-carnitine profile obtained from the sibling's original newborn screening cards demonstrated a similar, but less pronounced abnormal profile. In the proband, the initial metabolic crisis was controlled with 10% dextrose solution and oral riboflavin followed by specific diet (Basic-F and medium chain triglyceride (MCT). This clinical report demonstrates a familial history of repeated neonatal deaths explained by VLCAD deficiency, and the clinical evolution of the latest affected, surviving sibling. It shows that very early metabolic screening is an effective approach to avoid sudden unexpected death.

  1. Effect of fatty acyl chain length and structure on the lamellar gel to liquid-crystalline and lamellar to reversed hexagonal phase transitions of aqueous phosphatidylethanolamine dispersions

    SciTech Connect

    Lewis, R.N.A.H.; Mannock, D.A.; McElhaney, R.N.; Turner, D.C.; Gruner, S.M. )

    1989-01-24

    The lamellar gel/liquid-crystalline and the lamellar liquid-crystalline/reversed hexagonal phase transitions of aqueous dispersions of a number of synthetic phosphatidylethanolamines containing linear saturated, branched chain, and alicyclic fatty acyl chains of varying length were studied by differential scanning calorimetry, {sup 31}P nuclear magnetic resonance spectroscopy, and X-ray diffraction. For any given homologous series of phosphatidylethanolamines containing a single chemical class of fatty acids, the lamellar gel/liquid-crystalline phase transition temperature increases and the lamellar liquid-crystalline/reversed hexagonal phase transition temperature decreases with increases in hydrocarbon chain length. For a series of phosphatidylethanolamines of the same hydrocarbon chain length but with different chemical structures, both the lamellar gel/liquid-crystalline and the lamellar liquid-crystalline/reversed hexagonal phase transition temperatures vary markedly and in the same direction. These results suggest that for any given hydrocarbon chain length, there may be a critical thickness at which the liquid-crystalline phosphatidylethanolamine bilayer becomes unstable with respect to inverted nonbilayer phases such as the H{sub II} phase and that the temperature at which this critical thickness is reached is dependent upon that bilayers proximity to the hydrocarbon chain-melting phase transition temperature.

  2. Molecular cloning and nutrient regulation analysis of long chain acyl-CoA synthetase 1 gene in grass carp, Ctenopharyngodon idella L.

    PubMed

    Cheng, Han-Liang; Chen, Shuai; Xu, Jian-He; Yi, Le-Fei; Peng, Yong-Xing; Pan, Qian; Shen, Xin; Dong, Zhi-Guo; Zhang, Xia-Qing; Wang, Wen-Xiang

    2017-02-01

    Long chain acyl-CoA synthetase 1 (ACSL1), a key regulatory enzyme of fatty acid metabolism, catalyzes the conversion of long-chain fatty acids to acyl-coenzyme A. The full-length cDNAs of ACSL1a and ACSL1b were cloned from the liver of a grass carp. Both cDNAs contained a 2094bp open reading frame encoding 697 amino acids. Amino acid sequence alignment showed that ACSL1a shared 73.5% sequence identity with ACSL1b. Each of the two ACSL1s proteins had a transmembrane domain, a P-loop domain, and L-, A-, and G-motifs, which were relatively conserved in comparison to other vertebrates. Relative expression profile of ACSL1 mRNAs in different tissues indicated that ACSL1a is highly expressed in heart, mesenteric adipose, and brain tissues, whereas ACSL1b is highly expressed in heart, white muscle, foregut, and liver tissues. Nutrient regulation research showed that the expression levels of ACSL1a and ACSL1b were significantly down-regulated when 3, 6, and 9% fish oil were added in diet of grass carp as compared to the control group. However, no significant difference in the levels of ACSL1 mRNA was observed between the experimental groups. This study demonstrated the relationship between ACSL1a and ACSL1b genes in grass carp and laid a foundation for further research on ACSL family members in other species.

  3. Isolated 2-methylbutyrylglycinuria caused by short/branched-chain acyl-CoA dehydrogenase deficiency: identification of a new enzyme defect, resolution of its molecular basis, and evidence for distinct acyl-CoA dehydrogenases in isoleucine and valine metabolism.

    PubMed

    Andresen, B S; Christensen, E; Corydon, T J; Bross, P; Pilgaard, B; Wanders, R J; Ruiter, J P; Simonsen, H; Winter, V; Knudsen, I; Schroeder, L D; Gregersen, N; Skovby, F

    2000-11-01

    Acyl-CoA dehydrogenase (ACAD) defects in isoleucine and valine catabolism have been proposed in clinically diverse patients with an abnormal pattern of metabolites in their urine, but they have not been proved enzymatically or genetically, and it is unknown whether one or two ACADs are involved. We investigated a patient with isolated 2-methylbutyrylglycinuria, suggestive of a defect in isoleucine catabolism. Enzyme assay of the patient's fibroblasts, using 2-methylbutyryl-CoA as substrate, confirmed the defect. Sequence analysis of candidate ACADs revealed heterozygosity for the common short-chain ACAD A625 variant allele and no mutations in ACAD-8 but a 100-bp deletion in short/branched-chain ACAD (SBCAD) cDNA from the patient. Our identification of the SBCAD gene structure (11 exons; >20 kb) enabled analysis of genomic DNA. This showed that the deletion was caused by skipping of exon 10, because of homozygosity for a 1228G-->A mutation in the patient. This mutation was not present in 118 control chromosomes. In vitro transcription/translation experiments and overexpression in COS cells confirmed the disease-causing nature of the mutant SBCAD protein and showed that ACAD-8 is an isobutyryl-CoA dehydrogenase and that both wild-type proteins are imported into mitochondria and form tetramers. In conclusion, we report the first mutation in the SBCAD gene, show that it results in an isolated defect in isoleucine catabolism, and indicate that ACAD-8 is a mitochondrial enzyme that functions in valine catabolism.

  4. Characterization of trans-monounsaturated alkenyl chains in total plasmalogens (1-O-alk-1'-enyl-2-acyl glycerophospholipids) from sheep heart.

    PubMed

    Wolff, Robert L

    2002-08-01

    In the present study, we investigated the alkenyl chains from sheep heart plasmalogens (1-O-alk-1'-enyl-2-acyl glycerophospholipids) after their conversion into trimethylene dioxyalkanyl (TMDOA) derivatives. Particular attention was given to monounsaturated alkenyl chains (C18 mainly). For this purpose, a combination of silver ion TLC and GLC on highly polar, very long capillary columns was applied to TMDOA derivatives. Approximately 30 different alkenyl chains could be separated, and the main observation was that the component previously reported as a cis-9 18:1 alkenyl chain in plasmalogens embraces in fact a wide range of trans and cis isomers, in amounts equal to 7.9 and 5.6%, respectively, of total alkenyl chains. Concerning the trans-monoenoate fraction, isomers with their ethylenic bond spanning from delta6-delta8 to delta16 were tentatively identified on the basis of their distribution profile, which was similar to that of trans-18:1 acids prepared and isolated from sheep adipose tissue. The main trans-monoenoic C18 alkenyl chain in sheep heart plasmalogens would thus have its double bond in position 11, which seems logical, as alkenyl chains are derived from the corresponding alcohols, themselves issued from the corresponding FA, and in this particular case, vaccenic (trans-11 18:1) acid. cis-Monoenoic C18 alkenyl chains also appear more complex than realized earlier, showing in particular isomers with their ethylenic bond farther than the delta9 position, in addition to the main isomer derived from oleic acid. Several trans-16:1 alkenyl chains could be observed (totaling ca. 1%), but cis-16:1 isomers were present in trace amounts only.

  5. Chemical Reporters for Exploring Protein Acylation

    PubMed Central

    Thinon, Emmanuelle; Hang, Howard C.

    2015-01-01

    Proteins are acylated by a variety of metabolites that regulates many important cellular pathways in all kingdoms of life. Acyl groups in cells can vary in structure from the smallest unit, acetate, to modified long chain fatty acids, all of which can be activated and covalently attached to diverse amino acid side chains and consequently modulate protein function. For example, acetylation of Lys residues can alter the charge state of proteins and generate new recognition elements for protein–protein interactions. Alternatively, long chain fatty-acylation targets proteins to membranes and enables spatial control of cell signalling. To facilitate the analysis of protein acylation in biology, acyl analogues bearing alkyne or azide tags have been developed that enable fluorescent imaging and proteomic profiling of modified proteins using bioorthogonal ligation methods. Herein, we summarize the currently available acylation chemical reporters and highlight their utility to discover and quantify the roles of protein acylation in biology. PMID:25849926

  6. Increased long chain acyl-Coa synthetase activity and fatty acid import is linked to membrane synthesis for development of picornavirus replication organelles.

    PubMed

    Nchoutmboube, Jules A; Viktorova, Ekaterina G; 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

  7. The vertical location of α-tocopherol in phosphatidylcholine membranes is not altered as a function of the degree of unsaturation of the fatty acyl chains.

    PubMed

    Ausili, Alessio; de Godos, Ana M; Torrecillas, Alejandro; Aranda, Francisco J; Corbalán-García, Senena; Gómez-Fernández, Juan C

    2017-03-01

    α-Tocopherol is a natural preservative that prevents free radical chain oxidations in biomembranes. We have studied the location of α-tocopherol in model membranes formed by different unsaturated phosphatidylcholines, namely 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphocholine (PLPC), 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (PAPC) and 1-palmitoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine (PDPC). Small angle X-ray diffraction revealed that α-tocopherol was well mixed with all the phospholipids. In all the cases only one lamellar phase was detected. Very modest changes occasioned by α-tocopherol were observed in the electron density profiles. The results obtained from quenching of α-tocopherol intrinsic fluorescence by acrylamide showed that this vitamin was inefficiently quenched in the four types of membranes, indicating that the fluorescent chromanol ring was poorly accessible for this hydrophilic quencher. Compatible with that, quenching by doxyl derivatives of phosphatidylcholines indicated that the chromanol ring was close in the four membranes to the nitroxide probe located at position 5. Quenching by doxyl-phosphatidylcholines also indicated that the efficiency of quenching was higher in POPC than in the other unsaturated phospholipids. (1)H-MAS-NMR showed that α-tocopherol induced chemical shifts of protons from the phospholipids, especially of those bonded to carbons 2 and 3 of the acyl chains of the four phospholipids studied. The (1)H-MAS-NMR NOESY results suggested that the lower part of the chromanol ring was located between the C3 of the fatty acyl chains and the centre of the hydrophobic monolayer for the four phospholipid membranes studied. Taken together, these results suggest that α-tocopherol is located, in all the membranes studied, with the chromanol ring within the hydrophobic palisade but not far away from the lipid-water interface.

  8. Compound heterozygous mutations of ACADS gene in newborn with short chain acyl-CoA dehydrogenase deficiency: case report and literatures review

    PubMed Central

    An, Se Jin; Kim, Sook Za; Kim, Gu Hwan; Yoo, Han Wook

    2016-01-01

    Short-chain acyl-CoA dehydrogenase deficiency (SCADD) is a rare autosomal recessive mitochondrial disorder of fatty acid β-oxidation, and is associated with mutations in the acyl-CoA dehydrogenase (ACADS) gene. Recent advances in spectrometric screening for inborn errors of metabolism have helped detect several metabolic disorders, including SCADD, without symptoms in the neonate period. This allows immediate initiation of treatment and monitoring, so they remain largely symptomless metabolic disease. Here, we report a 15-month-old asymptomatic male, who was diagnosed with SCADD by newborn screening. Spectrometric screening for inborn errors of metabolism 72 hours after birth revealed an elevated butyrylcarnitine (C4) concentration of 2.25 µmol/L (normal, <0.99 µmol/L). Urinary excretion of ethylmalonic acid was also elevated, as detected by urine organic acid analysis. To confirm the diagnosis of SCADD, direct sequencing analysis of 10 coding exons and the exon-intron boundaries of the ACADS gene were performed. Subsequent sequence analysis revealed compound heterozygous missense mutations c.164C>T (p.Pro55Leu) and c.1031A>G (p.Glu344Gly) on exons 2 and 9, respectively. The patient is now growing up, unretarded by symptoms such as seizure and developmental delay. PMID:28018444

  9. Recognition of medium-chain acyl-CoA dehydrogenase deficiency in asymptomatic siblings of children dying of sudden infant death or Reye-like syndromes.

    PubMed

    Roe, C R; Millington, D S; Maltby, D A; Kinnebrew, P

    1986-01-01

    The medium-chain acyl-CoA dehydrogenase (MCAD) deficiency of mitochondrial beta oxidation has been identified in two asymptomatic siblings in a family in which two previous deaths had been recorded, one attributed to sudden infant death syndrome and the other to Reye syndrome. Recognition of this disorder in one of the deceased and in the surviving siblings was accomplished by detection of a diagnostic metabolite, octanoylcarnitine, using a new mass spectrometric technique. This resulted in early treatment with L-carnitine supplement in the survivors, which should prevent metabolic deterioration. Further studies suggest that breast-feeding may be protective for infants with MCAD deficiency. Families with children who have had Reye syndrome or in which sudden infant death has occurred are at risk for MCAD deficiency. We suggest that survivors and asymptomatic siblings should be tested for this treatable disorder.

  10. Biochemical engineering of the N-acyl side chain of sialic acids alters the kinetics of a glycosylated potassium channel Kv3.1.

    PubMed

    Hall, M Kristen; Reutter, Werner; Lindhorst, Thisbe; Schwalbe, Ruth A

    2011-10-20

    The sialic acid of complex N-glycans can be biochemically engineered by substituting the physiological precursor N-acetylmannosamine with non-natural N-acylmannosamines. The Kv3.1 glycoprotein, a neuronal voltage-gated potassium channel, contains sialic acid. Western blots of the Kv3.1 glycoprotein isolated from transfected B35 neuroblastoma cells incubated with N-acylmannosamines verified sialylated N-glycans attached to the Kv3.1 glycoprotein. Outward ionic currents of Kv3.1 transfected B35 cells treated with N-pentanoylmannosamine or N-propanoylmannosamine had slower activation and inactivation rates than those of untreated cells. Therefore, the N-acyl side chain of sialic acid is intimately connected with the activation and inactivation rates of this glycosylated potassium channel.

  11. Long chain acyl-CoA synthetase 3-mediated phosphatidylcholine synthesis is required for assembly of very low density lipoproteins in human hepatoma Huh7 cells.

    PubMed

    Yao, Hongbing; Ye, Jin

    2008-01-11

    Hepatocytes play a crucial role in regulating lipid metabolism by exporting cholesterol and triglyceride into plasma through secretion of very low density lipoproteins (VLDL). VLDL production is also required for release of hepatitis C virus (HCV) from infected hepatocytes. Here, we show that long chain acyl-CoA synthetase 3 (ACSL3) plays a crucial role in secretion of VLDL and HCV from hepatocytes. In cultured human hepatoma Huh7 cells, ACSL3 is specifically required for incorporation of fatty acids into phosphatidylcholine. In cells receiving small interfering RNA targeting ACSL3, secretion of apolipoprotein B, the major protein component of VLDL, was inhibited and the lipoprotein was rapidly degraded. This inhibition in secretion was completely eliminated when these cells were treated with phosphatidylcholine. Treatment of cells with small interfering RNA targeting ACSL3 also inhibited secretion of HCV from Huh7-derived cells. These results identify ACSL3 as a new enzymatic target to limit VLDL secretion and HCV infection.

  12. Commentary on a Delphi clinical practice protocol for the diagnosis and management of very long chain acyl-CoA dehydrogenase deficiency by Arnold et al.

    PubMed

    Marsden, Deborah Louise

    2009-03-01

    Very long chain acyl-CoA dehydrogenase deficiency (VLCAD) can now be detected by newborn screening by tandem mass spectrometry. The incidence is higher than previously estimated because of the identification of potentially milder later onset variants by screening. Although there is little information in the literature on the optimal management of rare inborn errors, there is a need for management guidelines, especially for non-specialist providers in the community. In the accompanying article, Arnold et al. present a diagnostic and management guideline for VLCAD, developed by the Delphi method for gaining consensus from a panel of 14 metabolic specialists. While consensus was gained for some issues, there was no clear consensus for several important management issues, particularly for the later onset variants. Clearly, there is an urgent need for multinational collaborative protocol driven outcomes studies that will provide the data necessary to establish robust guidelines for inborn errors of metabolism.

  13. 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

  14. 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.

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

    PubMed

    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.

  16. Arabidopsis acyl-CoA-binding protein ACBP3 participates in plant response to hypoxia by modulating very-long-chain fatty acid metabolism.

    PubMed

    Xie, Li-Juan; Yu, Lu-Jun; Chen, Qin-Fang; Wang, Feng-Zhu; Huang, Li; Xia, Fan-Nv; Zhu, Tian-Ren; Wu, Jian-Xin; Yin, Jian; Liao, Bin; Yao, Nan; Shu, Wensheng; Xiao, Shi

    2015-01-01

    In Arabidopsis thaliana, acyl-CoA-binding proteins (ACBPs) are encoded by a family of six genes (ACBP1 to ACBP6), and are essential for diverse cellular activities. Recent investigations suggest that the membrane-anchored ACBPs are involved in oxygen sensing by sequestration of group VII ethylene-responsive factors under normoxia. Here, we demonstrate the involvement of Arabidopsis ACBP3 in hypoxic tolerance. ACBP3 transcription was remarkably induced following submergence under both dark (DS) and light (LS) conditions. ACBP3-overexpressors (ACBP3-OEs) showed hypersensitivity to DS, LS and ethanolic stresses, with reduced transcription of hypoxia-responsive genes as well as accumulation of hydrogen peroxide in the rosettes. In contrast, suppression of ACBP3 in ACBP3-KOs enhanced plant tolerance to DS, LS and ethanol treatments. By analyses of double combinations of OE-1 with npr1-5, coi1-2, ein3-1 as well as ctr1-1 mutants, we observed that the attenuated hypoxic tolerance in ACBP3-OEs was dependent on NPR1- and CTR1-mediated signaling pathways. Lipid profiling revealed that both the total amounts and very-long-chain species of phosphatidylserine (C42:2- and C42:3-PS) and glucosylinositolphosphorylceramides (C22:0-, C22:1-, C24:0-, C24:1-, and C26:1-GIPC) were significantly lower in ACBP3-OEs but increased in ACBP3-KOs upon LS exposure. By microscale thermophoresis analysis, the recombinant ACBP3 protein bound VLC acyl-CoA esters with high affinities in vitro. Further, a knockout mutant of MYB30, a master regulator of very-long-chain fatty acid (VLCFA) biosynthesis, exhibited enhanced sensitivities to LS and ethanolic stresses, phenotypes that were ameliorated by ACBP3-RNAi. Taken together, these findings suggest that Arabidopsis ACBP3 participates in plant response to hypoxia by modulating VLCFA metabolism.

  17. Effect of Acylglycerol Composition and Fatty Acyl Chain Length on Lipid Digestion in pH-Stat Digestion Model and Simulated In Vitro Digestion Model.

    PubMed

    Qi, Jin F; Jia, Cai H; Shin, Jung A; Woo, Jeong M; Wang, Xiang Y; Park, Jong T; Hong, Soon T; Lee, K-T

    2016-02-01

    In this study, a pH-stat digestion model and a simulated in vitro digestion model were employed to evaluate the digestion degree of lipids depending on different acylglycerols and acyl chain length (that is, diacylglycerol [DAG] compared with soybean oil representing long-chain triacylglycerol compared with medium-chain triacylglycerol [MCT]). In the pH-stat digestion model, differences were observed among the digestion degrees of 3 oils using digestion rate (k), digestion half-time (t1/2 ), and digestion extent (Φmax). The results showed the digestion rate order was MCT > soybean oil > DAG. Accordingly, the order of digestion half-times was MCT < soybean oil < DAG. In simulated in vitro digestion model, digestion rates (k') and digestion half-times (t'1/2 ) were also obtained and the results showed a digestion rate order of MCT (k' = 0.068 min(-1) ) > soybean oil (k' = 0.037 min(-1) ) > DAG (k' = 0.024 min(-1) ). Consequently, the order of digestion half-times was MCT (t'1/2 = 10.20 min) < soybean oil (t'1/2 = 18.74 min) < DAG (t'1/2 = 29.08 min). The parameters obtained using the 2 models showed MCT was digested faster than soybean oil, and that soybean oil was digested faster than DAG.

  18. 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

  19. Structure, supramolecular organization and phase behavior of N-acyl-β-alanines: Structural homologues of mammalian brain constituents N-acylglycine and N-acyl-GABA.

    PubMed

    Sivaramakrishna, D; Swamy, Musti J

    2016-12-01

    N-Acyl-β-alanines (NABAs) are structural homologues of N-acylglycines (NAGs) and N-acyl-γ-aminobutyric acids (NAGABAs), and achiral isomers of N-acylalanines, which are all present in mammalian brain and other tissues and modulate activity of biological receptors with various functions. In the present study, we synthesized and characterized a homologous series of NABAs bearing saturated acyl chains (n=8-20) and investigated their supramolecular organization and thermotropic phase behavior. In differential scanning calorimetric (DSC) studies, most of the NABAs gave one or two minor transitions before the main chain-melting phase transition in the dry state as well as upon hydration with water, but gave only a single transition when hydrated with buffer (pH7.6). Transition enthalpies (ΔHt) and entropies (ΔSt), obtained from the DSC studies showed linear dependence on the chain length in the dry state and upon hydration with buffer, whereas odd-even alteration was observed when hydrated with water. The crystal structures of N-lauroyl-β-alanine (NLBA) and N-myristoyl-β-alanine (NMBA) were solved in monoclinic system in the P21/c space group. Both NLBA and NMBA were packed in tilted bilayers with head-to-head (and tail-to-tail) arrangement with tilt angles of 33.28° and 34.42°, respectively. Strong hydrogen bonding interactions between COOH groups of the molecules from opposite leaflets as well as NH⋯O hydrogen bonds between the amide groups from adjacent molecules in the same leaflet as well as dispersion interactions between the acyl chains stabilize the bilayer structure. The d-spacings calculated from powder X-ray diffraction studies showed odd-even alteration with odd-chain length compounds exhibiting higher values as compared to the even-chain length ones and the tilt angles calculated from the PXRD data are higher for the even chain NABAs. These observations are relevant to developing structure-activity relationships for these amphiphiles and understand

  20. 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 (

  1. Effect of small chain N acyl homoserine lactone quorum sensing signals on biofilms of food-borne pathogens.

    PubMed

    A, Jamuna Bai; V, Ravishankar Rai

    2016-09-01

    Quorum sensing or cell to cell communication which includes inter- and intra-cellular communication has been implicated in the production of virulence factor and formation of biofilm in food-borne pathogens. In the present study, the effect of quorum sensing signals on the biofilms of food-borne pathogens has been elucidated. N-butryl homoserine lactone and N-hexanoyl homoserine lactone belonging to acyl homoserine lactone (AHL) family of signaling molecules were investigated for their effect on the biofilm formation (attachment and exopolymeric substance production) in the food-borne pathogens Escherichia coli, Salmonella enterica serovar Typhimurium and Vibrio parahemolyticus. The signaling molecules at a concentration of 1 µM were capable of increasing biofilm formation in all the tested pathogens. There was an increase in the attachment of the bacterial cells and biomass as observed by microtiter plate assay and exopolymeric substances production in the biofilms in presence of the AHLs. Further, it needs to be elucidated if the effect of AHLS on the biofilms of E. coli and S. enterica serovar Typhimurium is SdiA dependent.

  2. 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.

  3. Ontogeny of mRNA expression and activity of long-chain acyl-CoA synthetase (ACSL) isoforms in Mus musculus heart.

    PubMed

    de Jong, Hendrik; Neal, Andrea C; Coleman, Rosalind A; Lewin, Tal M

    2007-01-01

    Long-chain acyl-CoA synthetases (ACSL) activate fatty acids (FA) and provide substrates for virtually every metabolic pathway that catabolizes FA or synthesizes complex lipids. We have hypothesized that each of the five cloned ACSL isoforms partitions FA towards specific downstream pathways. Adult heart expresses all five cloned ACSL isoforms, but their independent functional roles have not been elucidated. Studies implicate ACSL1 in both oxidative and lipid synthetic pathways. To clarify the functional role of ACSL1 and the other ACSL isoforms (3-6), we examined ACS specific activity and Acsl mRNA expression in the developing mouse heart which increases FA oxidative pathways for energy production after birth. Compared to the embryonic heart, ACS specific activity was 14-fold higher on post-natal day 1 (P1). On P1, as compared to the fetus, only Acsl1 mRNA increased, whereas transcripts for the other Acsl isoforms remained the same, suggesting that ACSL1 is the major isoform responsible for activating long-chain FA for myocardial oxidation after birth. In contrast, the mRNA abundance of Acsl3 was highest on E16, and decreased dramatically by P7, suggesting that ACSL3 may play a critical role during the development of the fetal heart. Our data support the hypothesis that each ACSL has a specific role in the channeling of FA towards distinct metabolic fates.

  4. Evidence that the major metabolites accumulating in medium-chain acyl-CoA dehydrogenase deficiency disturb mitochondrial energy homeostasis in rat brain.

    PubMed

    Schuck, Patrícia Fernanda; Ferreira, Gustavo da Costa; Tonin, Anelise Miotti; Viegas, Carolina Maso; Busanello, Estela Natacha Brandt; Moura, Alana Pimentel; Zanatta, Angela; Klamt, Fábio; Wajner, Moacir

    2009-11-03

    Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is an inherited metabolic disorder of fatty acid oxidation in which the affected patients predominantly present high levels of octanoic (OA) and decanoic (DA) acids and their glycine and carnitine by-products in tissues and body fluids. It is clinically characterized by episodic encephalopathic crises with coma and seizures, as well as by progressive neurological involvement, whose pathophysiology is poorly known. In the present work, we investigated the in vitro effects of OA and DA on various parameters of energy homeostasis in mitochondrial preparations from brain of young rats. We found that OA and DA markedly increased state 4 respiration and diminished state 3 respiration as well as the respiratory control ratio, the mitochondrial membrane potential and the matrix NAD(P)H levels. In addition, DA-elicited increase in oxygen consumption in state 4 respiration was partially prevented by atractyloside, indicating the involvement of the adenine nucleotide translocator. OA and DA also reduced ADP/O ratio, CCCP-stimulated respiration and the activities of respiratory chain complexes. The data indicate that the major accumulating fatty acids in MCADD act as uncouplers of oxidative phosphorylation and as metabolic inhibitors. Furthermore, DA, but not OA, provoked a marked mitochondrial swelling and cytochrome c release from mitochondria, reflecting a permeabilization of the inner mitochondrial membrane. Taken together, these data suggest that OA and DA impair brain mitochondrial energy homeostasis that could underlie at least in part the neuropathology of MCADD.

  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

    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

  6. 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

  7. 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.

  8. 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.

  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.

  10. Sudden unexpected infant death (SUDI) in a newborn due to medium chain acyl CoA dehydrogenase (MCAD) deficiency with an unusual severe genotype

    PubMed Central

    2012-01-01

    Medium chain acyl CoA dehydrogenase deficiency (MCAD) is the most common inborn error of fatty acid oxidation. This condition may lead to cellular energy shortage and cause severe clinical events such as hypoketotic hypoglycemia, Reye syndrome and sudden death. MCAD deficiency usually presents around three to six months of life, following catabolic stress as intercurrent infections or prolonged fasting, whilst neonatal-onset of the disease is quite rare. We report the case of an apparently healthy newborn who suddenly died at the third day of life, in which the diagnosis of MCAD deficiency was possible through peri-mortem blood-spot acylcarnitine analysis that showed very high concentrations of octanoylcarnitine. Genetic analysis at the ACADM locus confirmed the biochemical findings by demonstrating the presence in homozygosity of the frame-shift c.244dup1 (p.Trp82LeufsX23) mutation, a severe genotype that may explain the unusual and very early fatal outcome in this newborn. This report confirms that inborn errors of fatty acid oxidation represent one of the genetic causes of sudden unexpected deaths in infancy (SUDI) and underlines the importance to include systematically specific metabolic screening in any neonatal unexpected death. PMID:23095120

  11. AHL signaling molecules with a large acyl chain enhance biofilm formation on sulfur and metal sulfides by the bioleaching bacterium Acidithiobacillus ferrooxidans.

    PubMed

    González, Alex; Bellenberg, Sören; Mamani, Sigde; Ruiz, Lina; Echeverría, Alex; Soulère, Laurent; Doutheau, Alain; Demergasso, Cecilia; Sand, Wolfgang; Queneau, Yves; Vera, Mario; Guiliani, Nicolas

    2013-04-01

    Biofilm formation plays a pivotal role in bioleaching activities of bacteria in both industrial and natural environments. Here, by visualizing attached bacterial cells on energetic substrates with different microscopy techniques, we obtained the first direct evidence that it is possible to positively modulate biofilm formation of the extremophilic bacterium Acidithiobacillus ferrooxidans on sulfur and pyrite surfaces by using Quorum Sensing molecules of the N-acylhomoserine lactone type (AHLs). Our results revealed that AHL-signaling molecules with a long acyl chain (12 or 14 carbons) increased the adhesion of A. ferrooxidans cells to these substrates. In addition, Card-Fish experiments demonstrated that C14-AHL improved the adhesion of indigenous A. ferrooxidans cells from a mixed bioleaching community to pyrite. Finally, we demonstrated that this improvement of cell adhesion is correlated with an increased production of extracellular polymeric substances. Our results open up a promising means to develop new strategies for the improvement of bioleaching efficiency and metal recovery, which could also be used to control environmental damage caused by acid mine/rock drainage.

  12. Genetic basis for correction of very-long-chain acyl-coenzyme A dehydrogenase deficiency by bezafibrate in patient fibroblasts: toward a genotype-based therapy.

    PubMed

    Gobin-Limballe, S; Djouadi, F; Aubey, F; Olpin, S; Andresen, B S; Yamaguchi, S; Mandel, H; Fukao, T; Ruiter, J P N; Wanders, R J A; McAndrew, R; Kim, J J; Bastin, J

    2007-12-01

    Very-long-chain acyl-coenzyme A dehydrogenase (VLCAD) deficiency is an inborn mitochondrial fatty-acid beta-oxidation (FAO) defect associated with a broad mutational spectrum, with phenotypes ranging from fatal cardiopathy in infancy to adolescent-onset myopathy, and for which there is no established treatment. Recent data suggest that bezafibrate could improve the FAO capacities in beta-oxidation-deficient cells, by enhancing the residual level of mutant enzyme activity via gene-expression stimulation. Since VLCAD-deficient patients frequently harbor missense mutations with unpredictable effects on enzyme activity, we investigated the response to bezafibrate as a function of genotype in 33 VLCAD-deficient fibroblasts representing 45 different mutations. Treatment with bezafibrate (400 microM for 48 h) resulted in a marked increase in FAO capacities, often leading to restoration of normal values, for 21 genotypes that mainly corresponded to patients with the myopathic phenotype. In contrast, bezafibrate induced no changes in FAO for 11 genotypes corresponding to severe neonatal or infantile phenotypes. This pattern of response was not due to differential inductions of VLCAD messenger RNA, as shown by quantitative real-time polymerase chain reaction, but reflected variable increases in measured VLCAD residual enzyme activity in response to bezafibrate. Genotype cross-analysis allowed the identification of alleles carrying missense mutations, which could account for these different pharmacological profiles and, on this basis, led to the characterization of 9 mild and 11 severe missense mutations. Altogether, the responses to bezafibrate reflected the severity of the metabolic blockage in various genotypes, which appeared to be correlated with the phenotype, thus providing a new approach for analysis of genetic heterogeneity. Finally, this study emphasizes the potential of bezafibrate, a widely prescribed hypolipidemic drug, for the correction of VLCAD deficiency and

  13. 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

  14. Measuring long-chain acyl-coenzyme A concentrations and enrichment using liquid chromatography/tandem mass spectrometry with selected reaction monitoring.

    PubMed

    Blachnio-Zabielska, Agnieszka U; Koutsari, Christina; Jensen, Michael D

    2011-08-15

    Long-chain acyl-coenzymes A (acyl-CoAs) (LCACoA) are the activated forms of long-chain fatty acids and serve as key lipid metabolites. Excess accumulation of intracellular LCACoA, diacylglycerols (DAGs) and ceramides may create insulin resistance with respect to glucose metabolism. We present a new method to measure LCACoA concentrations and isotopic enrichment of palmitoyl-CoA ([U-(13) C]16-CoA) and oleoyl-CoA ([U-(13) C]18:1-CoA) using ultra-performance liquid chromatography/tandem mass spectrometry (UPLC/MS/MS) to quantitate seven different LCACoA (C14-CoA, C16-CoA, C16:1-CoA, C18-CoA, C18:1-CoA, C18:2-CoA, C20-CoA). The molecules are separated on a reversed-phase UPLC column using a binary gradient with ammonium hydroxide (NH(4) OH) in water and NH(4) OH in acetonitrile (ACN). The LCACoA are quantified using selected reaction monitoring (SRM) on a triple quadrupole mass spectrometer in positive electrospray ionization (ESI) mode. All LCACoA ions except enriched palmitate enrichment of palmitoyl-CoA ([U(-13)C]16-CoA) and oleoyl-CoA ([U(-13)C]18:1-CoA) using ultra-performance liquid chromatography/mass spectrometry (UPLC/MS/MS) to quantitate seven different LCACoA (C14-CoA, C16-CoA, C16:1-CoA, C18-CoA, C18:1-CoA, C18:2-CoA, C20-CoA). The molecules are separated on a reversed-phase UPLC column using a binary gradient with ammonium hydroxide (NH(4) OH) in water and NH(4) OH in acetonitrile. The LCACoA are quantified using selected reaction monitoring (SRM) on a triple quadrupolemass spectrometer in positive electrospray ionization (ESI) mode. All LCACoA ions except enriched palmitate and oleate were monitored as [M+2+H](+) and [U(13)C]16-CoA and [U(13)C]18:1-CoA were monitored as [M+16+H](+) and [M+18+H](+), respectively. The method is simple, sensitive and efficient (run time as short as 5 min) and allowed us to measure the concentration and detect enrichment in intramyocellular [U(13) C]16-CoA and [U(13) C]18:1-CoA during a low dose intravenous infusion of [U(13

  15. A Rare Case of Short-Chain Acyl-COA Dehydrogenase Deficiency: The Apparent Rarity of the Disorder Results in Under Diagnosis.

    PubMed

    Reddy, G Shilpa; Sujatha, M

    2011-07-01

    Short-chain acyl-CoA dehydrogenase (ACAD) deficiency is an extremely rare inherited mitochondrial disorder of fat metabolism. This belongs to a group of diseases known as fatty acid oxidation disorders. Screening programmes have provided evidence that all the fatty acid oxidation disorders combined are among the most common inborn errors of metabolism. Mitochondrial beta oxidation of fatty acids is an essential energy producing pathway. It is a particularly important pathway during prolonged periods of starvation and during periods of reduced caloric intake due to gastrointestinal illness or increased energy expenditure during febrile illness. The most common presentation is an acute episode of life threatening coma and hypoglycemia induced by a period of fasting due to defective hepatic ketogenesis. Here, the case of a 4 month old female patient who had seizures since the third day of her birth and persistent hypoglycemia is described. She was born to parents of second degree consanguinity after 10 years of infertility treatment. There was history of delayed cry after birth. Metabolic screening for TSH, galactosemia, 17-OHP, G6PD, cystic fibrosis, biotinidase were normal. Tandem mass spectrometric (TMS) screening for blood amino acids, organic acids, fatty acids showed elevated butyryl carnitine (C4) as 3.40 μmol/L (normal <2.00 μmol/L), hexanoyl carnitine (C6) as 0.92 μmol/L (normal <0.72 μmol/L), C4/C3 as 2.93 μmol/L (normal <1.18 μmol/L). The child was started immediately on carnitor syrup (carnitine) 1/2 ml twice daily. Limitation of fasting stress and dietary fat was advised. Baby responded well by gaining weight and seizures were controlled. Until now, less than 25 patients have been reported worldwide. The limited number of patients diagnosed until now is due to the rarity of the disorder resulting in under diagnosis.

  16. Data mining methods for classification of Medium-Chain Acyl-CoA dehydrogenase deficiency (MCADD) using non-derivatized tandem MS neonatal screening data.

    PubMed

    Van den Bulcke, Tim; Vanden Broucke, Paul; Van Hoof, Viviane; Wouters, Kristien; Vanden Broucke, Seppe; Smits, Geert; Smits, Elke; Proesmans, Sam; Van Genechten, Toon; Eyskens, François

    2011-04-01

    Newborn screening programs for severe metabolic disorders using tandem mass spectrometry are widely used. Medium-Chain Acyl-CoA dehydrogenase deficiency (MCADD) is the most prevalent mitochondrial fatty acid oxidation defect (1:15,000 newborns) and it has been proven that early detection of this metabolic disease decreases mortality and improves the outcome. In previous studies, data mining methods on derivatized tandem MS datasets have shown high classification accuracies. However, no machine learning methods currently have been applied to datasets based on non-derivatized screening methods. A dataset with 44,159 blood samples was collected using a non-derivatized screening method as part of a systematic newborn screening by the PCMA screening center (Belgium). Twelve MCADD cases were present in this partially MCADD-enriched dataset. We extended three data mining methods, namely C4.5 decision trees, logistic regression and ridge logistic regression, with a parameter and threshold optimization method and evaluated their applicability as a diagnostic support tool. Within a stratified cross-validation setting, a grid search was performed for each model for a wide range of model parameters, included variables and classification thresholds. The best performing model used ridge logistic regression and achieved a sensitivity of 100%, a specificity of 99.987% and a positive predictive value of 32% (recalibrated for a real population), obtained in a stratified cross-validation setting. These results were further validated on an independent test set. Using a method that combines ridge logistic regression with variable selection and threshold optimization, a significantly improved performance was achieved compared to the current state-of-the-art for derivatized data, while retaining more interpretability and requiring less variables. The results indicate the potential value of data mining methods as a diagnostic support tool.

  17. FAT/CD36 is located on the outer mitochondrial membrane, upstream of long-chain acyl-CoA synthetase, and regulates palmitate oxidation.

    PubMed

    Smith, Brennan K; Jain, Swati S; Rimbaud, Stéphanie; Dam, Aaron; Quadrilatero, Joe; Ventura-Clapier, Renée; Bonen, Arend; Holloway, Graham P

    2011-07-01

    FAT/CD36 (fatty acid translocase/Cluster of Differentiation 36), a plasma membrane fatty-acid transport protein, has been found on mitochondrial membranes; however, it remains unclear where FAT/CD36 resides on this organelle or its functional role within mitochondria. In the present study, we demonstrate, using several different approaches, that in skeletal muscle FAT/CD36 resides on the OMM (outer mitochondrial membrane). To determine the functional role of mitochondrial FAT/CD36 in this tissue, we determined oxygen consumption rates in permeabilized muscle fibres in WT (wild-type) and FAT/CD36-KO (knockout) mice using a variety of substrates. Despite comparable muscle mitochondrial content, as assessed by unaltered mtDNA (mitochondrial DNA), citrate synthase, β-hydroxyacyl-CoA dehydrogenase, cytochrome c oxidase complex IV and respiratory capacities [maximal OXPHOS (oxidative phosphorylation) respiration] in WT and KO mice, palmitate-supported respiration was 34% lower in KO animals. In contrast, palmitoyl-CoA-supported respiration was unchanged. These results indicate that FAT/CD36 is key for palmitate-supported respiration. Therefore we propose a working model of mitochondrial fatty-acid transport, in which FAT/CD36 is positioned on the OMM, upstream of long-chain acyl-CoA synthetase, thereby contributing to the regulation of mitochondrial fatty-acid transport. We further support this model by providing evidence that FAT/CD36 is not located in mitochondrial contact sites, and therefore does not directly interact with carnitine palmitoyltransferase-I as original proposed.

  18. Long chain acyl-CoA synthetase-3 is a molecular target for peroxisome proliferator-activated receptor delta in HepG2 hepatoma cells.

    PubMed

    Cao, Aiqin; Li, Hai; Zhou, Yue; Wu, Minhao; Liu, Jingwen

    2010-05-28

    ACSL3 is a member of the long chain acyl-CoA synthetase (ACSL) family that plays key roles in fatty acid metabolism in various tissues in an isozyme-specific manner. Our previous studies showed that ACSL3 was transcriptionally up-regulated by the cytokine oncostatin M (OSM) in HepG2 cells, accompanied by reduced cellular triglyceride content and enhanced beta-oxidation. In this study, we investigated the molecular mechanism underlying the OSM-induced activation of ACSL3 gene transcription in HepG2 cells. We showed that OSM treatment resulted in a coordinated elevation of mRNA levels of ACSL3 and peroxisome proliferator-activated receptor delta (PPARdelta). The effect of OSM on ACSL3 mRNA expression was inhibited by cellular depletion of PPARdelta. By utilizing a PPARdelta agonist, L165041, we demonstrated that activation of PPARdelta led to increases in ACSL3 promoter activity, mRNA level, and protein level in HepG2 cells. Analysis of the ACSL3 promoter sequence identified two imperfect PPAR-responsive elements (PPRE) located in the ACSL3 promoter region -944 to -915, relative to the transcription start site. The up-regulation of ACSL3 promoter activity by PPARdelta was abolished by deletion of this PPRE-containing region or mutation to disrupt the binding sites. Direct interactions of PPARdelta with ACSL3-PPRE sequences were demonstrated by gel mobility shift and chromatin immunoprecipitation assays. Finally, we provided in vivo evidence showing that activation of PPARdelta by L165041 in hamsters increased ACSL3 mRNA and protein levels in the liver. These new findings define ACSL3 as a novel molecular target of PPARdelta in HepG2 cells and provide a regulatory mechanism for ACSL3 transcription in liver tissue.

  19. Reduction of serum free fatty acids and triglycerides by liver-targeted expression of long chain acyl-CoA synthetase 3.

    PubMed

    Wu, Minhao; Cao, Aiqin; Dong, Bin; Liu, Jingwen

    2011-05-01

    ACSL3 is a member of the long chain acyl-CoA synthetase (ACSL) family that consists of 5 isozymes responsible for cellular fatty acid metabolism in various tissues in an isozyme-specific manner. Our previous studies have demonstrated that expression of ACSL3 mRNA and protein in liver was specifically increased after feeding hamsters with a fat- and cholesterol-enriched diet, providing the first in vivo evidence for the regulated expression of ACSL3 in liver tissue. The aim of the current study was to further investigate the role of ACSL3 in regulating hepatic lipid metabolism in vitro and in vivo. We utilized an adenoviral-mediated gene delivery approach to exogenously express hamster ACSL3 in hamster liver as well as in HepG2 cells. Transduction of HepG2 cells with Ad-hamACSL3 adenovirus elevated total cellular ACSL enzyme activity, which was accompanied by a significant reduction of cellular contents of triglycerides and total phospholipids. Immunostaining and confocal microscopy studies revealed that ACSL3 was localized to endoplasmic reticulum and mitochondria. In vivo, infection of hamsters with Ad-hamACSL3 led to sustained expression of ACSL3 mRNA and protein in liver two weeks after infection. Importantly, compared with Ad-GFP control virus infected hamsters, we observed significantly lower free fatty acids and triglycerides plus modest reduction of phospholipids in the serum of Ad-hamACSL3 infected animals. Furthermore, triglyceride levels were significantly reduced in Ad-hamACSL3 infected hamster liver. Altogether, these results provide important and physiologically relevant evidence that strengthens the link between ACSL3 expression and hepatic reduction of triglycerides and fatty acids.

  20. High-fructose diet downregulates long-chain acyl-CoA synthetase 3 expression in liver of hamsters via impairing LXR/RXR signaling pathway.

    PubMed

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

    2013-05-01

    Long-chain acyl-CoA synthetases (ACSL) play key roles in fatty acid metabolism in liver and other metabolic tissues in an isozyme-specific manner. In this study, we examined the effects of a fructose-enriched diet on expressions of ACSL isoforms in the liver of hamsters. We showed that the fructose diet markedly reduced the mRNA and protein expressions of ACSL3 in hamster liver without significant effects on other ACSLs. The decrease in ACSL3 abundance was accompanied by a reduction in ACSL-catalyzed synthesis of arachidonyl-CoA and oleoyl-CoA in liver homogenates of hamsters fed the fructose diet as opposed to normal diet. We further showed that fructose diet specifically reduced expressions of three key components of the LXR signaling pathway, namely, liver X receptor (LXR)α, LXRβ, and retinoid X receptor (RXR)β. Exogenous expression and activation of LXRα/β increased hamster ACSL3 promoter activities in a LXR-responsive element (LXRE)-dependent fashion. Finally, we showed that treating hamsters with LXR agonist GW3965 increased hepatic ACSL3 expression without affecting other ACSL isoforms. Furthermore, the ligand-induced increases of ACSL3 expression were accompanied with the reduction of hepatic triglyceride levels in GW3965-treated hamster liver. Altogether, our studies demonstrate that fructose diet has a negative impact on LXR signaling pathway in liver tissue and reduction of ACSL3 expression/activity could be a causal factor for fructose-induced hepatic steatosis.

  1. Acylcarnitine profiles during carnitine loading and fasting tests in a Japanese patient with medium-chain acyl-CoA dehydrogenase deficiency.

    PubMed

    Yokoi, Kyoko; Ito, Tetsuya; Maeda, Yasuhiro; Nakajima, Yoko; Ueta, Akihito; Nomura, Takayasu; Koyama, Norihisa; Kato, Ineko; Suzuki, Satoshi; Kurono, Yukihisa; Sugiyama, Naruji; Togari, Hajime

    2007-12-01

    Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is rare among Asian individuals, and the clinical course and biochemical findings remain unclear. We report herein a 3-year-old Japanese girl with MCADD. The diagnosis was suggested by acylcarnitine profiles and confirmed by enzyme activity and genetic analysis after clinical presentation. Our described method with high-performance liquid chromatography/tandem mass spectrometry allows quantification of levels of n-octanoylcarnitine (C8-N) and other isomers (e.g. valproylcarnitine). We examined the patient's acylcarnitine profiles in serum and urine samples during carnitine loading and 14-hr fasting tests with/without carnitine supplementation. Under hypocarnitinemia, serum level of C8-N was 0.16 micromol/l and C8-N/decanoylcarnitine (C10) ratio was 1.8, which did not correspond to the diagnostic criteria for MCADD. However, intravenous carnitine loading test (100 mg/kg/day for 3 days and 50 mg/kg/day for 1 day) led to increased serum C8-N levels and urinary excretion was obvious, strongly suggesting MCADD. In the fasting test with carnitine supplementation, marked production of acylcarnitines (C8-N > C2 > C6 > C10) was found, compared to the fasting test without carnitine supplementation. These results indicate that carnitine supplementation may be useful for detoxification of accumulated acylcarnitines even in an asymptomatic state. Moreover, the one-point examination for serum C8-N level and/or C8-N/C10 ratio may make the diagnosis of MCADD difficult, particularly in the presence of significant hypocarnitinemia. To avoid this pitfall, attention should be given to serum levels of free carnitine, and carnitine loading may be demanded in hypocarnitinemia.

  2. Prolonged QT interval and lipid alterations beyond β-oxidation in very long-chain acyl-CoA dehydrogenase null mouse hearts

    PubMed Central

    Gélinas, Roselle; Thompson-Legault, Julie; Bouchard, Bertrand; Daneault, Caroline; Mansour, Asmaa; Gillis, Marc-Antoine; Charron, Guy; Gavino, Victor; Labarthe, François

    2011-01-01

    Patients with very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency frequently present cardiomyopathy and heartbeat disorders. However, the underlying factors, which may be of cardiac or extra cardiac origins, remain to be elucidated. In this study, we tested for metabolic and functional alterations in the heart from 3- and 7-mo-old VLCAD null mice and their littermate counterparts, using validated experimental paradigms, namely, 1) ex vivo perfusion in working mode, with concomitant evaluation of myocardial contractility and metabolic fluxes using 13C-labeled substrates under various conditions; as well as 2) in vivo targeted lipidomics, gene expression analysis as well as electrocardiogram monitoring by telemetry in mice fed various diets. Unexpectedly, when perfused ex vivo, working VLCAD null mouse hearts maintained values similar to those of the controls for functional parameters and for the contribution of exogenous palmitate to β-oxidation (energy production), even at high palmitate concentration (1 mM) and increased energy demand (with 1 μM epinephrine) or after fasting. However, in vivo, these hearts displayed a prolonged rate-corrected QT (QTc) interval under all conditions examined, as well as the following lipid alterations: 1) age- and condition-dependent accumulation of triglycerides, and 2) 20% lower docosahexaenoic acid (an omega-3 polyunsaturated fatty acid) in membrane phospholipids. The latter was independent of liver but affected by feeding a diet enriched in saturated fat (exacerbated) or fish oil (attenuated). Our finding of a longer QTc interval in VLCAD null mice appears to be most relevant given that such condition increases the risk of sudden cardiac death. PMID:21685264

  3. Probing the role of the ceramide acyl chain length and sphingosine unsaturation in model skin barrier lipid mixtures by (2)H solid-state NMR spectroscopy.

    PubMed

    Stahlberg, Sören; Školová, Barbora; Madhu, Perunthiruthy K; Vogel, Alexander; Vávrová, Kateřina; Huster, Daniel

    2015-05-05

    We investigated equimolar mixtures of ceramides with lignoceric acid and cholesterol as models for the human stratum corneum by differential scanning calorimetry and (2)H solid-state NMR spectroscopy. Our reference system consisted of lignoceroyl sphingosine (Cer[NS24]), which represents one of the ceramides in the human stratum corneum. Furthermore, the effect of ceramide acyl chain truncation to 16 carbons as in Cer[NS16] and the loss of the C4 trans double bond as in dihydroceramide Cer[NDS24] were studied. Fully relaxed (2)H NMR spectra were acquired for each deuterated component of each mixture separately, allowing the quantitative determination of the individual lipid phases. At skin temperature, the reference system containing Cer[NS24] is characterized by large portions of each component of the mixture in a crystalline phase, which largely restricts the permeability of the skin lipid barrier. The loss of the C4 trans double bond in Cer[NDS24] leads to the replacement of more than 25% of the crystalline phase by an isotropic phase of the dihydroceramide that shows the importance of dihydroceramide desaturation in the formation of the skin lipid barrier. The truncated Cer[NS16] is mostly found in the gel phase at skin temperature, which may explain its negative effect on the transepidermal water loss in atopic dermatitis patients. These significant alterations in the phase behavior of all lipids are further reflected at elevated temperatures. The molecular insights of our study may help us to understand the importance of the structural parameters of ceramides in healthy and compromised skin barriers.

  4. Characterization of recombinant long-chain rat acyl-CoA synthetase isoforms 3 and 6: identification of a novel variant of isoform 6.

    PubMed

    Van Horn, Cynthia G; Caviglia, Jorge M; Li, Lei O; Wang, Shuli; Granger, Deborah A; Coleman, Rosalind A

    2005-02-08

    The metabolism of long-chain fatty acids in brain and their incorporation into signaling molecules such as diacylglycerol and LPA and into structural components of membranes, including myelin, requires activation by long-chain acyl-CoA synthetase (ACSL). Because ACSL3 and ACSL6 are the predominant ACSL isoforms in brain, we cloned and characterized these isoforms from rat brain and identified a novel ACSL6 clone (ACSL6_v2). ACSL6_v2 and the previously reported ACSL6_v1 represent splice variants that include exon 13 or 14, respectively. Homologue sequences of both of these variants are present in the human and mouse databases. ACSL3, ACSL6_v1, and ACSL6_v2 with Flag-epitopes at the C-termini were expressed in Escherichia coli and purified on Flag-affinity columns. The three recombinant proteins were characterized. Compared to ACSL4, another brain isoform, ACSL3, ACSL6_v1, and ACSL6_v2 showed similarities in kinetic values for CoA, palmitate, and arachidonate, but their apparent Km values for oleate were 4- to 6-fold lower than for ACSL4. In a direct competition assay with palmitate, all the polyunsaturated fatty acids tested were strong competitors only for ACSL4 with IC50 values of 0.5 to 5 microM. DHA was also strongly preferred by ACSL6_v2. The apparent Km value for ATP of ACSL6_v1 was 8-fold higher than that of ACSL6_v2. ACSL3 and the two variants of ACSL6 were more resistant than ACSL4 to heat inactivation. Despite the high amino acid identity between ACSL3 and ACSL4, rosiglitazone inhibited only ACSL4. Triacsin C, an inhibitor of ACSL1 and ACSL4, also inhibited ACSL3, but did not inhibit the ACSL6 variants. These data further document important differences in the closely related ACSL isoforms and show that amino acid changes near the consensus nucleotide binding site alter function in the two splice variants of ACSL6.

  5. 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

  6. Acyl hydrolases from trans-AT polyketide synthases target acetyl units on acyl carrier proteins.

    PubMed

    Jenner, Matthew; Afonso, Jose P; Kohlhaas, Christoph; Karbaum, Petra; Frank, Sarah; Piel, Jörn; Oldham, Neil J

    2016-04-18

    Acyl hydrolase (AH) domains are a common feature of trans-AT PKSs. They have been hypothesised to perform a proofreading function by removing acyl chains from stalled sites. This study determines the substrate tolerance of the AH PedC for a range of acyl-ACPs. Clear preference towards short, linear acyl-ACPs is shown, with acetyl-ACP the best substrate. These results imply a more targeted housekeeping role for PedC: namely the removal of unwanted acetyl groups from ACP domains caused by erroneous transfer of acetyl-CoA, or possibly by decarboxylation of malonyl-ACP.

  7. The Penicillium chrysogenum aclA gene encodes a broad-substrate-specificity acyl-coenzyme A ligase involved in activation of adipic acid, a side-chain precursor for cephem antibiotics.

    PubMed

    Koetsier, Martijn J; Gombert, Andreas K; Fekken, Susan; Bovenberg, Roel A L; van den Berg, Marco A; Kiel, Jan A K W; Jekel, Peter A; Janssen, Dick B; Pronk, Jack T; van der Klei, Ida J; Daran, Jean-Marc

    2010-01-01

    Activation of the cephalosporin side-chain precursor to the corresponding CoA-thioester is an essential step for its incorporation into the beta-lactam backbone. To identify an acyl-CoA ligase involved in activation of adipate, we searched in the genome database of Penicillium chrysogenum for putative structural genes encoding acyl-CoA ligases. Chemostat-based transcriptome analysis was used to identify the one presenting the highest expression level when cells were grown in the presence of adipate. Deletion of the gene renamed aclA, led to a 32% decreased specific rate of adipate consumption and a threefold reduction of adipoyl-6-aminopenicillanic acid levels, but did not affect penicillin V production. After overexpression in Escherichia coli, the purified protein was shown to have a broad substrate range including adipate. Finally, protein-fusion with cyan-fluorescent protein showed co-localization with microbody-borne acyl-transferase. Identification and functional characterization of aclA may aid in developing future metabolic engineering strategies for improving the production of different cephalosporins.

  8. 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

  9. 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

  10. The tissue-specific expression and developmental regulation of two nuclear genes encoding rat mitochondrial proteins. Medium chain acyl-CoA dehydrogenase and mitochondrial malate dehydrogenase.

    PubMed

    Kelly, D P; Gordon, J I; Alpers, R; Strauss, A W

    1989-11-15

    To study the regulation of nuclear genes which encode mitochondrial enzymes involved in oxidative metabolism, absolute levels of mRNA encoding rat medium chain acyl-CoA dehydrogenase (MCAD) and rat mitochondrial malate dehydrogenase (mMDH) were determined in developing and adult male rat tissues. MCAD mRNA is expressed in a variety of adult male tissues with highest steady state levels in heart, adrenal, and skeletal muscle and lowest levels in brain, lung, and testes. In comparison, steady state levels of mMDH mRNA in adult male rat tissues were similar to those of MCAD mRNA in heart, small intestine, adrenal, and skeletal muscle but markedly different in brain, stomach, and testes. Thus, the steady-state levels of MCAD and mMDH mRNA are highest in adult tissues with high energy requirements. Dot blot analysis of RNA prepared from late fetal, suckling, and weaning rat heart, liver, and brain demonstrated the presence of MCAD and mMDH mRNA during the fetal period in all three tissues. Both MCAD and mMDH mRNA levels increased 2-2.5-fold at birth followed by a decline during the first postnatal week in heart and liver. The patterns of accumulation of these mRNAs in heart and liver during the weaning and early adult periods were also similar, although the absolute levels were significantly different. Brain MCAD mRNA levels were consistently low (less than 0.1 pg/micrograms total cellular RNA) throughout the developmental stages. However, brain mMDH mRNA levels exhibited a marked increase during the weaning period, reaching a peak concentration which is higher than the level of mMDH mRNA in heart and liver at any point during development. These results indicate that the level of expression of the nuclear genes encoding MCAD and mMDH is tissue-specific and developmentally regulated. The patterns of MCAD and mMDH mRNA accumulation parallel the changes in energy metabolism which occur during development and among adult tissues.

  11. Electrospray Ionization Tandem Mass Spectrometry (Esi-Ms/Ms) Analysis of the Lipid Molecular Species Composition of Yeast Subcellular Membranes Reveals Acyl Chain-Based Sorting/Remodeling of Distinct Molecular Species En Route to the Plasma Membrane

    PubMed Central

    Schneiter, Roger; Brügger, Britta; Sandhoff, Roger; Zellnig, Günther; Leber, Andrea; Lampl, Manfred; Athenstaedt, Karin; Hrastnik, Claudia; Eder, Sandra; Daum, Günther; Paltauf, Fritz; Wieland, Felix T.; Kohlwein, Sepp D.

    1999-01-01

    Nano-electrospray ionization tandem mass spectrometry (nano-ESI-MS/MS) was employed to determine qualitative differences in the lipid molecular species composition of a comprehensive set of organellar membranes, isolated from a single culture of Saccharomyces cerevisiae cells. Remarkable differences in the acyl chain composition of biosynthetically related phospholipid classes were observed. Acyl chain saturation was lowest in phosphatidylcholine (15.4%) and phosphatidylethanolamine (PE; 16.2%), followed by phosphatidylserine (PS; 29.4%), and highest in phosphatidylinositol (53.1%). The lipid molecular species profiles of the various membranes were generally similar, with a deviation from a calculated average profile of ∼± 20%. Nevertheless, clear distinctions between the molecular species profiles of different membranes were observed, suggesting that lipid sorting mechanisms are operating at the level of individual molecular species to maintain the specific lipid composition of a given membrane. Most notably, the plasma membrane is enriched in saturated species of PS and PE. The nature of the sorting mechanism that determines the lipid composition of the plasma membrane was investigated further. The accumulation of monounsaturated species of PS at the expense of diunsaturated species in the plasma membrane of wild-type cells was reversed in elo3Δ mutant cells, which synthesize C24 fatty acid-substituted sphingolipids instead of the normal C26 fatty acid-substituted species. This observation suggests that acyl chain-based sorting and/or remodeling mechanisms are operating to maintain the specific lipid molecular species composition of the yeast plasma membrane. PMID:10459010

  12. The mitochondrial precursor protein apocytochrome c strongly influences the order of the headgroup and acyl chains of phosphatidylserine dispersions. A sup 2 H and sup 31 P NMR study

    SciTech Connect

    Jordi, W.; de Kroon, A.I.P.M.; Killian, A.; de Kruijff, B. )

    1990-03-06

    Deuterium and phosphorus nuclear magnetic resonance techniques were used to study the interaction of the mitochondrial precursor protein apocytochrome c with headgroup-deuterated (dioleoylphosphatidyl-L-(2-{sup 2}H{sub 1})serine) and acyl chain deuterated (1,2-(11,11-{sup 2}H{sub 2})dioleoylphosphatidylserine) dispersions. Binding of the protein to dioleoylphosphatidylserine liposomes results in phosphorus nuclear magnetic resonance spectra typical of phospholipids undergoing fast axial rotation in extended liquid-crystalline bilayers with a reduced residual chemical shift anisotropy and an increased line width. {sup 2}H NMR spectra on headgroup-deuterated dioleoylphosphatidylserine dispersions showed a decrease in quadrupolar splitting and a broadening of the signal on interaction with apocytochrome c. Addition of increasing amounts of apocytochrome c to the acyl chain deuterated dioleoylphosphatidylserine dispersions results in the gradual appearance of a second component in the spectra with a 44% reduced quadrupolar splitting. Such large reduction of the quadrupolar splitting has never been observed for any protein studied yet. The induction of a new spectral component with a well-defined reduced quadrupolar splitting seems to be confined to the N-terminus since addition of a small hydrophilic amino-terminal peptide (residues 1-38) also induces a second component with a strongly reduced quadrupolar splitting. A chemically synthesized peptide corresponding to amino acid residues 2-17 of the presequence of the mitochondrial protein cytochrome oxidase subunit IV also has a large perturbing effect on the order of the acyl chains, indicating that the observed effects may be a property shared by many mitochondrial precursor proteins. Implications of these data for the import of apocytochrome c into mitochondria will be discussed.

  13. 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.

  14. Ghrelin acylation and metabolic control.

    PubMed

    Al Massadi, O; Tschöp, M H; Tong, J

    2011-11-01

    Since its discovery, many physiologic functions have been ascribed to ghrelin, a gut derived hormone. The presence of a median fatty acid side chain on the ghrelin peptide is required for the binding and activation of the classical ghrelin receptor, the growth hormone secretagogue receptor (GHSR)-1a. Ghrelin O-acyl transferase (GOAT) was recently discovered as the enzyme responsible for this acylation process. GOAT is expressed in all tissues that have been found to express ghrelin and has demonstrated actions on several complex endocrine organ systems such as the hypothalamus-pituitary-gonadal, insular and adrenal axis as well as the gastrointestinal (GI) tract, bone and gustatory system. Ghrelin acylation is dependent on the function of GOAT and the availability of substrates such as proghrelin and short- to medium-chain fatty acids (MCFAs). This process is governed by GOAT activity and has been shown to be modified by dietary lipids. In this review, we provided evidence that support an important role of GOAT in the regulation of energy homeostasis and glucose metabolism by modulating acyl ghrelin (AG) production. The relevance of GOAT and AG during periods of starvation remains to be defined. In addition, we summarized the recent literature on the metabolic effects of GOAT specific inhibitors and shared our view on the potential of targeting GOAT for the treatment of metabolic disorders such as obesity and type 2 diabetes.

  15. 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 PAGES

    Coursolle, Dan; Shanklin, John; Lian, Jiazhang; ...

    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

  16. 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.

  17. 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.

  18. Hydrophobic matching controls the tilt and stability of the dimeric platelet-derived growth factor receptor (PDGFR) β transmembrane segment.

    PubMed

    Muhle-Goll, Claudia; Hoffmann, Silke; Afonin, Sergii; Grage, Stephan L; Polyansky, Anton A; Windisch, Dirk; Zeitler, Marcel; Bürck, Jochen; Ulrich, Anne S

    2012-07-27

    The platelet-derived growth factor receptor β is a member of the cell surface receptor tyrosine kinase family and dimerizes upon activation. We determined the structure of the transmembrane segment in dodecylphosphocholine micelles by liquid-state NMR and found that it forms a stable left-handed helical dimer. Solid-state NMR and oriented circular dichroism were used to measure the tilt angle of the helical segments in macroscopically aligned model membranes with different acyl chain lengths. Both methods showed that decreasing bilayer thickness (DEPC-POPC-DMPC) led to an increase in the helix tilt angle from 10° to 30° with respect to the bilayer normal. At the same time, reconstitution of the comparatively long hydrophobic segment became less effective, eventually resulting in complete protein aggregation in the short-chain lipid DLPC. Unrestrained molecular dynamics simulations of the dimer were carried out in explicit lipid bilayers (DEPC, POPC, DMPC, sphingomyelin), confirming the observed dependence of the helix tilt angle on bilayer thickness. Notably, molecular dynamics revealed that the left-handed dimer gets tilted en bloc, whereas conformational transitions to alternative (e.g. right-handed dimeric) states were not supported. The experimental data along with the simulation results demonstrate a pronounced interplay between the platelet-directed growth factor receptor β transmembrane segment and the bilayer thickness. The effect of hydrophobic mismatch might play a key role in the redistribution and activation of the receptor within different lipid microdomains of the plasma membrane in vivo.

  19. Acyl-CoA binding proteins: multiplicity and function.

    PubMed

    Gossett, R E; Frolov, A A; Roths, J B; Behnke, W D; Kier, A B; Schroeder, F

    1996-09-01

    The physiological role of long-chain fatty acyl-CoA is thought to be primarily in intermediary metabolism of fatty acids. However, recent data show that nM to microM levels of these lipophilic molecules are potent regulators of cell functions in vitro. Although long-chain fatty acyl-CoA are present at several hundred microM concentration in the cell, very little long-chain fatty acyl-CoA actually exists as free or unbound molecules, but rather is bound with high affinity to membrane lipids and/or proteins. Recently, there is growing awareness that cytosol contains nonenzymatic proteins also capable of binding long-chain fatty acyl-CoA with high affinity. Although the identity of the cytosolic long-chain fatty acyl-CoA binding protein(s) has been the subject of some controversy, there is growing evidence that several diverse nonenzymatic cytosolic proteins will bind long-chain fatty acyl-CoA. Not only does acyl-CoA binding protein specifically bind medium and long-chain fatty acyl-CoA (LCFA-CoA), but ubiquitous proteins with multiple ligand specificities such as the fatty acid binding proteins and sterol carrier protein-2 also bind LCFA-CoA with high affinity. The potential of these acyl-CoA binding proteins to influence the level of free LCFA-CoA and thereby the amount of LCFA-CoA bound to regulatory sites in proteins and enzymes is only now being examined in detail. The purpose of this article is to explore the identity, nature, function, and pathobiology of these fascinating newly discovered long-chain fatty acyl-CoA binding proteins. The relative contributions of these three different protein families to LCFA-CoA utilization and/or regulation of cellular activities are the focus of new directions in this field.

  20. 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

    2016-03-04

    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.

  1. 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 Central

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

    2016-01-01

    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

  2. Acylation of Glucagon-Like Peptide-2: Interaction with Lipid Membranes and In Vitro Intestinal Permeability

    PubMed Central

    Trier, Sofie; Linderoth, Lars; Bjerregaard, Simon; Andresen, Thomas Lars; Rahbek, Ulrik Lytt

    2014-01-01

    Background Acylation of peptide drugs with fatty acid chains has proven beneficial for prolonging systemic circulation as well as increasing enzymatic stability without disrupting biological potency. Acylation has furthermore been shown to increase interactions with the lipid membranes of mammalian cells. The extent to which such interactions hinder or benefit delivery of acylated peptide drugs across cellular barriers such as the intestinal epithelia is currently unknown. The present study investigates the effect of acylating peptide drugs from a drug delivery perspective. Purpose We hypothesize that the membrane interaction is an important parameter for intestinal translocation, which may be used to optimize the acylation chain length for intestinal permeation. This work aims to characterize acylated analogues of the intestinotrophic Glucagon-like peptide-2 by systematically increasing acyl chain length, in order to elucidate its influence on membrane interaction and intestinal cell translocation in vitro. Results Peptide self-association and binding to both model lipid and cell membranes was found to increase gradually with acyl chain length, whereas translocation across Caco-2 cells depended non-linearly on chain length. Short and medium acyl chains increased translocation compared to the native peptide, but long chain acylation displayed no improvement in translocation. Co-administration of a paracellular absorption enhancer was found to increase translocation irrespective of acyl chain length, whereas a transcellular enhancer displayed increased synergy with the long chain acylation. Conclusions These results show that membrane interactions play a prominent role during intestinal translocation of an acylated peptide. Acylation benefits permeation for shorter and medium chains due to increased membrane interactions, however, for longer chains insertion in the membrane becomes dominant and hinders translocation, i.e. the peptides get ‘stuck’ in the cell

  3. Metabolic engineering of omega-3 long-chain polyunsaturated fatty acids in plants using an acyl-CoA Delta6-desaturase with omega3-preference from the marine microalga Micromonas pusilla.

    PubMed

    Petrie, James R; Shrestha, Pushkar; Mansour, Maged P; Nichols, Peter D; Liu, Qing; Singh, Surinder P

    2010-05-01

    Long-chain (> or = C20) polyunsaturated fatty acids (LC-PUFA) EPA and DHA (20:5(Delta5,8,11,14,17) and 22:6(Delta4,7,10,13,16,19)) have well-documented health benefits against coronary heart disease, rheumatoid arthritis and other disorders. Currently, the predominant sources of these fatty acids are marine fish and algal oils, but research is being conducted to ensure that a sustainable, land-based production system can be developed. We here describe the metabolic engineering of an artificial pathway that produces 26% EPA in leaf triacylglycerol using a newly-identified Delta6-desaturase from the marine microalga Micromonas pusilla. We also demonstrate that this enzyme appears to function as an acyl-CoA desaturase that has preference for omega3 substrates both in planta and in yeast. Phylogenetic analysis indicates that this desaturase shares highly conserved motifs with previously described acyl-CoA Delta6-desaturases.

  4. 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.

    PubMed

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

    2013-11-01

    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 4h. 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 trafficking of exogenous C16:0 and C22:6 into PA was significant where there was 6.9- and 5.3-fold increased incorporation, respectively, over the control; C18:3 and C20:4 also trended to increase in the PA pool while there were no changes for C18:1 and C18:2. The trafficking of C18:3 into PC and PI trended higher and approached significance. In the case of C20:4, expression of

  5. 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

    PubMed Central

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

    2014-01-01

    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 4hr. 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 trafficking of exogenous C16:0 and C22:6 into PA was significant where there was 6.9- and 5.3-fold increased incorporation, respectively, over the control; C18:3 and C20:4 also trended to increase in the PA pool while there were no changes for C18:1 and C18:2. The trafficking of C18:3 into PC and PI trended higher and approached significance. In the case of C20:4, expression of

  6. 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

  7. dAcsl, the Drosophila ortholog of acyl-CoA synthetase long-chain family member 3 and 4, inhibits synapse growth by attenuating bone morphogenetic protein signaling via endocytic recycling.

    PubMed

    Liu, Zhihua; Huang, Yan; Hu, Wen; Huang, Sheng; Wang, Qifu; Han, Junhai; Zhang, Yong Q

    2014-02-19

    Fatty acid metabolism plays an important role in brain development and function. Mutations in acyl-CoA synthetase long-chain family member 4 (ACSL4), which converts long-chain fatty acids to acyl-CoAs, result in nonsyndromic X-linked mental retardation. ACSL4 is highly expressed in the hippocampus, a structure critical for learning and memory. However, the underlying mechanism by which mutations of ACSL4 lead to mental retardation remains poorly understood. We report here that dAcsl, the Drosophila ortholog of ACSL4 and ACSL3, inhibits synaptic growth by attenuating BMP signaling, a major growth-promoting pathway at neuromuscular junction (NMJ) synapses. Specifically, dAcsl mutants exhibited NMJ overgrowth that was suppressed by reducing the doses of the BMP pathway components, accompanied by increased levels of activated BMP receptor Thickveins (Tkv) and phosphorylated mothers against decapentaplegic (Mad), the effector of the BMP signaling at NMJ terminals. In addition, Rab11, a small GTPase involved in endosomal recycling, was mislocalized in dAcsl mutant NMJs, and the membrane association of Rab11 was reduced in dAcsl mutant brains. Consistently, the BMP receptor Tkv accumulated in early endosomes but reduced in recycling endosomes in dAcsl mutant NMJs. dAcsl was also required for the recycling of photoreceptor rhodopsin in the eyes, implying a general role for dAcsl in regulating endocytic recycling of membrane receptors. Importantly, expression of human ACSL4 rescued the endocytic trafficking and NMJ phenotypes of dAcsl mutants. Together, our results reveal a novel mechanism whereby dAcsl facilitates Rab11-dependent receptor recycling and provide insights into the pathogenesis of ACSL4-related mental retardation.

  8. Thermotropic phase behavior of model membranes composed of phosphatidylcholines containing cis-monounsaturated acyl chain homologues of oleic acid: differential scanning calorimetric and /sup 31/P NMR spectroscopic studies

    SciTech Connect

    Lewis, R.N.A.H.; Sykes, B.D.; McElhaney, R.N.

    1988-02-09

    The thermotropic phase behavior of dioleoylphosphatidylcholine and six of its longer chain homologues was studied by differential scanning calorimetry and /sup 31/P nuclear magnetic resonance (NMR) spectroscopy. Aqueous dispersions of these compounds all exhibit a single endotherm upon heating but upon cooling exhibit at least two exotherms, both of which occur at temperatures lower than those of their heating endotherm. The single transition observed upon heating was shown by /sup 31/P NMR spectroscopy to be a net conversion from a condensed, subgel-like phase (L/sub c/ phase) to the liquid-crystalline state. Aqueous ethylene glycol dispersions of these compounds also exhibit single endotherms upon heating and cooling exotherms centered at temperatures lower than those of their corresponding heating endotherm. However, the behavior of the aqueous ethylene glycol dispersions differs with respect to their transition temperatures and enthalpies as well as the extent of undercooling observed, and there is some evidence of discontinuities in the cooling behavior of the odd- and even-numbered members of the homologous series. Like the aqueous dispersions, /sup 31/P NMR spectroscopy also shows that the calorimetric events observed in aqueous ethylene glycol involve net interconversions between an L/sub c/-like phase and the liquid-crystalline state. These results demonstrate that although the presence of a cis double bond can perturb the solid-state packing of the acyl chains, its presence does not preclude the formation of highly ordered subgel-like phases in lipid bilayers. In the particular case of these unsaturated phosphatidylcholines, the formation of the subgel phases is more kinetically favorable than is the case with their saturated n-acyl counterparts.

  9. Metabolism of ricinoleic acid into gamma-decalactone: beta-oxidation and long chain acyl intermediates of ricinoleic acid in the genus Sporidiobolus sp.

    PubMed

    Blin-Perrin, C; Molle, D; Dufosse, L; Le-Quere, J L; Viel, C; Mauvais, G; Feron, G

    2000-07-01

    In order to study differences in gamma-decalactone production in yeast, four species of Sporidiobolus were cultivated with 5% of methyl ricinoleate as the lactone substrate. In vivo studies showed different time courses of intermediates of ricinoleic acid breakdown between the four species. In vitro studies of the beta-oxidation system were conducted with crude cell extracts of Sporidiobolus spp. and with ricinoleyl-CoA (RCoA) as substrate. The beta-oxidation was detected by measuring acyl-CoA oxidase, 3-hydroxyacyl-CoA dehydrogenase activities, and acetyl-CoA production. The time courses of the CoA esters resulting from RCoA breakdown by crude extract of Sporidiobolus spp. permit the proposal of different metabolic models in the yeast. These models explained the differences observed during in vivo studies.

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

    PubMed

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

    1995-12-01

    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.

  11. 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

  12. Tilted fuel cell apparatus

    DOEpatents

    Cooper, John F.; Cherepy, Nerine; Krueger, Roger L.

    2005-04-12

    Bipolar, tilted embodiments of high temperature, molten electrolyte electrochemical cells capable of directly converting carbon fuel to electrical energy are disclosed herein. The bipolar, tilted configurations minimize the electrical resistance between one cell and others connected in electrical series. The tilted configuration also allows continuous refueling of carbon fuel.

  13. Physiological Consequences of Compartmentalized Acyl-CoA Metabolism*

    PubMed Central

    Cooper, Daniel E.; Young, Pamela A.; Klett, Eric L.; Coleman, Rosalind A.

    2015-01-01

    Meeting the complex physiological demands of mammalian life requires strict control of the metabolism of long-chain fatty acyl-CoAs because of the multiplicity of their cellular functions. Acyl-CoAs are substrates for energy production; stored within lipid droplets as triacylglycerol, cholesterol esters, and retinol esters; esterified to form membrane phospholipids; or used to activate transcriptional and signaling pathways. Indirect evidence suggests that acyl-CoAs do not wander freely within cells, but instead, are channeled into specific pathways. In this review, we will discuss the evidence for acyl-CoA compartmentalization, highlight the key modes of acyl-CoA regulation, and diagram potential mechanisms for controlling acyl-CoA partitioning. PMID:26124277

  14. 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

  15. Synthesis of fluorescent C24-ceramide: evidence for acyl chain length dependent differences in penetration of exogenous NBD-ceramides into human skin.

    PubMed

    Novotný, Jakub; Pospechová, Katerina; Hrabálek, Alexandr; Cáp, Robert; Vávrová, Katerina

    2009-12-15

    Topical skin lipid supplementation may provide opportunities for controlling ceramide (Cer) deficiency in skin diseases such as atopic dermatitis or psoriasis. Here we describe the synthesis of a long-chain 7-nitrobenzo[c][1,2,5]oxadiazol-4-yl (NBD)-labeled Cer and its different penetration through human skin compared to widely used short-chain fluorescent Cer tools.

  16. 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.

  17. 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.

  18. 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

  19. Tilting a wobbly chair

    NASA Astrophysics Data System (ADS)

    Cross, Rod

    2017-03-01

    If a small object is placed under the front leg of a chair, the chair tilts backwards. If the object is placed under a rear leg, the chair tilts sideways. The effect is surprising but can be analysed in terms of elementary physics.

  20. 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

  1. 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

  2. Unusual long-chain N-acyl homoserine lactone production by and presence of quorum quenching activity in bacterial isolates from diseased tilapia fish.

    PubMed

    Chang, Chien-Yi; Koh, Chong-Lek; Sam, Choon-Kook; Chan, Xin-Yue; Yin, Wai Fong; Chan, Kok Gan

    2012-01-01

    Growth-dependent cell-cell communication termed quorum sensing is a key regulatory system in bacteria for controlling gene expression including virulence factors. In this study five potential bacterial pathogens including Bacillus sp. W2.2, Klebsiella sp. W4.2, Pseudomonas sp. W3 and W3.1 and Serratia sp. W2.3 were isolated from diseased Tilapia fish in Malaysia, supplied by the leading global fish supplier. Proteolytic activity assays confirmed that with the exception of Klebsiella sp. W4.2, all isolates showed distinct proteolytic activity. Furthermore Bacillus sp. W2.2 and Pseudomonas sp. strains W3 and W3.1 also displayed haemolytic activity. By using high resolution liquid chromatography mass spectrometry, we revealed the presence of unusually long-chain N-(3-oxohexadecanoyl)-homoserine lactone (3-oxo-C16-HSL) from Pseudomonas sp. W3.1 and N-dodecanoyl-homoserine lactone (C12-HSL) from Serratia sp. W2.3, respectively. Interestingly, Pseudomonas sp. W3.1 also produced a wide range of Pseudomonas quinolone signalling (PQS) molecules. Pseudomonas sp. W3 did not show any quorum sensing properties but possessed quorum quenching activity that inactivated AHLs. This study is the first documentation that shows unusual long-chain AHLs production in Serratia sp. and Pseudomonas sp. isolated from diseased fish and the latter also produce a wide range of PQS molecules.

  3. Unusual Long-Chain N-Acyl Homoserine Lactone Production by and Presence of Quorum Quenching Activity in Bacterial Isolates from Diseased Tilapia Fish

    PubMed Central

    Chang, Chien-Yi; Koh, Chong-Lek; Sam, Choon-Kook; Chan, Xin-Yue; Yin, Wai Fong; Chan, Kok Gan

    2012-01-01

    Growth-dependent cell-cell communication termed quorum sensing is a key regulatory system in bacteria for controlling gene expression including virulence factors. In this study five potential bacterial pathogens including Bacillus sp. W2.2, Klebsiella sp. W4.2, Pseudomonas sp. W3 and W3.1 and Serratia sp. W2.3 were isolated from diseased Tilapia fish in Malaysia, supplied by the leading global fish supplier. Proteolytic activity assays confirmed that with the exception of Klebsiella sp. W4.2, all isolates showed distinct proteolytic activity. Furthermore Bacillus sp. W2.2 and Pseudomonas sp. strains W3 and W3.1 also displayed haemolytic activity. By using high resolution liquid chromatography mass spectrometry, we revealed the presence of unusually long-chain N-(3-oxohexadecanoyl)-homoserine lactone (3-oxo-C16-HSL) from Pseudomonas sp. W3.1 and N-dodecanoyl-homoserine lactone (C12-HSL) from Serratia sp. W2.3, respectively. Interestingly, Pseudomonas sp. W3.1 also produced a wide range of Pseudomonas quinolone signalling (PQS) molecules. Pseudomonas sp. W3 did not show any quorum sensing properties but possessed quorum quenching activity that inactivated AHLs. This study is the first documentation that shows unusual long-chain AHLs production in Serratia sp. and Pseudomonas sp. isolated from diseased fish and the latter also produce a wide range of PQS molecules. PMID:22952864

  4. Progress toward Understanding Protein S-acylation: Prospective in Plants.

    PubMed

    Li, Yaxiao; Qi, Baoxiu

    2017-01-01

    S-acylation, also known as S-palmitoylation or palmitoylation, is a reversible post-translational lipid modification in which long chain fatty acid, usually the 16-carbon palmitate, covalently attaches to a cysteine residue(s) throughout the protein via a thioester bond. It is involved in an array of important biological processes during growth and development, reproduction and stress responses in plant. S-acylation is a ubiquitous mechanism in eukaryotes catalyzed by a family of enzymes called Protein S-Acyl Transferases (PATs). Since the discovery of the first PAT in yeast in 2002 research in S-acylation has accelerated in the mammalian system and followed by in plant. However, it is still a difficult field to study due to the large number of PATs and even larger number of putative S-acylated substrate proteins they modify in each genome. This is coupled with drawbacks in the techniques used to study S-acylation, leading to the slower progress in this field compared to protein phosphorylation, for example. In this review we will summarize the discoveries made so far based on knowledge learnt from the characterization of protein S-acyltransferases and the S-acylated proteins, the interaction mechanisms between PAT and its specific substrate protein(s) in yeast and mammals. Research in protein S-acylation and PATs in plants will also be covered although this area is currently less well studied in yeast and mammalian systems.

  5. Progress toward Understanding Protein S-acylation: Prospective in Plants

    PubMed Central

    Li, Yaxiao; Qi, Baoxiu

    2017-01-01

    S-acylation, also known as S-palmitoylation or palmitoylation, is a reversible post-translational lipid modification in which long chain fatty acid, usually the 16-carbon palmitate, covalently attaches to a cysteine residue(s) throughout the protein via a thioester bond. It is involved in an array of important biological processes during growth and development, reproduction and stress responses in plant. S-acylation is a ubiquitous mechanism in eukaryotes catalyzed by a family of enzymes called Protein S-Acyl Transferases (PATs). Since the discovery of the first PAT in yeast in 2002 research in S-acylation has accelerated in the mammalian system and followed by in plant. However, it is still a difficult field to study due to the large number of PATs and even larger number of putative S-acylated substrate proteins they modify in each genome. This is coupled with drawbacks in the techniques used to study S-acylation, leading to the slower progress in this field compared to protein phosphorylation, for example. In this review we will summarize the discoveries made so far based on knowledge learnt from the characterization of protein S-acyltransferases and the S-acylated proteins, the interaction mechanisms between PAT and its specific substrate protein(s) in yeast and mammals. Research in protein S-acylation and PATs in plants will also be covered although this area is currently less well studied in yeast and mammalian systems. PMID:28392791

  6. Tilted disordered Weyl semimetals

    NASA Astrophysics Data System (ADS)

    Trescher, Maximilian; Sbierski, Björn; Brouwer, Piet W.; Bergholtz, Emil J.

    2017-01-01

    Although Lorentz invariance forbids the presence of a term that tilts the energy-momentum relation in the Weyl Hamiltonian, a tilted dispersion is not forbidden and, in fact, generic for condensed matter realizations of Weyl semimetals. We here investigate the combined effect of such a tilted Weyl dispersion and the presence of potential disorder. In particular, we address the influence of a tilt on the disorder-induced phase transition between a quasiballistic phase at weak disorder, in which the disorder is an irrelevant perturbation, and a diffusive phase at strong disorder. Our main result is that the presence of a tilt leads to a reduction of the critical disorder strength for this transition or, equivalently, that increasing the tilt at fixed disorder strength drives the system through the phase transition to the diffusive strong-disorder phase. Notably this obscures the tilt-induced Lifshitz transition to an overtilted type II Weyl phase at any finite disorder strength. Our results are supported by analytical calculations using the self-consistent Born approximation and numerical calculations of the density of states and of transport properties.

  7. Room temperature ordering of dipalmitoyl phosphatidylserine bilayers induced by short chain alcohols.

    PubMed

    Wachtel, E; Bach, D; Miller, I R

    2013-01-01

    Using differential scanning calorimetry and small and wide angle X-ray diffraction, we show that, following extended incubation at room temperature, methanol, propanol, and three of the isomers of butanol can induce ordering in dipalmitoyl phosphatidylserine (DPPS) gel phase bilayers. The organization of the bilayers in the presence of ethanol, described previously, is now observed to be a general effect of short chain alcohols. Evidence is presented for tilting of the acyl chains with respect to the bilayer normal in the presence of ethanol or propanol. However, the different chain lengths of the alcohols, and isomeric form, influence the thermal stability of the ordered gel to different extents. This behavior is unlike that of the gel state phosphatidylcholine analog which, in the presence of short chain alcohols, undergoes hydrocarbon chain interdigitation. Dipalmitoyl phosphatidylcholine added to DPPS in the presence of 20 vol% ethanol, acts to suppress the ordered gel phase.

  8. Tilt Table Test

    MedlinePlus

    ... and you're monitored closely. Most people regain consciousness almost immediately. In some cases, if blood pressure ... horizontal position, and you may not actually lose consciousness. When your tilt table test is complete, you ...

  9. Engineering a disulfide bond in the lid hinge region of Rhizopus chinensis lipase: increased thermostability and altered acyl chain length specificity.

    PubMed

    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 t(1/2) value at 60°C and a 7°C increase of T(m) 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 (k(cat)) 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.

  10. 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

  11. Unveiling the Pathogenic Molecular Mechanisms of the Most Common Variant (p.K329E) in Medium-Chain Acyl-CoA Dehydrogenase Deficiency by in Vitro and in Silico Approaches.

    PubMed

    Bonito, Cátia A; Nunes, Joana; Leandro, João; Louro, Filipa; Leandro, Paula; Ventura, Fátima V; Guedes, Rita C

    2016-12-27

    Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is the most common genetic disorder affecting the mitochondrial fatty acid β-oxidation pathway. The mature and functional form of human MCAD (hMCAD) is a homotetramer assembled as a dimer of dimers (monomers A/B and C/D). Each monomer binds a FAD cofactor, necessary for the enzyme's activity. The most frequent mutation in MCADD results from the substitution of a lysine with a glutamate in position 304 of mature hMCAD (p.K329E in the precursor protein). Here, we combined in vitro and in silico approaches to assess the impact of the p.K329E mutation on the protein's structure and function. Our in silico results demonstrated for the first time that the p.K329E mutation, despite lying at the dimer-dimer interface and being deeply buried inside the tetrameric core, seems to affect the tetramer surface, especially the β-domain that forms part of the catalytic pocket wall. Additionally, the molecular dynamics data indicate a stronger impact of the mutation on the protein's motions in dimer A/B, while dimer C/D remains similar to the wild type. For dimer A/B, severe disruptions in the architecture of the pockets and in the FAD and octanoyl-CoA binding affinities were also observed. The presence of unaffected pockets (C/D) in the in silico studies may explain the decreased enzymatic activity determined for the variant protein (46% residual activity). Moreover, the in silico structural changes observed for the p.K329E variant protein provide an explanation for the structural instability observed experimentally, namely, the disturbed oligomeric profile, thermal stability, and conformational flexibility, with respect to the wild-type.

  12. Differential turnover of phospholipid acyl groups in mouse peritoneal macrophages

    SciTech Connect

    Kuwae, T.; Schmid, P.C.; Johnson, S.B.; Schmid, H.H. )

    1990-03-25

    Phospholipid acyl turnover was assessed in mouse peritoneal exudate cells which consisted primarily of macrophages. The cells were incubated for up to 5 h in media containing 40% H218O, and uptake of 18O into ester carbonyls of phospholipids was determined by gas chromatography-mass spectrometry of hydrogenated methyl esters. The uptake was highest in choline phospholipids and phosphatidylinositol, less in ethanolamine phospholipids, and much less in phosphatidylserine. Acyl groups at the sn-1 and sn-2 positions of diacyl glycerophospholipids, including arachidonic and other long-chain polyunsaturated fatty acids, acquired 18O at about the same rate. Acyl groups of alkylacyl glycerophosphocholine exhibited lower rates of 18O uptake, and acyl groups of ethanolamine plasmalogens (alkenylacyl glycerophosphoethanolamines) acquired only minimal amounts of 18O within 5 h, indicating a low average acyl turnover via free fatty acids. Pulse experiments with exogenous 3H-labeled arachidonic acid supported the concept that acylation of alkenyl glycerophosphoethanolamine occurs by acyl transfer from other phospholipids rather than via free fatty acids and acyl-CoA. The 18O content of intracellular free fatty acids increased gradually over a 5-h period, whereas in extracellular free fatty acids it reached maximal 18O levels within the first hour. Arachidonate and other long-chain polyunsaturated fatty acids were found to participate readily in deacylation-reacylation reactions but were present only in trace amounts in the free fatty acid pools inside and outside the cells. We conclude that acyl turnover of macrophage phospholipids through hydrolysis and reacylation is rapid but tightly controlled so that appreciable concentrations of free arachidonic acid do not occur.

  13. The Level of Circulating Octanoate Does Not Predict Ghrelin O-Acyl Transferase (GOAT)-Mediated Acylation of Ghrelin During Fasting

    PubMed Central

    Nikolayev, Alexander; Liu, Jianhua; Pezzoli, Suzan S.; Farhy, Leon S.; Patrie, James; Gaylinn, Bruce D.; Heiman, Mark; Thorner, Michael O.

    2015-01-01

    Background: Acyl-ghrelin is a 28-amino acid peptide released from the stomach. Ghrelin O-acyl transferase (GOAT) attaches an 8-carbon medium-chain fatty acid (MCFA) (octanoate) to serine 3 of ghrelin. This acylation is necessary for the activity of ghrelin. Animal data suggest that MCFAs provide substrate for GOAT and an increase in nutritional octanoate increases acyl-ghrelin. Objectives: To address the question of the source of substrate for acylation, we studied whether the decline in ghrelin acylation during fasting is associated with a decline in circulating MCFAs. Methods: Eight healthy young men (aged 18–28 years, body mass index range, 20.6–26.2 kg/m2) had blood drawn every 10 minutes for acyl- and desacyl-ghrelin and every hour for free fatty acids (FFAs) during the last 24 hours of a 61.5-hour fast and during a fed day. FFAs were measured by a highly sensitive liquid chromatography-mass spectroscopy method. Acyl- and desacyl-ghrelin were measured in an in-house assay; the results were published previously. Ghrelin acylation was assessed by the ratio of acyl-ghrelin to total ghrelin. Results: With the exception of MCFAs C8 and C10, all other FFAs, the MCFAs (C6 and C12), and the long-chain fatty acids (C14–C18) significantly increased with fasting (P < .05). There was no significant association between the fold change in ghrelin acylation and circulating FFAs. Conclusions: These results suggest that changes in circulating MCFAs are not linked to the decline in ghrelin acylation during fasting and support the hypothesis that acylation of ghrelin depends at least partially on the availability of gastroluminal MCFAs or the regulation of GOAT activity. PMID:25337923

  14. Acylation of salmon calcitonin modulates in vitro intestinal peptide flux through membrane permeability enhancement.

    PubMed

    Trier, Sofie; Linderoth, Lars; Bjerregaard, Simon; Strauss, Holger M; Rahbek, Ulrik L; Andresen, Thomas L

    2015-10-01

    Acylation of peptide drugs with fatty acid chains has proven beneficial for prolonging systemic circulation, as well as increasing enzymatic stability and interactions with lipid cell membranes. Thus, acylation offers several potential benefits for oral delivery of therapeutic peptides, and we hypothesize that tailoring the acylation may be used to optimize intestinal translocation. This work aims to characterize acylated analogues of the therapeutic peptide salmon calcitonin (sCT), which lowers blood calcium, by systematically increasing acyl chain length at two positions, in order to elucidate its influence on intestinal cell translocation and membrane interaction. We find that acylation drastically increases in vitro intestinal peptide flux and confers a transient permeability enhancing effect on the cell layer. The analogues permeabilize model lipid membranes, indicating that the effect is due to a solubilization of the cell membrane, similar to transcellular oral permeation enhancers. The effect is dependent on pH, with larger effect at lower pH, and is impacted by acylation chain length and position. Compared to the unacylated peptide backbone, N-terminal acylation with a short chain provides 6- or 9-fold increase in peptide translocation at pH 7.4 and 5.5, respectively. Prolonging the chain length appears to hamper translocation, possibly due to self-association or aggregation, although the long chain acylated analogues remain superior to the unacylated peptide. For K(18)-acylation a short chain provides a moderate improvement, whereas medium and long chain analogues are highly efficient, with a 12-fold increase in permeability compared to the unacylated peptide backbone, on par with currently employed oral permeation enhancers. For K(18)-acylation the medium chain acylation appears to be optimal, as elongating the chain causes greater binding to the cell membrane but similar permeability, and we speculate that increasing the chain length further may

  15. Tilt rotor aircraft aeroacoustics

    NASA Technical Reports Server (NTRS)

    George, Albert R.; Smith, Charles A.; Maisel, Martin D.; Brieger, John T.

    1989-01-01

    This paper studies the state of knowledge and the needed improvement in noise methodology and measurements for tilt rotor aircraft. Similarities and differences between tilt rotor aeroacoustic conditions and helicopter and propeller experience are identified. A discussion of the possible principal noise mechanisms throughout the flight envelope shows a need for further experimental and analytical investigations to develop an adequate understanding of the important sources and influencing factors. Existing experimental data from flight tests suggest terminal area noise reduction by operating within certain portions of the conversion flight envelope. Prediction methods are found to provide approximate indications only for low frequency harmonic and broadband noise for several of the tilt rotor's operating conditions. The acoustic effects of the hover case 'fountain' flow are pronounced and need further research. Impulsive noise and high frequency harmonic noise remain problems, as on helicopters, pending major improvements in wake, unsteady aerodynamics, and acoustics methodology.

  16. Tilt rotor hover aeroacoustics

    NASA Technical Reports Server (NTRS)

    Coffen, Charles David

    1992-01-01

    The methodology, results, and conclusions of a study of tilt rotor hover aeroacoustics and aerodynamics are presented. Flow visualization and hot wire velocity measurement were performed on a 1/12-scale model of the XV-15 Tilt Rotor Aircraft in hover. The wing and fuselage below the rotor cause a complex recirculating flow. Results indicate the physical dimensions and details of the flow including the relative unsteadiness and turbulence characteristics of the flow. Discrete frequency harmonic thickness and the loading noise mechanism were predicted using WOPWOP for the standard metal blades and the Advanced Technology Blades. The recirculating flow created by the wing below the rotor is a primary sound mechanism for a hovering tilt rotor. The effects of dynamic blade response should be included for fountain flow conditions which produce impulsive blade loading. Broadband noise mechanisms were studied using Amiet's method with azimuthally varying turbulence characteristics derived from the measurements. The recirculating fountain flow with high turbulence levels in the recirculating zone is the dominant source of broadband noise for a hovering rotor. It is shown that tilt rotor hover aeroacoustic noise mechanisms are now understood. Noise predictions can be made based on reasonably accurate aerodynamic models developed here.

  17. Tilt changes of short duration

    USGS Publications Warehouse

    McHugh, Stuart

    1976-01-01

    Section I of this report contains a classification scheme for short period tilt data. For convenience, all fluctuations in the local tilt field of less than 24 hours duration will be designated SP (i.e., short period) tilt events. Three basic categories of waveshape appearance are defined, and the rules for naming the waveforms are outlined. Examples from tilt observations at four central California sites are provided. Section II contains some coseismic tilt data. Fourteen earthquakes in central California, ranging in magnitude from 2.9 to 5.2, were chosen for study on four tiltmeters within 10 source dimensions of the epicenters. The raw records from each of the four tiltmeters at the times of the earthquakes were photographed and are presented in this section. Section III contains documentation of computer programs used in the analysis of the short period tilt data. Program VECTOR computes the difference vector of a tilt event and displays the sequence of events as a head-to-tail vector plot. Program ONSTSP 1) requires two component digitized tilt data as input, 2) scales and plots the data, and 3) computes and displays the amplitude, azimuth, and normalized derivative of the tilt amplitude. Program SHARPS computes the onset sharpness, (i.e., the normalized derivative of the tilt amplitude at the onset of the tilt event) as a function of source-station distance from a model of creep-related tilt changes. Program DSPLAY plots the digitized data.

  18. 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

  19. 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.

  20. 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...

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

    ClinicalTrials.gov

    2016-09-15

    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

  2. Synthesis of acyl arbutin by an immobilized lipase and its suppressive ability against lipid oxidation in a bulk system and O/W emulsion.

    PubMed

    Nagai, Mizuka; Watanabe, Yoshiyuki; Nomura, Masato

    2009-11-01

    Acyl arbutin was synthesized through the condensation of arbutin with a saturated fatty acid (C6-18) by the immobilized lipase in a batch reaction. The conversion at 10 and 20 g/l-solvent of immobilized lipase reached 45% over 2 d, but the initial reaction rate per amount of immobilized lipase decreased at 20 g/l-solvent. The radical scavenging activity of acyl arbutin in an ethanol solution was independent of the acyl chain length, although the rate constant, k, estimated for the oxidation of methyl linoleate in a bulk system with acyl arbutin by using the Weibull equation, decreased as the acyl chain length increased. This indicates the antioxidative ability of acyl arbutin with a long acyl chain to be due to its lipophilicity. Furthermore, it is suggested that dodecanoyl arbutin mainly acted on the interface between the oil and water phases in an O/W emulsion, and effectively suppressed the oxidation induced at the interface.

  3. Tilted string cosmologies

    NASA Astrophysics Data System (ADS)

    Clancy, Dominic; Feinstein, Alexander; Lidsey, James E.; Tavakol, Reza

    1999-04-01

    Global symmetries of the string effective action are employed to generate tilted, homogeneous Bianchi type VIh string cosmologies from a previously known stiff perfect fluid solution to Einstein gravity. The dilaton field is not constant on the surfaces of homogeneity. The future asymptotic state of the models is interpreted as a plane wave and is itself an exact solution to the string equations of motion to all orders in the inverse string tension. An inhomogeneous generalization of the Bianchi type III model is also found.

  4. A novel plasmid for detection of N-acyl homoserine lactones.

    PubMed

    Ling, Elizabeth A; Ellison, Matthew L; Pesci, Everett C

    2009-07-01

    Many bacteria utilize acyl-homoserine lactones as cell to cell signals that can regulate the expression of numerous genes. Structural differences in acyl-homoserine lactones produced by different bacteria, such as acyl side chain length and the presence or absence of an oxy group, make many of the commonly used detection bioassays impractical for broad range detection. Here we present a simple, broad range acyl-homoserine lactone detection bioassay that can be used to detect a wide range of these chemical signals. A plasmid (pEAL01) was constructed and transformed into Pseudomonas aeruginosa strain QSC105 to allow for detection of a broad range of acyl-homoserine lactones through induction of a lasB'-lacZ transcriptional fusion. Monitoring beta-galactosidase activity from this bioassay showed that P. aeruginosa strain QSC105 (pEAL01) could detect the presence of eight acyl-homoserine lactones tested at physiological concentrations. This novel strain could also detect acyl-homoserine lactones from the extracts of four different bacteria that produce different acyl-homoserine lactones signals. These data indicate that strain QSC105 (pEAL01) can be used to detect a wide variety of acyl-homoserine lactones by a simple beta-galactosidase assay and this bioassay could be a useful and inexpensive tool to quickly identify the presence of these signal molecules.

  5. Fatty acid acylation of rat brain myelin proteolipid protein in vitro: identification of the lipid donor.

    PubMed

    Bizzozero, O A; Lees, M B

    1986-02-01

    The immediate acyl chain donor for fatty acid esterification of proteolipid protein (PLP) was identified in an in vitro system. Rat brain total membranes, after removal of crude nuclear and mitochondrial fractions, were incubated with radioactive acyl donors, extracted with chloroform/methanol, and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In the presence of [3H]palmitic acid, CoA, ATP, and Mg2+, acylation of endogenous PLP occurred at a linear rate for at least 2 h. The radioactivity was associated with the protein via an ester linkage, mainly as palmitic acid. Omission of ATP, CoA, Mg2+, or all three reduced fatty acid incorporation into PLP to 44, 27, 8, and 4%, respectively, of the values in the complete system. Incubation of the membrane fraction with [3H]palmitoyl-CoA in the absence of CoA and ATP led to highly labeled PLP. These data demonstrate that activation of free fatty acid is required for acylation. Phospholipids and glycolipids were not able to acylate the PLP directly. Finally, when isolated myelin was incubated with [3H]palmitoyl-CoA in the absence of cofactors, only PLP was labeled, thus confirming the identity of palmitoyl-CoA as the direct acyl chain donor and suggesting that the acylating activity and the PLP pool available for acylation are both in the myelin.

  6. Selective acylation of plasma membrane proteins of Mycoplasma agalactiae: the causal agent of agalactia.

    PubMed

    Le Hénaff, M; Guéguen, M M; Fontenelle, C

    2000-01-01

    Revealed by in vivo labeling with (14)C-palmitic acid, about 15 acylated proteins were identified in the plasma membrane of Mycoplasma agalactiae (type strain PG2), including the major component p40. Triton X-114 phase partitioning and Western blotting demonstrated the amphiphilic properties of the acyl proteins and showed that they were also antigenic components. Chemical analyses of fatty acids bound to proteins revealed the following selectivity order within acylation: stearic acid (18:0) > linoleic acid (18:2c) approximately palmitic acid (16:0) > oleic acid (18:1c) > myristic acid (14:0), with 16:0 and 18:1c preferred for the O-acylation and 18:0 for the N-acylation. The ratio [O-ester- + amide-bound acyl chains]/O-ester-linked chains being close to 1.4 as well as the presence of S-glycerylcysteine suggest that acyl proteins in M. agalactiae are true lipoproteins containing N-acyl diacyl glycerylcysteine, probably processed by a mechanism analogous to that described for Gram-negative eubacteria.

  7. 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…

  8. Synthesis and evaluation of novel acyl derivatives from jatropha oil as potential lubricant basestocks.

    PubMed

    Sammaiah, Arukali; Padmaja, Korlipara V; Prasad, Rachapudi B N

    2014-05-21

    A novel class of jatropha oil-based acylated derivatives from hydroxy alkyl esters of jatropha fatty acids (C1, C3, C4, and C8) and various anhydrides (C2, C3, C4, and C6) were synthesized and their physicochemical and lubricant properties reported. Jatropha fatty acid alkyl esters were dihydroxylated using the in situ performic acid method and further acylated with different anhydrides to produce acylated derivatives. Acylated derivatives of dihydroxy jatropha fatty acid alkyl esters were charaterized by NMR, FTIR, GC, and GC-MS analysis and were evaluated for their viscosity, viscosity index, pour and flash points, and oxidation stability. Most of the derivatives are either in ISO VG 22 or 32 viscosity grade with good viscosity index. It was observed that increase in acyl chain length and branching in the end-chain ester improved the pour point of the diacyl derivatives. All of the hexanoylated esters exhibited better oxidation stability compared to other acylated products, and their pour points are comparable to those of synthetic esters such as TMP trioleates. In general, isoalcohol esters with longer acyl chains showed promise as potential candidates for hydraulic fluids and metal-working fluids in ISO VG 22 and 32 viscosity range.

  9. 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

  10. Identification of Unusual Phospholipid Fatty Acyl Compositions of Acanthamoeba castellanii

    PubMed Central

    Palusinska-Szysz, Marta; Kania, Magdalena; Turska-Szewczuk, Anna; Danikiewicz, Witold; Russa, Ryszard; Fuchs, Beate

    2014-01-01

    Acanthamoeba are opportunistic protozoan pathogens that may lead to sight-threatening keratitis and fatal granulomatous encephalitis. The successful prognosis requires early diagnosis and differentiation of pathogenic Acanthamoeba followed by aggressive treatment regimen. The plasma membrane of Acanthamoeba consists of 25% phospholipids (PL). The presence of C20 and, recently reported, 28- and 30-carbon fatty acyl residues is characteristic of amoeba PL. A detailed knowledge about this unusual PL composition could help to differentiate Acanthamoeba from other parasites, e.g. bacteria and develop more efficient treatment strategies. Therefore, the detailed PL composition of Acanthamoeba castellanii was investigated by 31P nuclear magnetic resonance spectroscopy, thin-layer chromatography, gas chromatography, high performance liquid chromatography and liquid chromatography-mass spectrometry. Normal and reversed phase liquid chromatography coupled with mass spectrometric detection was used for detailed characterization of the fatty acyl composition of each detected PL. The most abundant fatty acyl residues in each PL class were octadecanoyl (18∶0), octadecenoyl (18∶1 Δ9) and hexadecanoyl (16∶0). However, some selected PLs contained also very long fatty acyl chains: the presence of 28- and 30-carbon fatty acyl residues was confirmed in phosphatidylethanolamine (PE), phosphatidylserine, phosphatidic acid and cardiolipin. The majority of these fatty acyl residues were also identified in PE that resulted in the following composition: 28∶1/20∶2, 30∶2/18∶1, 28∶0/20∶2, 30∶2/20∶4 and 30∶3/20∶3. The PL of amoebae are significantly different in comparison to other cells: we describe here for the first time unusual, very long chain fatty acids with Δ5-unsaturation (30∶35,21,24) and 30∶221,24 localized exclusively in specific phospholipid classes of A. castellanii protozoa that could serve as specific biomarkers for the presence of these

  11. 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

  12. 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

  13. 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.

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

    ClinicalTrials.gov

    2016-11-23

    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

  15. How cholesterol interacts with membrane proteins: an exploration of cholesterol-binding sites including CRAC, CARC, and tilted domains.

    PubMed

    Fantini, Jacques; Barrantes, Francisco J

    2013-01-01

    The plasma membrane of eukaryotic cells contains several types of lipids displaying high biochemical variability in both their apolar moiety (e.g., the acyl chain of glycerolipids) and their polar head (e.g., the sugar structure of glycosphingolipids). Among these lipids, cholesterol is unique because its biochemical variability is almost exclusively restricted to the oxidation of its polar -OH group. Although generally considered the most rigid membrane lipid, cholesterol can adopt a broad range of conformations due to the flexibility of its isooctyl chain linked to the polycyclic sterane backbone. Moreover, cholesterol is an asymmetric molecule displaying a planar α face and a rough β face. Overall, these structural features open up a number of possible interactions between cholesterol and membrane lipids and proteins, consistent with the prominent regulatory functions that this unique lipid exerts on membrane components. The aim of this review is to describe how cholesterol interacts with membrane lipids and proteins at the molecular/atomic scale, with special emphasis on transmembrane domains of proteins containing either the consensus cholesterol-binding motifs CRAC and CARC or a tilted peptide. Despite their broad structural diversity, all these domains bind cholesterol through common molecular mechanisms, leading to the identification of a subset of amino acid residues that are overrepresented in both linear and three-dimensional membrane cholesterol-binding sites.

  16. Tilts in strong ground motion

    USGS Publications Warehouse

    Graizer, V.

    2006-01-01

    Most instruments used in seismological practice to record ground motion are pendulum seismographs, velocigraphs, or accelerographs. In most cases it is assumed that seismic instruments are only sensitive to the translational motion of the instrument's base. In this study the full equation of pendulum motion, including the inputs of rotations and tilts, is considered. It is shown that tilting the accelerograph's base can severely impact its response to the ground motion. The method of tilt evaluation using uncorrected strong-motion accelerograms was first suggested by Graizer (1989), and later tested in several laboratory experiments with different strong-motion instruments. The method is based on the difference in the tilt sensitivity of the horizontal and vertical pendulums. The method was applied to many of the strongest records of the Mw 6.7 Northridge earthquake of 1994. Examples are shown when relatively large tilts of up to a few degrees occurred during strong earthquake ground motion. Residual tilt extracted from the strong-motion record at the Pacoima Dam-Upper Left Abutment reached 3.1?? in N45??E direction, and was a result of local earthquake-induced tilting due to high-amplitude shaking. This value is in agreement with the residual tilt measured by using electronic level a few days after the earthquake. The method was applied to the building records from the Northridge earthquake. According to the estimates, residual tilt reached 2.6?? on the ground floor of the 12-story Hotel in Ventura. Processing of most of the strongest records of the Northridge earthquake shows that tilts, if happened, were within the error of the method, or less than about 0.5??.

  17. Acylation type determines ghrelin's effects on energy homeostasis in rodents.

    PubMed

    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; Tschöp, Matthias H

    2012-10-01

    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.

  18. Monolignol acylation and lignin structure in some nonwoody plants: a 2D NMR study.

    PubMed

    Martínez, Angel T; Rencoret, Jorge; Marques, Gisela; Gutiérrez, Ana; Ibarra, David; Jiménez-Barbero, Jesús; del Río, José C

    2008-11-01

    Lignins from three nonwoody angiosperms were analyzed by 2D NMR revealing important differences in their molecular structures. The Musa textilis milled-wood-lignin (MWL), with a syringyl-to-guaiacyl (S/G) ratio of 9, was strongly acylated (near 85% of side-chains) at the gamma-carbon by both acetates and p-coumarates, as estimated from (1)H-(13)C correlations in C(gamma)-esterified and C(gamma)-OH units. The p-coumarate H(3,5)-C(3,5) correlation signal was completely displaced by acetylation, and disappeared after alkali treatment, indicating that p-coumaric acid was esterified maintaining its free phenolic group. By contrast, the Cannabis sativa MWL (S/G approximately 0.8) was free of acylating groups, and the Agave sisalana MWL (S/G approximately 4) showed high acylation degree (near 80%) but exclusively with acetates. Extensive C(gamma)-acylation results in the absence (in M. textilis lignin) or low abundance (4% in A. sisalana lignin) of beta-beta' resinol linkages, which require free C(gamma)-OH to form the double tetrahydrofuran ring. However, minor signals revealed unusual acylated beta-beta' structures confirming that acylation is produced at the monolignol level, in agreement with chromatographic identification of gamma-acetylated sinapyl alcohol among the plant extractives. In contrast, resinol substructures involved 22% side-chains in the C.sativa MWL. The ratio between beta-beta' and beta-O-4' side-chains in these and other MWL varied from 0.32 in C.sativa MWL to 0.02 in M. textilis MWL, and was inversely correlated with the degree of acylation. The opposite was observed for the S/G ratio that was directly correlated with the acylation degree. Monolignol acylation is discussed as a mechanism potentially involved in the control of lignin structure.

  19. 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

  20. Acyl tunichlorins: a new class of nickel chlorins isolated from the Caribbean tunicate Trididemnum solidum.

    PubMed Central

    Sings, H L; Bible, K C; Rinehart, K L

    1996-01-01

    A new class of nickel-containing chlorins (acyl tunichlorins) has been isolated from the Caribbean tunicate Trididemnum solidum. The structures of 28 of these nickel (II) hydroporphyrins were elucidated using mass spectrometry, one- and two-dimensional NMR spectroscopy, and chemical degradation/derivatization. Unique structural features of these compounds include the diversity of aliphatic side chains, which are derived from C14:0 to C22:6 fatty acids, and their location at an unprecedented position at C-2a on the hydroporphyrin nucleus. No chlorins with ester-linked acyl side chains at C-2a have been reported previously. Although the exact biological role that these compounds play in T. solidum remains unknown, acyl tunichlorins represent the only nickel-containing chlorins to be isolated from a living system and are the C-2a acyl derivatives of tunichlorin, a nickel chlorin reported by this laboratory in 1988. PMID:8855217

  1. Cardiopulmonary readjustments in passive tilt

    NASA Technical Reports Server (NTRS)

    Matalon, S. V.; Farhi, L. E.

    1979-01-01

    The readjustment of cardiopulmonary variables in human volunteers at various tilt angles on a tilt board is studied. Five healthy subjects (18-31 yr) with thorough knowledge of the experimental protocol are tested, passively tilted from the supine to the upright position in 15-deg increments in random sequence. The parameters measured are cardiac output (Q), heart rate (HR), stroke volume (SV), minute and alveolar ventilation /V(E) and V(A)/, functional residual capacity (FRC), and arterial-end-tidal P(CO2) pressure difference. It is found that changes in Q and FRC are linearly related to the sine of the tilt angle, indicating that either reflexes are absent or their net effect is proportional to the effects of gravity. This is clearly not the case for other variables /HR, SV, V(E), V(A)/, where it is possible to demonstrate threshold values for the appearance of secondary changes.

  2. 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

  3. Activation of Exogenous Fatty Acids to Acyl-Acyl Carrier Protein Cannot Bypass FabI Inhibition in Neisseria*

    PubMed Central

    Yao, Jiangwei; Bruhn, David F.; Frank, Matthew W.; Lee, Richard E.; Rock, Charles O.

    2016-01-01

    Neisseria is a Gram-negative pathogen with phospholipids composed of straight chain saturated and monounsaturated fatty acids, the ability to incorporate exogenous fatty acids, and lipopolysaccharides that are not essential. The FabI inhibitor, AFN-1252, was deployed as a chemical biology tool to determine whether Neisseria can bypass the inhibition of fatty acid synthesis by incorporating exogenous fatty acids. Neisseria encodes a functional FabI that was potently inhibited by AFN-1252. AFN-1252 caused a dose-dependent inhibition of fatty acid synthesis in growing Neisseria, a delayed inhibition of growth phenotype, and minimal inhibition of DNA, RNA, and protein synthesis, showing that its mode of action is through inhibiting fatty acid synthesis. Isotopic fatty acid labeling experiments showed that Neisseria encodes the ability to incorporate exogenous fatty acids into its phospholipids by an acyl-acyl carrier protein-dependent pathway. However, AFN-1252 remained an effective antibacterial when Neisseria were supplemented with exogenous fatty acids. These results demonstrate that extracellular fatty acids are activated by an acyl-acyl carrier protein synthetase (AasN) and validate type II fatty acid synthesis (FabI) as a therapeutic target against Neisseria. PMID:26567338

  4. 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.

  5. Correlation between length and tilt of lipid tails

    SciTech Connect

    Kopelevich, Dmitry I.; Nagle, John F.

    2015-10-21

    It is becoming recognized from simulations, and to a lesser extent from experiment, that the classical Helfrich-Canham membrane continuum mechanics model can be fruitfully enriched by the inclusion of molecular tilt, even in the fluid, chain disordered, biologically relevant phase of lipid bilayers. Enriched continuum theories then add a tilt modulus κ{sub θ} to accompany the well recognized bending modulus κ. Different enrichment theories largely agree for many properties, but it has been noticed that there is considerable disagreement in one prediction; one theory postulates that the average length of the hydrocarbon chain tails increases strongly with increasing tilt and another predicts no increase. Our analysis of an all-atom simulation favors the latter theory, but it also shows that the overall tail length decreases slightly with increasing tilt. We show that this deviation from continuum theory can be reconciled by consideration of the average shape of the tails, which is a descriptor not obviously includable in continuum theory.

  6. Linear ion-trap MSn with high resolution mass spectrometry reveals structural diversity of epidermal 1-O-acyl ceramide family in mouse epidermis.

    PubMed

    Lin, Meei-Hua; Miner, Jeffery; Turk, John; Hsu, Fong-Fu

    2017-02-02

    1-O-acylceramide is a new class of epidermal ceramide found in humans and mice. Here, we report ESI linear ion-trap (LIT) multiple stage mass spectrometric (MSn) approach with high resolution towards structural characterization of this lipid family isolated from mice. Molecular species desorbed as the [M + H]+ ions was subjected to LIT MS2 to yield predominately the [M + H - H2O]+ ions, followed by MS3 to cleave the 1-O-acyl residue to yield the [M + H - H2O - (1-O-fatty acid)]+ ions. The structures of the N-acyl chain and long-chain base (LCB) of the molecule were determined by MS4 on ([M + H - H2O - (1-O-fatty acid)]+) ions that yielded multiple sets of specific ions. Using this approach, isomers varied in the 1-O-acyl (from 14:0- to 26:0-O-acyl) and N-acyl chains (from 20:0- to 26:0-N-acyl) with 18:1-sphingosine as the major LCB were found for the entire family. Minor isomers consisting of 16:1- 17:1-, 18:2-, and 19:1-sphingosine LCB, with odd fatty acyl chain, or with monounsaturated N- or O- fatty acyl substituents were also identified. An estimation of more than 700 1-O-acylceramide species, largely isobaric isomers are present, underscoring the complexity of this ceramide family.

  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. An insight on acyl migration in solvent-free ethanolysis of model triglycerides using Novozym 435.

    PubMed

    Sánchez, Daniel Alberto; Tonetto, Gabriela Marta; Ferreira, María Luján

    2016-02-20

    In this work, the ethanolysis of triglycerides catalyzed by immobilized lipase was studied, focusing on the secondary reaction of acyl migration. The catalytic tests were performed in a solvent-free reaction medium using Novozym 435 as biocatalyst. The selected experimental variables were biocatalyst loading (5-20mg), reaction time (30-90min), and chain length of the fatty acids in triglycerides with and without unsaturation (short (triacetin), medium (tricaprylin) and long (tripalmitin/triolein)). The formation of 2-monoglyceride by ethanolysis of triglycerides was favored by long reaction times and large biocatalyst loading with saturated short- to medium-chain triglycerides. In the case of long-chain triglycerides, the formation of this monoglyceride was widely limited by acyl migration. In turn, acyl migration increased the yield of ethyl esters and minimized the content of monoglycerides and diglycerides. Thus, the enzymatic synthesis of biodiesel was favored by long-chain triglycerides (which favor the acyl migration), long reaction times and large biocatalyst loading. The conversion of acylglycerides made from long-chain fatty acids with unsaturation was relatively low due to limitations in their access to the active site of the lipase.

  9. 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

  10. 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.

  11. Resolution enhancement in tilted coordinates

    NASA Astrophysics Data System (ADS)

    Hariri Naghadeh, Diako; Keith Morley, Christopher

    2016-11-01

    Deconvolution is applied to remove source wavelet effects from seismograms. The results are resolution enhancement that enables detection of thin layers. Following enhancement of resolution, low frequency and high angle reflectors, particularly at great depth, appear as low amplitude and semi-invisible reflectors that are difficult to track and pick. A new approach to enhance resolution is introduced that estimates a derivative using continuous wavelet transform in tilted coordinates. The results are compared with sparse spike deconvolution, curvelet deconvolution and inverse quality filtering in wavelet domain. The positive consequence of the new method is to increase sampling of high dip features by changing the coordinate system from Cartesian to tilted. To compare those methods a complex data set was chosen that includes high angle faults and chaotic mass transport complex. Image enhancement using curvelet deconvolution shows a chaotic system as a non-chaotic one. The results show that sparse spike deconvolution and inverse quality filtering in wavelet domain are able to enhance resolution more than curvelet deconvolution especially at great depth but it is impossible to follow steep dip reflectors after resolution enhancement using these methods, especially when their apparent dips are more than 45°. By estimating derivatives in a continuous wavelet transform from tilted data sets similar resolution enhancement as the other deconvolution methods is achieved but additionally steep dipping reflectors are imaged much better than others. Subtracted results of the enhanced resolution data set using new method and the other introduced methods show that steeply dipping reflectors are highlighted as a particular ability of the new method. The results show that high frequency recovery in Cartesian co-ordinate is accompanied by inability to image steeply dipping reflectors especially at great depths. Conversely recovery of high frequency data and imaging of the data

  12. 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.

  13. Effects of higher dietary protein intake on energy balance and metabolic control in children with long-chain 3-hydroxy acyl-CoA dehydrogenase (LCHAD) or trifunctional protein (TFP) deWciency

    PubMed Central

    Gillingham, Melanie B.; Purnell, Jonathan Q.; Jordan, Julia; Stadler, Diane; Haqq, Andrea M.; Harding, Cary O.

    2009-01-01

    The incidence of overweight and obesity is increasing among children with long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) or mitochondrial trifunctional (TFP) deficiency. Traditional treatment includes fasting avoidance and consumption of a low-fat, high-carbohydrate diet. A diet higher in protein and lower in carbohydrate may help to lower total energy intake while maintaining good metabolic control. To determine the short-term safety and eYcacy of a high protein diet, subjects were admitted to the General Clinical Research Center and fed an ad-libitum high-protein diet and a high-carbohydrate diet for 6 days each using a randomized, crossover design. Nine subjects with LCHAD or TFP deficiency, age 7–14 were enrolled. Body composition was determined by DEXA. Total energy intake was evaluated daily. Resting energy expenditure and substrate utilization were determined by indirect calorimetry. Post-prandial metabolic responses of plasma glucose, insulin, leptin, ghrelin, acylcarnitines, and triglyceride were determined in response to a liquid meal. Subjects had a higher fat mass, lower lean mass and higher plasma leptin levels compared to reference values. While on the high protein diet energy consumption was an average of 50 kcals/day lower (p=0.02) and resting energy expenditure was an average of 170 kcals/day higher (p=0.05) compared to the high carbohydrate diet. Short-term higher protein diets were safe, well tolerated, and resulted in lowered energy intake and increased energy expenditure than the standard high-carbohydrate diet. Long-term studies are needed to determine whether higher protein diets will reduce the risk of overweight and obesity in children with LCHAD or TFP deficiency. PMID:16996288

  14. 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

  15. The cytotoxic effect of 2-acylated-1,4-naphthohydroquinones on leukemia/lymphoma cells.

    PubMed

    Pedroza, Diego A; De Leon, Fernando; Varela-Ramirez, Armando; Lema, Carolina; Aguilera, Renato J; Mito, Shizue

    2014-01-15

    Here, we tested seven 2-acylated-1,4-hydronaphthoquinones for their cytotoxic effects on a panel of cancer lymphoma/leukemia cells and compared to a non-cancer origin cell line. Several naphthohydroquinones exhibited selective cytotoxic effects on lymphoma/leukemia cells with lowest activity on non-cancer cells. The mode of cell death induced by an acylated naphthohydroquinone, which has a long alkyl chain, was found to be via apoptosis. Furthermore, the naphthohydroquinone provoked mitochondria depolarization and activation of its downstream effector, caspase-3, thus implicating the intrinsic apoptotic pathway as its mechanism to exert cell death.

  16. Localization of acyl coenzyme A:cholesterol acyltransferase gene to human chromosome 1q25

    SciTech Connect

    Chang, C.C.Y.; Chang, W.; Chang, T.Y. ); Noll, W.W.; Nutile-McMenemy, N. ); Lindsay, E.A.; Baldini, A. )

    1994-01-01

    Acyl coenzyme A:cholesterol acyltransferase (ACAT) is an intracellular enzyme that catalyzes the formation of cholesterol esters from cholesterol and long-chain fatty acyl-coenzyme A. It is believed that ACAT plays a key role in lipoprotein metabolism and atherogenesis. Recently the authors' laboratory succeeded in molecular cloning and functional expression of human macrophage ACAT cDNA. They have now mapped the ACAT gene to chromosome 1, band q25 by using fluorescence in situ hybridization to metaphase chromosomes, and by Southern blotting analysis of human-hamster somatic cell hybrid panels.

  17. The cytotoxic effect of 2-acylated-1,4-naphthohydroquinones on leukemia/lymphoma cells

    PubMed Central

    Pedroza, Diego A.; De Leon, Fernando; Varela-Ramirez, Armando; Lema, Carolina; Aguilera, Renato J.; Mito, Shizue

    2014-01-01

    Here, we tested seven 2-acylated-1,4-hydronaphthoquinones for their cytotoxic effects on a panel of cancer lymphoma/leukemia cells and compared to a non-cancer origin cell line. Several naphthohydroquinones exhibited selective cytotoxic effects on lymphoma/leukemia cells with lowest activity on non-cancer cells. The mode of cell death induced by an acylated naphthohydroquinone, which has a long alkyl chain, was found to be via apoptosis. Furthermore, the naphthohydroquinone provoked mitochondria depolarization and activation of its downstream effector, caspase-3, thus implicating the intrinsic apoptotic pathway as its mechanism to exert cell death. PMID:24368029

  18. Paleomagnetic vectors and tilted dikes

    NASA Astrophysics Data System (ADS)

    Borradaile, G. J.

    2001-04-01

    Where tectonic deformation reorients rocks without penetrative strain, their paleomagnetic vectors may be restored to their original attitudes by untilting. For strata, paleomagnetic inclination is readily restored but the tilt axis must be precisely known if paleodeclination is required. For dikes, without the knowledge of the rotation(s), neither declination nor inclination of the paleomagnetic vector can be uniquely defined. Furthermore, back-rotating dike orientations to an upright attitude assumes primary verticality whereas primary dike dips are bimodal across the spreading axes (e.g. Troodos ophiolite, Cyprus). In the Cyprus ophiolite, the dikes of the Limassol Forest Transform Zone are tilted due to uplift of the mantle-sequence rocks and deflected against the Arakapas Fault. Their paleomagnetic vectors may be restored rotating about the two axes defined by the strike and the vertical, or about a net axis that is possibly the actual tectonic rotation axis. This net axis is determined from the tectonic regional dispersion of the dike orientations. In this test case, the results of the restorations differ slightly but underline the difficulty in selecting the best restoration procedure and the greater difficulty of restoring the paleomagnetic data from dikes vis à vis strata. For dikes, it is recommended that the paleomagnetic vectors are restored using average dike orientations to minimize the inaccuracies due to the large primary variation in dike orientation.

  19. 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...

  20. 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.

  1. TILTING TABLE AREA, PDP ROOM, LEVEL +27’, LOOKING NORTHWEST. TILTING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    TILTING TABLE AREA, PDP ROOM, LEVEL +27’, LOOKING NORTHWEST. TILTING TABLE MARKED BY WHITE ELECTRICAL CORD IN LOWER LEFT CENTER - Physics Assembly Laboratory, Area A/M, Savannah River Site, Aiken, Aiken County, SC

  2. Study of Triheptanoin for Treatment of Long-Chain Fatty Acid Oxidation Disorder

    ClinicalTrials.gov

    2017-03-21

    Very Long-chain acylCoA Dehydrogenase (VLCAD) Deficiency; Carnitine Palmitoyltransferase 2 (CPT2) Deficiency; Mitochondrial Trifunctional Protein (TFP) Deficiency; Long-chain 3 hydroxyacylCoA Dehydrogenase (LCHAD) Deficiency

  3. Tilting Uranus without a Collision

    NASA Astrophysics Data System (ADS)

    Rogoszinski, Zeeve; Hamilton, Douglas P.

    2016-10-01

    The most accepted hypothesis for the origin of Uranus' 98° obliquity is a giant collision during the late stages of planetary accretion. This model requires a single Earth mass object striking Uranus at high latitudes; such events occur with a probability of about 10%. Alternatively, Uranus' obliquity may have arisen from a sequence of smaller impactors which lead to a uniform distribution of obliquities. Here we explore a third model for tilting Uranus using secular spin-orbit resonance theory. We investigate early Solar System configurations in which a secular resonance between Uranus' axial precession frequency and another planet's orbital node precession frequency might occur.Thommes et al. (1999) hypothesized that Uranus and Neptune initially formed between Jupiter and Saturn, and were then kicked outward. In our scenario, Neptune leaves first while Uranus remains behind. As an exterior Neptune slowly migrates outward, it picks up both Uranus and Saturn in spin-orbit resonances (Ward and Hamilton 2004; Hamilton and Ward 2004). Only a distant Neptune has a nodal frequency slow enough to resonate with Uranus' axial precession.This scenario, with diverging orbits, results in resonance capture. As Neptune migrates outward its nodal precession slows. While in resonance, Uranus and Saturn each tilt a bit further, slowing their axial precession rates to continually match Neptune's nodal precession rate. Tilting Uranus to high obliquities takes a few 100 Myrs. This timescale may be too long to hold Uranus captive between Jupiter and Saturn, and we are investigating how to reduce it. We also find that resonance capture is rare if Uranus' initial obliquity is greater than about 10°, as the probability of capture decreases as the planet's initial obliquity increases. We will refine this estimate by quantifying capture statistics, and running accretion simulations to test the likelihood of a low early obliquity. Our preliminary findings show that most assumptions about

  4. Interactions of acyl-coenzyme A with phosphatidylcholine bilayers and serum albumin

    SciTech Connect

    Boylan, J.G.; Hamilton, J.A. )

    1992-01-21

    Interactions of oleoyl- and octanoyl-coenzyme A (CoA) with phosphatidylcholine (PC) vesicles and bovine serum albumin (BSA) were investigated by NMR spectroscopy. Binding of acyl-CoA to small unilamellar PC vesicles and to BSA was detected by changes in {sup 13}C and {sup 31}P chemical shifts relative to the chemical shifts for aqueous acyl-CoA. PC vesicles remained intact with {le} 15 mol % oleoyl-CoA, while higher oleoyl-CoA proportions produced mixed micelles. In contrast, {sup 13}C spectra revealed rapid exchange (ms) of octanoyl-CoA between the aqueous phase and PC vesicles and a low affinity for the bilayer. Thus, the binding affinity of acyl-CoA for PC bilayers is dependent on the acyl chain length. Addition of ({sup 13}C)carboxyl-enriched oleic acid to oleoyl-CoA/BSA mixtures revealed simultaneous binding of oleic acid and oleoyl-CoA to BSA, with some perturbation of binding interactions. Thus, BSA contains multiple binding sites for oleoyl-CoA and can bind fatty acid and acyl-CoA simultaneously.

  5. Generation of fatty acids by an acyl esterase in the bioluminescent system of Photobacterium phosphoreum

    SciTech Connect

    Carey, L.M.; Rodriguez, A.; Meighen, E.

    1984-08-25

    The fatty acid reductase complex from Photobacterium phosphoreum has been discovered to have a long chain ester hydrolase activity associated with the 34K protein component of the complex. This protein has been resolved from the other components (50K and 58K) of the fatty acid reductase complex with a purity of > 95% and found to catalyze the transfer of acyl groups from acyl-CoA primarily to thiol acceptors with a low level of transfer to glycerol and water. Addition of the 50K protein of the complex caused a dramatic change in specificity increasing the transfer to oxygen acceptors. The acyl-CoA hydrolase activity increased almost 10-fold, and hence free fatty acids can be generated by the 34K protein when it is present in the fatty acid reductase complex. Hydrolysis of acyl-S-mercaptoethanol and acyl-1-glycerol and the ATP-dependent reduction of the released fatty acids to aldehyde for the luminescent reaction were also demonstrated for the reconstituted fatty acid reductase complex, raising the possibility that the immediate source of fatty acids for this reaction in vivo could be the membrane lipids and/or the fatty acid synthetase system.

  6. 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.

  7. Acyl-CoA oxidase complexes control the chemical message produced by Caenorhabditis elegans.

    PubMed

    Zhang, Xinxing; Feng, Likui; Chinta, Satya; Singh, Prashant; Wang, Yuting; Nunnery, Joshawna K; Butcher, Rebecca A

    2015-03-31

    Caenorhabditis elegans uses ascaroside pheromones to induce development of the stress-resistant dauer larval stage and to coordinate various behaviors. Peroxisomal β-oxidation cycles are required for the biosynthesis of the fatty acid-derived side chains of the ascarosides. Here we show that three acyl-CoA oxidases, which catalyze the first step in these β-oxidation cycles, form different protein homo- and heterodimers with distinct substrate preferences. Mutations in the acyl-CoA oxidase genes acox-1, -2, and -3 led to specific defects in ascaroside production. When the acyl-CoA oxidases were expressed alone or in pairs and purified, the resulting acyl-CoA oxidase homo- and heterodimers displayed different side-chain length preferences in an in vitro activity assay. Specifically, an ACOX-1 homodimer controls the production of ascarosides with side chains with nine or fewer carbons, an ACOX-1/ACOX-3 heterodimer controls the production of those with side chains with seven or fewer carbons, and an ACOX-2 homodimer controls the production of those with ω-side chains with less than five carbons. Our results support a biosynthetic model in which β-oxidation enzymes act directly on the CoA-thioesters of ascaroside biosynthetic precursors. Furthermore, we identify environmental conditions, including high temperature and low food availability, that induce the expression of acox-2 and/or acox-3 and lead to corresponding changes in ascaroside production. Thus, our work uncovers an important mechanism by which C. elegans increases the production of the most potent dauer pheromones, those with the shortest side chains, under specific environmental conditions.

  8. Acyl-CoA oxidase complexes control the chemical message produced by Caenorhabditis elegans

    PubMed Central

    Zhang, Xinxing; Feng, Likui; Chinta, Satya; Singh, Prashant; Wang, Yuting; Nunnery, Joshawna K.; Butcher, Rebecca A.

    2015-01-01

    Caenorhabditis elegans uses ascaroside pheromones to induce development of the stress-resistant dauer larval stage and to coordinate various behaviors. Peroxisomal β-oxidation cycles are required for the biosynthesis of the fatty acid-derived side chains of the ascarosides. Here we show that three acyl-CoA oxidases, which catalyze the first step in these β-oxidation cycles, form different protein homo- and heterodimers with distinct substrate preferences. Mutations in the acyl-CoA oxidase genes acox-1, -2, and -3 led to specific defects in ascaroside production. When the acyl-CoA oxidases were expressed alone or in pairs and purified, the resulting acyl-CoA oxidase homo- and heterodimers displayed different side-chain length preferences in an in vitro activity assay. Specifically, an ACOX-1 homodimer controls the production of ascarosides with side chains with nine or fewer carbons, an ACOX-1/ACOX-3 heterodimer controls the production of those with side chains with seven or fewer carbons, and an ACOX-2 homodimer controls the production of those with ω-side chains with less than five carbons. Our results support a biosynthetic model in which β-oxidation enzymes act directly on the CoA-thioesters of ascaroside biosynthetic precursors. Furthermore, we identify environmental conditions, including high temperature and low food availability, that induce the expression of acox-2 and/or acox-3 and lead to corresponding changes in ascaroside production. Thus, our work uncovers an important mechanism by which C. elegans increases the production of the most potent dauer pheromones, those with the shortest side chains, under specific environmental conditions. PMID:25775534

  9. Large optics inspection, tilting, and washing stand

    DOEpatents

    Ayers, Marion Jay; Ayers, Shannon Lee

    2012-10-09

    A large optics stand provides a risk free means of safely tilting large optics with ease and a method of safely tilting large optics with ease. The optics are supported in the horizontal position by pads. In the vertical plane the optics are supported by saddles that evenly distribute the optics weight over a large area.

  10. Large optics inspection, tilting, and washing stand

    DOEpatents

    Ayers, Marion Jay; Ayers, Shannon Lee

    2010-08-24

    A large optics stand provides a risk free means of safely tilting large optics with ease and a method of safely tilting large optics with ease. The optics are supported in the horizontal position by pads. In the vertical plane the optics are supported by saddles that evenly distribute the optics weight over a large area.

  11. Tip--tilt compensation for astronomical imaging

    SciTech Connect

    Olivier, S.S. ); Gavel, D.T. )

    1994-01-01

    We present a performance analysis of tip--tilt-compensation systems that use natural stars as tilt references. Taking into account properties of the atmosphere and of the galactic stellar populations, we optimize operating parameters over the system to determine performance limits for several varieties of tip--tilt-compensation system operating on a 10-m telescope on Mauna Kea, Hawaii. We find that, for systems that use a single tilt reference star, if the image of the star is uncorrected, a one-axis root-mean-square tilt residual of less than 190 nrad can be obtained for at least 99% of all astronomical objects, whereas if the image of the tilt reference star is fully corrected this limit drops to 90 nrad. For systems that use two tilt reference stars the limits drop to 160 nrad if the images of the stars are uncorrected and to 60 nrad if the images of the stars are fully corrected. These residual tilt levels would permit [ital V]-band images with long-exposure resolution of 8.5, 4.2, 7.3, and 2.9 times the diffraction limit, respectively, where the diffraction-limited resolution in the [ital V] band is 0.011 arcsec. These results may be compared with the typical seeing of 0.75 arcsec.

  12. 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

  13. 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.

  14. Unacylated ghrelin promotes adipogenesis in rodent bone marrow via ghrelin O-acyl transferase and GHS-R1a activity: evidence for target cell-induced acylation

    PubMed Central

    Hopkins, Anna L.; Nelson, Timothy A. S.; Guschina, Irina A.; Parsons, Lydia C.; Lewis, Charlotte L.; Brown, Richard C.; Christian, Helen C.; Davies, Jeffrey S.; Wells, Timothy

    2017-01-01

    Despite being unable to activate the cognate ghrelin receptor (GHS-R), unacylated ghrelin (UAG) possesses a unique activity spectrum that includes promoting bone marrow adipogenesis. Since a receptor mediating this action has not been identified, we re-appraised the potential interaction of UAG with GHS-R in the regulation of bone marrow adiposity. Surprisingly, the adipogenic effects of intra-bone marrow (ibm)-infused acylated ghrelin (AG) and UAG were abolished in male GHS-R-null mice. Gas chromatography showed that isolated tibial marrow adipocytes contain the medium-chain fatty acids utilised in the acylation of UAG, including octanoic acid. Additionally, immunohistochemistry and immunogold electron microscopy revealed that tibial marrow adipocytes show prominent expression of the UAG-activating enzyme ghrelin O-acyl transferase (GOAT), which is located in the membranes of lipid trafficking vesicles and in the plasma membrane. Finally, the adipogenic effect of ibm-infused UAG was completely abolished in GOAT-KO mice. Thus, the adipogenic action of exogenous UAG in tibial marrow is dependent upon acylation by GOAT and activation of GHS-R. This suggests that UAG is subject to target cell-mediated activation – a novel mechanism for manipulating hormone activity. PMID:28361877

  15. 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

  16. The Acyl Desaturase CER17 Is Involved in Producing Wax Unsaturated Primary Alcohols and Cutin Monomers.

    PubMed

    Yang, Xianpeng; Zhao, Huayan; Kosma, Dylan K; Tomasi, Pernell; Dyer, John M; Li, Rongjun; Liu, Xiulin; Wang, Zhouya; Parsons, Eugene P; Jenks, Matthew A; Lü, Shiyou

    2017-02-01

    We report n-6 monounsaturated primary alcohols (C26:1, C28:1, and C30:1 homologs) in the cuticular waxes of Arabidopsis (Arabidopsis thaliana) inflorescence stem, a class of wax not previously reported in Arabidopsis. The Arabidopsis cer17 mutant was completely deficient in these monounsaturated alcohols, and CER17 was found to encode a predicted ACYL-COENZYME A DESATURASE LIKE4 (ADS4). Studies of the Arabidopsis cer4 mutant and yeast variously expressing CER4 (a predicted fatty acyl-CoA reductase) with CER17/ADS4, demonstrated CER4's principal role in synthesis of these monounsaturated alcohols. Besides unsaturated alcohol deficiency, cer17 mutants exhibited a thickened and irregular cuticle ultrastructure and increased amounts of cutin monomers. Although unsaturated alcohols were absent throughout the cer17 stem, the mutation's effects on cutin monomers and cuticle ultrastructure were much more severe in distal than basal stems, consistent with observations that the CER17/ADS4 transcript was much more abundant in distal than basal stems. Furthermore, distal but not basal stems of a double mutant deficient for both CER17/ADS4 and LONG-CHAIN ACYL-COA SYNTHETASE1 produced even more cutin monomers and a thicker and more disorganized cuticle ultrastructure and higher cuticle permeability than observed for wild type or either mutant parent, indicating a dramatic genetic interaction on conversion of very long chain acyl-CoA precursors. These results provide evidence that CER17/ADS4 performs n-6 desaturation of very long chain acyl-CoAs in both distal and basal stems and has a major function associated with governing cutin monomer amounts primarily in the distal segments of the inflorescence stem.

  17. Short-chain ceramides decrease skin barrier properties.

    PubMed

    Novotný, J; Janůsová, B; Novotný, M; Hrabálek, A; Vávrová, K

    2009-01-01

    Stratum corneum ceramides are major determinants of skin barrier function. Although their physiological and pathological role has been widely investigated, to date no structure-activity relationships have been established. In this study, a series of short-chain ceramide analogues with polar head structure identical to ceramide NS, a sphingosine length of 12 carbons and an acyl chain length of 2-12 carbons was synthesized. Their effect on skin permeability was evaluated using porcine skin and two model drugs, theophylline and indomethacin, and compared to that of a physiological ceramide NS. The results showed that the ceramide chain length was crucial for their barrier properties. Ceramides with a 4- to 8-carbon acyl chain were able to increase skin permeability for both drugs up to 10.8 times with maximum effect at a 6-carbon acyl chain. No increase in permeability was found for ceramide analogues with 2- and 12-carbon acyl chains and ceramide NS. The same relationships were obtained for skin concentrations of the model drugs. The relationship between ceramide acyl chain length and its ability to perturb skin barrier showed striking similarity to the behavior of short-chain ceramides in sphingomyelin/phospholipid membranes and confirmed that short-chain ceramides do not act as natural ceramides and their use as experimental tools should be cautious.

  18. Characterization of complex, heterogeneous lipid A samples using HPLC-MS/MS technique I. Overall analysis with respect to acylation, phosphorylation and isobaric distribution.

    PubMed

    Sándor, Viktor; Dörnyei, Ágnes; Makszin, Lilla; Kilár, Ferenc; Péterfi, Zoltán; Kocsis, Béla; Kilár, Anikó

    2016-11-01

    We established a new reversed phase-high performance liquid chromatography method combined with electrospray ionization quadrupole time-of-flight tandem mass spectrometry for the simultaneous determination and structural characterization of different lipid A types in bacteria (Escherichia coli O111, Salmonella adelaide O35 and Proteus morganii O34) showing serological cross-reactivity. The complex lipid A mixtures (obtained by simple extraction and acid hydrolysis of the outer membrane lipopolysaccharides) were separated and detected without phosphate derivatization. Several previously unidentified ions were detected, which differed in the number and type of acyl chains and number of phosphate groups. In several cases, we observed the different retention of isobaric lipid A species, which had different secondary fatty acyl distribution at the C2' or the C3' sites. The fragmentation of the various, C4' monophosphorylated lipid A species in deprotonated forms provided structural assignment for each component. Fragmentation pathways of the tri-acylated, tetra-acylated, penta-acylated, hexa-acylated and hepta-acylated lipid A components and of the lipid A partial structures are suggested. As standards, the hexa-acylated ion at m/z 1716 with the E. coli-type acyl distribution and the hepta-acylated ion at m/z 1954 with the Salmonella-type acyl distribution were used. The results confirmed the presence of multiple forms of lipid A in all strains analyzed. In addition, the negative-ion mode MS permitted efficient detection for non-phosphorylated lipid A components, too. Copyright © 2016 John Wiley & Sons, Ltd.

  19. ROMPgel beads in IRORI format: acylations revisited.

    PubMed

    Roberts, Richard S

    2005-01-01

    Functionalized "designer" polymers derived from ring-opening metathesis polymerization (ROMPgels) are attractive for their high loading, high purity, and ease of synthesis. Their physical state may vary from liquid to gel to granular solid, making a general method of handling these polymers difficult. By incorporating a suitable norbornene-substituted linker on standard Wang beads, ROMPgels can be easily grafted onto the resin, adding the convenience of a bead format while still maintaining the high loading and excellent site accessibility. This advantage is demonstrated by the use of an N-hydroxysuccinimide ROMPgel (3.3 mmol g(-1), a 3-fold increase from the parent linker resin) in IRORI Kan format. Conditions for the acylation of these IRORI-formatted ROMPgels are reported, along with the scope and limitations of the choice of acylating reagents. Yields are greatly improved by the use of perfluorinated solvents as a nonparticipating cosolvent in the acylation process. A simple titration method for the quantification of the acylated ROMPgels is also reported. Spent Kans are regenerated after each use without apparent loss of activity or purity after several cycles. Due to the high loading and reduced swelling of the ROMPgel resin, up to 0.39 mmol acyl group has successfully been recovered from a single IRORI miniKan, demonstrating the high capacity of the resin and applicability to both lead discovery and optimization programs.

  20. Location and biosynthesis of monoterpenyl fatty acyl esters in rose petals.

    PubMed

    Dunphy, Patrick J

    2006-06-01

    The upper epidermal layer of cells and the epicuticular wax surface of Lady Seton rose petals are sites of biosynthesis and accumulation, respectively, of a family of terpenyl fatty acyl esters. These esters are based mainly on the acyclic monoterpene alcohol geraniol coupled primarily to fatty acids of chain lengths 16-20 and in mass terms represent from 14% to 64% of the total monoterpenes present in the petals. The lipophilic nature of these non-volatile esters of the monoterpene alcohols contrasts with that of the lipophilic volatile parent alcohols themselves and with the hydrophilic, non-volatile, glucoside derivative of the other principal petal fragrant compounds, the phenylpropanoids, beta-phenyl ethanol and benzyl alcohol. These latter compounds are also synthesised and are resident in the petal. Biosynthetic studies confirmed that the petal upper epidermal cell layer has the capacity to incorporate mevalonic acid into the monoterpene component of the fatty acyl ester. The biosynthesis of the monoterpene component of the fatty acyl ester occurs via the mevalonic acid pathway in Lady Seton as well as in the hybrid tea rose Fragrant Cloud. In the latter flower the biosynthesis of geraniol was biosynthetically trans as was the formation of nerol and citronellol. Both geraniol and nerol were shown to be precursors of citronellol via an NADPH dependent reductase reaction. Oleic acid is assimilated into the acyl moiety of the terpenyl ester in Lady Seton isolated petal discs. It is probable that the lipophilic non-volatile terpenyl fatty acyl esters represent a stable storage form of the corresponding alcohols from their residency within the epicuticular wax layer. These acyl esters may realise, on hydrolysis, additional aroma notes from the living flower and potentially commercially significant quantities of the fragrant terpenols during oil of rose essence production.

  1. Ralstonia solanacearum RSp0194 Encodes a Novel 3-Keto-Acyl Carrier Protein Synthase III.

    PubMed

    Mao, Ya-Hui; Ma, Jin-Cheng; Li, Feng; Hu, Zhe; Wang, Hai-Hong

    2015-01-01

    Fatty acid synthesis (FAS), a primary metabolic pathway, is essential for survival of bacteria. Ralstonia solanacearum, a β-proteobacteria member, causes a bacterial wilt affecting more than 200 plant species, including many economically important plants. However, thus far, the fatty acid biosynthesis pathway of R. solanacearum has not been well studied. In this study, we characterized two forms of 3-keto-ACP synthase III, RsFabH and RsFabW, in R. solanacearum. RsFabH, the homologue of Escherichia coli FabH, encoded by the chromosomal RSc1050 gene, catalyzes the condensation of acetyl-CoA with malonyl-ACP in the initiation steps of fatty acid biosynthesis in vitro. The RsfabH mutant lost de novo fatty acid synthetic ability, and grows in medium containing free fatty acids. RsFabW, a homologue of Pseudomonas aeruginosa PA3286, encoded by a megaplasmid gene, RSp0194, condenses acyl-CoA (C2-CoA to C10-CoA) with malonyl-ACP to produce 3-keto-acyl-ACP in vitro. Although the RsfabW mutant was viable, RsfabW was responsible for RsfabH mutant growth on medium containing free fatty acids. Our results also showed that RsFabW could condense acyl-ACP (C4-ACP to C8-ACP) with malonyl-ACP, to produce 3-keto-acyl-ACP in vitro, which implies that RsFabW plays a special role in fatty acid synthesis of R. solanacearum. All of these data confirm that R. solanacearum not only utilizes acetyl-CoA, but also, utilizes medium-chain acyl-CoAs or acyl-ACPs as primers to initiate fatty acid synthesis.

  2. 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.

  3. Heterologous expression of the acyl-acyl carrier protein thioesterase gene from the plant Umbellularia californica mediates polyhydroxyalkanoate biosynthesis in recombinant Escherichia coli.

    PubMed

    Rehm, B H; Steinbüchel, A

    2001-03-01

    The acyl-acyl carrier protein (ACP) thioesterase cDNA from the plant Umbellularia californica was functionally expressed in various recombinant Escherichia coli strains in order to establish a new metabolic route toward medium-chain-length polyhydroxyalkanoate (PHA(MCL)) biosynthesis from non-related carbon sources. Coexpression of the PHA synthase genes from Ralstonia eutropha and Pseudomonas aeruginosa, or only the PHA synthase gene from P. aeruginosa, respectively, showed PHA(MCL) accumulation when the type II PHA synthase from P. aeruginosa was produced. Both wild-type E. coli and various fad mutants were investigated; and only when the beta-oxidation pathway was impaired PHA(MCL) accumulation from gluconate was observed, contributing to about 6% of cellular dry weight. Thus coexpression of type II PHA synthase gene with cDNA encoding the medium-chain acyl-ACP thioesterase from U. californica established a new PHA(MCL) biosynthesis pathway, connecting fatty acid de novo biosynthesis with fatty acid beta-oxidation, using a non-related carbon source.

  4. In silico prediction of acyl glucuronide reactivity

    NASA Astrophysics Data System (ADS)

    Potter, Tim; Lewis, Richard; Luker, Tim; Bonnert, Roger; Bernstein, Michael A.; Birkinshaw, Timothy N.; Thom, Stephen; Wenlock, Mark; Paine, Stuart

    2011-11-01

    Drugs and drug candidates containing a carboxylic acid moiety, including many widely used non-steroidal anti-inflammatory drugs (NSAIDs) are often metabolized to form acyl glucuronides (AGs). NSAIDs such as Ibuprofen are amongst the most widely used drugs on the market, whereas similar carboxylic acid drugs such as Suprofen have been withdrawn due to adverse events. Although the link between these AG metabolites and toxicity is not proven, there is circumstantial literature evidence to suggest that more reactive acyl glucuronides may, in some cases, present a greater risk of exhibiting toxic effects. We wished therefore to rank the reactivity of potential new carboxylate-containing drug candidates, and performed kinetic studies on synthetic acyl glucuronides to benchmark our key compounds. Driven by the desire to quickly rank the reactivity of compounds without the need for lengthy synthesis of the acyl glucuronide, a correlation was established between the degradation half-life of the acyl glucuronide and the half life for the hydrolysis of the more readily available methyl ester derivative. This finding enabled a considerable broadening of chemical property space to be investigated. The need for kinetic measurements was subsequently eliminated altogether by correlating the methyl ester hydrolysis half-life with the predicted 13C NMR chemical shift of the carbonyl carbon together with readily available steric descriptors in a PLS model. This completely in silico prediction of acyl glucuronide reactivity is applicable within the earliest stages of drug design with low cost and acceptable accuracy to guide intelligent molecular design. This reactivity data will be useful alongside the more complex additional pharmacokinetic exposure and distribution data that is generated later in the drug discovery process for assessing the overall toxicological risk of acidic drugs.

  5. Dynamic of charged planar geometry in tilted and non-tilted frames

    SciTech Connect

    Sharif, M. Zaeem Ul Haq Bhatti, M.

    2015-05-15

    We investigate the dynamics of charged planar symmetry with an anisotropic matter field subject to a radially moving observer called a tilted observer. The Einstein-Maxwell field equations are used to obtain a relation between non-tilted and tilted frames and between kinematical and dynamical quantities. Using the Taub mass formalism and conservation laws, two evolution equations are developed to analyze the inhomogeneities in the tilted congruence. It is found that the radial velocity (due to the tilted observer) and the electric charge have a crucial effect on the inhomogeneity factor. Finally, we discuss the stability in the non-tilted frame in the pure diffusion case and examine the effects of the electromagnetic field.

  6. Exploration of an imide capture/N,N-acyl shift sequence for asparagine native peptide bond formation.

    PubMed

    Mhidia, Reda; Boll, Emmanuelle; Fécourt, Fabien; Ermolenko, Mikhail; Ollivier, Nathalie; Sasaki, Kaname; Crich, David; Delpech, Bernard; Melnyk, Oleg

    2013-06-15

    Imide capture of a C-terminal peptidylazide with a side-chain thioacid derivative of an N-terminally protected aspartyl peptide leads to the formation of an imide bond bringing the two peptide ends into close proximity. Unmasking of the N(α) protecting group and intramolecular acyl migration results in the formation of a native peptide bond to asparagine.

  7. Downregulation of carnitine acyl-carnitine translocase by miRNAs 132 and 212 amplifies glucose-stimulated insulin secretion.

    PubMed

    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; Attie, Alan D

    2014-11-01

    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.

  8. 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

  9. Novel Structural Components Contribute to the High Thermal Stability of Acyl Carrier Protein from Enterococcus faecalis*

    PubMed Central

    Park, Young-Guen; Jung, Min-Cheol; Song, Heesang; Jeong, Ki-Woong; Bang, Eunjung; Hwang, Geum-Sook; Kim, Yangmee

    2016-01-01

    Enterococcus faecalis is a Gram-positive, commensal bacterium that lives in the gastrointestinal tracts of humans and other mammals. It causes severe infections because of high antibiotic resistance. E. faecalis can endure extremes of temperature and pH. Acyl carrier protein (ACP) is a key element in the biosynthesis of fatty acids responsible for acyl group shuttling and delivery. In this study, to understand the origin of high thermal stabilities of E. faecalis ACP (Ef-ACP), its solution structure was investigated for the first time. CD experiments showed that the melting temperature of Ef-ACP is 78.8 °C, which is much higher than that of Escherichia coli ACP (67.2 °C). The overall structure of Ef-ACP shows the common ACP folding pattern consisting of four α-helices (helix I (residues 3–17), helix II (residues 39–53), helix III (residues 60–64), and helix IV (residues 68–78)) connected by three loops. Unique Ef-ACP structural features include a hydrophobic interaction between Phe45 in helix II and Phe18 in the α1α2 loop and a hydrogen bonding between Ser15 in helix I and Ile20 in the α1α2 loop, resulting in its high thermal stability. Phe45-mediated hydrophobic packing may block acyl chain binding subpocket II entry. Furthermore, Ser58 in the α2α3 loop in Ef-ACP, which usually constitutes a proline in other ACPs, exhibited slow conformational exchanges, resulting in the movement of the helix III outside the structure to accommodate a longer acyl chain in the acyl binding cavity. These results might provide insights into the development of antibiotics against pathogenic drug-resistant E. faecalis strains. PMID:26631734

  10. Novel Structural Components Contribute to the High Thermal Stability of Acyl Carrier Protein from Enterococcus faecalis.

    PubMed

    Park, Young-Guen; Jung, Min-Cheol; Song, Heesang; Jeong, Ki-Woong; Bang, Eunjung; Hwang, Geum-Sook; Kim, Yangmee

    2016-01-22

    Enterococcus faecalis is a Gram-positive, commensal bacterium that lives in the gastrointestinal tracts of humans and other mammals. It causes severe infections because of high antibiotic resistance. E. faecalis can endure extremes of temperature and pH. Acyl carrier protein (ACP) is a key element in the biosynthesis of fatty acids responsible for acyl group shuttling and delivery. In this study, to understand the origin of high thermal stabilities of E. faecalis ACP (Ef-ACP), its solution structure was investigated for the first time. CD experiments showed that the melting temperature of Ef-ACP is 78.8 °C, which is much higher than that of Escherichia coli ACP (67.2 °C). The overall structure of Ef-ACP shows the common ACP folding pattern consisting of four α-helices (helix I (residues 3-17), helix II (residues 39-53), helix III (residues 60-64), and helix IV (residues 68-78)) connected by three loops. Unique Ef-ACP structural features include a hydrophobic interaction between Phe(45) in helix II and Phe(18) in the α1α2 loop and a hydrogen bonding between Ser(15) in helix I and Ile(20) in the α1α2 loop, resulting in its high thermal stability. Phe(45)-mediated hydrophobic packing may block acyl chain binding subpocket II entry. Furthermore, Ser(58) in the α2α3 loop in Ef-ACP, which usually constitutes a proline in other ACPs, exhibited slow conformational exchanges, resulting in the movement of the helix III outside the structure to accommodate a longer acyl chain in the acyl binding cavity. These results might provide insights into the development of antibiotics against pathogenic drug-resistant E. faecalis strains.

  11. Tunable Oleo-Furan Surfactants by Acylation of Renewable Furans

    PubMed Central

    2016-01-01

    An important advance in fluid surface control was the amphiphilic surfactant composed of coupled molecular structures (i.e., hydrophilic and hydrophobic) to reduce surface tension between two distinct fluid phases. However, implementation of simple surfactants has been hindered by the broad range of applications in water containing alkaline earth metals (i.e., hard water), which disrupt surfactant function and require extensive use of undesirable and expensive chelating additives. Here we show that sugar-derived furans can be linked with triglyceride-derived fatty acid chains via Friedel–Crafts acylation within single layer (SPP) zeolite catalysts. These alkylfuran surfactants independently suppress the effects of hard water while simultaneously permitting broad tunability of size, structure, and function, which can be optimized for superior capability for forming micelles and solubilizing in water. PMID:27924310

  12. 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.

  13. The tilt illusion: phenomenology and functional implications.

    PubMed

    Clifford, Colin W G

    2014-11-01

    The perceived orientation of a line or grating is affected by the orientation structure of the surrounding image: the tilt illusion. Here, I offer a selective review of the literature on the tilt illusion, focusing on functional aspects. The review explores the merits of mechanistic accounts of the tilt illusion based upon sensory gain control in which neuronal responses are normalized by the pooled activity of other units. The role of inhibition between orientation-selective neurons is discussed, and it is argued that their associated disinhibition must also be taken into account in order to model the full angular dependence of the tilt illusion on surround orientation. Parallels are drawn with adaptation as modulation by the temporal rather than spatial context within which an image fragment is processed. The chromatic selectivity of the tilt illusion and the extent of its dependence on the visibility of the surround are used to infer characteristics of the neuronal normalization pools and the loci in the cortical processing hierarchy at which gain control operates. Finally, recent evidence is discussed as to the possible clinical relevance of the tilt illusion as a biomarker for schizophrenia.

  14. Tilted planes in 3D image analysis

    NASA Astrophysics Data System (ADS)

    Pargas, Roy P.; Staples, Nancy J.; Malloy, Brian F.; Cantrell, Ken; Chhatriwala, Murtuza

    1998-03-01

    Reliable 3D wholebody scanners which output digitized 3D images of a complete human body are now commercially available. This paper describes a software package, called 3DM, being developed by researchers at Clemson University and which manipulates and extracts measurements from such images. The focus of this paper is on tilted planes, a 3DM tool which allows a user to define a plane through a scanned image, tilt it in any direction, and effectively define three disjoint regions on the image: the points on the plane and the points on either side of the plane. With tilted planes, the user can accurately take measurements required in applications such as apparel manufacturing. The user can manually segment the body rather precisely. Tilted planes assist the user in analyzing the form of the body and classifying the body in terms of body shape. Finally, titled planes allow the user to eliminate extraneous and unwanted points often generated by a 3D scanner. This paper describes the user interface for tilted planes, the equations defining the plane as the user moves it through the scanned image, an overview of the algorithms, and the interaction of the tilted plane feature with other tools in 3DM.

  15. Acyl anion free N-heterocyclic carbene organocatalysis.

    PubMed

    Ryan, Sarah J; Candish, Lisa; Lupton, David W

    2013-06-21

    Reaction discovery using N-heterocyclic carbene organocatalysis has been dominated by the chemistry of acyl anion equivalents. Recent studies demonstrate that NHCs are far more diverse catalysts, with a variety of reactions discovered that proceed without acyl anion equivalent formation. In this tutorial review selected examples of acyl anion free NHC catalysis using carbonyl compounds are presented.

  16. Highly acylated (acetylated and/or p-coumaroylated) native lignins from diverse herbaceous plants.

    PubMed

    del Río, José C; Rencoret, Jorge; Marques, Gisela; Gutiérrez, Ana; Ibarra, David; Santos, J Ignacio; Jiménez-Barbero, Jesús; Zhang, Liming; Martínez, Angel T

    2008-10-22

    The structure of lignins isolated from the herbaceous plants sisal ( Agave sisalana), kenaf ( Hibiscus cannabinus), abaca ( Musa textilis) and curaua ( Ananas erectifolius) has been studied upon spectroscopic (2D-NMR) and chemical degradative (derivatization followed by reductive cleavage) methods. The analyses demonstrate that the structure of the lignins from these plants is highly remarkable, being extensively acylated at the gamma-carbon of the lignin side chain (up to 80% acylation) with acetate and/or p-coumarate groups and preferentially over syringyl units. Whereas the lignins from sisal and kenaf are gamma-acylated exclusively with acetate groups, the lignins from abaca and curaua are esterified with acetate and p-coumarate groups. The structures of all these highly acylated lignins are characterized by a very high syringyl/guaiacyl ratio, a large predominance of beta- O-4' linkages (up to 94% of all linkages), and a strikingly low proportion of traditional beta-beta' linkages, which indeed are completely absent in the lignins from abaca and curaua. The occurrence of beta-beta' homocoupling and cross-coupling products of sinapyl acetate in the lignins from sisal and kenaf indicates that sinapyl alcohol is acetylated at the monomer stage and that, therefore, sinapyl acetate should be considered as a real monolignol involved in the lignification reactions.

  17. 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.

  18. Acylated pregnane glycosides from Caralluma russeliana.

    PubMed

    Abdel-Sattar, Essam; Ahmed, Ahmed A; Hegazy, Mohamed-Elamir F; Farag, Mohamed A; Al-Yahya, Mohammad Abdul-Aziz

    2007-05-01

    The chloroform extract of the aerial parts of Caralluma russeliana yielded four acylated pregnane glycosides, namely russeliosides E-H, three were found now. The structures of the compounds were elucidated using MS, 1H NMR, 13C NMR, 1H-1H COSY, HMQC, NOESY and HMBC experiments.

  19. Acylation of the Type 3 Secretion System Translocon Using a Dedicated Acyl Carrier Protein

    PubMed Central

    Agrebi, Rym; Canestrari, Mickaël J.; Mignot, Tâm; Lebrun, Régine; Bouveret, Emmanuelle

    2017-01-01

    Bacterial pathogens often deliver effectors into host cells using type 3 secretion systems (T3SS), the extremity of which forms a translocon that perforates the host plasma membrane. The T3SS encoded by Salmonella pathogenicity island 1 (SPI-1) is genetically associated with an acyl carrier protein, IacP, whose role has remained enigmatic. In this study, using tandem affinity purification, we identify a direct protein-protein interaction between IacP and the translocon protein SipB. We show, by mass spectrometry and radiolabelling, that SipB is acylated, which provides evidence for a modification of the translocon that has not been described before. A unique and conserved cysteine residue of SipB is identified as crucial for this modification. Although acylation of SipB was not essential to virulence, we show that this posttranslational modification promoted SipB insertion into host-cell membranes and pore-forming activity linked to the SPI-1 T3SS. Cooccurrence of acyl carrier and translocon proteins in several γ- and β-proteobacteria suggests that acylation of the translocon is conserved in these other pathogenic bacteria. These results also indicate that acyl carrier proteins, known for their involvement in metabolic pathways, have also evolved as cofactors of new bacterial protein lipidation pathways. PMID:28085879

  20. Molar absorptivity and color characteristics of acylated and non-acylated pelargonidin-based anthocyanins.

    PubMed

    Giusti, M M; Rodríguez-Saona, L E; Wrolstad, R E

    1999-11-01

    The effects of glycosylation and acylation on the spectral characteristics, molar absorptivity, and color attributes of purified acylated and non-acylated pelargonidin derivatives were compared. Pigments were obtained from strawberries, radishes, red-fleshed potatoes, and partially hydrolyzed radish pigments. Individual pigments were isolated by using semipreparative HPLC. Spectral and color (CIELch) attributes of purified pigments were measured. Molar absorptivity ranged from 15 600 to 39 590 for pelargonidin-3-glucoside (pg-3-glu) and pg-3-rutinoside-5-glucoside acylated with p-coumaric acid, respectively. The presence of cinnamic acid acylation had a considerable impact on spectral and color characteristics, causing a bathochromic shift of lambda(max). Sugar substitution also played an important role, with a hypsochromic shift caused by the presence of glycosylation. Pg-3, 5-diglu and pg-3,5-triglu possessed a higher hue angle (>40 degrees ) than the other pg derivatives at pH 1.0, corresponding to the yellow-orange region of the color solid. Acylation with malonic acid did not affect lambda(max) and showed little effect on color characteristics. The solvent system had an effect not only on the molar absorptivity, but also on the visual color characteristic of the pigments.

  1. Cloning of nitroalkane oxidase from Fusarium oxysporum identifies a new member of the acyl-CoA dehydrogenase superfamily

    PubMed Central

    Daubner, S. Colette; Gadda, Giovanni; Valley, Michael P.; Fitzpatrick, Paul F.

    2002-01-01

    The flavoprotein nitroalkane oxidase (NAO) from Fusarium oxysporum catalyzes the oxidation of nitroalkanes to the respective aldehydes with production of nitrite and hydrogen peroxide. The sequences of several peptides from the fungal enzyme were used to design oligonucleotides for the isolation of a portion of the NAO gene from an F. oxysporum genomic DNA preparation. This sequence was used to clone the cDNA for NAO from an F. oxysporum cDNA library. The sequence of the cloned cDNA showed that NOA is a member of the acyl-CoA dehydrogenase (ACAD) superfamily. The members of this family share with NAO a mechanism that is initiated by proton removal from carbon, suggesting a common chemical reaction for this superfamily. NAO was expressed in Escherichia coli and the recombinant enzyme was characterized. Recombinant NAO has identical kinetic parameters to enzyme isolated from F. oxysporum but is isolated with oxidized FAD rather than the nitrobutyl-FAD found in the fungal enzyme. NAO purified from E. coli or from F. oxysporum has no detectable ACAD activity on short- or medium-chain acyl CoAs, and medium-chain acyl-CoA dehydrogenase and short-chain acyl-CoA dehydrogenase are unable to catalyze oxidation of nitroalkanes. PMID:11867731

  2. Calibration method of tilt and azimuth angles for alignment of TEM tomographic tilt series

    NASA Astrophysics Data System (ADS)

    Hayashida, Misa; Terauchi, Shinya; Fujimoto, Toshiyuki

    2011-10-01

    This paper describes the calibration method of the tilt and azimuth angles of specimen using a digital protractor and a laser autocollimator for alignment of electron tomography. It also suggests an easy method to check whether the specimen is tilted by 180.0°, and whether the azimuth angle is 0.0°; the method involves the use of two images of a rod-shaped specimen collected before and after a 180.0° tilt. The method is based on the assumption that these images are symmetric about the tilt axis when the azimuth angle is 0.0°. In addition, we used an experiment to demonstrate the effect of the incorrect angles on reconstructed images and simulated the image quality against distance away from tilt axis.

  3. 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

    2015-11-06

    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.

  4. 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

    Vu, Hieu Sy; Roth, Mary R; Tamura, Pamela; Samarakoon, Thilani; Shiva, Sunitha; Honey, Samuel; Lowe, Kaleb; Schmelz, Eric A; Williams, Todd D; Welti, Ruth

    2014-04-01

    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 (galactose-acylated monogalactosyldiacylglycerol) 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.

  5. Tilt assembly for tracking solar collector assembly

    DOEpatents

    Almy, Charles; Peurach, John; Sandler, Reuben

    2012-01-24

    A tilt assembly is used with a solar collector assembly of the type comprising a frame, supporting a solar collector, for movement about a tilt axis by pivoting a drive element between first and second orientations. The tilt assembly comprises a drive element coupler connected to the drive element and a driver, the driver comprising a drive frame, a drive arm and a drive arm driver. The drive arm is mounted to the drive frame for pivotal movement about a drive arm axis. Movement on the drive arm mimics movement of the drive element. Drive element couplers can extend in opposite directions from the outer portion of the drive arm, whereby the assembly can be used between adjacent solar collector assemblies in a row of solar collector assemblies.

  6. Advances in tilt rotor noise prediction

    NASA Technical Reports Server (NTRS)

    George, A. R.; Coffen, C. D.; Ringler, T. D.

    1992-01-01

    The two most serious tilt rotor external noise problems, hover noise and blade-vortex interaction noise, are studied. The results of flow visualization and inflow velocity measurements document a complex, recirculating highly unsteady and turbulent flow due to the rotor-wing-body interactions characteristic of tilt rotors. The wing under the rotor is found to obstruct the inflow, causing a deficit in the inflow velocities over the inboard region of the rotor. Discrete frequency harmonic thickness and loading noise mechanisms in hover are examined by first modeling tilt rotor hover aerodynamics and then applying various noise prediction methods using the WOPWOP code. The analysis indicates that the partial ground plane created by the wing below the rotor results in a primary sound source for hover.

  7. Tilted cone beam VCT reconstruction algorithm

    NASA Astrophysics Data System (ADS)

    Hsieh, Jiang; Tang, Xiangyang

    2005-04-01

    Reconstruction algorithms for volumetric CT have been the focus of many studies. Several exact and approximate reconstruction algorithms have been proposed for step-and-shoot and helical scanning trajectories to combat cone beam related artifacts. In this paper, we present a closed form cone beam reconstruction formula for tilted gantry data acquisition. Although several algorithms were proposed to compensate for errors induced by the gantry tilt, none of the algorithms addresses the case in which the cone beam geometry is first rebinned to a set of parallel beams prior to the filtered backprojection. Because of the rebinning process, the amount of iso-center adjustment depends not only on the projection angle and tilt angle, but also on the reconstructed pixel location. The proposed algorithm has been tested extensively on both 16 and 64 slice VCT with phantoms and clinical data. The efficacy of the algorithm is clearly demonstrated by the experiments.

  8. 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

  9. Microwave Brightness Temperatures of Tilted Convective Systems

    NASA Technical Reports Server (NTRS)

    Hong, Ye; Haferman, Jeffrey L.; Olson, William S.; Kummerow, Christian D.

    1998-01-01

    Aircraft and ground-based radar data from the Tropical Ocean and Global Atmosphere Coupled-Ocean Atmosphere Response Experiment (TOGA COARE) show that convective systems are not always vertical. Instead, many are tilted from vertical. Satellite passive microwave radiometers observe the atmosphere at a viewing angle. For example, the Special Sensor Microwave/Imager (SSM/I) on Defense Meteorological Satellite Program (DMSP) satellites and the Tropical Rainfall Measurement Mission (TRMM) Microwave Imager (TMI) on the TRMM satellite have an incident angle of about 50deg. Thus, the brightness temperature measured from one direction of tilt may be different than that viewed from the opposite direction due to the different optical depth. This paper presents the investigation of passive microwave brightness temperatures of tilted convective systems. To account for the effect of tilt, a 3-D backward Monte Carlo radiative transfer model has been applied to a simple tilted cloud model and a dynamically evolving cloud model to derive the brightness temperature. The radiative transfer results indicate that brightness temperature varies when the viewing angle changes because of the different optical depth. The tilt increases the displacements between high 19 GHz brightness temperature (Tb(sub 19)) due to liquid emission from lower level of cloud and the low 85 GHz brightness temperature (Tb(sub 85)) due to ice scattering from upper level of cloud. As the resolution degrades, the difference of brightness temperature due to the change of viewing angle decreases dramatically. The dislocation between Tb(sub 19) and Tb(sub 85), however, remains prominent.

  10. Acyl-CoA thioesterase-2 facilitates mitochondrial fatty acid oxidation in the liver[S

    PubMed Central

    Moffat, Cynthia; Bhatia, Lavesh; Nguyen, Teresa; Lynch, Peter; Wang, Miao; Wang, Dongning; Ilkayeva, Olga R.; Han, Xianlin; Hirschey, Matthew D.; Claypool, Steven M.; Seifert, Erin L.

    2014-01-01

    Acyl-CoA thioesterase (Acot)2 localizes to the mitochondrial matrix and hydrolyses long-chain fatty acyl-CoA into free FA and CoASH. Acot2 is expressed in highly oxi­dative tissues and is poised to modulate mitochondrial FA oxidation (FAO), yet its biological role is unknown. Using a model of adenoviral Acot2 overexpression in mouse liver (Ad-Acot2), we show that Acot2 increases the utilization of FA substrate during the daytime in ad libitum-fed mice, but the nighttime switch to carbohydrate oxidation is similar to control mice. In further support of elevated FAO in Acot2 liver, daytime serum ketones were higher in Ad-Acot2 mice, and overnight fasting led to minimal hepatic steatosis as compared with control mice. In liver mitochondria from Ad-Acot2 mice, phosphorylating O2 consumption was higher with lipid substrate, but not with nonlipid substrate. This increase depended on whether FA could be activated on the outer mitochondrial membrane, suggesting that the FA released by Acot2 could be effluxed from mitochondria then taken back up again for oxidation. This circuit would prevent the build-up of inhibitory long-chain fatty acyl-CoA esters. Altogether, our findings indicate that Acot2 can enhance FAO, possibly by mitigating the accumulation of FAO intermediates within the mitochondrial matrix. PMID:25114170

  11. Modifications of the acyl-d-alanyl-d-alanine terminus affecting complex-formation with vancomycin

    PubMed Central

    Nieto, M.; Perkins, H. R.

    1971-01-01

    Vancomycin forms complexes with peptides terminating in d-alanyl-d-alanine that are analogous to the biosynthetic precursors of bacterial mucopeptides. The specificity of complex-formation has been studied by means of many synthetic peptides, prepared by both solid-phase and conventional methods. The following conclusions can be drawn: (a) three amide linkages are required to form a stable complex; (b) the terminal carboxyl group must be free; (c) the carboxyl terminal and subterminal residues must be either glycine or of the d-configuration; (d) the size of the side chain in these residues greatly influences the affinity for vancomycin, a methyl group being the optimum in each case; (e) the nature of the side chain in the third and fourth residues has a smaller effect on complex-formation, but an l-configuration was somewhat better than a d-configuration in the third position. In addition to acyl-d-alanyl-d-alanine, other peptides that occur in bacterial cell walls will combine with vancomycin, although less strongly, e.g. acyl-d-alanyl-d-α-amino acid (where the terminal d-residue may form the cross-link in mucopeptide structure) and acyl-l-alanyl-d-glutamylglycine (a sequence found in the mucopeptide of Micrococcus lysodeikticus and related organisms). These results throw some light on the specificity of the uptake of vancomycin by living bacteria. PMID:5124386

  12. Some THEMIS tip-tilt images .

    NASA Astrophysics Data System (ADS)

    Bommier, V.

    In the MTR (`MulTiRaies', i.e. multiline spectropolarimetry) mode of THEMIS, a map is the result of a reconstruction from a scan of the solar image on the spectrograph entrance slit. The result of image motion appears as zigzags along non-vertical lines or structures in the map. As an image stabilization system, the new tip-tilt acts in reducing such zigzags. A map is presented obtained with the tip-tilt ON where nearly no zigzag is visible.

  13. Combined Scanning Transmission Electron Microscopy Tilt- and Focal Series

    SciTech Connect

    Dahmen, Tim; Baudoin, Jean-Pierre G; Lupini, Andrew R; Kubel, Christian; Slusallek, Phillip; De Jonge, Niels

    2014-01-01

    In this study, a combined tilt- and focal series is proposed as a new recording scheme for high-angle annular dark-field scanning transmission electron microscopy (STEM) tomography. Three-dimensional (3D) data were acquired by mechanically tilting the specimen, and recording a through-focal series at each tilt direction. The sample was a whole-mount macrophage cell with embedded gold nanoparticles. The tilt focal algebraic reconstruction technique (TF-ART) is introduced as a new algorithm to reconstruct tomograms from such combined tilt- and focal series. The feasibility of TF-ART was demonstrated by 3D reconstruction of the experimental 3D data. The results were compared with a conventional STEM tilt series of a similar sample. The combined tilt- and focal series led to smaller missing wedge artifacts, and a higher axial resolution than obtained for the STEM tilt series, thus improving on one of the main issues of tilt series-based electron tomography.

  14. Synthesis and characterization of O-acylated-ω-hydroxy fatty acids as skin-protecting barrier lipids.

    PubMed

    Pérez, B; Dahlgaard, S E; Bulsara, P; Rawlings, A V; Jensen, M M; Dong, M; Glasius, M; Clarke, M J; Guo, Z

    2017-03-15

    A series of O-acylated-ω-hydroxy fatty acids (Acyl acids) of up to 34 carbons were synthesized and characterized through DSC, FTIR and Langmuir isotherm measurements to identify potential replacements to petrolatum, a highly used occlusive technology that if unrefined, it can potentially be classified as carcinogenic. Fourier transform infrared spectroscopy studies demonstrated that long acyl acids engender orthorhombic packing; packing behavior that is predominant in the lipid matrix of healthy stratum corneum, the outmost layer of the skin. In addition, Differential Scanning Calorimetry (DSC) and Langmuir isotherm studies suggested that the length of the hydrocarbon chain and the position of the ester bond influence the molecular organization of the acyl acids. For instance, 16-(tetradecanoyloxy)hexadecanoic acid (30 carbons) displayed a higher melting point (mp=68°C) than 10-(stearoyloxy)decanoic acid (28 carbons; mp=63°C) and 10-(tetradecanoyloxy)decanoic acid (24 carbons; mp=55°C) according to DSC. Moreover, Langmuir isotherm studies showed that mixtures of acyl acid with distearoylphosphatidylcholine improved packing behavior. Finally, Water Vapor Transmission Rate (WVTR) measurements showed that the compounds in fact decrease WVTR compared to untreated control (P<0.001) which demonstrates the potential of these ingredients as occlusive technologies to combat skin barrier diseases.

  15. Acyl glucuronides: the good, the bad and the ugly.

    PubMed

    Regan, Sophie L; Maggs, James L; Hammond, Thomas G; Lambert, Craig; Williams, Dominic P; Park, B Kevin

    2010-10-01

    Acyl glucuronidation is the major metabolic conjugation reaction of most carboxylic acid drugs in mammals. The physiological consequences of this biotransformation have been investigated incompletely but include effects on drug metabolism, protein binding, distribution and clearance that impact upon pharmacological and toxicological outcomes. In marked contrast, the exceptional but widely disparate chemical reactivity of acyl glucuronides has attracted far greater attention. Specifically, the complex transacylation and glycation reactions with proteins have provoked much inconclusive debate over the safety of drugs metabolised to acyl glucuronides. It has been hypothesised that these covalent modifications could initiate idiosyncratic adverse drug reactions. However, despite a large body of in vitro data on the reactions of acyl glucuronides with protein, evidence for adduct formation from acyl glucuronides in vivo is limited and potentially ambiguous. The causal connection of protein adduction to adverse drug reactions remains uncertain. This review has assessed the intrinsic reactivity, metabolic stability and pharmacokinetic properties of acyl glucuronides in the context of physiological, pharmacological and toxicological perspectives. Although numerous experiments have characterised the reactions of acyl glucuronides with proteins, these might be attenuated substantially in vivo by rapid clearance of the conjugates. Consequently, to delineate a relationship between acyl glucuronide formation and toxicological phenomena, detailed pharmacokinetic analysis of systemic exposure to the acyl glucuronide should be undertaken adjacent to determining protein adduct concentrations in vivo. Further investigation is required to ascertain whether acyl glucuronide clearance is sufficient to prevent covalent modification of endogenous proteins and consequentially a potential immunological response.

  16. Endogenous N-acyl taurines regulate skin wound healing

    PubMed Central

    Sasso, Oscar; Pontis, Silvia; Armirotti, Andrea; Cardinali, Giorgia; Kovacs, Daniela; Migliore, Marco; Summa, Maria; Moreno-Sanz, Guillermo; Picardo, Mauro; Piomelli, Daniele

    2016-01-01

    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

  17. Multiple acyl-CoA dehydrogenation deficiency as decreased acyl-carnitine profile in serum.

    PubMed

    Wen, Bing; Li, Duoling; Li, Wei; Zhao, Yuying; Yan, Chuanzhu

    2015-06-01

    We report a case with late onset riboflavin-responsive multiple acyl-CoA dehydrogenation deficiency (MADD) characterized by decreased acyl-carnitine profile in serum which is consistent with primary systemic carnitine deficiency (CDSP) while just the contrary to a typical MADD. This patient complained with muscle weakness, muscle pain and intermittent vomiting, and was diagnosed as polymyositis, received prednisone therapy before consulted with us. Muscle biopsy revealed mild lipid storage. The findings of serum acyl-carnitines were consistent with CDSP manifesting as decreased free and total carnitines in serum. But oral L-carnitine supplementation was not very effective to this patient and mutation analysis of the SLC22A5 gene for CDSP was normal. Later, another acyl-carnitine analysis revealed a typical MADD profile in serum, which was characterized by increased multiple acyl-carnitines. Compound heterozygous mutations were identified in electron transferring-flavoprotein dehydrogenase (ETFDH) gene which confirmed the diagnosis of MADD. After administration of riboflavin, he improved dramatically, both clinically and biochemically. Thus, late onset riboflavin-responsive MADD should be included in the differential diagnosis for adult carnitine deficiency.

  18. New Acylated Flavonol Glycosides and a Phenolic Profile of Pritzelago alpina, a Forgotten Edible Alpine Plant.

    PubMed

    Corradi, Elisabetta; De Mieri, Maria; Cadisch, Larissa; Abbet, Christian; Hamburger, Matthias; Potterat, Olivier

    2016-02-01

    Thirteen acylated flavonoid glycosides, 1-13, including eleven new congeners, 3-13, were isolated from the aerial parts of Pritzelago alpina (Brassicaceae) by a combination of column chromatography on Sephadex LH-20, and preparative and semi-preparative HPLC. The structures were established by extensive NMR and MS experiments in combination with acid hydrolysis and sugar analysis by GC/MS. The new compounds were shown to be kaempferol and quercetin glycosides acylated for most of them by a branched short chain fatty acid or a hydroxycinnamic acid residue on the sugar portion. As shown by a HPLC-DAD analysis of a MeOH extract, these compounds are the main phenolic constituents in the aerial parts of the plant.

  19. [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.

  20. "Happiness and Education": Tilting at Windmills?

    ERIC Educational Resources Information Center

    Verducci, Susan

    2013-01-01

    This essay explores the question: Is Nel Noddings a visionary who sees past the constraints of contemporary education or is she, like Don Quixote, madly tilting at windmills in her description and defense of happiness as an educational aim? Viewing the educational aim of happiness as an ideal raises substantial challenges for the practicality of…

  1. Tilting and shifting modes in a spheromak

    SciTech Connect

    Jardin, S.C.; Chance, M.S.; Dewar, R.L.; Grimm, R.C.; Monticello, D.A.

    1981-04-01

    In the absence of a conducting wall, typical spheromak plasmas are unstable to tilting and/or shifting modes. The effects of the cross-sectional shape, aspect ratio, and the location of a conducting wall on the stability of these modes are investigated.

  2. Rotatable prism for pan and tilt

    NASA Technical Reports Server (NTRS)

    Ball, W. B.

    1980-01-01

    Compact, inexpensive, motor-driven prisms change field of view of TV camera. Camera and prism rotate about lens axis to produce pan effect. Rotating prism around axis parallel to lens produces tilt. Size of drive unit and required clearance are little more than size of camera.

  3. Tilt/Integral/Derivative Compensators For Controllers

    NASA Technical Reports Server (NTRS)

    Lurie, Boris J.

    1995-01-01

    Tilt/integral/derivative (TID) compensators for tunable feedback control systems offer advantages over proportional/integral/derivative compensators. Designed and adjusted more easily, and made to reject disturbances more strongly and less sensitive to variations in parameters of controlled system.

  4. Behavior of Tilted Angle Shear Connectors

    PubMed Central

    Khorramian, Koosha; Maleki, Shervin; Shariati, Mahdi; Ramli Sulong, N. H.

    2015-01-01

    According to recent researches, angle shear connectors are appropriate to transfer longitudinal shear forces across the steel-concrete interface. Angle steel profile has been used in different positions as L-shaped or C-shaped shear connectors. The application of angle shear connectors in tilted positions is of interest in this study. This study investigates the behaviour of tilted-shaped angle shear connectors under monotonic loading using experimental push out tests. Eight push-out specimens are tested to investigate the effects of different angle parameters on the ultimate load capacity of connectors. Two different tilted angles of 112.5 and 135 degrees between the angle leg and steel beam are considered. In addition, angle sizes and lengths are varied. Two different failure modes were observed consisting of concrete crushing-splitting and connector fracture. By increasing the size of connector, the maximum load increased for most cases. In general, the 135 degrees tilted angle shear connectors have a higher strength and stiffness than the 112.5 degrees type. PMID:26642193

  5. Phase behavior and nanoscale structure of phospholipid membranes incorporated with acylated C14-peptides.

    PubMed

    Pedersen, Tina B; Kaasgaard, Thomas; Jensen, Morten Ø; Frokjaer, Sven; Mouritsen, Ole G; Jørgensen, Kent

    2005-10-01

    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 A 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.

  6. Structural Changes in Ceramide Bilayers Rationalize Increased Permeation through Stratum Corneum Models with Shorter Acyl Tails.

    PubMed

    Paloncýová, Markéta; Vávrová, Kateřina; Sovová, Žofie; DeVane, Russell; Otyepka, Michal; Berka, Karel

    2015-07-30

    Ceramides are indispensable constituents of the stratum corneum (SC), the uppermost impermeable layer of human skin. Ceramides with shorter (four- to eight-carbon acyl chains) fatty acid chains increase skin and model membrane permeability, while further shortening of the chain leads to increased resistance to penetration almost as good as that of ceramides from healthy skin (24 carbons long on average). Here we address the extent to which the atomistic CHARMM36 and coarse-grain MARTINI molecular dynamics (MD) simulations reflect the skin permeability data. As a result, we observed the same bell-shaped permeability trend for water that was observed in the skin and multilayer membrane experiments for model compounds. We showed that the enhanced permeability of the short ceramides is mainly caused by the disturbance of their headgroup conformation because of their inability to accommodate the shorter lipid acyl chain into a typical hairpin conformation, which further led to their destabilization and phase separation. As MD simulations described well delicate structural features of SC membranes, they seem to be suitable for further studies of the SC superstructure, including the development of skin penetration enhancers for transdermal drug delivery and skin toxicity risk assessment studies.

  7. NASA/HAA Advanced Rotorcraft Technology and Tilt Rotor Workshop. Volume 7: Tilt Rotor Session

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The technical characteristics of the XV-15 aircraft were discussed. Program objectives, concept evaluation, tilt rotor experiments and civil market applications are presented. The XV-15 status and test schedule are also included.

  8. Tilt and Translation Motion Perception during Pitch Tilt with Visual Surround Translation

    NASA Technical Reports Server (NTRS)

    O'Sullivan, Brita M.; Harm, Deborah L.; Reschke, Millard F.; Wood, Scott J.

    2006-01-01

    The central nervous system must resolve the ambiguity of inertial motion sensory cues in order to derive an accurate representation of spatial orientation. Previous studies suggest that multisensory integration is critical for discriminating linear accelerations arising from tilt and translation head motion. Visual input is especially important at low frequencies where canal input is declining. The NASA Tilt Translation Device (TTD) was designed to recreate postflight orientation disturbances by exposing subjects to matching tilt self motion with conflicting visual surround translation. Previous studies have demonstrated that brief exposures to pitch tilt with foreaft visual surround translation produced changes in compensatory vertical eye movement responses, postural equilibrium, and motion sickness symptoms. Adaptation appeared greatest with visual scene motion leading (versus lagging) the tilt motion, and the adaptation time constant appeared to be approximately 30 min. The purpose of this study was to compare motion perception when the visual surround translation was inphase versus outofphase with pitch tilt. The inphase stimulus presented visual surround motion one would experience if the linear acceleration was due to foreaft self translation within a stationary surround, while the outofphase stimulus had the visual scene motion leading the tilt by 90 deg as previously used. The tilt stimuli in these conditions were asymmetrical, ranging from an upright orientation to 10 deg pitch back. Another objective of the study was to compare motion perception with the inphase stimulus when the tilts were asymmetrical relative to upright (0 to 10 deg back) versus symmetrical (10 deg forward to 10 deg back). Twelve subjects (6M, 6F, 22-55 yrs) were tested during 3 sessions separated by at least one week. During each of the three sessions (out-of-phase asymmetrical, in-phase asymmetrical, inphase symmetrical), subjects were exposed to visual surround translation

  9. The Acyl Desaturase CER17 Is Involved in Producing Wax Unsaturated Primary Alcohols and Cutin Monomers1[OPEN

    PubMed Central

    Yang, Xianpeng; Zhao, Huayan; Kosma, Dylan K.; Dyer, John M.; Li, Rongjun; Liu, Xiulin; Wang, Zhouya; Jenks, Matthew A.

    2017-01-01

    We report n-6 monounsaturated primary alcohols (C26:1, C28:1, and C30:1 homologs) in the cuticular waxes of Arabidopsis (Arabidopsis thaliana) inflorescence stem, a class of wax not previously reported in Arabidopsis. The Arabidopsis cer17 mutant was completely deficient in these monounsaturated alcohols, and CER17 was found to encode a predicted ACYL-COENZYME A DESATURASE LIKE4 (ADS4). Studies of the Arabidopsis cer4 mutant and yeast variously expressing CER4 (a predicted fatty acyl-CoA reductase) with CER17/ADS4, demonstrated CER4’s principal role in synthesis of these monounsaturated alcohols. Besides unsaturated alcohol deficiency, cer17 mutants exhibited a thickened and irregular cuticle ultrastructure and increased amounts of cutin monomers. Although unsaturated alcohols were absent throughout the cer17 stem, the mutation’s effects on cutin monomers and cuticle ultrastructure were much more severe in distal than basal stems, consistent with observations that the CER17/ADS4 transcript was much more abundant in distal than basal stems. Furthermore, distal but not basal stems of a double mutant deficient for both CER17/ADS4 and LONG-CHAIN ACYL-COA SYNTHETASE1 produced even more cutin monomers and a thicker and more disorganized cuticle ultrastructure and higher cuticle permeability than observed for wild type or either mutant parent, indicating a dramatic genetic interaction on conversion of very long chain acyl-CoA precursors. These results provide evidence that CER17/ADS4 performs n-6 desaturation of very long chain acyl-CoAs in both distal and basal stems and has a major function associated with governing cutin monomer amounts primarily in the distal segments of the inflorescence stem. PMID:28069670

  10. Internal tilting mode stability of non-sperical spheromak

    SciTech Connect

    Yamazaki, K.

    1980-06-01

    Fixed boundary tilting mode stability is analyzed for spheromak with arbitrarily shaped cross section. A prolate spheromak can be stabilized against tilting mode by adding a conducting shell of triangular or trapesoidal half-cross section.

  11. Characterization of a structurally and functionally diverged acyl-acyl carrier protein desaturase from milkweed seed.

    PubMed

    Cahoon, E B; Coughlan, S J; Shanklin, J

    1997-04-01

    A cDNA for a structurally variant acyl-acyl carrier protein (ACP) desaturase was isolated from milkweed (Asclepias syriaca) seed, a tissue enriched in palmitoleic (16:1delta9)* and cis-vaccenic (18:1delta11) acids. Extracts of Escherichia coli that express the milkweed cDNA catalyzed delta9 desaturation of acyl-ACP substrates, and the recombinant enzyme exhibited seven- to ten-fold greater specificity for palmitoyl (16:0)-ACP and 30-fold greater specificity for myristoyl (14:0)-ACP than did known delta9-stearoyl (18:0)-ACP desaturases. Like other variant acyl-ACP desaturases reported to date, the milkweed enzyme contains fewer amino acids near its N-terminus compared to previously characterized delta9-18:0-ACP desaturases. Based on the activity of an N-terminal deletion mutant of a delta9-18:0-ACP desaturase, this structural feature likely does not account for differences in substrate specificities.

  12. Inverse solutions for tilting orthogonal double prisms.

    PubMed

    Li, Anhu; Ding, Ye; Bian, Yongming; Liu, Liren

    2014-06-10

    An analytical reverse solution and actual examples are given to show how to direct a laser beam from a pair of orthogonal prisms to given targets in free space. Considering the influences of double-prism structural parameters, a lookup table method to seek the numerical reverse solution of each prism's tilting angle is also proposed for steering the double-prism orientation to track a target position located in the near field. Some case studies, as well as a specified elliptical target trajectory scanned by the cam-based driving double prisms, exhibit the significant application values of the theoretical derivation. The analytic reverse and numerical solutions can be generalized to investigate the synthesis of scanning patterns and the controlling strategy of double-prism tilting motion, the potentials of which can be explored to perform the orientation and position tracking functions in applications of precision engineering fields.

  13. A COLLISIONLESS SCENARIO FOR URANUS TILTING

    SciTech Connect

    Boue, Gwenael; Laskar, Jacques

    2010-03-20

    The origin of the high inclination of Uranus' spin-axis (Uranus' obliquity) is one of the great unanswered questions about the solar system. Giant planets are believed to form with nearly zero obliquity, and it has been shown that the present behavior of Uranus' spin is essentially stable. Several attempts were made in order to solve this problem. Here we report numerical simulations showing that Uranus' axis can be tilted during the planetary migration, without the need of a giant impact, provided that the planet had an additional satellite and a temporary large inclination. This might have happened during the giant planet instability phase described in the Nice model. In our scenario, the satellite is ejected after the tilt by a close encounter at the end of the migration. This model can both explain Uranus' large obliquity and bring new constraints on the planet orbital evolution.

  14. A CFD study of tilt rotor flowfields

    NASA Technical Reports Server (NTRS)

    Fejtek, Ian; Roberts, Leonard

    1989-01-01

    The download on the wing produced by the rotor wake of a tilt rotor vehicle in hover is of major concern because of its severe impact on payload-carrying capability. In a concerted effort to understand the fundamental fluid dynamics that cause this download, and to help find ways to reduce it, computational fluid dynamics (CFD) is employed to study this problem. The thin-layer Navier-Stokes equations are used to describe the flow, and an implicit, finite difference numerical algorithm is the method of solution. The methodology is developed to analyze the tilt rotor flowfield. Included are discussions of computations of an airfoil and wing in freestream flows at -90 degrees, a rotor alone, and wing/rotor interaction in two and three dimensions. Preliminary results demonstrate the feasibility and great potential of the present approach. Recommendations are made for both near-term and far-term improvements to the method.

  15. Tilted foil polarization of radioactive beam nuclei

    NASA Astrophysics Data System (ADS)

    Goldring, Gvirol

    1992-11-01

    Tilted foil polarization has up to now been mostly applied to nuclear reaction products recoiling out of a target traversed by a primary particle beam. Being a universal phenomenon it can be applied equally well to beams of particles, primary or secondary, radioactive or other. There are however some technical considerations arising from the nature of the beam particles. Radioactive beams are associated with ground state nuclei. They usually have low nuclear spin and as a consequence-as will be shown later-low polarization. Secondary beams are usually low in intensity and do not impose any constraints on the foils they traverse; unlike intense primary heavy ion beams which, if they traverse the foils, essentially limit the foil material to carbon. We review here briefly the tilted foil polarization process and then discuss an experiment with an isomer beam. Finally we review experiments with radioactive beams, past, present and planned for the future.

  16. Acylated flavonol glycoside from Platanus orientalis.

    PubMed

    Tantry, Mudasir A; Akbar, Seema; Dar, Javid A; Irtiza, Syed; Galal, Ahmed; Khuroo, Mohammad A; Ghazanfar, Khalid

    2012-03-01

    The ethylacetate and n-butanol fractions of ethanolic extract of Platanus orientalis leaves led to the isolation of new acylated flavonol glycoside as 3',5,7-trihydroxy-4'-methoxyflavonol 3-[O-2-O-(2,4-Dihydroxy)-E-cinnamoyl-α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranosyl (1→2)]-β-D-glucopyranoside, along with seven known compounds. All the compounds were characterized by NMR including 2D NMR techniques. The isolates were evaluated for NF-κB, nitric oxide (NO), aromatase and QR2 chemoprevention activities and some of them appeared to be modestly active.

  17. Spatiotopic coding during dynamic head tilt

    PubMed Central

    Turi, Marco; Burr, David C.

    2016-01-01

    Humans maintain a stable representation of the visual world effortlessly, despite constant movements of the eyes, head, and body, across multiple planes. Whereas visual stability in the face of saccadic eye movements has been intensely researched, fewer studies have investigated retinal image transformations induced by head movements, especially in the frontal plane. Unlike head rotations in the horizontal and sagittal planes, tilting the head in the frontal plane is only partially counteracted by torsional eye movements and consequently induces a distortion of the retinal image to which we seem to be completely oblivious. One possible mechanism aiding perceptual stability is an active reconstruction of a spatiotopic map of the visual world, anchored in allocentric coordinates. To explore this possibility, we measured the positional motion aftereffect (PMAE; the apparent change in position after adaptation to motion) with head tilts of ∼42° between adaptation and test (to dissociate retinal from allocentric coordinates). The aftereffect was shown to have both a retinotopic and spatiotopic component. When tested with unpatterned Gaussian blobs rather than sinusoidal grating stimuli, the retinotopic component was greatly reduced, whereas the spatiotopic component remained. The results suggest that perceptual stability may be maintained at least partially through mechanisms involving spatiotopic coding. NEW & NOTEWORTHY Given that spatiotopic coding could play a key role in maintaining visual stability, we look for evidence of spatiotopic coding after retinal image transformations caused by head tilt. To this end, we measure the strength of the positional motion aftereffect (PMAE; previously shown to be largely spatiotopic after saccades) after large head tilts. We find that, as with eye movements, the spatial selectivity of the PMAE has a large spatiotopic component after head rotation. PMID:27903636

  18. A tilted cold dark matter cosmological scenario

    NASA Technical Reports Server (NTRS)

    Cen, Renyue; Gnedin, Nickolay Y.; Kofman, Lev A.; Ostriker, Jeremiah P.

    1992-01-01

    A new cosmological scenario based on CDM but with a power spectrum index of about 0.7-0.8 is suggested. This model is predicted by various inflationary models with no fine tuning. This tilted CDM model, if normalized to COBE, alleviates many problems of the standard CDM model related to both small-scale and large-scale power. A physical bias of galaxies over dark matter of about two is required to fit spatial observations.

  19. Dry tilt network at Mount Rainier, Washington

    USGS Publications Warehouse

    Dzurisin, Daniel; Johnson, Daniel J.; Symonds, R.B.

    1984-01-01

    In addition to its primary responsibility of monitoring active Mount St. Helens, the David A. Johnston Cascades Volcano Observatory (CVO) has been charged with obtaining baseline geodetic and geochemical information at each of the other potentially active Cascade volcanoes. Dry tilt and/or trilateration networks were established during 1975-82 at Mount Baker, Mount St. Helens, Mount Hood, Mount Shasta, Lassen Peak, Crater Lake, and Long Valley caldera; coverage was extended during September 1982 to include Mount Rainier.

  20. A miniature tilting pad gas lubricated bearing

    NASA Technical Reports Server (NTRS)

    Sixsmith, H.; Swift, W. L.

    1983-01-01

    This paper describes the design and development of a miniature tilting pad gas bearing developed for use in very small turbomachines. The bearings have been developed for cryogenic turboexpanders with shaft diameters down to about 0.3 cm and rotational speeds up to one million rpm. Cryogenic expansion turbines incorporating this type of bearing should be suitable for refrigeration rates down to about 10 w.

  1. Estimating Insolation Incident on Tilted Surfaces

    NASA Technical Reports Server (NTRS)

    Elkin, R. E.; Toelle, R. G.

    1983-01-01

    ASHMET computer program estimates amount of solar insolation incident on surfaces of several types of solar collectors, including fixed-position flat-plate, monthly-tilt-adjusted flat-plat, beam-tracting, and fixed-azimuthtracker. Basic methodology employed in ASHMET is to use ASHRAE relationships to obtain clear-day total daily insolation incident on collector surface of representative day of each month of year. ASHMET is interactive program and prompts user for all required data.

  2. Optimum orientation of tilting solar concentrator arrays

    NASA Astrophysics Data System (ADS)

    Harting, E.; Giutronich, J. E.

    1984-01-01

    This note shows that there is a considerable degree of freedom in selecting the orientation of a field of tilting solar concentrators, without changing the path of the sun across the concentrator acceptance angle, and hence without affecting performance. The orientation of a particular array may be chosen to more closely match the natural terrain, thus reducing site preparation costs. Further, a proper choice may improve overall performance in situations where the average daily insolation is asymmetrical about local noon.

  3. Modulation of FadR Binding Capacity for Acyl-CoA Fatty Acids Through Structure-Guided Mutagenesis

    DOE PAGES

    Bacik, John-Paul; Yeager, Chris M.; Twary, Scott N.; ...

    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

  4. 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.

  5. INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Realization of Fine Tip Tilting by 16-Step Line Tilting

    NASA Astrophysics Data System (ADS)

    Ding, Lu; Chen, Ying-Tian; Hu, Sen; Zhang, Yang

    2010-07-01

    Following Chen's method [Common. Theor. Phys. 52 (2009) 549] to use 8-step line tilting to realize tip tilting, to achieve finer rotation, it is discovered that a 16-step line tilting method may realize a rotation two order smaller than that achieved by 8-step.

  6. Tilt compensated MOEMS projector as input device

    NASA Astrophysics Data System (ADS)

    Grüger, Heinrich; Heberer, Andreas; Gerwig, Christian; Nauber, Petra; Scholles, Michael; Lakner, Hubert

    2007-02-01

    Silicon micro machining once headed into two directions: MEMS (micro electro mechanical systems) based sensors like accelerometers and gyroscopes on the one hand, MOEMS (micro opto electro mechanical systems) based actuators like scanner mirrors on the other hand. Now both directions meet again: A tilt compensated projector module uses a two dimensional excited scanner mirror as well as accelerometers and gyroscopes. The projector module can have a minimum size of 30 x 15 x 15 mm 3 with a monochrome red laser source (λ = 635 nm). It reaches a resolution of 640 x 480 pixels (VGA) and a frame rate of 50fps. Colour projection requires lager size due to the lack of compact green laser sources. The tilt and roll angles are measured statically by a three axes accelerometer, fast movement is detected dynamically by three single axis gyroscopes. Thus tilt of the projection systems was compensated successfully. The dynamic range was set to 300 x 300 pixels for sufficient system dynamic. Furthermore the motion detection was used to achieve control and input device functions. The first demonstration and test system consists of a projector mounted at the axis of a PC racing wheel together with the additional inertial measurement unit (IMU) system. It was shown that projection and input function work well together. Using this approach, new possibilities for hand-held devices arise in the close future.

  7. TILT, WARP, AND SIMULTANEOUS PRECESSIONS IN DISKS

    SciTech Connect

    Montgomery, M. M.

    2012-07-10

    Warps are suspected in disks around massive compact objects. However, the proposed warping source-non-axisymmetric radiation pressure-does not apply to white dwarfs. In this Letter, we report the first smoothed particle hydrodynamic simulations of accretion disks in SU UMa-type systems that naturally tilt, warp, and simultaneously precess in the prograde and retrograde directions using white dwarf V344 Lyrae in the Kepler field as our model. After {approx}79 days in V344 Lyrae, the disk angular momentum L{sub d} becomes misaligned to the orbital angular momentum L{sub o} . As the gas stream remains normal to L{sub o} , hydrodynamics (e.g., the lift force) is a likely source to disk tilt. In addition to tilt, the outer disk annuli cyclically change shape from circular to highly eccentric due to tidal torques by the secondary star. The effect of simultaneous prograde and retrograde precession is a warp of the colder, denser midplane as seen along the disk rim. The simulated rate of apsidal advance to nodal regression per orbit nearly matches the observed ratio in V344 Lyrae.

  8. WIYN tip-tilt module performance

    NASA Astrophysics Data System (ADS)

    Claver, Charles F.; Corson, Charles; Gomez, R. Richard, Jr.; Daly, Philip N.; Dryden, David M.; Abareshi, Behzod

    2003-02-01

    The WIYN Tip-Tilt Module (WTTM) is an addition to the existing Instrument Adapter System (IAS) providing a high performance optical-NIR image stabilized port on the WIYN 3.5m telescope. The WTTM optical system uses a 3-mirror off-axis design along with a high bandwidth tilt mirror. The WTTM is a reimaging system with 15% magnification producing a 4x4 arcminute field of view and near diffraction limited imagery from 400-2000nm. The optics are diamond turned in electroless Nickel over an Aluminum substrate. The WTTM opto-mechanical assembly was designed and built using the principals of the "build-to-print" technique, where the entire system is fabricated and assembled to tolerance with no adjustments. A unique high performance error sensor, using an internal mirrorlette array that feeds 4 fiber coupled avalanche photodiode photon counters, provides the tilt signal. The system runs under the Real-Time Linux operating system providing a maximum closed loop rate of 3khz. In this paper we report on the successful lab testing, verification of the "build-to-print" technique and on telescope performance of the WTTM.

  9. Endothelial cell palmitoylproteomics identifies novel lipid modified targets and potential substrates for protein acyl transferases

    PubMed Central

    Marin, Ethan P.; Derakhshan, Behrad; Lam, TuKiet T.; Davalos, Alberto; Sessa, William C.

    2012-01-01

    Rationale Protein S-palmitoylation is the post-translational attachment of a saturated 16-carbon palmitic acid to a cysteine side chain via a thioester bond. Palmitoylation can affect protein localization, trafficking, stability, and function. The extent and roles of palmitoylation in endothelial cell (EC) biology is not well understood, in part due to technological limits on palmitoylprotein detection. Objective To develop a method using acyl-biotinyl exchange (ABE) technology coupled with mass spectrometry to globally isolate and identify palmitoylproteins in EC. Methods and Results More than 150 putative palmitoyl proteins were identified in EC using ABE and mass spectrometry. Among the novel palmitoylproteins identified is superoxide dismutase 1 (SOD1), an intensively studied enzyme that protects all cells from oxidative damage. Mutation of cysteine 6 prevents palmitoylation, leads to reduction in SOD1 activity in vivo and in vitro, and inhibits nuclear localization, thereby supporting a functional role for SOD1 palmitoylation. Moreover, we used ABE to search for substrates of particular protein acyl transferases in EC. We found that palmitoylation of the cell adhesion protein PECAM1 is dependent on the protein acyl transferase ZDHHC21. We show that knockdown of ZDHHC21 leads to reduced levels of PECAM1 at the cell surface. Conclusions Our data demonstrate the utility of EC palmitoylproteomics to reveal new insights into the role of this important post-translational lipid modification in EC biology. PMID:22496122

  10. 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...

  11. Acyl-CoA binding protein expression is fiber type- specific and elevated in muscles from the obese insulin-resistant Zucker rat.

    PubMed

    Franch, Jesper; Knudsen, Jens; Ellis, Bronwyn A; Pedersen, Preben K; Cooney, Gregory J; Jensen, Jørgen

    2002-02-01

    Accumulation of acyl-CoA is hypothesized to be involved in development of insulin resistance. Acyl-CoA binds to acyl-CoA binding protein (ACBP) with high affinity, and therefore knowledge about ACBP concentration is important for interpreting acyl-CoA data. In the present study, we used a sandwich enzyme-linked immunosorbent assay to quantify ACBP concentration in different muscle fiber types. Furthermore, ACBP concentration was compared in muscles from lean and obese Zucker rats. Expression of ACBP was highest in the slow-twitch oxidative soleus muscle and lowest in the fast-twitch glycolytic white gastrocnemius (0.46 +/- 0.02 and 0.16 +/- 0.005 microg/mg protein, respectively). Expression of ACBP was soleus > red gastrocnemius > extensor digitorum longus > white gastrocnemius. Similar fiber type differences were found for carnitine palmitoyl transferase (CPT)-1, and a correlation was observed between ACBP and CPT-1. Muscles from obese Zucker rats had twice the triglyceride content, had approximately twice the long-chain acyl CoA content, and were severely insulin resistant. ACBP concentration was approximately 30% higher in all muscles from obese rats. Activities of CPT-1 and 3-hydroxy-acyl-CoA dehydrogenase were increased in muscles from obese rats, whereas citrate synthase activity was similar. In conclusion, ACBP expression is fiber type-specific with the highest concentration in oxidative muscles and the lowest in glycolytic muscles. The 90% increase in the concentration of acyl-CoA in obese Zucker muscle compared with only a 30% increase in the concentration of ACBP supports the hypothesis that an increased concentration of free acyl-CoA is involved in the development of insulin resistance.

  12. Investigation of the phase behaviour of systems containing lecithin and 2-acyl lysolecithin derivatives.

    PubMed

    Trotta, M; Gallarate, M; Pattarino, F; Carlotti, M E

    1999-11-10

    A series of modified phospholipids (m-PC) possessing different acyl chains in position 2, from butanoyl to hexadecanoyl, were prepared by partial synthesis from soybean lysolecithin. They were used with soybean lecithin to construct phase diagrams containing ethanol as cosolvent, water and medium chain triglycerides (MCT) or isopropyl myristate (IPM) as oils. The weight ratios lecithin:m-PC and surfactants:ethanol were kept constant at 1:1. The results indicate that the m-PCs have a strong effect on the microemulsion (L) and liquid crystalline (LC) domains in the water-rich/oil-poor part of the phase diagrams, although all diagrams correspond to a single lecithin:m-PC ratio. On decreasing the acyl chain length, and thus increasing the hydrophilicity of the surfactant, there was a corresponding increase in the L area, which moved towards the aqueous corner of the phase diagrams. The LC phase was detected only in the presence of the hexadecanoyl derivative for the systems containing MCT, and it was not detected only in the presence of the butanoyl derivative for the systems containing IPM. The use of a second hydrophilic surfactant to adjust the packing properties of the lecithin-alcohol systems, and/or to increase the fluidity of the surfactant film, increased the region of existence of the isotropic systems. This may be of importance in the formulation of drug delivery systems, especially those which are diluted by biological fluids upon administration.

  13. Tilting Saturn without Tilting Jupiter or Ejecting an Ice Giant: Constraints on migration

    NASA Astrophysics Data System (ADS)

    McNeil, Douglas S.; Lee, M. H.

    2010-10-01

    The obliquities of the giant planets preserve information about their migration and encounter histories. Are the classic Nice models (Tsiganis et al. 2005) or the resonant Nice models (Morbidelli et al. 2007) compatible with Jupiter's 3 degree tilt and Saturn's 27? Here we consider the obliquity evolution of the giants during the planetesimal-driven migration phase using two methods: (1) a purely secular integration of the Laplace-Lagrange equations with spin, and (2) a hybrid N-body scheme with full interactions between the Sun and the giants but imposed prescriptions for migration and eccentricity and inclination damping. We find that it is difficult to reproduce today's obliquity values as migration timescales sufficient to tilt Saturn via the Hamilton & Ward (2004) secular spin-orbit resonance mechanism generally suffice to tilt Jupiter more than is observed. Moreover, long migration timescales which make tilting Saturn easier simultaneously reduce the survival fraction (to below 20% for timescales longer than 20 Myr.) We discuss the constraints these observations provide on the dynamical history of the giant planets, and the remaining possibility of tilting Saturn during a late very slow migration of Neptune to its present location after the main phase of migration is complete. [This work was supported by Hong Kong RGC grant HKU 7024/08P.

  14. 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…

  15. Synthesis of Amino Acid-Derived Cyclic Acyl Amidines for Use in β-Strand Peptidomimetics

    PubMed Central

    Hammond, Ming C.; Bartlett, Paul A.

    2008-01-01

    The acyl amidine represented by the 4,5-dihydro-2(3H)-pyrazinone ring system 2 is isosteric to the vinylogous amide of the 1,2-dihydro-3(6H)-pyridinone 1, but its assembly from separate amine and amide components enables ready incorporation of an amino acid side chain with correct regio- and stereochemistry. β-Strand peptidomimetics incorporating amino acid analogues based on 2 have recently been shown to be potent, protease-resistant ligands to a PDZ protein-interaction domain. Two routes to the protected dipeptide analogue 3 are described. PMID:17371075

  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. Arabidopsis membrane-associated acyl-CoA-binding protein ACBP1 is involved in stem cuticle formation.

    PubMed

    Xue, Yan; Xiao, Shi; Kim, Juyoung; Lung, Shiu-Cheung; Chen, Liang; Tanner, Julian A; Suh, Mi Chung; Chye, Mee-Len

    2014-10-01

    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.

  18. The solution structure of acyl carrier protein from Mycobacterium tuberculosis.

    PubMed

    Wong, Hing C; Liu, Gaohua; Zhang, Yong-Mei; Rock, Charles O; Zheng, Jie

    2002-05-03

    Acyl carrier protein (ACP) performs the essential function of shuttling the intermediates between the enzymes that constitute the type II fatty acid synthase system. Mycobacterium tuberculosis is unique in producing extremely long mycolic acids, and tubercular ACP, AcpM, is also unique in possessing a longer carboxyl terminus than other ACPs. We determined the solution structure of AcpM using protein NMR spectroscopy to define the similarities and differences between AcpM and the typical structures. The amino-terminal region of the structure is well defined and consists of four helices arranged in a right-handed bundle held together by interhelical hydrophobic interactions similar to the structures of other bacterial ACPs. The unique carboxyl-terminal extension from helix IV has a "melted down" feature, and the end of the molecule is a random coil. A comparison of the apo- and holo-forms of AcpM revealed that the 4'-phosphopantetheine group oscillates between two states; in one it is bound to a hydrophobic groove on the surface of AcpM, and in another it is solvent-exposed. The similarity between AcpM and other ACPs reveals the conserved structural motif that is recognized by all type II enzymes. However, the function of the coil domain extending from helix IV to the carboxyl terminus remains enigmatic, but its structural characteristics suggest that it may interact with the very long chain intermediates in mycolic acid biosynthesis or control specific protein-protein interactions.

  19. Characterization of esterified cassava starch with long alkyl side chains and different substitution degrees.

    PubMed

    Barrios, Simón E; Giammanco, Giuseppe; Contreras, Jesús M; Laredo, Estrella; López-Carrasquero, Francisco

    2013-08-01

    The present work describes the characterization and thermal properties of hydrophobic starch obtained by the esterification of cassava starch with acyl imidazoles, acid chlorides and methyl ester derivatives of fatty acids with n-alkyl chains with 12-22 carbon atoms, in order to compare the dependence of their properties as a function of the length of the side chain and the methodology used for their synthesis. The n-acyl starches presented degrees of substitution (DS) between 0.06 and 1.2. Most of the derivatives obtained with acyl imidazoles were found to be stable at temperatures up to 300°C, whereas those synthesized with acid chlorides or methyl ester decomposed below. Finally, when the n-acyl starches were substituted with n-alkyl side chains of 16 or more carbon atoms, they were capable to crystallize in separate paraffinic phases independent of the starch backbone.

  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.

  1. 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

  2. Cysteine-286 as the site of acylation of the Lux-specific fatty acyl-CoA reductase.

    PubMed

    Lee, C Y; Meighen, E A

    1997-04-04

    The channelling of fatty acids into the fatty aldehyde substrate for the bacterial bioluminescence reaction is catalyzed by a fatty acid reductase multienzyme complex, which channels fatty acids through the thioesterase (LuxD), synthetase (LuxE) and reductase (LuxC) components. Although all three components can be readily acylated in extracts of different luminescent bacteria, this complex has been successfully purified only from Photobacterium phosphoreum and the sites of acylation identified on LuxD and LuxE. To identify the acylation site on LuxC, the nucleotide sequence of P. phosphoreum luxC has been determined and the gene expressed in a mutant Escherichia coli strain. Even in crude extracts, the acylated reductase intermediate as well as acyl-CoA reductase activity could be readily detected, providing the basis for analysis of mutant reductases. Comparison of the amino-acid sequences of LuxC from P. phosphoreum, P. leiognathi and other luminescent bacteria, showed that only three cysteine residues (C171, C279, and C286) were conserved. As a cysteine residue on LuxC has been implicated in fatty acyl transfer, each of the conserved cysteine residues of the P. phosphoreum and P. leiognathi reductases was converted to a serine residue, and the properties of the mutant proteins examined. Only mutation of C286-blocked reductase activity and prevented formation of the acylated reductase intermediate, showing that C286 is the site of acylation on LuxC.

  3. 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

    2016-09-06

    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.

  4. Structural characterization of acyl-CoA oxidases reveals a direct link between pheromone biosynthesis and metabolic state in Caenorhabditis elegans

    PubMed Central

    Zhang, Xinxing; Jones, Rachel A.; Bruner, Steven D.; Butcher, Rebecca A.

    2016-01-01

    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

  5. 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

  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

    2015-07-30

    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.

  7. Magnetic nanocap arrays with tilted magnetization

    NASA Astrophysics Data System (ADS)

    Albrecht, Manfred

    2009-03-01

    In modern magnetic recording materials the ``superparamagnetic effect'' has become increasingly important as new magnetic hard disk drive products are designed for higher storage densities. In this regard, patterned media [1], where two-dimensional arrays of nanostructures are used, is one of the concepts that might provide the required areal density in future magnetic recording devices. However, also nanostructure arrays will ultimately need high anisotropy material such as L10-FePt to provid enough thermal stability and thus much higher writing fields than currently obtainable from perpendicular magnetic recording heads. One proposed solution to this problem is the use of tilted magnetic recording media [2]. The basic idea is to tilt the easy axis of the magnetic medium from the perpendicular direction to 45 degree. In this case, the switching field will be reduced by a foctor of two in the Stoner-Wohlfarth limit. Recently, this approach was realized by oblique film deposition onto arrays of self-assembled spherical particles [3-5]. In this presentation, recent results on different film systems including Co/Pt multilayers, FePt and CoPtCr-SiO2 alloys which have been deposited onto SiO2 particle monolayers will be presented. It turned out that by tuning the growth conditions single domain nanocaps with enhanced magnetic coercivity and tilted anisostropy axis can be achieved even for particle sizes below 50 nm. [4pt] [1] B. D. Terris and T. Thomson, J. Phys. D: Appl. Phys. 38 (2005) R199 [0pt] [2] J.-P. Wang, Nat. Mater. 4, 191 (2005). [0pt] [3] M. Albrecht et al., Nat. Mater. 4, 203 (2005). [0pt] [4] T. Ulbrich et al., Phys. Rev. Lett. 96 (2006) 077202. [0pt] [5] D. Makarov et al., Appl. Phys. Lett. 93, 153112 (2008).

  8. Can imaginary head tilt shorten postrotatory nystagmus?

    NASA Technical Reports Server (NTRS)

    Gianna-Poulin, C. C.; Voelker, C. C.; Erickson, B.; Black, F. O.

    2001-01-01

    In healthy subjects, head tilt upon cessation of a constant-velocity yaw head rotation shortens the duration of postrotatory nystagmus. The presumed mechanism for this effect is that the velocity storage of horizontal semicircular canal inputs is being discharged by otolith organ inputs which signal a constant yaw head position when the head longitudinal axis is no longer earth-vertical. In the present study, normal subjects were rotated head upright in the dark on a vertical-axis rotational chair at 60 degrees/s for 75 s and were required to perform a specific task as soon as the chair stopped. Horizontal position of the right eye was recorded with an infra-red video camera. The average eye velocity (AEV) was measured over a 30-s interval following chair acceleration/deceleration. The ratios (postrotatory AEV/perrotatory AEV) were 1.1 (SD 0.112) when subjects (N=10) kept their head erect, 0.414 (SD 0.083) when subjects tilted their head forward, 1.003 (SD 0.108) when subjects imagined watching a TV show, 1.012 (SD 0.074) when subjects imagined looking at a painting on a wall, and 0.995 (SD 0.074) when subjects imagined floating in a prone position on a lake. Thus, while actual head tilt reduced postrotatory nystagmus, the imagination tasks did not have a statistically significant effect on postrotatory nystagmus. Therefore, velocity storage does not appear to be under the influence of cortical neural signals when subjects imagine that they are floating in a prone orientation.

  9. Efficient odd straight medium chain free fatty acid production by metabolically engineered Escherichia coli.

    PubMed

    Wu, Hui; San, Ka-Yiu

    2014-11-01

    Free fatty acids (FFAs) can be used as precursors for the production of biofuels or chemicals. Different composition of FFAs will be useful for further modification of the biofuel/biochemical quality. Microbial biosynthesis of even chain FFAs can be achieved by introducing an acyl-acyl carrier protein thioesterase gene into E. coli. In this study, odd straight medium chain FFAs production was investigated by using metabolic engineered E. coli carrying acyl-ACP thioesterase (TE, Ricinus communis), propionyl-CoA synthase (Salmonella enterica), and β-ketoacyl-acyl carrier protein synthase III (four different sources) with supplement of extracellular propionate. By using these metabolically engineered E. coli, significant quantity of C13 and C15 odd straight-chain FFAs could be produced from glucose and propionate. The highest concentration of total odd straight chain FFAs attained was 1205 mg/L by the strain HWK201 (pXZ18, pBHE2), and 85% of the odd straight chain FFAs was C15. However, the highest percentage of odd straight chain FFAs was achieved by the strain HWK201 (pXZ18, pBHE3) of 83.2% at 48 h. This strategy was also applied successfully in strains carrying different TE, such as the medium length acyl-ACP thioesterase gene from Umbellularia californica. C11 and C13 became the major odd straight-chain FFAs.

  10. A hydrophobic loop in acyl-CoA binding protein is functionally important for binding to palmitoyl-coenzyme A: a molecular dynamics study.

    PubMed

    Vallejo, Diego F G; Grigera, J Raúl; Costabel, Marcelo D

    2008-04-01

    Acyl-CoA binding protein (ACBP) plays a key role in lipid metabolism, interacting via a partly unknown mechanism with high affinity with long chain fatty acyl-CoAs (LCFA-CoAs). At present there is no study of the microscopic way ligand binding is accomplished. We analyzed this process by molecular dynamics (MDs) simulations. We proposed a computational model of ligand, able to reproduce some evidence from nuclear magnetic resonance (NMR) data, quantitative time resolved fluorometry and X-ray crystallography. We found that a hydrophobic loop, not in the active site, is important for function. Besides, multiple sequence alignment shows hydrophobicity (and not the residues itselves) conservation.

  11. 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.

  12. Fatty acyl-CoA elongation in Blatella germanica integumental microsomes.

    PubMed

    Juárez, M Patricia

    2004-08-01

    Insect cuticular hydrocarbons are synthesized de novo in integumental tissue through the concerted action of fatty acid synthases (FASs), fatty acyl-CoA elongases, a reductase, and a decarboxylase to produce hydrocarbons and CO2. Elongation of fatty acyl-CoAs to very long chain fatty acids was studied in the integumental microsomes of the German cockroach, Blatella germanica. Incubation of [1-14C]palmitoyl-CoA, malonyl-CoA, and NADPH resulted in the production of 18-CoA with minor amounts of C20, C22, C24, C30, and C32 labeled acyl-CoA moieties. Similar experiments with [1-14C]stearoyl-CoA rendered C20-CoA as the major product, and lesser amounts of C22 and C24-CoAs were also detected. After solubilization of the microsomal FAS, kinetic parameters were determined radiochemically or by measuring NADPH consumption. The reaction velocity was linear for up to 3 min incubation time, and with a protein concentration up to 0.025 microg/microl. The effect of the chain length on the reaction velocity was compared for palmitoyl-CoA, stearoyl-CoA, and eicosanoyl-CoA. The optimal substrate concentration was 10 microM for C16-CoA, between 8 and 12 microM for C18-CoA, and close to 3 microM for C20-CoA. In vivo hydrocarbon biosynthesis was inhibited from 55.5 to 72.5% in the presence of 1 mM trichloroacetic acid, a known inhibitor of elongation reactions.

  13. Functionalized chitosan derivatives as nonviral vectors: physicochemical properties of acylated N,N,N-trimethyl chitosan/oligonucleotide nanopolyplexes.

    PubMed

    Santos, Joyce C C; Moreno, Pedro M D; Mansur, Alexandra A P; Leiro, Victoria; Mansur, Herman S; Pêgo, Ana Paula

    2015-11-07

    Cationic polymers have recently attracted attention due to their proven potential for nonviral gene delivery. In this study, we report novel biocompatible nanocomplexes produced using chemically functionalized N,N,N-trimethyl chitosan (TMC) with different N-acyl chain lengths (C5-C18) associated with single-stranded oligonucleotides. The TMC derivatives were synthesized by covalent coupling reactions of quaternized chitosan with n-pentanoic (C5), n-decanoic (C10), and n-octadecanoic (C18) fatty acids, which were extensively characterized by Fourier transform-infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance ((1)H NMR). These N-acylated TMC derivatives (TMCn) were used as cationic polymeric matrices for encapsulating anionic 18-base single-stranded thiophosphorylated oligonucleotides (ssONs), leading to the formation of polyplexes further characterized by zeta potential (ZP), dynamic light scattering (DLS), binding affinity, transfection efficiency and in vitro cytotoxicity assays. The results demonstrated that the length of the grafted hydrophobic N-acyl chain and the relative amino:phosphate groups ratio (N/P ratio) between the TMC derivatives and ssON played crucial roles in determining the physicochemical properties of the obtained nanocomplexes. While none of the tested derivatives showed appreciable cytotoxicity, the type of acyl chain had a remarkable influence on the cell transfection capacity of TMC-ssON nanocomplexes with the derivatives based on stearic acid showing the best performance based on the results of in vitro assays using a model cell line expressing luciferase (HeLa/Luc705).

  14. Visually-induced tilt during parabolic flights.

    PubMed

    Cheung, B S; Howard, I P; Money, K E

    1990-01-01

    A helmet-mounted visual display system was used to study visually induced sensations of self-motion (vection) about the roll, pitch and yaw axes under normal gravity condition (1g) and during the microgravity and hypergravity phases of parabolic flights aboard the NASA KC-135 aircraft. Under each gravity condition, the following parameters were investigated: (1) the subject's perceived body vertical with eyes closed and with eyes open gazing at a stationary random dot display; (2) the magnitude of sensations of body tilt with respect to the subjective vertical, while the subject viewed displays rotating about the roll, pitch and yaw axes; (3) the magnitude of vection; (4) latency of vection. All eleven subjects perceived a definite "up and down" orientation throughout the course of the flight. During the microgravity phase, the average magnitudes of perceived body tilt and self-motion increased significantly, and there was no significant difference in vection latency. These results show that there is a rapid onset of increased dependence on visual inputs for perception of self-orientation and self-motion in weightlessness, and a decreased dependence on otolithic and somatosensory graviceptive information. Anti-motion sickness drugs appear not to affect the parameters measured.

  15. 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.

  16. Synthesis of coenzyme A thioesters using methyl acyl phosphates in an aqueous medium.

    PubMed

    Pal, Mohan; Bearne, Stephen L

    2014-12-28

    Regioselective S-acylation of coenzyme A (CoA) is achieved under aqueous conditions using various aliphatic and aromatic carboxylic acids activated as their methyl acyl phosphate monoesters. Unlike many hydrophobic activating groups, the anionic methyl acyl phosphate mixed anhydride is more compatible with aqueous solvents, making it useful for conducting acylation reactions in an aqueous medium.

  17. Lipid membranes and acyl-CoA esters promote opposing effects on acyl-CoA binding protein structure and stability.

    PubMed

    Micheletto, Mariana C; Mendes, Luís F S; Basso, Luis G M; Fonseca, Raquel G; Costa-Filho, Antonio J

    2017-04-05

    Acyl-CoA Binding Proteins (ACBP) form a housekeeping family of proteins that is responsible for the buffering of long chain acyl-coenzyme A esters (LCFA-CoA) inside the cell. Even though numerous studies have focused on the characterization of different members of the ACBP family, the knowledge about the impact of both LCFA-CoA and phospholipids on ACBP structure and stability remains scarce. Besides, there are still controversies regarding the possible interaction of ACBP with biological membranes, even though this might be essential for the cargo capture and delivery. In this study, we observed that LCFA-CoA and phospholipids play opposite roles on protein stability and that the interaction with the membrane is dictated by electrostatic interaction. Furthermore, the results support the hypothesis that the LCFA-CoA delivery is driven by the increase of the negative charge on the membrane surface. The combined influence played by the different molecules on ACBP structure is discussed on the light of cargo capture/delivery giving new insights about this important process.

  18. Probing the Phosphopantetheine Arm Conformations of Acyl Carrier Proteins Using Vibrational Spectroscopy

    PubMed Central

    2015-01-01

    Acyl carrier proteins (ACPs) are universal and highly conserved domains central to both fatty acid and polyketide biosynthesis. These proteins tether reactive acyl intermediates with a swinging 4′-phosphopantetheine (Ppant) arm and interact with a suite of catalytic partners during chain transport and elongation while stabilizing the growing chain throughout the biosynthetic pathway. The flexible nature of the Ppant arm and the transient nature of ACP–enzyme interactions impose a major obstacle to obtaining structural information relevant to understanding polyketide and fatty acid biosynthesis. To overcome this challenge, we installed a thiocyanate vibrational spectroscopic probe on the terminal thiol of the ACP Ppant arm. This site-specific probe successfully reported on the local environment of the Ppant arm of two ACPs previously characterized by solution NMR, and was used to determine the solution exposure of the Ppant arm of an ACP from 6-deoxyerythronolide B synthase (DEBS). Given the sensitivity of the probe’s CN stretching band to conformational distributions resolved on the picosecond time scale, this work lays a foundation for observing the dynamic action-related structural changes of ACPs using vibrational spectroscopy. PMID:25080832

  19. Recognition of Acyl Carrier Proteins by Ketoreductases in Assembly Line Polyketide Synthases

    PubMed Central

    Ostrowski, Matthew P.; Cane, David E.; Khosla, Chaitan

    2016-01-01

    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 a ca. 10-50-fold preference for substrate attached to its native ACP domain, whereas the KR from DEBS module 6 actually displayed a ca. 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

  20. The Inflammatory Response in Acyl-CoA Oxidase 1 Deficiency (Pseudoneonatal Adrenoleukodystrophy)

    PubMed Central

    El Hajj, H. I.; Vluggens, A.; Andreoletti, P.; Ragot, K.; Mandard, S.; Kersten, S.; Waterham, H. R.; Lizard, G.; Wanders, R. J. A.; Reddy, J. K.

    2012-01-01

    Among several peroxisomal neurodegenerative disorders, the pseudoneonatal adrenoleukodystrophy (P-NALD) is characterized by the acyl-coenzyme A oxidase 1 (ACOX1) deficiency, which leads to the accumulation of very-long-chain fatty acids (VLCFA) and inflammatory demyelination. However, the components of this inflammatory process in P-NALD remain elusive. In this study, we used transcriptomic profiling and PCR array analyses to explore inflammatory gene expression in patient fibroblasts. Our results show the activation of IL-1 inflammatory pathway accompanied by the increased secretion of two IL-1 target genes, IL-6 and IL-8 cytokines. Human fibroblasts exposed to very-long-chain fatty acids exhibited increased mRNA expression of IL-1α and IL-1β cytokines. Furthermore, expression of IL-6 and IL-8 cytokines in patient fibroblasts was down-regulated by MAPK, p38MAPK, and Jun N-terminal kinase inhibitors. Thus, the absence of acyl-coenzyme A oxidase 1 activity in P-NALD fibroblasts triggers an inflammatory process, in which the IL-1 pathway seems to be central. The use of specific kinase inhibitors may permit the modulation of the enhanced inflammatory status. PMID:22508517

  1. Modes of tilting during extensional core complex development.

    PubMed

    Coleman, D S; Walker, J D

    1994-01-14

    Crustal extension and formation of the Mineral Mountains core complex, Utah, involved tilting of the Mineral Mountains batholith and associated faults during hanging wall and footwall deformation. The batholith was folded in the hanging wall of the Beaver Valley fault between 11 and 9 million years ago yielding about 45 degrees of tilt. Subsequently, the batholith was unroofed along the Cave Canyon detachment fault, and the batholith and fault were tilted approximately 40 degrees during footwall uplift. Recognition of deformed dikes beneath the detachment fault establishes the importance of footwall tilt during formation of extensional core complexes and demonstrates that footwall rebound can be an important process during extension.

  2. Transient cardio-respiratory responses to visually induced tilt illusions

    NASA Technical Reports Server (NTRS)

    Wood, S. J.; Ramsdell, C. D.; Mullen, T. J.; Oman, C. M.; Harm, D. L.; Paloski, W. H.

    2000-01-01

    Although the orthostatic cardio-respiratory response is primarily mediated by the baroreflex, studies have shown that vestibular cues also contribute in both humans and animals. We have demonstrated a visually mediated response to illusory tilt in some human subjects. Blood pressure, heart and respiration rate, and lung volume were monitored in 16 supine human subjects during two types of visual stimulation, and compared with responses to real passive whole body tilt from supine to head 80 degrees upright. Visual tilt stimuli consisted of either a static scene from an overhead mirror or constant velocity scene motion along different body axes generated by an ultra-wide dome projection system. Visual vertical cues were initially aligned with the longitudinal body axis. Subjective tilt and self-motion were reported verbally. Although significant changes in cardio-respiratory parameters to illusory tilts could not be demonstrated for the entire group, several subjects showed significant transient decreases in mean blood pressure resembling their initial response to passive head-up tilt. Changes in pulse pressure and a slight elevation in heart rate were noted. These transient responses are consistent with the hypothesis that visual-vestibular input contributes to the initial cardiovascular adjustment to a change in posture in humans. On average the static scene elicited perceived tilt without rotation. Dome scene pitch and yaw elicited perceived tilt and rotation, and dome roll motion elicited perceived rotation without tilt. A significant correlation between the magnitude of physiological and subjective reports could not be demonstrated.

  3. The normal response to prolonged passive head up tilt testing

    PubMed Central

    Petersen, M; Williams, T; Gordon, C; Chamberlain-Webbe..., R; Sutton, R

    2000-01-01

    OBJECTIVE—To define the responses to head up tilt in a large group of normal adult subjects using the most widely employed protocol for tilt testing.
METHODS—127 normal subjects aged 19-88 years (mean (SD), 49 (20) years) without a previous history of syncope underwent tilt testing at 60° for 45 minutes or until syncope intervened. Blood pressure monitoring was performed with digital photoplethysmography, providing continuous, non-invasive, beat to beat heart rate and pressure measurements.
RESULTS—13% of subjects developed vasovagal syncope after a mean (SD) tilt time of 31.7 (12.4) minutes (range 8.5-44.9 minutes). Severe cardioinhibition during syncope was observed less often than is reported in patients investigated for syncope. There were no differences in the age or sex distributions of subjects with positive or negative outcomes, or in the proportions with cardioinhibitory and vasodepressor vasovagal syncope compared with previously reported patient populations. Subjects with negative outcomes showed age related differences in heart rate and blood pressure behaviour throughout tilt.
CONCLUSIONS—False positive results with tilting appear to be common. This has important implications for the use of diagnostic tilt testing. The magnitude of the heart rate and blood pressure changes observed during negative tilts largely invalidates previously suggested criteria for abnormal non-syncopal outcomes.


Keywords: syncope; head up tilt; postural hypotension PMID:11040011

  4. Combined scanning transmission electron microscopy tilt- and focal series.

    PubMed

    Dahmen, Tim; Baudoin, Jean-Pierre; Lupini, Andrew R; Kübel, Christian; Slusallek, Philipp; de Jonge, Niels

    2014-04-01

    In this study, a combined tilt- and focal series is proposed as a new recording scheme for high-angle annular dark-field scanning transmission electron microscopy (STEM) tomography. Three-dimensional (3D) data were acquired by mechanically tilting the specimen, and recording a through-focal series at each tilt direction. The sample was a whole-mount macrophage cell with embedded gold nanoparticles. The tilt-focal algebraic reconstruction technique (TF-ART) is introduced as a new algorithm to reconstruct tomograms from such combined tilt- and focal series. The feasibility of TF-ART was demonstrated by 3D reconstruction of the experimental 3D data. The results were compared with a conventional STEM tilt series of a similar sample. The combined tilt- and focal series led to smaller "missing wedge" artifacts, and a higher axial resolution than obtained for the STEM tilt series, thus improving on one of the main issues of tilt series-based electron tomography.

  5. Prediction of the heliospheric current sheet tilt - 1992-1996

    NASA Technical Reports Server (NTRS)

    Suess, S. T.; Mccomas, D. J.; Hoeksema, J. T.

    1993-01-01

    Heliospheric current sheet tilt evolves systematically over the solar cycle. Here we show that this evolution is different than the sunspot cycle and that tilt for the period 1992-1996 can be predicted using persistence. That is, the tilt over the coming cycle will be the same as for the past cycle. The Ulysses spacecraft has passed Jupiter and is moving out of the plane of the ecliptic, so we use the prediction of the changing heliospheric current sheet tilt to predict that Ulysses will pass beyond the envelope, or maximum latitude, of the heliospheric current sheet in November 1993.

  6. The activity of Rhizomuchor miehei lipase as a biocatalyst in enzymatic acylation of cyclic alcohol

    NASA Astrophysics Data System (ADS)

    Iftitah, Elvina Dhiaul; Srihardyastuti, Arie; Ariefin, Mokhamat

    2017-03-01

    We report the activity of Rhizomuchor miehei lipase (RML) as a biocatalyst, in particular the investigations concerning the effort of substrate-structure reactivity on the enzymatic acylation. The acylation was studied using acetic anhydride as an acyl donor and performed in n-hexane as a solvent. The selectivity of the enzymatic acylation was revealed by Gas Chromatography-Mass Spectra. We observed that, RML has shown different behavior when catalyzing the acylation of isopulegol and mixture of isopulegol and citronellal (ratio 1:1). The chemoselectivity for the O-acylation was improved when the acyl acceptor included mixture of isopulegol and citronellal

  7. Differential fatty acid selection during biosynthetic S-acylation of a transmembrane protein (HEF) and other proteins in insect cells (Sf9) and in mammalian cells (CV1).

    PubMed

    Reverey, H; Veit, M; Ponimaskin, E; Schmidt, M F

    1996-09-27

    The transmembrane glycoprotein HEF and its acylation deficient mutant M1 were expressed in Sf9 insect cells infected with recombinant baculovirus and in CV1 mammalian cells using the vaccinia T7 system. In insect cells (Sf9), both wild type HEF and HEF(M1) are synthesized in their precursor form HEF0, which appears as a double band in SDS gels. Digestion with glycopeptidase F and endoglycosidase H reveals that the larger 84-kDa form is modified by the attachment of unprocessed carbohydrates of the high mannose type whereas the smaller 76-kDa form is non-glycosylated. As revealed by in vitro labeling experiments with palmitic acid another modification of HEF is the attachment of a long chain fatty acid to cysteine residue Cys-652 which is located at the internal border of the cytoplasmic membrane. After labeling with [3H]palmitic acid in both systems only HEF(WT) is acylated, whereas HEF(M1) is not. High performance liquid chromatography analysis of the fatty acids bound to HEF(WT) expressed in Sf9 insect cells reveals nearly 80% of palmitic acid. In contrast to this finding, the acylation pattern of HEF expressed in CV1 cells shows nearly the same amounts of stearic and palmitic acid (40%). Since the interconversion of the input [3H]palmitic acid to stearic acid is even lower in CV1 cells than in insect cells, it follows that only HEF expressed in mammalian, but not in insect cells selects for stearic acid during its biosynthetic acylation. We extended our study to acylation of endogenous proteins in Sf9 cells. In finding only palmitate linked to protein we present evidence that, in contrast to mammalian cells, insect cells (Sf9) cannot transfer stearic acid to polypeptide. This finding favors the hypothesis of enzymatic acylation over non-enzymatic mechanisms of acyl transfer to protein.

  8. 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}.

  9. Arabidopsis Acyl-CoA-binding protein ACBP2 interacts with an ethylene-responsive element-binding protein, AtEBP, via its ankyrin repeats.

    PubMed

    Li, Hong-Ye; Chye, Mee-Len

    2004-01-01

    Cytosolic acyl-CoA-binding proteins (ACBP) bind long-chain acyl-CoAs and act as intracellular acyl-CoA transporters and maintain acyl-CoA pools. Arabidopsis thaliana ACBP2 shows conservation at the acyl-CoA-binding domain to cytosolic ACBPs but is distinct by the presence of an N-terminal transmembrane domain and C-terminal ankyrin repeats. The function of the acyl-CoA-binding domain in ACBP2 has been confirmed by site-directed mutagenesis and four conserved residues crucial for palmitoyl-CoA binding have been identified. Results from ACBP2:GFP fusions transiently expressed in onion epidermal cells have demonstrated that the transmembrane domain functions in plasma membrane targeting, suggesting that ACBP2 transfers acyl-CoA esters to this membrane. In this study, we investigated the significance of its ankyrin repeats in mediating protein-protein interactions by yeast two-hybrid analysis and in vitro protein-binding assays; we showed that ACBP2 interacts with the A. thaliana ethylene-responsive element-binding protein AtEBP via its ankyrin repeats. This interaction was lacking in yeast two-hybrid analysis upon removal of the ankyrin repeats. When the subcellular localizations of ACBP2 and AtEBP were further investigated using autofluorescent protein fusions in transient expression by agroinfiltration of tobacco leaves, the DsRed:ACBP2 fusion protein was localized to the plasma membrane while the GFP:AtEBP fusion protein was targeted to the nucleus and plasma membrane. Co-expression of DsRed:ACBP2 and GFP:AtEBP showed a common localization of both proteins at the plasma membrane, suggesting that ACBP2 likely interacts with AtEBP at the plasma membrane.

  10. 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

  11. Novel inhibitory action of tunicamycin homologues suggests a role for dynamic protein fatty acylation in growth cone-mediated neurite extension

    PubMed Central

    1994-01-01

    In neuronal growth cones, the advancing tips of elongating axons and dendrites, specific protein substrates appear to undergo cycles of posttranslational modification by covalent attachment and removal of long-chain fatty acids. We show here that ongoing fatty acylation can be inhibited selectively by long-chain homologues of the antibiotic tunicamycin, a known inhibitor of N-linked glycosylation. Tunicamycin directly inhibits transfer of palmitate to protein in a cell-free system, indicating that tunicamycin inhibition of protein palmitoylation reflects an action of the drug separate from its previously established effects on glycosylation. Tunicamycin treatment of differentiated PC12 cells or dissociated rat sensory neurons, under conditions in which protein palmitoylation is inhibited, produces a prompt cessation of neurite elongation and induces a collapse of neuronal growth cones. These growth cone responses are rapidly reversed by washout of the antibiotic, even in the absence of protein synthesis, or by addition of serum. Two additional lines of evidence suggest that the effects of tunicamycin on growth cones arise from its ability to inhibit protein long-chain acylation, rather than its previously established effects on protein glycosylation and synthesis. (a) The abilities of different tunicamycin homologues to induce growth cone collapse very systematically with the length of the fatty acyl side- chain of tunicamycin, in a manner predicted and observed for the inhibition of protein palmitoylation. Homologues with fatty acyl moieties shorter than palmitic acid (16 hydrocarbons), including potent inhibitors of glycosylation, are poor inhibitors of growth cone function. (b) The tunicamycin-induced impairment of growth cone function can be reversed by the addition of excess exogenous fatty acid, which reverses the inhibition of protein palmitoylation but has no effect on the inhibition of protein glycosylation. These results suggest an important role for

  12. Bayesian Energy Landscape Tilting: Towards Concordant Models of Molecular Ensembles

    PubMed Central

    Beauchamp, Kyle A.; Pande, Vijay S.; Das, Rhiju

    2014-01-01

    Predicting biological structure has remained challenging for systems such as disordered proteins that take on myriad conformations. Hybrid simulation/experiment strategies have been undermined by difficulties in evaluating errors from computational model inaccuracies and data uncertainties. Building on recent proposals from maximum entropy theory and nonequilibrium thermodynamics, we address these issues through a Bayesian energy landscape tilting (BELT) scheme for computing Bayesian hyperensembles over conformational ensembles. BELT uses Markov chain Monte Carlo to directly sample maximum-entropy conformational ensembles consistent with a set of input experimental observables. To test this framework, we apply BELT to model trialanine, starting from disagreeing simulations with the force fields ff96, ff99, ff99sbnmr-ildn, CHARMM27, and OPLS-AA. BELT incorporation of limited chemical shift and 3J measurements gives convergent values of the peptide’s α, β, and PPII conformational populations in all cases. As a test of predictive power, all five BELT hyperensembles recover set-aside measurements not used in the fitting and report accurate errors, even when starting from highly inaccurate simulations. BELT’s principled framework thus enables practical predictions for complex biomolecular systems from discordant simulations and sparse data. PMID:24655513

  13. 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.

  14. Engineering Escherichia coli for odd straight medium chain free fatty acid production.

    PubMed

    Wu, Hui; San, Ka-Yiu

    2014-10-01

    Microbial biosynthesis of free fatty acids (FFAs) can be achieved by introducing an acyl-acyl carrier protein thioesterase gene into Escherichia coli. The engineered E. coli usually produced even chain FFAs. In this study, propionyl-CoA synthetase (prpE) from Salmonella enterica was overexpressed in two efficient even chain FFAs producers, ML103 (pXZM12) carrying the acyl-ACP thioesterase gene from Umbellularia californica and ML103 (pXZ18) carrying the acyl-ACP thioesterase gene from Ricinus communis combined with supplement of extracellular propionate. With these metabolically engineered E. coli, the odd straight chain FFAs, undecanoic acid (C11:0), tridecanoic acid (C13:0), and pentadecanoic acid (C15:0) were produced from glucose and propionate. The highest total odd straight chain FFAs produced by ML103 (pXZM12, pBAD-prpE) reached 276 mg/l with a ratio of 23.43 % of the total FFAs. In ML103 (pXZ18, pBAD-prpE), the highest total odd straight chain FFAs accumulated to 297 mg/l, and the ratio reached 17.68 % of the total FFAs. Due to the different substrate specificity of the acyl-ACP thioesterases, the major odd straight chain FFA components of ML103 (pXZM12, pBAD-prpE) were undecanoic acid and tridecanoic acid, while the ML103 (pXZ18, pBAD-prpE) preferred pentadecanoic acid.

  15. Acylated cyanidin 3-sambubioside-5-glucosides in Matthiola incana.

    PubMed

    Saito, N; Tatsuzawa, F; Nishiyama, A; Yokoi, M; Shigihara, A; Honda, T

    1995-03-01

    Four acylated cyanidin 3-sambubioside-5-glucosides were isolated from purple-violet flowers of Matthiola incana and their structures were determined by chemical and spectroscopic methods. Three acylated anthocyanins were cyanidin 3-O-(6-O-acyl-2-O-(2-O-sinapyl-beta-D-xylopyranosyl)-beta-D- glucopyranosides)-5-O-(6-O-malonyl-beta-D-glucopyranosides), in which the acyl group is p-coumaryl, caffeyl or ferulyl, respectively. The remaining pigment is free from malonic acid and was identified as cyanidin 3-O-(6-O-trans-ferulyl-2-O-(2- O-trans-sinapyl-beta-D-xylopyranosyl)-beta-D-glucopyranoside)-5-O- (beta-D-glucopyranoside). Analysis of the anthocyanin constituents in 16 purple-violet cultivars revealed that they contained the above triacylated anthocyanins in variable amounts as main pigments. An aromatic pair of pigments containing sinapic and ferulic acids are considered to produce an important intramolecular effect, making bluish colours in these flowers.

  16. Upright Perception and Ocular Torsion Change Independently during Head Tilt

    PubMed Central

    Otero-Millan, Jorge; Kheradmand, Amir

    2016-01-01

    We maintain a stable perception of the visual world despite continuous movements of our eyes, head and body. Perception of upright is a key aspect of such orientation constancy. Here we investigated whether changes in upright perception during sustained head tilt were related to simultaneous changes in torsional position of the eyes. We used a subjective visual vertical (SVV) task, modified to track changes in upright perception over time, and a custom video method to measure ocular torsion simultaneously. We tested 12 subjects in upright position, during prolonged (~15 min) lateral head tilts of 20 degrees, and also after the head returned to upright position. While the head was tilted, SVV drifted in the same direction as the head tilt (left tilt: −5.4 ± 1.4° and right tilt: +2.2 ± 2.1°). After the head returned to upright position, there was an SVV aftereffect with respect to the pre-tilt baseline, which was also in the same direction as the head tilt (left tilt: −3.9 ± 0.6° and right tilt: +2.55 ± 1.0°). Neither the SVV drift nor the SVV aftereffect were correlated with the changes in ocular torsion. Using the Bayesian spatial-perception model we show that the pattern of SVV drift and aftereffect in our results could be explained by a drift and an adaptation in sensory inputs that encode head orientation. The fact that ocular torsion (mainly driven by the otoliths) could not account for the perceptual changes suggests that neck proprioception could be the primary source of drift in upright perception during head tilt, and subsequently the aftereffect in upright position. PMID:27909402

  17. 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

  18. Acyl Meldrum's acid derivatives: application in organic synthesis

    NASA Astrophysics Data System (ADS)

    Janikowska, K.; Rachoń, J.; Makowiec, S.

    2014-07-01

    This review is focused on an important class of Meldrum's acid derivatives commonly known as acyl Meldrum's acids. The preparation methods of these compounds are considered including the recently proposed and rather rarely used ones. The chemical properties of acyl Meldrum's acids are described in detail, including thermal stability and reactions with various nucleophiles. The possible mechanisms of these transformations are analyzed. The bibliography includes 134 references.

  19. Oxidative activation of dihydropyridine amides to reactive acyl donors.

    PubMed

    Funder, Erik Daa; Trads, Julie B; Gothelf, Kurt V

    2015-01-07

    Amides of 1,4-dihydropyridine (DHP) are activated by oxidation for acyl transfer to amines, alcohols and thiols. In the reduced form the DHP amide is stable towards reaction with amines at room temperature. However, upon oxidation with DDQ the acyl donor is activated via a proposed pyridinium intermediate. The activated intermediate reacts with various nucleophiles to give amides, esters, and thio-esters in moderate to high yields.

  20. Tilt anisoplanatism in extended turbulence propagation

    NASA Astrophysics Data System (ADS)

    Magee, Eric P.; Whiteley, Matthew R.; Das, Shashikala T.; Welsh, Byron M.

    2003-04-01

    The use of high-energy laser (HEL) weapon systems in tactical air-to-ground target engagements offers great promise for revolutionizing the USAF's war-fighting capabilities. Laser directed-energy systems will enable ultra-precision strike with minimal collateral damage and significant stand-off range for the aerial platform. The tactical directed energy application differs in many crucial ways from the conventional approach used in missile defense. Tactical missions occur at much lower altitudes and involve look-down to low-contrast ground targets instead of a high-contrast boosting missile. At these lower altitudes, the strength of atmospheric turbulence is greatly enhanced. Although the target slant ranges are much shorter, tactical missions may still involve moderate values of the Rytov number (0.1-0.5), and small isoplanatic angles compared to the diffraction angle. With increased density of air in the propagation path, and the potential for slow-moving or stationary ground targets, HEL-induced thermal blooming will certainly be a concern. In order to minimize the errors induced by tracking through thermal blooming, offset aimpoint tracking can be used. However, this will result in significant tilt anisoplanatism, thus degrading beam stabilization on target. In this paper we investigate the effects of extended turbulence on tracking (or tilt) anisoplanatism using theory and wave optics simulations. The simulations show good agreement with geometric optics predictions at angles larger than about 5 micro-radians (asymptotic regime) while at smaller angles the agreement is poor. We present a theoretical basis for this observation.

  1. 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

  2. Human acyl-CoA:cholesterol acyltransferase (ACAT) and its potential as a target for pharmaceutical intervention against atherosclerosis.

    PubMed

    Chang, Catherine; Dong, Ruhong; Miyazaki, Akira; Sakashita, Naomi; Zhang, Yi; Liu, Jay; Guo, Michael; Li, Bo-Liang; Chang, Ta-Yuan

    2006-03-01

    Acyl-CoA:cholesterol acyltransferase (ACAT) catalyzes the formation of cholesteryl esters from cholesterol and long-chain fatty-acyl-coenzyme A. At the single-cell level, ACAT serves as a regulator of intracellular cholesterol homeostasis. In addition, ACAT supplies cholesteryl esters for lipoprotein assembly in the liver and small intestine. Under pathological conditions, the accumulation of cholesteryl esters produced by ACAT in macrophages contributes to foam cell formation, a hallmark of the early stage of atherosclerosis. Several reviews addressing various aspects of ACAT and ACAT inhibitors are available. This review briefly outlines the current knowledge on the biochemical properties of human ACATs, and then focuses on discussing the merit of ACAT as a drug target for pharmaceutical interventions against atherosclerosis.

  3. Structure of Mycobacterium tuberculosis mtFabD, a malonyl-CoA:acyl carrier protein transacylase (MCAT).

    PubMed

    Ghadbane, Hemza; Brown, Alistair K; Kremer, Laurent; Besra, Gurdyal S; Fütterer, Klaus

    2007-10-01

    Mycobacteria display a unique and unusual cell-wall architecture, central to which is the membrane-proximal mycolyl-arabinogalactan-peptidoglycan core (mAGP). The biosynthesis of mycolic acids, which form the outermost layer of the mAGP core, involves malonyl-CoA:acyl carrier protein transacylase (MCAT). This essential enzyme catalyses the transfer of malonyl from coenzyme A to acyl carrier protein AcpM, thus feeding these two-carbon units into the chain-elongation cycle of the type II fatty-acid synthase. The crystal structure of M. tuberculosis mtFabD, the mycobacterial MCAT, has been determined to 3.0 A resolution by multi-wavelength anomalous dispersion. Phasing was facilitated by Ni2+ ions bound to the 20-residue N-terminal affinity tag, which packed between the two independent copies of mtFabD.

  4. 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.

  5. A PLP-dependent polyketide chain releasing mechanism in the biosynthesis of mycotoxin fumonisins in Fusarium verticillioides.

    PubMed

    Gerber, Ryan; Lou, Lili; Du, Liangcheng

    2009-03-11

    Fumonisins are polyketide-derived mycotoxins produced by several plant pathogenic fungi. The toxins cause several fatal diseases in domestic animals and are associated with esophageal cancer and neural tube defects in humans. Fumonisins contain a highly reduced, acyclic 18-carbon chain, which is synthesized by an iterative polyketide synthase (PKS). This PKS does not contain a thioesterase or cyclase domain that is found in other PKSs for the release of the covalently linked polyketide chain. In this study, we expressed the acyl carrier protein (ACP) of FUM1 and in vitro loaded acyl chains to the ACP from acyl-CoA using a promiscuous 4'-phosphopantetheinyl transferase. We then expressed FUM8, which is homologous to 2-oxoamine synthase genes, in yeast and showed that the enzyme is able to offload the acyl chains from ACP. Products resulted from the decarboxylative condensation between l-alanine and acyl-S-ACP were detected by GC-MS. The enzyme activity was dependent on pyridoxal 5'-phosphate (PLP), and C18-S-ACP was the preferred substrate. The results revealed a novel polyketide chain-releasing mechanism, in which a PLP-dependent enzyme catalyzes the termination and offloading of the polyketide chain as well as the introduction of a new carbon-carbon bond and an amino group to the chain. The mechanism is fundamentally different from the thioesterase/cyclase-catalyzed polyketide chain release found in bacterial and other fungal polyketide biosyntheses.

  6. Vesicle shape, molecular tilt, and the suppression of necks.

    PubMed

    Jiang, Hongyuan; Huber, Greg; Pelcovits, Robert A; Powers, Thomas R

    2007-09-01

    Can the presence of molecular-tilt order significantly affect the shapes of lipid bilayer membranes, particularly membrane shapes with narrow necks? Motivated by the propensity for tilt order and the common occurrence of narrow necks in the intermediate stages of biological processes such as endocytosis and vesicle trafficking, we examine how tilt order inhibits the formation of necks in the equilibrium shapes of vesicles. For vesicles with a spherical topology, point defects in the molecular order with a total strength of +2 are required. We study axisymmetric shapes and suppose that there is a unit-strength defect at each pole of the vesicle. The model is further simplified by the assumption of tilt isotropy: invariance of the energy with respect to rotations of the molecules about the local membrane normal. This isotropy condition leads to a minimal coupling of tilt order and curvature, giving a high energetic cost to regions with Gaussian curvature and tilt order. Minimizing the elastic free energy with constraints of fixed area and fixed enclosed volume determines the allowed shapes. Using numerical calculations, we find several branches of solutions and identify them with the branches previously known for fluid membranes. We find that tilt order changes the relative energy of the branches, suppressing thin necks by making them costly, leading to elongated prolate vesicles as a generic family of tilt-ordered membrane shapes.

  7. Tilt displacement range testing for a piezoelectric deformable mirror

    NASA Astrophysics Data System (ADS)

    Wang, Dongdong; Hao, Qun; Song, Yong; Cheng, Xuemin; Fan, Fan; Li, Heng

    2016-10-01

    In our previous works, we presented a zoom system and image stabilization design based on deformable mirrors (DMs). According to the high bandwidth and free edge characteristics of the piezoelectric deformable mirror (PDM), we tested the system's image-stable capability. We found the PDM could realize some tilt displacements while keeping a certain stable surface shape, it could obtain higher image stabilizing precision when integrated with the traditional mechanical image stabilization systems. In the design of the image stabilization system, the PDM's tilt displacement range is a key factor for consideration. So in this paper, we carried out a tilt displacement range testing experiment by using the OKO's 37-channel PDM. We measured and analyzed the variation of the tilt displacements in optical image stabilization process, and calculated the maximum tilt angle as the PDM surface shape was stabilized. We built an experimental platform consisting of a fixed target, an imaging system based on PDM, and a CCD camera. We used the ZYGO interferometer as an evaluation instrument to measure the surface shape stability. When the PDM surface had a tilt displacement, the image point of the fixed target on the camera sensor shifted correspondingly. The tilt angle of the PDM could be obtained by calculating this shift. The results showed that the maximum tilt angle of the PDM was 0.2mrad. The paper also analyzed the experiment errors when concerning about the off-axis error of the PDM deflection center.

  8. Two-dimensional dipolar scattering with a tilt

    SciTech Connect

    Ticknor, Christopher

    2011-09-15

    We study two-body dipolar scattering in two dimensions with a tilted polarization axis. This tilt reintroduces the anisotropic interaction in a controllable manner. As a function of this polarization angle, we present the scattering rates in both the threshold and semiclassical regimes. Additionally, we study the properties of the molecular bound states as a function of the polarization angle.

  9. TILTING ELECTRIC ARC FURNACE USED TO MELT BRONZE IN THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    TILTING ELECTRIC ARC FURNACE USED TO MELT BRONZE IN THE BRASS FOUNDRY BY MEANS OF AN ARC CREATED BETWEEN TWO HORIZONTAL ELECTRODES. WHEN MELTED, THE FURNACE TILTS, FILLING MOBILE LADLES FROM THE SPOUT. - Stockham Pipe & Fittings Company, Brass Foundry, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  10. V/STOL tilt rotor aircraft study. Volume 7: Tilt rotor flight control program feedback studies

    NASA Technical Reports Server (NTRS)

    Alexander, H. R.; Eason, W.; Gillmore, K.; Morris, J.; Spittle, R.

    1973-01-01

    An exploratory study has been made of the use of feedback control in tilt rotor aircraft. This has included the use of swashplate cyclic and collective controls and direct lift control. Various sensor and feedback systems are evaluated in relation to blade loads alleviation, improvement in flying qualities, and modal suppression. Recommendations are made regarding additional analytical and wind tunnel investigations and development of feedback systems in the full scale flight vehicle. Estimated costs and schedules are given.

  11. Acylated pregnane glycosides from Caralluma quadrangula.

    PubMed

    Abdallah, Hossam M; Osman, Abdel-Moneim M; Almehdar, Hussein; Abdel-Sattar, Essam

    2013-04-01

    In a previous study, the methanolic extract as well as the chloroform fraction of the aerial parts of Caralluma quadrangula (Forssk.) N.E.Br. indigenous to Saudi Arabia showed significant in vitro cytotoxic activity against breast cancer (MCF7) cell line. In a biologically-guided fractionation approach, four acylated pregnane glycosides were isolated from the chloroform fraction of C. quadrangula. The structures of the isolated compounds were elucidated by the analysis of their MS and NMR data. The compounds were identified as 12,20-di-O-benzoylboucerin 3-O-β-D-digitoxopyranosyl-(1→4)-β-D-canaropyranosyl-(1→4)-β-D-cymaropyranoside (1), 12,20-di-O-benzoylboucerin 3-O-β-D-cymaropyranosyl-(1→4)-β-D-canaropyranosyl-(1→4)-β-D-cymaropyranoside (2), 12,20-di-O-benzoylboucerin 3-O-β-D-glucopyranosyl-(1→4)-β-D-digitoxopyranosyl-(1→4)-β-D-canaropyranosyl-(1→4)-β-D-cymaropyranoside (3) and 12,20-di-O-benzoyl-3β,5α,12β,14β,20-pentahydroxy-(20R)-pregn-6-ene 3-O-β-D-glucopyranosyl-(1→4)-β-D-digitoxopyranosyl-(1→4)-β-D-canaropyranosyl-(1→4)-β-D-cymaropyranoside (4). The isolated compounds were tested for their cytotoxic activity against breast cancer (MCF7) cell line.

  12. LONG-TERM MEASUREMENTS OF SUNSPOT MAGNETIC TILT ANGLES

    SciTech Connect

    Li Jing; Ulrich, Roger K.

    2012-10-20

    Tilt angles of close to 30,600 sunspots are determined using Mount Wilson daily averaged magnetograms taken from 1974 to 2012, and SOHO/MDI magnetograms taken from 1996 to 2010. Within a cycle, more than 90% of sunspots have a normal polarity alignment along the east-west direction following Hale's law. The median tilts increase with increasing latitude (Joy's law) at a rate of {approx}0.{sup 0}5 per degree of latitude. Tilt angles of spots appear largely invariant with respect to time at a given latitude, but they decrease by {approx}0.{sup 0}9 per year on average, a trend that largely reflects Joy's law following the butterfly diagram. We find an asymmetry between the hemispheres in the mean tilt angles. On average, the tilts are greater in the Southern than in the Northern Hemisphere for all latitude zones, and the differences increase with increasing latitude.

  13. A single-tilt TEM stereomicroscopy technique for crystalline materials.

    PubMed

    McCabe, Rodney J; Misra, Amit; Mitchell, Terence E; Alexander, Kathleen B

    2003-02-01

    A new single-tilt technique for performing TEM stereomicroscopy of strain fields in crystalline materials has been developed. The technique is a weak beam technique that involves changing the value of g and/or s g while tilting across a set of Kikuchi bands. The primary benefit of the technique is it can be used with single-tilt TEM specimen holders including many specialty holders such as in situ straining, heating, and cooling holders. Standard stereo-TEM techniques are almost always limited to holders allowing two degrees of rotational freedom (i.e., double-tilt or tilt/rotation holders). An additional benefit of the new technique is that it eliminates the need to focus with the specimen height control. These advantages make it useful for stereo viewing or for quantitative stereomicroscopy provided necessary consideration is given to errors that may result from the technique.

  14. Description of a tilt wing mathematical model for piloted simulation

    NASA Technical Reports Server (NTRS)

    Totah, Joseph J.

    1991-01-01

    A tilt-wing mathematical model that was used in a piloted six-deg-of-freedom flight simulation application is presented. Two types of control systems developed for the model - a conventional programmed-flap wing-tilt control system and a geared-flap wing-tilt control system - are discussed. The objective of this effort was to develop the capability to study tilt-wing aircraft. Experienced tilt-wing pilots subjectively evaluated the model using programmed-flap control to assess the quality of the simulation. The objective was met and the model was then applied to study geared-flap control to investigate the possibility of eliminating the need for auxiliary pitch control devices. This was performed in the moving-base simulation environment, and the vehicle responses with programmed-flap and geared-flap control were compared.

  15. EFFECTIVE INNER RADIUS OF TILTED BLACK HOLE ACCRETION DISKS

    SciTech Connect

    Fragile, P. Chris

    2009-12-01

    One of the primary means of determining the spin a of an astrophysical black hole is by actually measuring the inner radius r {sub in} of a surrounding accretion disk and using that to infer a. By comparing a number of different estimates of r {sub in} from simulations of tilted accretion disks with differing black hole spins, we show that such a procedure can give quite wrong answers. Over the range 0 <= a/M <= 0.9, we find that, for moderately thick disks (H/r approx 0.2) with modest tilt (15 deg.), r {sub in} is nearly independent of spin. This result is likely dependent on tilt, such that for larger tilts, it may even be that r {sub in} would increase with increasing spin. In the opposite limit, we confirm through numerical simulations of untilted disks that, in the limit of zero tilt, r {sub in} recovers approximately the expected dependence on a.

  16. Marker-free dual-axis tilt series alignment

    PubMed Central

    Winkler, Hanspeter; Taylor, Kenneth A.

    2013-01-01

    Dual-axis tilt series in electron tomography are collected by successively tilting the object about two approximately orthogonal tilt axes. Here we report on the extension of marker-free image registration based on cross-correlation techniques to dual-axis tilt series. A simultaneous geometry refinement yields accurate parameters for the computati on of the final reconstruction. Both, image registration and 3D-reconstruction operate on the combined data from the paired single axis series rather than computing individual single axis tomograms followed by a separate combination step. We show that with simultaneous registration and reconstruction of dual-axis tilt series, tomograms with higher resolution are obtained than by merging separately computed tomograms. PMID:23435123

  17. Elastic bending and active tilting of myosin heads during muscle contraction.

    PubMed

    Dobbie, I; Linari, M; Piazzesi, G; Reconditi, M; Koubassova, N; Ferenczi, M A; Lombardi, V; Irving, M

    1998-11-26

    Muscle contraction is driven by a change in shape of the myosin head region that links the actin and myosin filaments. Tilting of the light-chain domain of the head with respect to its actin-bound catalytic domain is thought to be coupled to the ATPase cycle. Here, using X-ray diffraction and mechanical data from isolated muscle fibres, we characterize an elastic bending of the heads that is independent of the presence of ATP. Together, the tilting and bending motions can explain force generation in isometric muscle, when filament sliding is prevented. The elastic strain in the head is 2.0-2.7 nm under these conditions, contributing 40-50% of the compliance of the muscle sarcomere. We present an atomic model for changes in head conformation that accurately reproduces the changes in the X-ray diffraction pattern seen when rapid length changes are applied to muscle fibres both in active contraction and in the absence of ATP. The model predictions are relatively independent of which parts of the head are assumed to bend or tilt, but depend critically on the measured values of filament sliding and elastic strain.

  18. Key enzymes for biosynthesis of neutral lipid storage compounds in prokaryotes: properties, function and occurrence of wax ester synthases/acyl-CoA: diacylglycerol acyltransferases.

    PubMed

    Wältermann, Marc; Stöveken, Tim; Steinbüchel, Alexander

    2007-02-01

    Triacylglycerols (TAGs) and wax esters (WEs) are beside polyhydroxyalkanoates (PHAs) important storage lipids in some groups of prokaryotes. Accumulation of these lipids occurs in cells when they are cultivated under conditions of unbalanced growth in the presence of high concentrations of a suitable carbon source, which can be used for fatty acid and storage lipid biosyntheses. The key enzymes, which mediate both WE and TAG formations from long-chain acyl-coenzyme A (CoA) as acyl donor and long-chain fatty alcohols or diacylglycerols as respective acyl acceptors in bacteria, are WE synthases/acyl-CoA:diacylglycerol acyltransferases (WS/DGATs). The WS/DGATs identified so far represent rather unspecific enzymes with broad spectra of possible substrates; this makes them interesting for many biotechnological applications. This review traces the molecular structure and biochemical properties including the probable regions responsible for acyltransferase properties, enzymatic activity and substrate specifities. The phylogenetic relationships based on amino acid sequence similarities of this unique class of enzymes were revealed. Furthermore, recent advances in understanding the physiological functions of WS/DGATs in their natural hosts including pathogenic Mycobacterium tuberculosis were discussed.

  19. 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...

  20. Crossover from crossing to tilted vortex phase in Bi2Sr2CaCu2O8+δ single crystals near ab-plane

    NASA Astrophysics Data System (ADS)

    Mirkovic, Jovan; Buzdin, Alexandre; Kashiwagi, Takanari; Yamamoto, Takashi; Kadowaki, Kazuo

    2013-01-01

    In extremely anisotropic layered superconductors of Bi2Sr2CaCu2O8+δ the stacks of vortex pancakes (PV) and the Josephson vortex (JV) interpenetrate, and due to PV-JV mutual pinning energy, weakly interact and form various tilted and crossing lattice structures including vortex chains, stripes, mixed chain + lattice phases, etc. In order to study these phenomena, it is decisive to have excellent quality of samples and the ideal experimental techniques. The vortex phases in high-quality Bi2Sr2CaCu2O8+δ single crystals were studied by in-plane resistivity measurement and local ac magnetic permeability. The sharp crossover was shown by both techniques, deep in the vortex solid state separating the Abrikosov dominant ‘strong pinning’ phase from the Josephson dominant ‘weak pinning’ phase. Those two vortex states were recognized as the mixed chain + lattice vortex phase and chains (tilted) vortex phase, respectively.

  1. The effects of dipole tilt on magnetotail structure and dynamics

    NASA Technical Reports Server (NTRS)

    Walker, Raymond J.; Ashour-Abdalla, Maha; Ogino, Tatsuki

    1989-01-01

    A three-dimensional time-dependent global magnetohydrodynamic (MHD) model of the interaction between the solar wind and the earth's magnetosphere has been used to study the effects of dipole tilt on the structure and dynamics of the magnetotail. The location of the tail neutral sheet shifts in the north-south direction following changes in the dipole tilt. When the northern edge of the geomagnetic dipole is tilted toward the sun (positive tilt), it is above the geocentric solar magnetosphere (GSM) equator, while for negative tilt, it is below. The neutral sheet forms an arc across the tail in the y-z plane for nonzero tilt. For positive tilt, the neutral sheet rises above the GSM equatorial plane near the noon-midnight meridian and returns to the equator near the magnetopause. The position and shape of the neutral sheet result from the requirement that the earthward magnetic flux equals the tailward flux and can be well explained by a simple analytical model.

  2. A strategy for advancing tilt-rotor technology

    NASA Technical Reports Server (NTRS)

    Morlok, Edward K.; Schoendorfer, David L.

    1985-01-01

    Tilt-rotor technology has many features which make it a very promising development in aviation which might have application to a wide variety of transportation and logistics situations. However, aside from military applications and rather specialized industrial applications, little is known regarding the potential of tilt-rotor for commercial transportation and hence it is difficult to plan a development program which would gain support and be likely to produce a stream of significant benefits. The purpose is to attempt to provide some of this information in a manner that would be useful for preparing a strategy for development of tilt-rotor aircraft technology. Specifically, the objectives were: to identify promising paths of development and deployment of tilt-rotor aircraft technology in the air transportation system considering both benefits and disbenefits, and to identify any particular groups that are likely to benefit significantly and propose plans for gaining their support of research and development of this technology. Potential advantages of the tilt-rotor technology in the context of air transportation as a door-to-door system were identified, and then promising paths of development of such tilt-rotor systems were analyzed. These then lead to recommendations for specific studies, information dissemination and development of awareness of the tilt-rotor among specific transport-related groups.

  3. Classical and quantum mechanics of diatomic molecules in tilted fields.

    PubMed

    Arango, Carlos A; Kennerly, William W; Ezra, Gregory S

    2005-05-08

    We investigate the classical and quantum mechanics of diatomic molecules in noncollinear (tilted) static electric and nonresonant linearly polarized laser fields. The classical diatomic in tilted fields is a nonintegrable system, and we study the phase space structure for physically relevant parameter regimes for the molecule KCl. While exhibiting low-energy (pendular) and high-energy (free-rotor) integrable limits, the rotor in tilted fields shows chaotic dynamics at intermediate energies, and the degree of classical chaos can be tuned by changing the tilt angle. We examine the quantum mechanics of rotors in tilted fields. Energy-level correlation diagrams are computed, and the presence of avoided crossings quantified by the study of nearest-neighbor spacing distributions as a function of energy and tilting angle. Finally, we examine the influence of classical periodic orbits on rotor wave functions. Many wave functions in the tilted field case are found to be highly nonseparable in spherical polar coordinates. Localization of wave functions in the vicinity of classical periodic orbits, both stable and unstable, is observed for many states.

  4. Motion perception during tilt and translation after space flight

    NASA Astrophysics Data System (ADS)

    Clément, Gilles; Wood, Scott J.

    2013-11-01

    Preliminary results of an ongoing study examining the effects of space flight on astronauts' motion perception induced by independent tilt and translation motions are presented. This experiment used a sled and a variable radius centrifuge that translated the subjects forward-backward or laterally, and simultaneously tilted them in pitch or roll, respectively. Tests were performed on the ground prior to and immediately after landing. The astronauts were asked to report about their perceived motion in response to different combinations of body tilt and translation in darkness. Their ability to manually control their own orientation was also evaluated using a joystick with which they nulled out the perceived tilt while the sled and centrifuge were in motion. Preliminary results confirm that the magnitude of perceived tilt increased during static tilt in roll after space flight. A deterioration in the crewmember to control tilt using non-visual inertial cues was also observed post-flight. However, the use of a tactile prosthesis indicating the direction of down on the subject's trunk improved manual control performance both before and after space flight.

  5. Crystal lattice tilting in prismatic calcite.

    PubMed

    Olson, Ian C; Metzler, Rebecca A; Tamura, Nobumichi; Kunz, Martin; Killian, Christopher E; Gilbert, Pupa U P A

    2013-08-01

    We analyzed the calcitic prismatic layers in Atrina rigida (Ar), Haliotis iris (Hi), Haliotis laevigata (HL), Haliotis rufescens (Hrf), Mytilus californianus (Mc), Pinctada fucata (Pf), Pinctada margaritifera (Pm) shells, and the aragonitic prismatic layer in the Nautilus pompilius (Np) shell. Dramatic structural differences were observed across species, with 100-μm wide single-crystalline prisms in Hi, HL and Hrf, 1-μm wide needle-shaped calcite prisms in Mc, 1-μm wide spherulitic aragonite prisms in Np, 20-μm wide single-crystalline calcite prisms in Ar, and 20-μm wide polycrystalline calcite prisms in Pf and Pm. The calcite prisms in Pf and Pm are subdivided into sub-prismatic domains of orientations, and within each of these domains the calcite crystal lattice tilts gradually over long distances, on the order of 100 μm, with an angle spread of crystal orientation of 10-20°. Furthermore, prisms in Pf and Pm are harder than in any other calcite prisms analyzed, their nanoparticles are smaller, and the angle spread is strongly correlated with hardness in all shells that form calcitic prismatic layers. One can hypothesize a causal relationship of these correlated parameters: greater angle spread may confer greater hardness and resistance to wear, thus providing Pf and Pm with a structural advantage in their environment. This is the first structure-property relationship thus far hypothesized in mollusk shell prisms.

  6. Photovoltaic Modules: Effect of Tilt Angle on Soiling

    NASA Astrophysics Data System (ADS)

    Cano, Jose

    2011-12-01

    Photovoltaic (PV) systems are one of the next generation's renewable energy sources for our world energy demand. PV modules are highly reliable. However, in polluted environments, over time, they will collect grime and dust. There are also limited field data studies about soiling losses on PV modules. The study showed how important it is to investigate the effect of tilt angle on soiling. The study includes two sets of mini-modules. Each set has 9 PV modules tilted at 0, 5, 10, 15, 20, 23, 30, 33 and 40°. The first set called "Cleaned" was cleaned every other day. The second set called "Soiled" was never cleaned after the first day. The short circuit current, a measure of irradiance, and module temperature was monitored and recorded every two minutes over three months (January-March 2011). The data were analyzed to investigate the effect of tilt angle on daily and monthly soiling, and hence transmitted solar insolation and energy production by PV modules. The study shows that during the period of January through March 2011 there was an average loss due to soiling of approximately 2.02% for 0° tilt angle. Modules at tilt angles 23° and 33° also have some insolation losses but do not come close to the module at 0° tilt angle. Tilt angle 23° has approximately 1.05% monthly insolation loss, and 33° tilt angle has an insolation loss of approximately 0.96%. The soiling effect is present at any tilt angle, but the magnitude is evident: the flatter the solar module is placed the more energy it will lose.

  7. Influence of Vibrotactile Feedback on Controlling Tilt Motion After Spaceflight

    NASA Technical Reports Server (NTRS)

    Wood, S. J.; Rupert, A. H.; Vanya, R. D.; Esteves, J. T.; Clement, G.

    2011-01-01

    We hypothesize that adaptive changes in how inertial cues from the vestibular system are integrated with other sensory information leads to perceptual disturbances and impaired manual control following transitions between gravity environments. The primary goals of this ongoing post-flight investigation are to quantify decrements in manual control of tilt motion following short-duration spaceflight and to evaluate vibrotactile feedback of tilt as a sensorimotor countermeasure. METHODS. Data is currently being collected on 9 astronaut subjects during 3 preflight sessions and during the first 8 days after Shuttle landings. Variable radius centrifugation (216 deg/s, <20 cm radius) in a darkened room is utilized to elicit otolith reflexes in the lateral plane without concordant canal or visual cues. A Tilt-Translation Sled (TTS) is capable of synchronizing pitch tilt with fore-aft translation to align the resultant gravitoinertial vector with the longitudinal body axis, thereby eliciting canal reflexes without concordant otolith or visual cues. A simple 4 tactor system was implemented to provide feedback when tilt position exceeded predetermined levels in either device. Closed-loop nulling tasks are performed during random tilt steps or sum-of-sines (TTS only) with and without vibrotactile feedback of chair position. RESULTS. On landing day the manual control performance without vibrotactile feedback was reduced by >30% based on the gain or the amount of tilt disturbance successfully nulled. Manual control performance tended to return to baseline levels within 1-2 days following landing. Root-mean-square position error and tilt velocity were significantly reduced with vibrotactile feedback. CONCLUSIONS. These preliminary results are consistent with our hypothesis that adaptive changes in vestibular processing corresponds to reduced manual control performance following G-transitions. A simple vibrotactile prosthesis improves the ability to null out tilt motion within a

  8. 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.

  9. Isolation and Characterization of Two Safflower Oleoyl-Acyl Carrier Protein Thioesterase cDNA Clones

    PubMed Central

    Knutzon, Deborah S.; Bleibaum, Janice L.; Nelsen, Janet; Kridl, Jean C.; Thompson, Gregory A.

    1992-01-01

    Oleoyl-acyl carrier protein (18:1-ACP) thioesterase has been partially purified from developing safflower (Carthamus tinctorius) seeds. Protein species with molecular masses of 34 and 40 kD associated with thioesterase activity were identified and partially sequenced. Analysis of amino-terminal and internal cyanogen bromide peptide sequences revealed no differences in the primary structure of the two species. Amino acid sequence was used to design degenerate oligonucleotides for primers in a polymerase chain reaction (PCR) using safflower embryo cDNA as a template. A 380-base pair PCR product was used to isolate two classes of cDNA clones, designated 2-1 and 5-2, from the embryo cDNA library. Clone 2-1 encodes a 389-amino acid protein including a 60-amino acid transit peptide, and contains all of the protein sequence determined from the 34- and 40-kD proteins. Clone 5-2 encodes a 385-amino acid protein with 80% identity to that encoded by 2-1. Expression of the two safflower cDNA clones in Escherichia coli resulted in a 50- to 100-fold increase in the level of 18:1-ACP thioesterase activity. Both thioesterases are most active on 18:1-ACP; however, the enzyme encoded by 5-2 shows less discrimination against saturated 16- and 18-carbon acyl-ACP substrates. Images Figure 1 Figure 4 PMID:16653193

  10. An annotated database of Arabidopsis mutants of acyl lipid metabolism

    SciTech Connect

    McGlew, Kathleen; Shaw, Vincent; Zhang, Meng; Kim, Ryeo Jin; Yang, Weili; Shorrosh, Basil; Suh, Mi Chung; Ohlrogge, John

    2014-12-10

    Mutants have played a fundamental role in gene discovery and in understanding the function of genes involved in plant acyl lipid metabolism. The first mutant in Arabidopsis lipid metabolism (fad4) was described in 1985. Since that time, characterization of mutants in more than 280 genes associated with acyl lipid metabolism has been reported. This review provides a brief background and history on identification of mutants in acyl lipid metabolism, an analysis of the distribution of mutants in different areas of acyl lipid metabolism and presents an annotated database (ARALIPmutantDB) of these mutants. The database provides information on the phenotypes of mutants, pathways and enzymes/proteins associated with the mutants, and allows rapid access via hyperlinks to summaries of information about each mutant and to literature that provides information on the lipid composition of the mutants. Mutants for at least 30 % of the genes in the database have multiple names, which have been compiled here to reduce ambiguities in searches for information. Furthermore, the database should also provide a tool for exploring the relationships between mutants in acyl lipid-related genes and their lipid phenotypes and point to opportunities for further research.

  11. An annotated database of Arabidopsis mutants of acyl lipid metabolism

    DOE PAGES

    McGlew, Kathleen; Shaw, Vincent; Zhang, Meng; ...

    2014-12-10

    Mutants have played a fundamental role in gene discovery and in understanding the function of genes involved in plant acyl lipid metabolism. The first mutant in Arabidopsis lipid metabolism (fad4) was described in 1985. Since that time, characterization of mutants in more than 280 genes associated with acyl lipid metabolism has been reported. This review provides a brief background and history on identification of mutants in acyl lipid metabolism, an analysis of the distribution of mutants in different areas of acyl lipid metabolism and presents an annotated database (ARALIPmutantDB) of these mutants. The database provides information on the phenotypes ofmore » mutants, pathways and enzymes/proteins associated with the mutants, and allows rapid access via hyperlinks to summaries of information about each mutant and to literature that provides information on the lipid composition of the mutants. Mutants for at least 30 % of the genes in the database have multiple names, which have been compiled here to reduce ambiguities in searches for information. Furthermore, the database should also provide a tool for exploring the relationships between mutants in acyl lipid-related genes and their lipid phenotypes and point to opportunities for further research.« less

  12. Mars - Change in axial tilt due to climate?

    NASA Technical Reports Server (NTRS)

    Rubincam, David Parry

    1990-01-01

    The average tilt of Mars' equator with respect to its orbital plane may have increased significantly over the age of the solar system. Obliquity oscillations might have induced changes in the climate, which altered the mass distribution and hence the solar torque on the planet. Viscous deformation attributable to loading by the large polar caps expected at low obliquity may have induced secular changes in the axial tilt. Earth-like effective viscosities can account for virtually the entire present obliquity of 24.4 degrees. Thus the present average tilt of Mars may not be primordial.

  13. Mars: change in axial tilt due to climate?

    PubMed

    Rubincam, D P

    1990-05-11

    The average tilt of Mars' equator with respect to its orbital plane may have increased significantly over the age of the solar system. Obliquity oscillations might have induced changes in the climate, which altered the mass distribution and hence the solar torque on the planet. Viscous deformation attributable to loading by the large polar caps expected at low obliquity may have induced secular changes in the axial tilt. Earth-like effective viscosities can account for virtually the entire present obliquity of 24.4 degrees. Thus the present average tilt of Mars may not be primordial.

  14. Cosmic ray intensity and the tilt of the neutral sheet

    NASA Technical Reports Server (NTRS)

    Saito, T.; Swinson, D. B.

    1985-01-01

    Recent publications have related long-term variations in cosmic ray intensity at the Earth with long term variations in the tilt of the neutral sheet in the inner heliosphere. The tilt of the neutral sheet from 1971 to 1974 is compared with the cosmic ray intensity at Earth, recorded by the Mt. Washington neutron monitor. The remarkable large decreases in cosmic ray intensity which occurred in 1973 and 1974 correlate well with excursions in the tilt of the neutral sheet which occurred earlier during these same two years.

  15. Performance characterization of scanning beam steered by tilting double prisms.

    PubMed

    Li, Anhu; Yi, Wanli; Zuo, Qiyou; Sun, Wansong

    2016-10-03

    A pair of orthogonal tilting double prisms with a tracking precision better than submicroradian order exhibits a good application potential in laser tracking fields. In the paper, the beam scanning performance determined by both the structure parameters and the tilting motions of two prisms is overall investigated. The functional relation between the structure parameters and the exact beam scanning range is established, the capability of high-accuracy beam steering is validated together with the investigation of the scanning error sources and the nonlinear control laws, and the beam shape distortion degree under multi-parameter combinations is demonstrated. These studies can provide important references for the development of tilting double prisms.

  16. Evolution of acyl-ACP-thioesterases and β-ketoacyl-ACP-synthases revealed by protein-protein interactions

    PubMed Central

    Beld, Joris; Blatti, Jillian L.; Behnke, Craig; Mendez, Michael; Burkart, Michael D.

    2014-01-01

    The fatty acid synthase (FAS) is a conserved primary metabolic enzyme complex capable of tolerating cross-species engineering of domains for the development of modified and overproduced fatty acids. In eukaryotes, acyl-acyl carrier protein thioesterases (TEs) off-load mature cargo from the acyl carrier protein (ACP), and plants have developed TEs for short/medium-chain fatty acids. We showed that engineering plant TEs into the green microalga Chlamydomonas reinhardtii does not result in the predicted shift in fatty acid profile. Since fatty acid biosynthesis relies on substrate recognition and protein-protein interactions between the ACP and its partner enzymes, we hypothesized that plant TEs and algal ACP do not functionally interact. Phylogenetic analysis revealed major evolutionary differences between FAS enzymes, including TEs and ketoacyl synthases (KSs), in which the former is present only in some species, whereas the latter is present in all, and has a common ancestor. In line with these results, TEs appeared to be selective towards their ACP partners whereas KSs showed promiscuous behavior across bacterial, plant and algal species. Based on phylogenetic analyses, in silico docking, in vitro mechanistic crosslinking and in vivo algal engineering, we propose that phylogeny can predict effective interactions between ACPs and partner enzymes. PMID:25110394

  17. Mycobacterium tuberculosis beta-ketoacyl acyl carrier protein synthase III (mtFabH) assay: principles and method.

    PubMed

    Sachdeva, Sarbjot; Reynolds, Kevin A

    2008-01-01

    Fatty acid biosynthesis is one of the relatively newer targets in antibacterial drug discovery. The presence of distinct fatty acid synthases (FAS) in mammals and bacteria and the fact that most bacterial FAS enzymes are essential for viability make this a very attractive antimicrobial drug target. The enzyme beta-ketoacyl ACP synthase (KASIII or FabH) is the key enzyme that initiates fatty acid biosynthesis in a type II dissociated FAS. This enzyme catalyzes the condensation of acyl CoA and malonyl ACP (acyl carrier protein) to form a beta-ketoacyl ACP product, which is further processed to form mature fatty acids that are involved in various essential cellular processes and structures like phospholipid biosynthesis, cell wall formation, etc. Herein we describe a new assay for the Mycobacterium tuberculosis FabH (mtFabH) enzyme involved in a key initiation step in the synthesis of mycolic acids, which are an integral component of the cell wall. The assay eliminates the need for the cumbersome washing steps or specialty scintillation proximity assay beads and the preparation of acyl carrier proteins required in other assay formats. This discontinuous assay involves the reduction of radiolabled long-chain beta-ketoacyl CoA product to its dihydroxy derivative, which partitions into a nonpolar phase for quantitation, while the reduced radiolabeled substrate derivative remains in the aqueous phase.

  18. Trapping of the Enoyl-Acyl Carrier Protein Reductase–Acyl Carrier Protein Interaction

    PubMed Central

    Tallorin, Lorillee; Finzel, Kara; Nguyen, Quynh G.; Beld, Joris; La Clair, James J.; Burkart, Michael D.

    2016-01-01

    An ideal target for metabolic engineering, fatty acid biosynthesis remains poorly understood on a molecular level. These carrier protein-dependent pathways require fundamental protein–protein interactions to guide reactivity and processivity, and their control has become one of the major hurdles in successfully adapting these biological machines. Our laboratory has developed methods to prepare acyl carrier proteins (ACPs) loaded with substrate mimetics and cross-linkers to visualize and trap interactions with partner enzymes, and we continue to expand the tools for studying these pathways. We now describe application of the slow-onset, tight-binding inhibitor triclosan to explore the interactions between the type II fatty acid ACP from Escherichia coli, AcpP, and its corresponding enoyl-ACP reductase, FabI. We show that the AcpP–triclosan complex demonstrates nM binding, inhibits in vitro activity, and can be used to isolate FabI in complex proteomes. PMID:26938266

  19. A Comparative Analysis of Acyl-Homoserine Lactone Synthase Assays.

    PubMed

    Shin, Daniel; Frane, Nicole D; Brecht, Ryan M; Keeler, Jesse; Nagarajan, Rajesh

    2015-12-01

    Quorum sensing is cell-to-cell communication that allows bacteria to coordinate attacks on their hosts by inducing virulent gene expression, biofilm production, and other cellular functions, including antibiotic resistance. AHL synthase enzymes synthesize N-acyl-l-homoserine lactones, commonly referred to as autoinducers, to facilitate quorum sensing in Gram-negative bacteria. Studying the synthases, however, has proven to be a difficult road. Two assays, including a radiolabeled assay and a colorimetric (DCPIP) assay are well-documented in literature to study AHL synthases. In this paper, we describe additional methods that include an HPLC-based, C-S bond cleavage and coupled assays to investigate this class of enzymes. In addition, we compare and contrast each assay for both acyl-CoA- and acyl-ACP-utilizing synthases. The expanded toolkit described in this study should facilitate mechanistic studies on quorum sensing signal synthases and expedite discovery of antivirulent compounds.

  20. Asymmetric Allylboration of Acyl Imines Catalyzed by Chiral Diols

    PubMed Central

    Lou, Sha; Moquist, Philip N.; Schaus, Scott E.

    2008-01-01

    Chiral BINOL-derived diols catalyze the enantioselective asymmetric allylboration of acyl imines. The reaction requires 15 mol% of (S)-3,3′-Ph2-BINOL as the catalyst and allyldiisopropoxyborane as the nucleophile. The reaction products are obtained in good yields (75 – 94%) and high enantiomeric ratios (95:5 – 99.5:0.5) for aromatic and aliphatic imines. High diastereoselectivities (dr > 98:2) and enantioselectivities (er > 98:2) are obtained in the reactions of acyl imines with crotyldiisopropoxyboranes. This asymmetric transformation is directly applied to the synthesis of maraviroc, the selective CCR5 antagonist with potent activity against HIV-1 infection. Mechanistic investigations of the allylboration reaction including IR, NMR, and mass spectrometry study indicate that acyclic boronates are activated by chiral diols via exchange of one of the boronate alkoxy groups with activation of the acyl imine via hydrogen bonding. PMID:18020334

  1. Identification of N-acyl homoserine lactones produced by Gluconacetobacter diazotrophicus PAL5 cultured in complex and synthetic media.

    PubMed

    Nieto-Peñalver, Carlos G; Bertini, Elisa V; de Figueroa, Lucía I C

    2012-07-01

    The endophytic diazotrophic Gluconacetobacter diazotrophicus PAL5 was originally isolated from sugarcane (Saccharum officinarum). The biological nitrogen fixation, phytohormones secretion, solubilization of mineral nutrients and phytopathogen antagonism allow its classification as a plant growth-promoting bacterium. The recent genomic sequence of PAL5 unveiled the presence of a quorum sensing (QS) system. QS are regulatory mechanisms that, through the production of signal molecules or autoinducers, permit a microbial population the regulation of the physiology in a coordinated manner. The most studied autoinducers in gram-negative bacteria are the N-acyl homoserine lactones (AHLs). The usage of biosensor strains evidenced the presence of AHL-like molecules in cultures of G. diazotrophicus PAL5 grown in complex and synthetic media. Analysis of AHLs performed by LC-APCI-MS permitted the identification of eight different signal molecules, including C6-, C8-, C10-, C12- and C14-HSL. Mass spectra confirmed that this diazotrophic strain also synthesizes autoinducers with carbonyl substitutions in the acyl chain. No differences in the profile of AHLs could be determined under both culture conditions. However, although the level of short-chain AHLs was not affected, a decrease of 30% in the production of long-chain AHLs could be measured in synthetic medium.

  2. Lipid bilayers containing sphingomyelins and ceramides of varying N-acyl lengths: a glimpse into sphingolipid complexity.

    PubMed

    Jiménez-Rojo, Noemi; García-Arribas, Aritz B; Sot, Jesús; Alonso, Alicia; Goñi, Félix M

    2014-01-01

    The thermotropic properties of aqueous dispersions of sphingomyelins (SM) and ceramides (Cer) with N-acyl chains varying from C6:0 to C24:1, either pure or in binary mixtures, have been examined by differential scanning calorimetry. Even in the pure state, Cer and particularly SM exhibited complex endotherms, and their thermal properties did not vary in a predictable way with changes in structure. In some cases, e.g. C18:0 SM, atomic force microscopy revealed coexisting lamellar domains made of a single lipid. Partial chain interdigitation and metastable crystalline states were deemed responsible for the complex behavior. SM:Cer mixtures (90:10mol ratio) gave rise to bilayers containing separate SM-rich and Cer-rich domains. In vesicles made of more complex mixtures (SM:PE:Chol, 2:1:1), it is known that sphingomyelinase degradation of SM to Cer is accompanied by vesicle aggregation and release of aqueous contents. These vesicles did not reveal observable domain separation by confocal microscopy. Vesicle aggregation occurred at a faster rate for those bilayers that appeared to be more fluid according to differential scanning calorimetry. Content efflux rates measured by fluorescence spectroscopy were highest with C18:0 and C18:1 SM, and in general those rates did not vary regularly with other physical properties of SM or Cer. In general the individual SM and Cer appear to have particular thermotropic properties, often unrelated to the changes in N-acyl chain.

  3. Tilt of Emerging Bipolar Magnetic Regions on the Sun

    NASA Astrophysics Data System (ADS)

    Kosovichev, A. G.; Stenflo, J. O.

    2008-12-01

    Magnetic fields emerging from the Sun's interior carry information about the physical processes of magnetic field generation and transport in the convection zone. A statistical analysis of variations of the tilt angle of bipolar magnetic regions during the emergence, observed from SOHO MDI, shows that the systematic tilt with respect to the equator (Joy's law) is established by the middle of the emergence period. This suggests that the tilt is most likely generated below the surface. However, the data do not show evidence of a dependence of the tilt angle on the amount of flux or a relaxation of the bipolar orientation toward the east-west direction, in contrast to the predictions of the rising magnetic flux rope theories.

  4. Data Correction for Gantry-tilted Local CT.

    PubMed

    Liang, Hongzhu; Zhang, Cishen; Yan, Ming; Zhou, Jiayin

    2005-01-01

    Gantry-tilted helical multi-slice computed tomography (CT) refers to the helical scanning CT system equipped with multi-row detector operating at some gantry tilting angle. Its purpose is to avoid the area which is vulnerable to the X-ray radiation. The local tomography is to reduce the total radiation dose by only scanning the region of interest for image reconstruction. In this paper we consider the scanning scheme, and incorporate the local tomography technique with the gantry-tilted helical multi-slice CT. The image degradation problem caused by gantry tilting is studied, and a new error correction method is proposed to deal with this problem in the local CT. Computer simulation shows that the proposed method can enhance the local imaging performance in terms of image sharpness and artifacts reduction.

  5. NASA Now: Engineering Design: Tilt Rotors, Aircraft of the Future

    NASA Video Gallery

    Meet Carl Russell, a research aerospace engineer who is working on developing new innovations for air travel. Russell discusses how tilt rotors work, including a demonstration on how rotors use Ber...

  6. Effect of beam quality on tilt measurement using cyclic interferometer

    NASA Astrophysics Data System (ADS)

    Pretheesh Kumar, V. C.; Ganesan, A. R.; Joenathan, C.; Somasundaram, U.

    2016-08-01

    Accurate measurement of angles is extremely important in various metrological applications. Interferometry has always been an excellent technique for accurate measurements. Several methods have been proposed for accurate tilt measurement using interferometric techniques. Almost all of them use the Michelson configuration which is extremely sensitive to environmental vibrations and turbulences. We know that a cyclic interferometer is extremely stable. Even though it is not sensitive to displacement changes, it is twice sensitive to tilt compared to that of a Michelson interferometer. We have enhanced the sensitivity to measure tilt using multiple reflections in a cyclic interferometer. Since the input beam is collimated, we have studied the effect of aberration of the input beam on the accuracy of tilt measurement. Experimental results on this study are presented in this paper.

  7. Modulation of soleus H reflex by lateral tilting in man.

    PubMed

    Aiello, I; Rosati, G; Sau, G F; Cacciotto, R; Lentinu, M E; Tidore, B; Traccis, S

    1992-04-01

    Static vestibular influences on extensor tone of the lower limbs in man were studied by analyzing the changes in right soleus H-reflex (RSHR) area in relation to lateral tiltings. Eight normal adult volunteers were tested in an experimental situation designed to minimize all afferent inputs, except the vestibular ones. Each subject was seated on a chair which could be tilted laterally from the vertical to both sides. Lateral tiltings were applied at a random order from the vertical (0 degree, control position) to 4 degrees, 8 degrees, 12 degrees, 16 degrees, and 20 degrees of both sides (test positions). The results showed inhibition in SHR area of the leg ipsilateral to the tilting and facilitation of the contralateral SHR. These data indicate that, in man, as in the decerebrate cat, tonic labyrinth reflexes act asymmetrically and that, in static condition, the vestibular system modulates muscle tone of the lower limbs adequately to counteract lateral perturbation of upright position.

  8. Enthalpic Effects of Chain Length and Unsaturation on Water Permeability across Droplet Bilayers of Homologous Monoglycerides.

    PubMed

    Lopez, Maria; Evangelista, Sue Ellen; Morales, Melissa; Lee, Sunghee

    2017-01-31

    A deeper understanding of unassisted passive transport processes can better delineate basic lipid dynamics in biological membranes. A droplet interface bilayer (DIB) is made by contacting two aqueous droplets covered with a lipid monolayer, and has increasingly been employed as a model artificial biological membrane. In this study, we have investigated the effect of acyl chain structure of amphiphilic monoglycerides on the osmotic permeability of water across DIB membranes composed of these monoglycerides, where the acyl chain length (C14-C24), number of double bonds (1-4), and the position of double bond are varied systematically along the acyl chains. Both permeability values and activation energies have been extracted for water transport across a lipid bilayer formed of a homologous series of lipids, allowing us to make ready comparisons between the different lipids and potentially better elucidate the contributions that molecular motifs make to the permeation process.

  9. ACYL-ACYL CARRIER PROTEIN DESATURASE2 and 3 Are Responsible for Making Omega-7 Fatty Acids in the Arabidopsis Aleurone1[OPEN

    PubMed Central

    Bryant, Fiona M.; Munoz-Azcarate, Olaya; Kurup, Smita; Eastmond, Peter J.

    2016-01-01

    Omega-7 monounsaturated fatty acids (ω-7s) are specifically enriched in the aleurone of Arabidopsis (Arabidopsis thaliana) seeds. We found significant natural variation in seed ω-7 content and used a Multiparent Advanced Generation Inter-Cross population to fine-map a major quantitative trait loci to a region containing ACYL-ACYL CARRIER PROTEIN DESATURASE1 (AAD1) and AAD3. We found that AAD3 expression is localized to the aleurone where mutants show an approximately 50% reduction in ω-7 content. By contrast, AAD1 is localized to the embryo where mutants show a small reduction in ω-9 content. Enzymatic analysis has previously shown that AAD family members possess both stearoyl- and palmitoyl-ACP Δ9 desaturase activity, including the predominant isoform SUPPRESSOR OF SALICYLIC ACID INSENSITIVE2. However, aad3 ssi2 aleurone contained the same amount of ω-7s as aad3. Within the AAD family, AAD3 shares the highest degree of sequence similarity with AAD2 and AAD4. Mutant analysis showed that AAD2 also contributes to ω-7 production in the aleurone, and aad3 aad2 exhibits an approximately 85% reduction in ω-7s. Mutant analysis also showed that FATTY ACID ELONGASE1 is required for the production of very long chain ω-7s in the aleurone. Together, these data provide genetic evidence that the ω-7 pathway proceeds via Δ9 desaturation of palmitoyl-ACP followed by elongation of the product. Interestingly, significant variation was also identified in the ω-7 content of Brassica napus aleurone, with the highest level detected being approximately 47% of total fatty acids. PMID:27462083

  10. Human acyl-CoA dehydrogenase-9 plays a novel role in the mitochondrial beta-oxidation of unsaturated fatty acids.

    PubMed

    Ensenauer, Regina; He, Miao; Willard, Jan-Marie; Goetzman, Eric S; Corydon, Thomas J; Vandahl, Brian B; Mohsen, Al-Walid; Isaya, Grazia; Vockley, Jerry

    2005-09-16

    Unsaturated fatty acids play an important role in the prevention of human diseases such as diabetes, obesity, cancer, and neurodegeneration. However, their oxidation in vivo by acyl-CoA dehydrogenases (ACADs) that catalyze the first step of each cycle of mitochondrial fatty acid beta-oxidation is not entirely understood. Recently, a novel ACAD (ACAD-9) of unknown function that is highly homologous to human very-long-chain acyl-CoA dehydrogenase was identified by large-scale random sequencing. To characterize its enzymatic role, we have expressed ACAD-9 in Escherichia coli, purified it, and determined its pattern of substrate utilization. The N terminus of the mature form of the enzyme was identified by in vitro mitochondrial import studies of precursor protein. A 37-amino acid leader peptide was cleaved sequentially by two mitochondrial peptidases to yield a predicted molecular mass of 65 kDa for the mature subunit. Submitochondrial fractionation studies found native ACAD-9 to be associated with the mitochondrial membrane. Gel filtration analysis indicated that, like very-long-chain acyl-CoA dehydrogenase, ACAD-9 is a dimer, in contrast to the other known ACADs, which are tetramers. Purified mature ACAD-9 had maximal activity with long-chain unsaturated acyl-CoAs as substrates (C16:1-, C18:1-, C18:2-, C22:6-CoA). These results suggest a previously unrecognized role for ACAD-9 in the mitochondrial beta-oxidation of long-chain unsaturated fatty acids. Because of the substrate specificity and abundance of ACAD-9 in brain, we speculate that it may play a role in the turnover of lipid membrane unsaturated fatty acids that are essential for membrane integrity and structure.

  11. Potential O-acyl-substituted (-)-Epicatechin gallate prodrugs as inhibitors of DMBA/TPA-induced squamous cell carcinoma of skin in Swiss albino mice.

    PubMed

    Vyas, Sandeep; Manon, Benu; Vir Singh, Tej; Dev Sharma, Pritam; Sharma, Manu

    2011-04-01

    (-)-Epicatechin-3-gallate (1) is one of the principal catechins of green tea and exhibits cancer-preventive activities in various animal models. However, this compound is unstable in neutral or alkaline medium and, therefore, has a poor bioavailability. To improve its stability, O-acyl derivatives of 1 were prepared by isolating the partially purified tea catechin fraction from green tea extract and treating it with a variety of acylating agents. The resulting derivatives, compounds 2-6, were screened for their antitumor potential against 7,12-dimethylbenz[a]anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA)-induced squamous cell carcinogenesis of skin in mice. The results showed that the antitumor activity decreased with the increase in size of the chain length of the acyl groups, i.e., from compound 2, derivative with an Ac group, to compound 6, possessing a valeryl group. Moreover, the C(4) derivative with a branched acyl chain, 5, had a lower activity than the linear C(4) derivative 4. This reduction in the inhibitory activity may be due to the steric hindrance by the two Me groups. Moreover, significant increases in the protein levels analyzed by ELISA of c-Jun, p65, and p53 were observed in the skin of DMBA/TPA treated mice, whereas mice treated with 2 and DMBA/TPA had a similar expression of these transcription factors than the control mice. The prodrug potential of the O-acyl derivatives 2-6 showed that they were adequately stable to be absorbed intact from the intestine, more stable at gastric pH, and suitable for oral administration.

  12. Quantum chemical study of penicillin: Reactions after acylation

    NASA Astrophysics Data System (ADS)

    Li, Rui; Feng, Dacheng; Zhu, Feng

    The density functional theory methods were used on the model molecules of penicillin to determine the possible reactions after their acylation on ?-lactamase, and the results were compared with sulbactam we have studied. The results show that, the acylated-enzyme tetrahedral intermediate can evolves with opening of ?-lactam ring as well as the thiazole ring; the thiazole ring-open products may be formed via ?-lactam ring-open product or from tetrahedral intermediate directly. Those products, in imine or enamine form, can tautomerize via hydrogen migration. In virtue of the water-assisted, their energy barriers are obviously reduced.

  13. Which way is down? Positional distortion in the tilt illusion.

    PubMed

    Tomassini, Alessandro; Solomon, Joshua Adam; Morgan, Michael John

    2014-01-01

    Contextual information can have a huge impact on our sensory experience. The tilt illusion is a classic example of contextual influence exerted by an oriented surround on a target's perceived orientation. Traditionally, the tilt illusion has been described as the outcome of inhibition between cortical neurons with adjacent receptive fields and a similar preference for orientation. An alternative explanation is that tilted contexts could produce a re-calibration of the subjective frame of reference. Although the distinction is subtle, only the latter model makes clear predictions for unoriented stimuli. In the present study, we tested one such prediction by asking four naive subjects to estimate three positions (4, 6, and 8 o'clock) on an imaginary clock face within a tilted surround. To indicate their estimates, they used either an unoriented dot or a line segment, with one endpoint at fixation in the middle of the surround. The surround's tilt was randomly chosen from a set of orientations (± 75°, ± 65°, ± 55°, ± 45°, ± 35°, ± 25°, ± 15°, ± 5° with respect to vertical) across trials. Our results showed systematic biases consistent with the tilt illusion in both conditions. Biases were largest when observers attempted to estimate the 4 and 8 o'clock positions, but there was no significant difference between data gathered with the dot and data gathered with the line segment. A control experiment confirmed that biases were better accounted for by a local coordinate shift than to torsional eye movements induced by the tilted context. This finding supports the idea that tilted contexts distort perceived positions as well as perceived orientations and cannot be readily explained by lateral interactions between orientation selective cells in V1.

  14. Long Baseline Tilt Meter Array to Monitor Cascadia's Slow Earthquakes

    NASA Astrophysics Data System (ADS)

    Suszek, N.; Bilham, R.; Flake, R.; Melbourne, T. I.; Miller, M.

    2004-12-01

    Five biaxial Michelson tilt meters are currently being installed in the Puget Lowlands near Seattle to monitor dynamic tilt changes accompanying episodic slow earthquakes that occur at 20-40 km depth. Each tilt meter consists of a 1-2 m deep, 500-m-long, 15-cm diameter, horizontal, half-filled water-pipe, terminated by float sensors with sub-micron water-level resolution, similar to those that have operated unattended for the past decade within the Long Valley caldera. The sensors measure water height relative to the base of a pile driven to 10 m depth. A wide-body LVDT attached to this pile outside the reservoir, senses the motion of the core attached to the float within. The voltage indicating the position of the core is sampled 16 times a second, and digitally filtered before transmission via radio modem for storage as 1-minute samples in a remote computer. The computer gathers 16-bit water height, vault temperature, air pressure and various housekeeping data once per minute using remote telemetry. Installed during 2004, the first of the tilt meters, installed in 2004, float sensors at each end, and one in the center of each pipe, permit us to examine tilt signal coherence and local noise. Each adjacent pair of sensors has a tilt resolution of 2e-9 and a range of 8 microradians. We anticipate tilt signals with durations of 0.3-30 days, and amplitudes of less than 0.1 microradian associated with slow earthquakes. Anticipated noise levels in the tilt meters are 10-1000 times lower that these expected signals, similar to or better than signal-to-noise levels from planned strain meters of the PBO array.

  15. On the determination of fiber tilt angles in fiber diffraction.

    PubMed

    Stribeck, Norbert

    2009-01-01

    The common digital method that is used to eliminate the effect of fiber tilt from fiber diffraction patterns is based on an approximation given by Franklin & Gosling [Acta Cryst. (1953), 6, 678-685]. The estimate of the tilt angle is iteratively optimized in the so-called ;Fraser correction'. Building on the fundamental work of Polanyi [Z. Phys. (1921), 7, 149-180], the exact solution is presented.

  16. Cloning and functional characterization of ACAD-9, a novel member of human acyl-CoA dehydrogenase family.

    PubMed

    Zhang, Jia; Zhang, Weiping; Zou, Dajin; Chen, Guoyou; Wan, Tao; Zhang, Minghui; Cao, Xuetao

    2002-10-04

    Acyl-CoA dehydrogenases (ACADs) are a family of mitochondrial enzymes catalyzing the initial rate-limiting step in the beta-oxidation of fatty acyl-CoA. The reaction provides main source of energy for human heart and skeletal muscle. Eight human ACADs have been described. Deficiency of these enzymes, especially very long-chain acyl-CoA dehydrogenase (VLCAD), usually leads to severe human organic diseases, such as sudden death in infancy, infantile cardiomyopathy (CM), hypoketotic hypoglycemia, or hepatic dysfunction. By large-scale random sequencing, we identified a novel homolog of ACADs from human dendritic cell (DC) cDNA library. It contains an open reading frame (ORF) of 1866bp, which encodes a 621 amino acid protein. It shares approximately 47% amino acid identity and 65% similarity with human VLCAD. So, the novel molecule is named as acyl-CoA dehydrogenase-9 (ACAD-9), the ninth member of ACADs. The new gene consists of 18 exons and 17 introns, and is mapped to chromosome 3q26. It contains the two signatures shared by all members of the ACADs. ACAD-9 mRNA is ubiquitously expressed in most normal human tissues and cancer cell lines with high level of expression in heart, skeletal muscles, brain, kidney, and liver. Enzymatic assay proved that the recombinant ACAD-9 protein has the dehydrogenase activity on palmitoyl-coenzyme A (C16:0) and stearoyl-coenzyme A (C18:0). Our results indicate that ACAD-9 is a novel member of ACADs.

  17. Quantum phase transition in dimerised spin-1/2 chains

    NASA Astrophysics Data System (ADS)

    Das, Aparajita; Bhadra, Sreeparna; Saha, Sonali

    2015-11-01

    Quantum phase transition in dimerised antiferromagnetic Heisenberg spin chain has been studied. A staircase structure in the variation of concurrence within strongly coupled pairs with that of external magnetic field has been observed indicating multiple critical (or critical like) points. Emergence of entanglement due to external magnetic field or magnetic entanglement is observed for weakly coupled spin pairs too in the same dimer chain. Though closed dimerised isotropic XXX Heisenberg chains with different dimer strengths were mainly explored, analogous studies on open chains as well as closed anisotropic (XX interaction) chains with tilted external magnetic field have also been studied.

  18. Novel approach in LC-MS/MS using MRM to generate a full profile of acyl-CoAs: discovery of acyl-dephospho-CoAs[S

    PubMed Central

    Li, Qingling; Zhang, Shenghui; Berthiaume, Jessica M.; Simons, Brigitte; Zhang, Guo-Fang

    2014-01-01

    A metabolomic approach to selectively profile all acyl-CoAs was developed using a programmed multiple reaction monitoring (MRM) method in LC-MS/MS and was employed in the analysis of various rat organs. The programmed MRM method possessed 300 mass ion transitions with the mass difference of 507 between precursor ion (Q1) and product ion (Q3), and the precursor ion started from m/z 768 and progressively increased one mass unit at each step. Acyl-dephospho-CoAs resulting from the dephosphorylation of acyl-CoAs were identified by accurate MS and fragmentation. Acyl-dephospho-CoAs were also quantitatively scanned by the MRM method with the mass difference of 427 between Q1 and Q3 mass ions. Acyl-CoAs and dephospho-CoAs were assayed with limits of detection ranging from 2 to 133 nM. The accuracy of the method was demonstrated by assaying a range of concentrations of spiked acyl-CoAs with the results of 80–114%. The distribution of acyl-CoAs reflects the metabolic status of each organ. The physiological role of dephosphorylation of acyl-CoAs remains to be further characterized. The methodology described herein provides a novel strategy in metabolomic studies to quantitatively and qualitatively profile all potential acyl-CoAs and acyl-dephospho-CoAs. PMID:24367045

  19. Copper(II)/amine synergistically catalyzed enantioselective alkylation of cyclic N-acyl hemiaminals with aldehydes.

    PubMed

    Sun, Shutao; Mao, Ying; Lou, Hongxiang; Liu, Lei

    2015-07-07

    The first catalytic asymmetric alkylation of N-acyl quinoliniums with aldehydes has been described. A copper/amine synergistic catalytic system has been developed, allowing the addition of functionalized aldehydes to a wide range of electronically varied N-acyl quinoliniums in good yields with excellent enantiocontrol. The synergistic catalytic system was also effective for N-acyl dihydroisoquinoliniums and β-caboliniums, demonstrating the general applicability of the protocol in the enantioselective alkylation of diverse cyclic N-acyl hemiaminals.

  20. Age, splanchnic vasoconstriction, and heat stress during tilting

    NASA Technical Reports Server (NTRS)

    Minson, C. T.; Wladkowski, S. L.; Pawelczyk, J. A.; Kenney, W. L.

    1999-01-01

    During upright tilting, blood is translocated to the dependent veins of the legs and compensatory circulatory adjustments are necessary to maintain arterial pressure. For examination of the effect of age on these responses, seven young (23 +/- 1 yr) and seven older (70 +/- 3 yr) men were head-up tilted to 60 degrees in a thermoneutral condition and during passive heating with water-perfused suits. Measurements included heart rate (HR), cardiac output (Qc; acetylene rebreathing technique), central venous pressure (CVP), blood pressures, forearm blood flow (venous occlusion plethysmography), splanchnic and renal blood flows (indocyanine green and p-aminohippurate clearance), and esophageal and mean skin temperatures. In response to tilting in the thermoneutral condition, CVP and stroke volume decreased to a greater extent in the young men, but HR increased more, such that the fall in Qc was similar between the two groups in the upright posture. The rise in splanchnic vascular resistance (SVR) was greater in the older men, but the young men increased forearm vascular resistance (FVR) to a greater extent than the older men. The fall in Qc during combined heat stress and tilting was greater in the young compared with older men. Only four of the young men versus six of the older men were able to finish the second tilt without becoming presyncopal. In summary, the older men relied on a greater increase in SVR to compensate for a reduced ability to constrict the skin and muscle circulations (as determined by changes in FVR) during head-up tilting.

  1. Calculation of farfield distortion for a tilted-facet SOA

    SciTech Connect

    Ratowsky, R.P.; Dijaili, S.; Walker, J.; Patterson, F.; Kallman, J.; Deri, R.

    1996-04-01

    Semiconductor optical amplifiers (SOAs) are very important elements for telecommunications, computer communications, and signal processing applications. For stable, low noise operation, the modal reflection into the guided SOA mode must be minimized; modal reflectivity typically has to be kept below about {minus}40 dB. This can be accomplished by antireflection (AR) coatings, or by tilting of the SOA end facet. The latter approach has been vigorously pursued recently, because effective AR coatings require very high tolerances and have polarization-dependent reflectivities. Consequently, there has been a great deal of theoretical effort aimed at calculating the modal reflectivity from tilted interfaces, using a variety of approaches. However, there has been little attention directed toward calculating the transmitted field of a tilted-facet SOA. This is a problem of considerable importance, because the coupling of the SOA light to an element such as an optical fiber depends critically on the field distribution at the entrance plane to the fiber. Moreover, experimental measurements of the farfield of tilted-facet SOAs have revealed a curious crescent-shaped intensity distribution. To improve coupling efficiency it is important to understand to what extent this phenomenon is due to the SOA modal field distribution and to what extent it is due to the tilted interface. The authors explain the crescent-shaped farfield intensity distribution of tilted-facet SOAs using vector wave optics, and discuss implications for coupling to other optical elements.

  2. Three dimensional eye movements of squirrel monkeys following postrotatory tilt

    NASA Technical Reports Server (NTRS)

    Merfeld, D. M.; Young, L. R.; Paige, G. D.; Tomko, D. L.

    1993-01-01

    Three-dimensional squirrel monkey eye movements were recorded during and immediately following rotation around an earth-vertical yaw axis (160 degrees/s steady state, 100 degrees/s2 acceleration and deceleration). To study interactions between the horizontal angular vestibulo-ocular reflex (VOR) and head orientation, postrotatory VOR alignment was changed relative to gravity by tilting the head out of the horizontal plane (pitch or roll tilt between 15 degrees and 90 degrees) immediately after cessation of motion. Results showed that in addition to post rotatory horizontal nystagmus, vertical nystagmus followed tilts to the left or right (roll), and torsional nystagmus followed forward or backward (pitch) tilts. When the time course and spatial orientation of eye velocity were considered in three dimensions, the axis of eye rotation always shifted toward alignment with gravity, and the postrotatory horizontal VOR decay was accelerated by the tilts. These phenomena may reflect a neural process that resolves the sensory conflict induced by this postrotatory tilt paradigm.

  3. Tilted hexagonal post arrays: DNA electrophoresis in anisotropic media.

    PubMed

    Chen, Zhen; Dorfman, Kevin D

    2014-02-01

    Using Brownian dynamics simulations, we show that DNA electrophoresis in a hexagonal array of micron-sized posts changes qualitatively when the applied electric field vector is not coincident with the lattice vectors of the array. DNA electrophoresis in such "tilted" post arrays is superior to the standard "un-tilted" approach; while the time required to achieve a resolution of unity in a tilted post array is similar to an un-tilted array at a low-electric field strengths, this time (i) decreases exponentially with electric field strength in a tilted array and (ii) increases exponentially with electric field strength in an un-tilted array. Although the DNA dynamics in a post array are complicated, the electrophoretic mobility results indicate that the "free path," i.e. the average distance of ballistic trajectories of point-sized particles launched from random positions in the unit cell until they intersect the next post, is a useful proxy for the detailed DNA trajectories. The analysis of the free path reveals a fundamental connection between anisotropy of the medium and DNA transport therein that goes beyond simply improving the separation device.

  4. Skin cooling maintains cerebral blood flow velocity and orthostatic tolerance during tilting in heated humans

    NASA Technical Reports Server (NTRS)

    Wilson, Thad E.; Cui, Jian; Zhang, Rong; Witkowski, Sarah; Crandall, Craig G.

    2002-01-01

    Orthostatic tolerance is reduced in the heat-stressed human. The purpose of this project was to identify whether skin-surface cooling improves orthostatic tolerance. Nine subjects were exposed to 10 min of 60 degrees head-up tilting in each of four conditions: normothermia (NT-tilt), heat stress (HT-tilt), normothermia plus skin-surface cooling 1 min before and throughout tilting (NT-tilt(cool)), and heat stress plus skin-surface cooling 1 min before and throughout tilting (HT-tilt(cool)). Heating and cooling were accomplished by perfusing 46 and 15 degrees C water, respectively, though a tube-lined suit worn by each subject. During HT-tilt, four of nine subjects developed presyncopal symptoms resulting in the termination of the tilt test. In contrast, no subject experienced presyncopal symptoms during NT-tilt, NT-tilt(cool), or HT-tilt(cool). During the HT-tilt procedure, mean arterial blood pressure (MAP) and cerebral blood flow velocity (CBFV) decreased. However, during HT-tilt(cool), MAP, total peripheral resistance, and CBFV were significantly greater relative to HT-tilt (all P < 0.01). No differences were observed in calculated cerebral vascular resistance between the four conditions. These data suggest that skin-surface cooling prevents the fall in CBFV during upright tilting and improves orthostatic tolerance, presumably via maintenance of MAP. Hence, skin-surface cooling may be a potent countermeasure to protect against orthostatic intolerance observed in heat-stressed humans.

  5. Site-directed mutants, at position 166, of RTEM-1 beta-lactamase that form a stable acyl-enzyme intermediate with penicillin.

    PubMed

    Adachi, H; Ohta, T; Matsuzawa, H

    1991-02-15

    Class A beta-lactamases are known to hydrolyze substrates through a Ser70-linked acyl-enzyme intermediate, although the detailed mechanism remains unknown. On the basis of the tertiary structure of the active site, the role of Glu166 of class A enzymes was investigated by replacing the residue in RTEM-1 beta-lactamase with Ala, Asp, Gln, or Asn. All the mutants, in contrast to the wild-type, accumulated a covalent complex with benzylpenicillin which corresponds to an acyl-enzyme intermediate. For the Asp mutant, the complex decayed slowly and the hydrolytic activity was slightly retained both in vivo and in vitro. In contrast, the other mutants lost the hydrolytic activity completely and their complexes were stable. These results indicate that the side-chain carboxylate of Glu166 acts as a special catalyst for deacylation. Residues for deacylation have not been identified in other acyl enzymes, such as serine proteases and class C beta-lactamases. Furthermore, the acyl-enzyme intermediates obtained are so stable that they are considered to be ideal materials for crystallographic studies for elucidating the catalytic mechanism in more detail. In addition, the mutants can more easily form inclusion bodies than the wild-type, when they are produced in a large amount, suggesting that the residue also plays an important role in proper folding of the enzyme.

  6. The Endoplasmic Reticulum-Associated Maize GL8 Protein Is a Component of the Acyl-Coenzyme A Elongase Involved in the Production of Cuticular Waxes1

    PubMed Central

    Xu, Xiaojie; Dietrich, Charles R.; Lessire, Rene; Nikolau, Basil J.; Schnable, Patrick S.

    2002-01-01

    The gl8 gene is required for the normal accumulation of cuticular waxes on maize (Zea mays) seedling leaves. The predicted GL8 protein exhibits significant sequence similarity to a class of enzymes that catalyze the reduction of a ketone group to a hydroxyl group. Polyclonal antibodies raised against the recombinant Escherichia coli-expressed GL8 protein were used to investigate the function of this protein in planta. Subcellular fractionation experiments indicate that the GL8 protein is associated with the endoplasmic reticulum membranes. Furthermore, polyclonal antibodies raised against the partially purified leek (Allium porrum) microsomal acyl-coenzyme A (CoA) elongase can react with the E. coli-expressed GL8 protein. In addition, anti-GL8 immunoglobulin G inhibited the in vitro elongation of stearoyl-CoA by leek and maize microsomal acyl-CoA elongase. In combination, these findings indicate that the GL8 protein is a component of the acyl-CoA elongase. In addition, the finding that anti-GL8 immunoglobulin G did not significantly inhibit the 3-ketoacyl-CoA synthase, 3-ketoacyl-CoA dehydrase, and (E) 2,3-enoyl-CoA reductase partial reactions of leek or maize acyl-CoA elongase lends further support to our previous hypothesis that the GL8 protein functions as a β-ketoacyl reductase during the elongation of very long-chain fatty acids required for the production of cuticular waxes. PMID:11891248

  7. One-Step Conversion of Methyl Ketones to Acyl Chlorides.

    PubMed

    Zaragoza, Florencio

    2015-10-16

    Treatment of aromatic and heteroaromatic methyl ketones with sulfur monochloride and catalytic amounts of pyridine in refluxing chlorobenzene leads to the formation of acyl chlorides. Both electron-rich and electron-poor aryl methyl ketones can be used as starting materials. The resulting C1-byproduct depends on the precise reaction conditions chosen.

  8. Lubricity characteristics of seed oils modified by acylation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chemically modified seed oils via acylation of epoxidized and polyhydroxylated derivatives were investigated for their potential as candidates for lubrication. The native oil was preliminarily epoxidized and ring-opened in a one-pot reaction using formic acid-H2O2 followed by aqueous HCl treatment t...

  9. Mechanistic studies of malonic acid-mediated in situ acylation.

    PubMed

    Chandra, Koushik; Naoum, Johnny N; Roy, Tapta Kanchan; Gilon, Chaim; Gerber, R Benny; Friedler, Assaf

    2015-09-01

    We have previously introduced an easy to perform, cost-effective and highly efficient acetylation technique for solid phase synthesis (SPPS). Malonic acid is used as a precursor and the reaction proceeds via a reactive ketene that acetylates the target amine. Here we present a detailed mechanistic study of the malonic acid-mediated acylation. The influence of reaction conditions, peptide sequence and reagents was systematically studied. Our results show that the methodology can be successfully applied to different types of peptides and nonpeptidic molecules irrespective of their structure, sequence, or conformation. Using alkyl, phenyl, and benzyl malonic acid, we synthesized various acyl peptides with almost quantitative yields. The ketenes obtained from the different malonic acid derived precursors were characterized by in situ (1) H-NMR. The reaction proceeded in short reaction times and resulted in excellent yields when using uronium-based coupling agents, DIPEA as a base, DMF/DMSO/NMP as solvents, Rink amide/Wang/Merrifield resins, temperature of 20°C, pH 8-12 and 5 min preactivation at inert atmosphere. The reaction was unaffected by Lewis acids, transition metal ions, surfactants, or salt. DFT studies support the kinetically favorable concerted mechanism for CO2 and ketene formation that leads to the thermodynamically stable acylated products. We conclude that the malonic acid-mediated acylation is a general method applicable to various target molecules.

  10. Human perceptual overestimation of whole body roll tilt in hypergravity

    PubMed Central

    Newman, Michael C.; Oman, Charles M.; Merfeld, Daniel M.; Young, Laurence R.

    2014-01-01

    Hypergravity provides a unique