Biotransformation of nitroso aromatic compounds and 2-oxo acids to N-hydroxy-N-arylacylamides by thiamine-dependent enzymes in rat liver.

PubMed

Yoshioka, T; Uematsu, T

1998-07-01

The formation of N-hydroxy-N-arylacylamides from nitroso aromatic compounds and 2-oxo acids was investigated using rat liver subcellular fractions. Activities were found in both mitochondria and cytosol, except for activities for phenylpyruvate and glyoxylate; the former did not produce N-hydroxy-N-phenylphenylacetamide and the latter nonenzymatically produced N-hydroxy-N-phenylformamide with nitrosobenzene (NOB). The cytosolic activity of N-hydroxy-N-phenylglycolamide formation was indicated to be due to transketolase, which utilized hydroxypyruvate as a glycolic aldehyde donor to NOB. With mitochondria, 2-oxo acids (including hydroxypyruvate) served as substrates for the biotransformation of NOB to the corresponding N-hydroxy-N-phenylacylamides. The substrate preference was 2-oxobutyrate > pyruvate > 2-oxoisovalerate > 2-oxoisocaproate > 2-oxovalerate > 2-oxo-3-methylvalerate, judging from Vmax/half-saturating concentration for mitochondria values. The half-saturating concentrations for NOB were nearly constant. The mitochondrial activity was due to pyruvate dehydrogenase complex and branched-chain 2-oxo acid dehydrogenase complex (BCDHC). By using partially purified BCDHC, pyruvate and 2-oxobutyrate were found to be common substrates for both of the enzymes, and 2-oxoisovalerate was shown to be the most effective substrate for BCDHC. Analysis by the Taft equation indicated that the polar effects, rather than the steric effects, of the alkyl groups of 2-oxo acids are important for BCDHC-catalyzed formation of N-hydroxy-N-phenylacylamides. A positive Hammett constant obtained for the formation of N-hydroxy-N-arylisobutyramides indicates that an electron-withdrawing substituent makes the nitroso compounds susceptible to BCDHC-catalyzed biotransformation.

CTEPP STANDARD OPERATING PROCEDURE FOR EXTRACTING AND PREPARING URINE SAMPLES FOR ANALYSIS OF HYDROXY POLYCYCLIC AROMATIC HYDROCARBONS, PENTACHLOROPHENOL AND 2,4-D (SOP-5.21)

EPA Science Inventory

The method for extracting and preparing urine samples for analysis of hydroxy-polycyclic aromatic hydrocarbons, pentachlorophenol and 2,4-D is summarized in this SOP. It covers the extraction, concentration and methylation of samples that are to be analyzed by gas chromatography/...

Strong CH/O interactions between polycyclic aromatic hydrocarbons and water: Influence of aromatic system size.

PubMed

Veljković, Dušan Ž

2018-03-01

Energies of CH/O interactions between water molecule and polycyclic aromatic hydrocarbons with a different number of aromatic rings were calculated using ab initio calculations at MP2/cc-PVTZ level. Results show that an additional aromatic ring in structure of polycyclic aromatic hydrocarbons significantly strengthens CH/O interactions. Calculated interaction energies in optimized structures of the most stable tetracene/water complex is -2.27 kcal/mol, anthracene/water is -2.13 kcal/mol and naphthalene/water is -1.97 kcal/mol. These interactions are stronger than CH/O contacts in benzene/water complex (-1.44 kcal/mol) while CH/O contacts in tetracene/water complex are even stronger than CH/O contacts in pyridine/water complexes (-2.21 kcal/mol). Electrostatic potential maps for different polycyclic aromatic hydrocarbons were calculated and used to explain trends in the energies of interactions. Copyright © 2017 Elsevier Inc. All rights reserved.

Lanthanum Tricyanide-Catalyzed Acyl Silane-Ketone Benzoin Additions and Kinetic Resolution of Resultant α-Silyloxyketones

PubMed Central

Tarr, James C.

2010-01-01

We report the full account of our efforts on the lanthanum tricyanide-catalyzed acyl silane-ketone benzoin reaction. The reaction exhibits a wide scope in both acyl silane (aryl, alkyl) and ketone (aryl-alkyl, alkyl-alkyl, aryl-aryl, alkenyl-alkyl, alkynyl-alkyl) coupling partners. The diastereoselectivity of the reaction has been examined in both cyclic and acyclic systems. Cyclohexanones give products arising from equatorial attack by the acyl silane. The diastereoselectivity of acyl silane addition to acyclic α-hydroxy ketones can be controlled by varying the protecting group to obtain either Felkin-Ahn or chelation control. The resultant α-silyloxyketone products can be resolved with selectivity factors from 10 to 15 by subjecting racemic ketone benzoin products to CBS reduction. PMID:20392127

Lanthanum tricyanide-catalyzed acyl silane-ketone benzoin additions and kinetic resolution of resultant alpha-silyloxyketones.

PubMed

Tarr, James C; Johnson, Jeffrey S

2010-05-21

We report the full account of our efforts on the lanthanum tricyanide-catalyzed acyl silane-ketone benzoin reaction. The reaction exhibits a wide scope in both acyl silane (aryl, alkyl) and ketone (aryl-alkyl, alkyl-alkyl, aryl-aryl, alkenyl-alkyl, alkynyl-alkyl) coupling partners. The diastereoselectivity of the reaction has been examined in both cyclic and acyclic systems. Cyclohexanones give products arising from equatorial attack by the acyl silane. The diastereoselectivity of acyl silane addition to acyclic alpha-hydroxy ketones can be controlled by varying the protecting group to obtain either Felkin-Ahn or chelation control. The resultant alpha-silyloxyketone products can be resolved with selectivity factors from 10 to 15 by subjecting racemic ketone benzoin products to CBS reduction.

Aromatization of n-hexane over ZnO/H-ZSM-5 catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kanai, J.; Kawata, N.

The mechanism of transformation of n-hexane into aromatics over ZnO/H-ZSM-5 catalyst has been investigated. The yields of aromatics in the transformation of n-hexane over H-ZSM-5 are enhanced by mechanical mixing of ZnO as well as by ion exchange or impregnation of zinc cation. It is concluded that aromatization of n-hexane over ZnO/H-ZSM-5 is a bifunctional reaction, and that ZnO as well as H-ZSM-5 takes part both in the activation of n-hexane and in the aromatization of lower olefins. By contrasting the conversion of n-hexane with that of 1-hexane, it is found that aromatization of n-hexane over ZnO/H-ZSM-5 involves both themore » dehydrogenation of n-hexane into hexene and that of the oligomerized products into aromatics. It is proposed that ZnO catalyzes the dehydrogenation of n-hexane into hexene and of the oligomerized products into aromatics.« less

Rapid Identification of unstable acyl glucoside flavonoids of Oxytropis racemosa Turcz by high-performance liquid chromatography-diode array detection-electrospray ionisation/multi-stage mass spectrometry.

PubMed

Song, Shuang; Zheng, Xiu-Ping; Liu, Wei-Dong; Du, Rui-Fang; Feng, Zi-Ming; Zhang, Pei-Cheng; Bi, Li-Fu

2013-02-01

Oxytropis racemosa Turcz is an important minority medicine that is used mainly to improve children's indigestion, especially in inner Mongolia and Tibet. Previous studies indicated that the characteristic constituents of this plant are acylated flavonoids. Rapidly identify the characteristic chemical constituents of O. racemosa by high-performance liquid chromatography-diode array detection-electrospray ionisation/multi-stage mass spectrometry (HPLC-DAD-ESI/MS(n) ) and suggest a useful method to control the quality of this medicinal plant. In the HPLC fingerprint, 32 flavonoids were tentatively identified by a detailed analysis of their mass spectra, UV spectra and retention times. Furthermore, 13 flavonoids were confirmed by comparison with previously isolated compounds obtained from O. racemosa. In total, 32 flavonoids, including 13 flavonoids with 3-hydroxy-3-methylglutaric acid (HMG) moieties and four flavonoids with 3-malonyl moieties, were identified in the extract of O. racemosa. Among the compounds identified, 10 were characterised as new compounds for their particular acylated sugar moieties. The method described is effective for obtaining a comprehensive phytochemical profile of plants containing unstable acylated flavonoids. The method is also useful for constructing the chromatographic fingerprint of the minority medicine -O. racemosa Turcz for quality control. Copyright © 2012 John Wiley & Sons, Ltd.

Arabidopsis Deficient in Cutin Ferulate encodes a transferase required for feruloylation of ω-hydroxy fatty acids in cutin polyester.

PubMed

Rautengarten, Carsten; Ebert, Berit; Ouellet, Mario; Nafisi, Majse; Baidoo, Edward E K; Benke, Peter; Stranne, Maria; Mukhopadhyay, Aindrila; Keasling, Jay D; Sakuragi, Yumiko; Scheller, Henrik Vibe

2012-02-01

The cuticle is a complex aliphatic polymeric layer connected to the cell wall and covers surfaces of all aerial plant organs. The cuticle prevents nonstomatal water loss, regulates gas exchange, and acts as a barrier against pathogen infection. The cuticle is synthesized by epidermal cells and predominantly consists of an aliphatic polymer matrix (cutin) and intracuticular and epicuticular waxes. Cutin monomers are primarily C(16) and C(18) unsubstituted, ω-hydroxy, and α,ω-dicarboxylic fatty acids. Phenolics such as ferulate and p-coumarate esters also contribute to a minor extent to the cutin polymer. Here, we present the characterization of a novel acyl-coenzyme A (CoA)-dependent acyl-transferase that is encoded by a gene designated Deficient in Cutin Ferulate (DCF). The DCF protein is responsible for the feruloylation of ω-hydroxy fatty acids incorporated into the cutin polymer of aerial Arabidopsis (Arabidopsis thaliana) organs. The enzyme specifically transfers hydroxycinnamic acids using ω-hydroxy fatty acids as acyl acceptors and hydroxycinnamoyl-CoAs, preferentially feruloyl-CoA and sinapoyl-CoA, as acyl donors in vitro. Arabidopsis mutant lines carrying DCF loss-of-function alleles are devoid of rosette leaf cutin ferulate and exhibit a 50% reduction in ferulic acid content in stem insoluble residues. DCF is specifically expressed in the epidermis throughout all green Arabidopsis organs. The DCF protein localizes to the cytosol, suggesting that the feruloylation of cutin monomers takes place in the cytoplasm.

Aromaticity of benzene derivatives: an exploration of the Cambridge Structural Database.

PubMed

Majerz, Irena; Dziembowska, Teresa

2018-04-01

The harmonic oscillator model of aromaticity (HOMA) index, one of the most popular aromaticity indices for solid-state benzene rings in the Cambridge Structural Database (CSD), has been analyzed. The histograms of HOMA for benzene, for benzene derivatives with one formyl, nitro, amino or hydroxy group as well as the histograms for the derivatives with two formyl, nitro, amino or hydroxy groups in ortho, meta and para positions were investigated. The majority of the substituted benzene derivatives in the CSD are characterized by a high value of HOMA, indicating fully aromatic character; however, the distribution of the HOMA value from 1 to about 0 indicates decreasing aromaticity down to non-aromatic character. Among the benzene derivatives investigated, a significant decrease in aromaticity can be related to compounds with diamino and dinitro groups in the meta position.

Synthesis of Polyheterocyclic Pyrrolo[3,4-b]pyridin-5-ones via a One-Pot (Ugi-3CR/aza Diels-Alder/N-acylation/aromatization/SN2) Process. A Suitable Alternative towards Novel Aza-Analogues of Falipamil.

PubMed

Zamudio-Medina, Angel; García-González, Ailyn N; Herrera-Carrillo, Genesis K; Zárate-Zárate, Daniel; Benavides-Macías, Adriana; Tamariz, Joaquín; Ibarra, Ilich A; Islas-Jácome, Alejandro; González-Zamora, Eduardo

2018-03-27

We describe the one-pot synthesis of twenty polyheterocyclic pyrrolo[3,4- b ]pyridin-5-ones via a cascade process (Ugi-3CR/aza Diels-Alder/ N -acylation/aromatization) in 20 to 95% overall yields, as well as four pharmacologically promising analogues via an improved cascade process (Ugi-3CR/aza Diels-Alder/ N -acylation/aromatization/S N 2): two piperazine-linked pyrrolo[3,4- b ]pyridin-5-ones in 33 and 34%, and a couple of Falipamil aza-analogues in 30 and 35% overall yields. It is worth highlighting the good substrate scope found, because final products are furnished with alkyl, aryl, and heterocyclic substituents. The use of chain-ring tautomerizable isocyanides (as key reagents for the Ugi-type three component reaction) allowed for a rapid and efficient assembly of the polysubstituted oxindoles, which were used in situ toward the complex products, conferring features like robustness, sustainability, and the one-pot approach to this synthetic methodology.

An Unusual Fatty Acyl:Adenylate Ligase (FAAL)-Acyl Carrier Protein (ACP) Didomain in Ambruticin Biosynthesis.

PubMed

Hemmerling, Franziska; Lebe, Karen E; Wunderlich, Johannes; Hahn, Frank

2018-03-08

The divinylcyclopropane (DVC) fragment of the ambruticins is proposed to be formed by a unique polyene cyclisation mechanism, in which the unusual didomain AmbG plays a key role. It is proposed to activate the branched thioester carboxylic acid resulting from polyene cyclisation and to transfer it to its associated acyl carrier protein (ACP). After oxidative decarboxylation, the intermediate is channelled back into polyketide synthase (PKS) processing. AmbG was previously annotated as an adenylation-thiolation didomain with a very unusual substrate selectivity code but has not yet been biochemically studied. On the basis of sequence and homology model analysis, we reannotate AmbG as a fatty acyl:adenylate ligase (FAAL)-acyl carrier protein didomain with unusual substrate specificity. The expected adenylate-forming activity on fatty acids was confirmed by in vitro studies. AmbG also adenylates a number of structurally diverse carboxylic acids, including functionalised fatty acids and unsaturated and aromatic carboxylic acids. HPLC-MS analysis and competition experiments show that AmbG preferentially acylates its ACP with long-chain hydrophobic acids and tolerates a π system and a branch near the carboxylic acid. AmbG is the first characterised example of a FAAL-ACP didomain that is centrally located in a PKS and apparently activates a polyketidic intermediate. This is an important step towards deeper biosynthetic studies such as partial reconstitution of the ambruticin pathway to elucidate DVC formation. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Visible-light-promoted and one-pot synthesis of phenanthridines and quinolines from aldehydes and O-acyl hydroxylamine.

PubMed

An, Xiao-De; Yu, Shouyun

2015-06-05

A one-pot synthesis of phenanthridines and quinolines from commercially available or easily prepared aldehydes has been reported. O-(4-Cyanobenzoyl)hydroxylamine was utilized as the nitrogen source to generate O-acyl oximes in situ with aldehydes catalyzed by Brønsted acid. O-Acyl oximes were then subjected to visible light photoredox catalyzed cyclization via iminyl radicals to furnish aza-arenes. A variety of phenanthridines and quinolines have been prepared assisted by Brønsted acid and photocatalyst under visible light at room temperature with satisfactory yields.

Catalytic oxidation of o-aminophenols and aromatic amines by mushroom tyrosinase.

PubMed

Muñoz-Muñoz, Jose Luis; Garcia-Molina, Francisco; Garcia-Ruiz, Pedro Antonio; Varon, Ramon; Tudela, Jose; Rodriguez-Lopez, Jose N; Garcia-Canovas, Francisco

2011-12-01

The kinetics of tyrosinase acting on o-aminophenols and aromatic amines as substrates was studied. The catalytic constants of aromatic monoamines and o-diamines were both low, these results are consistent with our previous mechanism in which the slow step is the transfer of a proton by a hydroxyl to the peroxide in oxy-tyrosinase (Fenoll et al., Biochem. J. 380 (2004) 643-650). In the case of o-aminophenols, the hydroxyl group indirectly cooperates in the transfer of the proton and consequently the catalytic constants in the action of tyrosinase on these compounds are higher. In the case of aromatic monoamines, the Michaelis constants are of the same order of magnitude than for monophenols, which suggests that the monophenols bind better (higher binding constant) to the enzyme to facilitate the π-π interactions between the aromatic ring and a possible histidine of the active site. In the case of aromatic o-diamines, both the catalytic and Michaelis constants are low, the values of the catalytic constants being lower than those of the corresponding o-diphenols. The values of the Michaelis constants of the aromatic o-diamines are slightly lower than those of their corresponding o-diphenols, confirming that the aromatic o-diamines bind less well (lower binding constant) to the enzyme. Copyright © 2011 Elsevier B.V. All rights reserved.

Antimicrobial activity of 9-O-acyl- and 9-O-benzoyl-substituted berberrubines.

PubMed

Hong, S W; Kim, S H; Jeun, J A; Lee, S J; Kim, S U; Kim, J H

2000-05-01

In the course of a structure-activity relationship study on berberrubine derivatives, a series of compounds bearing 9-O-acyl-(4-6) and 9-O-benzoyl- (7) substituents was synthesized with the expectation of increasing the antimicrobial activity. One of the berberrubine derivatives, 9-lauroylberberrubine chloride was the most active against Gram-positive bacteria Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus luteus, Bacillus subtilis as well as the Gram-negative bacterium Klebsiella pneumoniae in comparison to berberine, the currently used antibiotic in clinic. This result suggested that the presence of lipophilic substituents of certain structures and sizes might be crucial for the optimal antimicrobial activity.

Method for preparation of 7-hydroxy-1,2,3,4-tetrahydroquinoline from 1,2,3,4-tetrahydroquinoline

DOEpatents

Field, G.; Hammond, P.R.

1994-02-01

Methods for the efficient preparation of 7-hydroxy-1,2,3,4-tetrahydroquinoline include a first method in which the acylation of m-aminophenol obtains a lactam which is reduced to give the desired quinoline and a second method in which tetrahydroquinoline is nitrated and hydrogenated and then hydrolyzed to obtain the desire quinoline. 7-hydroxy-1,2,3,4-tetrahydroquinoline is used in the efficient synthesis of four lasing dyes of the rhodamine class.

Method for preparation of 7-hydroxy-1,2,3,4-tetrahydroquinoline from 1,2,3,4-tetrahydroquinoline

DOEpatents

Field, George; Hammond, Peter R.

1994-01-01

Methods for the efficient preparation of 7-hydroxy-1,2,3,4-tetrahydroquinoline include a first method in which the acylation of m-aminophenol obtains a lactam which is reduced to give the desired quinoline and a second method in which tetrahydroquinoline is nitrated and hydrogenated and then hydrolyzed to obtain the desire quinoline. 7-hydroxy-1,2,3,4-tetrahydroquinoline is used in the efficient synthesis of four lasing dyes of the rhodamine class.

Arabidopsis Deficient in Cutin Ferulate Encodes a Transferase Required for Feruloylation of ω-Hydroxy Fatty Acids in Cutin Polyester1[W][OA

PubMed Central

Rautengarten, Carsten; Ebert, Berit; Ouellet, Mario; Nafisi, Majse; Baidoo, Edward E.K.; Benke, Peter; Stranne, Maria; Mukhopadhyay, Aindrila; Keasling, Jay D.; Sakuragi, Yumiko; Scheller, Henrik Vibe

2012-01-01

The cuticle is a complex aliphatic polymeric layer connected to the cell wall and covers surfaces of all aerial plant organs. The cuticle prevents nonstomatal water loss, regulates gas exchange, and acts as a barrier against pathogen infection. The cuticle is synthesized by epidermal cells and predominantly consists of an aliphatic polymer matrix (cutin) and intracuticular and epicuticular waxes. Cutin monomers are primarily C16 and C18 unsubstituted, ω-hydroxy, and α,ω-dicarboxylic fatty acids. Phenolics such as ferulate and p-coumarate esters also contribute to a minor extent to the cutin polymer. Here, we present the characterization of a novel acyl-coenzyme A (CoA)-dependent acyl-transferase that is encoded by a gene designated Deficient in Cutin Ferulate (DCF). The DCF protein is responsible for the feruloylation of ω-hydroxy fatty acids incorporated into the cutin polymer of aerial Arabidopsis (Arabidopsis thaliana) organs. The enzyme specifically transfers hydroxycinnamic acids using ω-hydroxy fatty acids as acyl acceptors and hydroxycinnamoyl-CoAs, preferentially feruloyl-CoA and sinapoyl-CoA, as acyl donors in vitro. Arabidopsis mutant lines carrying DCF loss-of-function alleles are devoid of rosette leaf cutin ferulate and exhibit a 50% reduction in ferulic acid content in stem insoluble residues. DCF is specifically expressed in the epidermis throughout all green Arabidopsis organs. The DCF protein localizes to the cytosol, suggesting that the feruloylation of cutin monomers takes place in the cytoplasm. PMID:22158675

Regioselective lipase-catalyzed synthesis of 3-o-acyl derivatives of resveratrol and study of their antioxidant properties.

PubMed

Torres, Pamela; Poveda, Ana; Jimenez-Barbero, Jesús; Ballesteros, Antonio; Plou, Francisco J

2010-01-27

One of the approaches to increasing the bioavailability of resveratrol is to protect its 3-OH phenolic group. In this work, regioselective acylation of resveratrol at 3-OH was achieved by transesterification with vinyl acetate catalyzed by immobilized lipase from Alcaligenes sp. (lipase QLG). The maximum yield of 3-O-acetylresveratrol was approximately 75%, as the lipase also catalyzes its further acetylation affording the diester 3,4'-di-O-acetylresveratrol and finally the peracetylated derivative. Long saturated and unsaturated fatty acid vinyl esters were also effective as acyl donors with similar regioselectivity. In contrast, lipase B from Candida antarctica catalyzes the acylation of the phenolic group 4'-OH with 80% yield and negligible formation of higher esters. The analysis of the antioxidant properties showed that the Trolox equivalent antioxidant capability (TEAC) values for the acetyl and stearoyl derivatives at 3-OH were, respectively, 40% and 25% referred to resveratrol. The addition of an acyl chain in the 3-OH position caused a higher loss of activity compared with that at the 4'-OH.

Mucinous (colloid) adenocarcinomas secrete distinct O-acylated forms of sialomucins: a histochemical study of gastric, colorectal and breast adenocarcinomas.

PubMed

Sáez, C; Japón, M A; Poveda, M A; Segura, D I

2001-12-01

Mucinous (colloid) adenocarcinomas represent a distinct group of tumours defined by the presence of large amounts of extracellular mucins. By using histochemical methods, we analysed mucins secreted by mucinous versus non-mucinous adenocarcinomas and looked for differential secretion profiles. Sixty-four adenocarcinomas were studied (23 colorectal, 17 gastric, and 24 breast tumours). Thirty-two tumours were of the colloid type. The following methods were applied to paraffin tissue sections: (i) Alcian blue (pH 2.5) and periodic acid-Schiff (PAS); (ii) high iron diamine and Alcian blue (pH 2.5); (iii) periodic acid borohydride, potassium hydroxide, and PAS; (iv) periodic acid-thionine Schiff, potassium hydroxide, and PAS; and (v) periodic acid-borohydride and PAS. Most adenocarcinomas secreted acidic mucins, with sialomucins predominating over sulfomucins, except for non-mucinous adenocarcinomas of the breast which showed predominant neutral mucins. All mucinous adenocarcinomas contained C9-O-acyl sialic acid as mono, di(C8,C9)-, or tri(C7,C8,C9)-O-acyl forms. Acidic mucins secreted by the majority of non-colloid adenocarcinomas consisted of non-O-acylated sialomucins. C9-O-acylation of sialic acid is a characteristic feature of mucinous adenocarcinomas and can be readily detected by histochemical methods.

40 CFR 721.10175 - 1-Propanaminium, N-(3-aminopropyl)-2-hydroxy-N,N-dimethyl-3-sulfo-, N-(C12-18 and C18-unsatd...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false 1-Propanaminium, N-(3-aminopropyl)-2... 1-Propanaminium, N-(3-aminopropyl)-2-hydroxy-N,N-dimethyl-3-sulfo-, N-(C12-18 and C18-unsatd. acyl... chemical substance identified as 1-Propanaminium, N-(3-aminopropyl)-2-hydroxy-N,N-dimethyl-3-sulfo-, N-(C12...

Enhancement of neurite outgrowth in PC12 cells stimulated with cyclic AMP and NGF by 6-acylated ascorbic acid 2-O-alpha-glucosides (6-Acyl-AA-2G), novel lipophilic ascorbate derivatives.

PubMed

Zhou, Xiaohua; Tai, Akihiro; Yamamoto, Itaru

2003-03-01

It has been shown that ascorbate (AsA) and its stable derivative, ascorbic acid 2-O-alpha-glucoside (AA-2G), do not elicit neurite outgrowth in PC12 cells. However, these ascorbates are synergistically enhanced by both dibutyryl cyclic AMP (Bt(2)cAMP)- and nerve growth factor (NGF)-induced neurite outgrowth in this model. In the present study, the effects of a series of novel lipophilic ascorbate derivatives, 6-acylated ascorbic acid 2-O-alpha-glucosides (6-Acyl-AA-2G), on neurite outgrowth induced by Bt(2)cAMP and NGF were examined in PC12 cells. We found that all the tested acylated ascorbate derivatives enhanced neurite formation induced by both agents in a dose-dependent manner. Of the 6-Acyl-AA-2G derivatives, 6-octanoyl ascorbic acid 2-O-alpha-glucoside (6-Octa-AA-2G) enhanced the Bt(2)cAMP-induced phosphorylated MAPK p44 and p42 expression. A alpha-glucosidase inhibitor, castanospermine, completely abrogated the promotion of neurite outgrowth and MAPK expression by 6-Octa-AA-2G. Addition of 6-Octa-AA-2G (0.5 mM) to PC12 cells caused a rapid and significant increase in intracellular AsA content, which reached a maximum and was maintained from 12 to 24 h after the culture. These findings suggest that 6-Acyl-AA-2G is rapidly hydrolyzed to AsA within the cell and enhances neurite differentiation through the interaction with the inducer-activated MAPK pathway.

Localization of acyl ghrelin- and des-acyl ghrelin-immunoreactive cells in the rat stomach and their responses to intragastric pH.

PubMed

Mizutani, Makoto; Atsuchi, Kaori; Asakawa, Akihiro; Matsuda, Norifumi; Fujimura, Masaki; Inui, Akio; Kato, Ikuo; Fujimiya, Mineko

2009-11-01

Acyl ghrelin has a 28-amino acid sequence with O-n-octanoyl acid modification at the serine 3 position, whereas des-acyl ghrelin has no octanoyl acid modification. Although these peptides exert different physiological functions, no previous studies have shown the different localization of acyl ghrelin and des-acyl ghrelin in the stomach. Here we have developed an antibody specific for des-acyl ghrelin that does not crossreact with acyl ghrelin. Both acyl ghrelin- and des-acyl ghrelin-immunoreactive cells were distributed in the oxyntic and antral mucosa of the rat stomach, with higher density in the antral mucosa than oxyntic mucosa. Immunofluorescence double staining showed that acyl ghrelin- and des-acyl ghrelin-positive reactions overlapped in closed-type round cells, whereas des-acyl ghrelin-positive reaction was found in open-type cells in which acyl ghrelin was negative. Acyl ghrelin-/des-acyl ghrelin-positive closed-type cells contain obestatin; on the other hand, des-acyl ghrelin-positive open-type cells contain somatostatin. We measured the release of acyl ghrelin and des-acyl ghrelin in vascularly perfused rat stomach by ELISA, and the effects of different intragastric pH levels on the release of each peptide were examined. The release of des-acyl ghrelin from the perfused stomach was greater at pH 2 than at pH 4; however, the release of acyl ghrelin was not affected by intragastric pH. The present study demonstrated the differential localization of acyl ghrelin and des-acyl ghrelin in the rat stomach and their different responses to the intragastric pH.

Gas Phase Dissociation Behavior of Acyl-Arginine Peptides.

PubMed

McGee, William M; McLuckey, Scott A

2013-11-15

The gas phase dissociation behavior of peptides containing acyl-arginine residues is investigated. These acylations are generated via a combination of ion/ion reactions between arginine-containing peptides and N -hydroxysuccinimide (NHS) esters and subsequent tandem mass spectrometry (MS/MS). Three main dissociation pathways of acylated arginine, labeled Paths 1-3, have been identified and are dependent on the acyl groups. Path 1 involves the acyl-arginine undergoing deguanidination, resulting in the loss of the acyl group and dissociation of the guanidine to generate an ornithine residue. This pathway generates selective cleavage sites based on the recently discussed "ornithine effect". Path 2 involves the coordinated losses of H 2 O and NH 3 from the acyl-arginine side chain while maintaining the acylation. We propose that Path 2 is initiated via cyclization of the δ-nitrogen of arginine and the C-terminal carbonyl carbon, resulting in rapid rearrangement from the acyl-arginine side chain and the neutral losses. Path 3 occurs when the acyl group contains α-hydrogens and is observed as a rearrangement to regenerate unmodified arginine while the acylation is lost as a ketene.

Synthesis of Acylated Xylan-Based Magnetic Fe3O4 Hydrogels and Their Application for H2O2 Detection

PubMed Central

Dai, Qing-Qing; Ren, Jun-Li; Peng, Feng; Chen, Xiao-Feng; Gao, Cun-Dian; Sun, Run-Cang

2016-01-01

Acylated xylan-based magnetic Fe3O4 nanocomposite hydrogels (ACX-MNP-gels) were prepared by fabricating Fe3O4 nanoctahedra in situ within a hydrogel matrix which was synthesized by the copolymerization of acylated xylan (ACX) with acrylamide and N-isopropylacrylamide under ultraviolet irradiation. The size of the Fe3O4 fabricated within the hydrogel matrix could be adjusted through controlling the crosslinking concentrations (C). The magnetic hydrogels showed desirable magnetic and mechanical properties, which were confirmed by XRD, Raman spectroscopy, physical property measurement system, SEM, TGA, and compression test. Moreover, the catalytic performance of the magnetic hydrogels was explored. The magnetic hydrogels (C = 7.5 wt %) presented excellent catalytic activity and provided a sensitive response to H2O2 detection even at a concentration level of 5 × 10−6 mol·L−1. This approach to preparing magnetic hydrogels loaded with Fe3O4 nanoparticles endows xylan-based hydrogels with new promising applications in biotechnology and environmental chemistry. PMID:28773811

Role of 3-Hydroxy Fatty Acid-Induced Hepatic Lipotoxicity in Acute Fatty Liver of Pregnancy

PubMed Central

Ibdah, Jamal A.

2018-01-01

Acute fatty liver of pregnancy (AFLP), a catastrophic illness for both the mother and the unborn offspring, develops in the last trimester of pregnancy with significant maternal and perinatal mortality. AFLP is also recognized as an obstetric and medical emergency. Maternal AFLP is highly associated with a fetal homozygous mutation (1528G>C) in the gene that encodes for mitochondrial long-chain hydroxy acyl-CoA dehydrogenase (LCHAD). The mutation in LCHAD results in the accumulation of 3-hydroxy fatty acids, such as 3-hydroxy myristic acid, 3-hydroxy palmitic acid and 3-hydroxy dicarboxylic acid in the placenta, which are then shunted to the maternal circulation leading to the development of acute liver injury observed in patients with AFLP. In this review, we will discuss the mechanistic role of increased 3-hydroxy fatty acid in causing lipotoxicity to the liver and in inducing oxidative stress, mitochondrial dysfunction and hepatocyte lipoapoptosis. Further, we also review the role of 3-hydroxy fatty acids in causing placental damage, pancreatic islet β-cell glucolipotoxicity, brain damage, and retinal epithelial cells lipoapoptosis in patients with LCHAD deficiency. PMID:29361796

Detecting and characterizing N-acyl-homoserine lactone signal molecules by thin-layer chromatography

PubMed Central

Shaw, Paul D.; Ping, Gao; Daly, Sean L.; Cha, Chung; Cronan, John E.; Rinehart, Kenneth L.; Farrand, Stephen K.

1997-01-01

Many Gram-negative bacteria regulate gene expression in response to their population size by sensing the level of acyl-homoserine lactone signal molecules which they produce and liberate to the environment. We have developed an assay for these signals that couples separation by thin-layer chromatography with detection using Agrobacterium tumefaciens harboring lacZ fused to a gene that is regulated by autoinduction. With the exception of N-butanoyl-l-homoserine lactone, the reporter detected acyl-homoserine lactones with 3-oxo-, 3-hydroxy-, and 3-unsubstituted side chains of all lengths tested. The intensity of the response was proportional to the amount of the signal molecule chromatographed. Each of the 3-oxo- and the 3-unsubstituted derivatives migrated with a unique mobility. Using the assay, we showed that some bacteria produce as many as five detectable signal molecules. Structures could be assigned tentatively on the basis of mobility and spot shape. The dominant species produced by Pseudomonas syringae pv. tabaci chromatographed with the properties of N-(3-oxohexanoyl)-l-homoserine lactone, a structure that was confirmed by mass spectrometry. An isolate of Pseudomonas fluorescens produced five detectable species, three of which had novel chromatographic properties. These were identified as the 3-hydroxy- forms of N-hexanoyl-, N-octanoyl-, and N-decanoyl-l-homoserine lactone. The assay can be used to screen cultures of bacteria for acyl-homoserine lactones, for quantifying the amounts of these molecules produced, and as an analytical and preparative aid in determining the structures of these signal molecules. PMID:9177164

New acylated clionasterol glycosides from Valeriana officinalis.

PubMed

Pullela, Srinivas V; Choi, Young Whan; Khan, Shabana I; Khan, Ikhlas A

2005-10-01

The chloroform extract of Valeriana officinalis led to the isolation of clionasterol-3-O-beta-D-glucopyranoside and a mixture of 6'-O-acyl-beta-D-glucosyl-clionasterols. The acyl moieties were identified as hexadecanoyl, 8 E,11 E-octadecadienoyl and 14-methylpentadecanoyl by alkaline hydrolysis followed by GC-MS analysis. The isolated compounds did not exhibit any anti-inflammatory, anticancer or cytotoxic activity when tested in a variety of in vitro cell-based assays.

Acylated flavonol tri- and tetraglycosides in the flavonoid metabolome of Cladrastis kentukea (Leguminosae).

PubMed

Kite, Geoffrey C; Rowe, Emily R; Lewis, Gwilym P; Veitch, Nigel C

2011-04-01

The foliar metabolome of Cladrastis kentukea (Leguminosae) contains a complex mixture of flavonoids including acylated derivatives of the 3-O-rhamnosyl(1→2)[rhamnosyl(1→6)]-galactosides of kaempferol and quercetin and their 7-O-rhamnosides, together with an array of non-acylated kaempferol and quercetin di-, tri- and tetraglycosides. Thirteen of the acylated flavonoids, 12 of which had not been reported previously, were characterised by spectroscopic and chemical methods. Eight of these were the four isomers of kaempferol 3-O-α-l-rhamnopyranosyl(1→2)[α-l-rhamnopyranosyl(1→6)]-(3/4-O-E/Z-p-coumaroyl-β-d-galactopyranoside) and their 7-O-α-l-rhamnopyranosides, and three were isomers of quercetin 3-O-α-l-rhamnopyranosyl(1→2)[α-l-rhamnopyranosyl(1→6)]-(3/4-O-E/Z-p-coumaroyl-β-d-galactopyranoside) - the remaining 4Z isomer was identified by LC-UV-MS analysis of a crude extract. The final two acylated flavonoids characterised by NMR were the 3E and 4E isomers of kaempferol 3-O-α-l-rhamnopyranosyl(1→2)[α-l-rhamnopyranosyl(1→6)]-(3/4-O-E-feruloyl-β-d-galactopyranoside)-7-O-α-l-rhamnopyranoside while the 3Z and 4Z isomers were again detected by LC-UV-MS. Using the observed fragmentation behaviour of the isolated compounds following a variety of MS experiments, a further 18 acylated flavonoids were given tentative structures by LC-MS analysis of a crude extract. Acylated flavonoids were absent from the flowers of C. kentukea, which contained an array of non-acylated kaempferol and quercetin glycosides. Immature fruits contained kaempferol 3-O-α-rhamnopyranosyl(1→2)[α-rhamnopyranosyl(1→6)]-β-galactopyranoside and its 7-O-α-rhamnopyranoside as the major flavonoids with acylated flavonoids, different from those in the leaves, only present as minor constituents. The presence of acylated flavonoids distinguishes the foliar flavonoid metabolome of C. kentukea from that of a closely related legume, Styphnolobium japonicum, which contains a similar

Polymorphism in 'L' shaped lipids: structure of N-, O-diacylethanolamines with mixed acyl chains.

PubMed

Tarafdar, Pradip K; Swamy, Musti J

2009-11-01

Although solid state polymorphism in lipids has been established by spectroscopic and calorimetric studies long ago, only in a few cases crystal structures of different polymorphs of the same compound have been reported, possibly due to difficulties in obtaining high quality single crystals of individual polymorphs. Recent studies show that N-, O-diacylethanolamines (DAEs) can be derived by the O-acylation of the stress-related lipids, the N-acylethanolamines under physiological conditions. In this study, two DAEs with mixed acyl chains, namely N-palmitoyl, O-octanoylethanolamine and N-palmitoyl, O-decanoylethanolamine have been synthesized and their three-dimensional structures were determined. Both the compounds were found to adopt 'L' shaped structures and exist in two polymorphic forms, alpha and beta. In the alpha form a mixed-type chain packing has been observed whereas in the beta form the chain packing is symmetric. Similar polymorphic forms are likely to exist in other 'L' shaped lipids such as 1,3-diacylglycerols and ceramides, where polymorphism has been detected earlier, but three-dimensional structures - which can give precise information about the packing at atomic resolution - have not been reported.

Effect of acyl chain length on selective biocatalytic deacylation on O-aryl glycosides and separation of anomers.

PubMed

Aggarwal, Neha; Arya, Anu; Mathur, Divya; Singh, Sukhdev; Tyagi, Abhilash; Kumar, Rajesh; Rana, Neha; Singh, Rajendra; Prasad, Ashok K

2014-04-01

It has been demonstrated that Lipozyme® TL IM (Thermomyces lanuginosus lipase immobilised on silica) can selectively deacylate the ester function involving the C-5' hydroxyl group of α-anomers over the other acyl functions of anomeric mixture of peracylated O-aryl α,β-D-ribofuranoside. The analysis of results of biocatalytic deacylation reaction revealed that the reaction time decreases with the increase in the acyl chain length from C1 to C4. The unique selectivity of Lipozyme® TL IM has been harnessed for the separation of anomeric mixture of peracylated O-aryl α,β-D-ribofuranosides, The lipase mediated selective deacylation methodology has been used for the synthesis of O-aryl α-D-ribofuranosides and O-aryl β-D-ribofuranosides in pure forms, which can be used as chromogenic substrate for the detection of pathogenic microbial parasites containing glycosidases. Copyright © 2014. Published by Elsevier Inc.

MICROBIAL METABOLISM OF AROMATIC COMPOUNDS I.

PubMed Central

Tabak, Henry H.; Chambers, Cecil W.; Kabler, Paul W.

1964-01-01

Tabak, Henry H. (Robert A. Taft Sanitary Engineering Center, Cincinnati, Ohio), Cecil W. Chambers, and Paul W. Kabler. Microbial metabolism of aromatic carbon compounds. I. Decomposition of phenolic compounds and aromatic hydrocarbons by phenol-adapted bacteria. J. Bacteriol. 87:910–919. 1964.—Bacteria from soil and related environments were selected or adapted to metabolize phenol, hydroxy phenols, nitrophenols, chlorophenols, methylphenols, alkylphenols, and arylphenols when cultured in mineral salts media with the specific substrate as the sole source of carbon. A phenol-adapted culture (substrate-induced enzyme synthesis proven) was challenged in respirometric tests with 104 related compounds; probable significant oxidative activity occurred with 65. Dihydric phenols were generally oxidized; trihydric phenols were not. Cresols and dimethylphenols were oxidized; adding a chloro group increased resistance. Benzoic and hydroxybenzoic acids were oxidized; sulfonated, methoxylated, nitro, and chlorobenzoic acids were not; m-toluic acid was utilized but not the o- and p-isomers. Benzaldehyde and p-hydroxybenzaldehyde were oxidized. In general, nitro- and chloro-substituted compounds and the benzenes were difficult to oxidize. PMID:14137630

Aromatic amine metabolism: immunochemical relationships of N-acetyltransferase and N,O-acyltransferase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Land, S.; Allaben, W.T.; King, C.M.

1986-05-01

Mutagenic and carcinogenic aromatic amines are acetylated in most organisms. Acetyl CoA and arylhydroxamic acids can serve as acetyl donors for N-Acetylation of amines to yield stable amides, or by O-acetylation of hydroxylamine derivatives to produce reactive metabolites that can react covalently with nucleic acid. Polyclonal antibodies against rat arylhydroxamic acid, N,O-acyltransferase (AHAT) have been compared for their abilities to react with this enzyme and the acetyl CoA-dependent N-acetyltransferase (NAT) of the rat, rabbit, hamster, mouse and human. Liver cytosols were treated with increasing quantities of antibodies from immune or control rabbits. Immune complexes were removed by treatment with proteinmore » A-Sepharose before assay of nucleic acid adduct formation by AHAT activation of N-hydroxy-2-acetylaminofluorene and the acetylation of 2-aminofluorene by NAT. Both rat activities, the AHAT of the hamster and the NAT of the mouse and human were removed by this treatment. No decrease in NAT activity of hamster, or of either rabbit cytosol activity was observed. Neither mouse nor human liver has appreciable AHAT activity. These data support the idea that AHAT and NAT of rat, AHAT of hamster and NAT of mouse and human liver are immunochemically related, but that NAT of the hamster is an immunochemically distinct peptide.« less

4-Aminobiphenyl Downregulation of NAT2 Acetylator Genotype–Dependent N- and O-acetylation of Aromatic and Heterocyclic Amine Carcinogens in Primary Mammary Epithelial Cell Cultures from Rapid and Slow Acetylator Rats

PubMed Central

Jefferson, Felicia A.; Xiao, Gong H.; Hein, David W.

2009-01-01

Aromatic and heterocyclic amine carcinogens present in the diet and in cigarette smoke induce breast tumors in rats. N-acetyltransferase 1 (NAT1) and N-acetyltransferase 2 (NAT2) enzymes have important roles in their metabolic activation and deactivation. Human epidemiological studies suggest that genetic polymorphisms in NAT1 and/or NAT2 modify breast cancer risk in women exposed to these carcinogens. p-Aminobenzoic acid (selective for rat NAT2) and sulfamethazine (SMZ; selective for rat NAT1) N-acetyltransferase catalytic activities were both expressed in primary cultures of rat mammary epithelial cells. PABA, 2-aminofluorene, and 4-aminobiphenyl N-acetyltransferase and N-hydroxy-2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine and N-hydroxy-2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline O-acetyltransferase activities were two- to threefold higher in mammary epithelial cell cultures from rapid than slow acetylator rats. In contrast, SMZ (a rat NAT1-selective substrate) N-acetyltransferase activity did not differ between rapid and slow acetylators. Rat mammary cells cultured in the medium supplemented 24 h with 10μM ABP showed downregulation in the N-and O-acetylation of all substrates tested except for the NAT1-selective substrate SMZ. This downregulation was comparable in rapid and slow NAT2 acetylators. These studies clearly show NAT2 acetylator genotype–dependent N- and O-acetylation of aromatic and heterocyclic amine carcinogens in rat mammary epithelial cell cultures to be subject to downregulation by the arylamine carcinogen ABP. PMID:18842621

Photocatalytic oxidation of aromatic amines using MnO2@g ...

EPA Pesticide Factsheets

An efficient and direct oxidation of aromatic amines to aromatic azo-compounds has been achieved using a MnO2@g-C3N4 catalyst under visible light as a source of energy at room temperature Prepared for submission to the journal, Advanced Materials Letters.

High concentrations of aromatic acylated anthocyanins found in cauline hairs in Plectranthus ciliatus.

PubMed

Jordheim, Monica; Calcott, Kate; Gould, Kevin S; Davies, Kevin M; Schwinn, Kathy E; Andersen, Øyvind M

2016-08-01

Vegetative shoots of a naturalized population of purple-leaved plectranthus (Plectranthus ciliatus, Lamiaceae) were found to contain four main anthocyanins: peonidin 3-(6″-caffeoyl-β-glucopyranoside)-5-β-glucopyranoside, peonidin 3-(6″-caffeoyl-β-glucopyranoside)-5-(6‴-malonyl-β-glucopyranoside), peonidin 3-(6″-E-p-coumaroyl-β-glucopyranoside)-5-(6‴-malonyl-β-glucopyranoside), and peonidin 3-(6″-E-p-coumaroyl-β-glucopyranoside)-5-β-glucopyranoside. The first three of these pigments have not been reported previously from any plant. They all follow the typical anthocyanin pattern of Lamiaceae, with universal occurrence of anthocyanidin 3,5-diglucosides and aromatic acylation with p-coumaric and sometimes caffeic acids; however, they differ by being based on peonidin. The four anthocyanins were present in the leaves (22.2 mg g(-1) DW), and in the xylem and interfascicular parenchyma of the stem. They were exceptionally abundant, among the highest reported for any plant organ, in epidermal hairs on some of the stem internodes (101 mg g(-1) DW). Anthocyanin content in these hairs increased more than three-fold from the youngest to the fourth-youngest internodes. In situ absorbances (λmax ≈ 545 nm) were bathochromic in comparison to absorbances of the isolated anthocyanins in their flavylium form in acidified aqueous solutions (λmax = 525 nm), suggesting that the anthocyanins occur both in quinoidal and flavylium forms in constant proportions in the anthocyanic hair cells. The most distinctive observation with respect to relative proportions of individual anthocyanins was found in de-haired internodes, for which anthocyanin caffeoyl-derivatives decreased, and anthocyanin coumaroyl-derivatives increased, from the youngest to the fourth-youngest internode. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Grapevine Anthocyanin Acyltransferase, Transcriptionally Regulated by VvMYBA, Can Produce Most Acylated Anthocyanins Present in Grape Skins1

PubMed Central

Rinaldo, Amy R.; Cavallini, Erika; Jia, Yong; Moss, Sarah M.A.; McDavid, Debra A.J.; Hooper, Lauren C.; Robinson, Simon P.; Tornielli, Giovanni B.; Zenoni, Sara; Ford, Christopher M.; Boss, Paul K.; Walker, Amanda R.

2015-01-01

Anthocyanins are flavonoid compounds responsible for red/purple colors in the leaves, fruit, and flowers of many plant species. They are produced through a multistep pathway that is controlled by MYB transcription factors. VvMYBA1 and VvMYBA2 activate anthocyanin biosynthesis in grapevine (Vitis vinifera) and are nonfunctional in white grapevine cultivars. In this study, transgenic grapevines with altered VvMYBA gene expression were developed, and transcript analysis was carried out on berries using a microarray technique. The results showed that VvMYBA is a positive regulator of the later stages of anthocyanin synthesis, modification, and transport in cv Shiraz. One up-regulated gene, ANTHOCYANIN 3-O-GLUCOSIDE-6″-O-ACYLTRANSFERASE (Vv3AT), encodes a BAHD acyltransferase protein (named after the first letter of the first four characterized proteins: BEAT [for acetyl CoA:benzylalcohol acetyltransferase], AHCT [for anthocyanin O-hydroxycinnamoyltransferase], HCBT [for anthranilate N-hydroxycinnamoyl/benzoyltransferase], and DAT [for deacetylvindoline 4-O-acetyltransferase]), belonging to a clade separate from most anthocyanin acyltransferases. Functional studies (in planta and in vitro) show that Vv3AT has a broad anthocyanin substrate specificity and can also utilize both aliphatic and aromatic acyl donors, a novel activity for this enzyme family found in nature. In cv Pinot Noir, a red-berried grapevine mutant lacking acylated anthocyanins, Vv3AT contains a nonsense mutation encoding a truncated protein that lacks two motifs required for BAHD protein activity. Promoter activation assays confirm that Vv3AT transcription is activated by VvMYBA1, which adds to the current understanding of the regulation of the BAHD gene family. The flexibility of Vv3AT to use both classes of acyl donors will be useful in the engineering of anthocyanins in planta or in vitro. PMID:26395841

Chemoselective O-acylation of hydroxyamino acids and amino alcohols under acidic reaction conditions: History, scope and applications

PubMed Central

2015-01-01

Summary Amino acids, whether natural, semisynthetic or synthetic, are among the most important and useful chiral building blocks available for organic chemical synthesis. In principle, they can function as inexpensive, chiral and densely functionalized starting materials. On the other hand, the use of amino acid starting materials routinely necessitates protective group chemistry, and in reality, large-scale preparations of even the simplest side-chain derivatives of many amino acids often become annoyingly strenuous due to the necessity of employing protecting groups, on one or more of the amino acid functionalities, during the synthetic sequence. However, in the case of hydroxyamino acids such as hydroxyproline, serine, threonine, tyrosine and 3,4-dihydroxyphenylalanine (DOPA), many O-acyl side-chain derivatives are directly accessible via a particularly expedient and scalable method not commonly applied until recently. Direct acylation of unprotected hydroxyamino acids with acyl halides or carboxylic anhydrides under appropriately acidic reaction conditions renders possible chemoselective O-acylation, furnishing the corresponding side-chain esters directly, on multigram-scale, in a single step, and without chromatographic purification. Assuming a certain degree of stability under acidic reaction conditions, the method is also applicable for a number of related compounds, such as various amino alcohols and the thiol-functional amino acid cysteine. While the basic methodology underlying this approach has been known for decades, it has evolved through recent developments connected to amino acid-derived chiral organocatalysts to become a more widely recognized procedure for large-scale preparation of many useful side-chain derivatives of hydroxyamino acids and related compounds. Such derivatives are useful in peptide chemistry and drug development, as amino acid amphiphiles for asymmetric catalysis, and as amino acid acrylic precursors for preparation of

Bis{2-meth­oxy-6-[tris­(hydroxy­meth­yl)methyl­imino­meth­yl]phenolato-κ3 O,N,O′}manganese(II) dimethanol solvate hemihydrate

PubMed Central

Zhang, Xiutang; Wei, Peihai; Dou, Jianmin; Li, Bin; Hu, Bo

2009-01-01

In the title complex, [Mn(C12H16NO5)2]·2CH3OH·0.5H2O, the MnII atom has a distorted octa­hedral coordination geometry in which two N atoms from two 6-meth­oxy-2-[tris­(hydroxy­meth­yl)methyl­imino­meth­yl]phenolate ligands adopt a trans arrangement. The Mn—O(H) bonds (mean length 2.134 Å) are significantly longer than the Mn—O and Mn—N bonds (mean length 2.011 and 2.027 Å, respectively), and the dihedral angle between the mean planes through the aromatic rings of the two ligands is 76.8 (1)°. A complex network of O—H⋯O hydrogen bonds is formed between the complexes and the uncoordinated methanol and water mol­ecules. The C and O atoms of one C—OH group are disordered with equal occupancies. PMID:21582076

Synthesis of densely substituted trans-configured 4-acylated piperidine-2,4-diones as 3:1 adducts of imines and ketenes.

PubMed

Cabrera, José; Hellmuth, Tina; Peters, René

2010-06-18

An operationally simple method is described to form densely substituted diastereomerically pure trans-configured and potentially biologically interesting 5,6-dihydropyridone derivatives as 3:1 adducts of ketenes formed in situ from acyl bromides and aromatic imines.

Ground-State Distortion in N-Acyl-tert-butyl-carbamates (Boc) and N-Acyl-tosylamides (Ts): Twisted Amides of Relevance to Amide N-C Cross-Coupling.

PubMed

Szostak, Roman; Shi, Shicheng; Meng, Guangrong; Lalancette, Roger; Szostak, Michal

2016-09-02

Amide N-C(O) bonds are generally unreactive in cross-coupling reactions employing low-valent transition metals due to nN → π*C═O resonance. Herein we demonstrate that N-acyl-tert-butyl-carbamates (Boc) and N-acyl-tosylamides (Ts), two classes of acyclic amides that have recently enabled the development of elusive amide bond N-C cross-coupling reactions with organometallic reagents, are intrinsically twisted around the N-C(O) axis. The data have important implications for the design of new amide cross-coupling reactions with the N-C(O) amide bond cleavage as a key step.

Kinetic Resolution of α-Hydroxy-Substituted Oxime Ethers by Enantioselective Cu-H-Catalyzed Si-O Coupling.

PubMed

Dong, Xichang; Kita, Yuji; Oestreich, Martin

2018-04-12

A catalyst-controlled enantioselective alcohol silylation by Cu-H-catalyzed dehydrogenative Si-O coupling of hydroxy groups α to an oxime ether and simple hydrosilanes is reported. The selectivity factors reached in this kinetic resolution are generally high (s≈50), and these reactions thereby provide reliable access to highly enantioenriched α-hydroxy-substituted oxime ethers. The synthetic usefulness of these compounds is also demonstrated. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Further acylated flavonol bisdesmosides from Sinocrassula indica.

PubMed

Xie, Hai-Hui; Yoshikawa, Masayuki

2013-01-01

Further investigation on the whole herbs of Sinocrassula indica (Crassulaceae) led to the isolation of four new acylated flavonol bisdesmosides, sinocrassosides A₁₃, B₆, B₇, and D₄, together with kaempferol 3-O-β-D-(6-O-acetyl)glucopyranosyl-7-O-α-L-rhamnopyranoside. Their structures were established by spectral and chemical methods.

Endogenous ghrelin-O-acyltransferase (GOAT) acylates local ghrelin in the hippocampus.

PubMed

Murtuza, Mohammad I; Isokawa, Masako

2018-01-01

Ghrelin is an appetite-stimulating peptide. Serine 3 on ghrelin must be acylated by octanoate via the enzyme ghrelin-O-acyltransferase (GOAT) for the peptide to bind and activate the cognate receptor, growth hormone secretagogue receptor type 1a (GHSR1a). Interest in GHSR1a increased dramatically when GHSR1a mRNA was demonstrated to be widespread in the brain, including the cortex and hippocampus, indicating that it has multifaceted functions beyond the regulation of metabolism. However, the source of octanoylated ghrelin for GHSR1a in the brain, outside of the hypothalamus, is not well understood. Here, we report the presence of GOAT and its ability to acylate non-octanoylated ghrelin in the hippocampus. GOAT immunoreactivity is aggregated at the base of the dentate granule cell layer in the rat and wild-type mouse. This immunoreactivity was not affected by the pharmacological inhibition of GHSR1a or the metabolic state-dependent fluctuation of systemic ghrelin levels. However, it was absent in the GHSR1a knockout mouse hippocampus, pointing the possibility that the expression of GHSR1a may be a prerequisite for the production of GOAT. Application of fluorescein isothiocyanate (FITC)-conjugated non-octanoylated ghrelin in live hippocampal slice culture (but not in fixed culture or in the presence of GOAT inhibitors) mimicked the binding profile of FITC-conjugated octanoylated ghrelin, suggesting that extracellularly applied non-octanoylated ghrelin was acylated by endogenous GOAT in the live hippocampus while GOAT being mobilized out of neurons. Our results will advance the understanding for the role of endogenous GOAT in the hippocampus and facilitate the search for the source of ghrelin that is intrinsic to the brain. © 2017 International Society for Neurochemistry.

Dichlorido[N′-(3,5-dichloro-2-hydroxy­benzyl­idene)pyridine-4-carbohydrazide-κN](1,10-phenanthroline-κ2 N,N′)cobalt(II) methanol monosolvate

PubMed Central

Wang, Yuan; Liu, Zheng; Liu, Baoyu

2009-01-01

In the title compound, [CoCl2(C13H9Cl2N3O2)2(C12H8N2)]·CH3OH, the CoII atom is octahedrally coordinated by two N atoms from the pyridyl rings of the tridentate N′-(3,5-dichloro-2-hydroxy­benzyl­idene)pyridine-4-carbohydrazide (H2 L) ligand, two N atoms from the 1,10-phenanthroline ligand and two chloride ions. The acyl­hydrazone groups are not involved into the coordination of the metal ion. In the crystal packing an extended three-dimensional network formed by N—H⋯Cl, N—H⋯O, O—H⋯N, O—H⋯N and O—H⋯Cl hydrogen bonds is observed. PMID:21578623

Putting corannulene in its place. Reactivity studies comparing corannulene with other aromatic hydrocarbons.

PubMed

George, Stephen R D; Frith, Thomas D H; Thomas, Donald S; Harper, Jason B

2015-09-14

A series of aromatic hydrocarbons were investigated so as to compare the reactivity of corannulene with planar aromatic hydrocarbons. Corannulene was found to be more reactive than benzene, naphthalene and triphenylene to Friedel-Crafts acylation whilst electrophilic aromatic bromination was also used to confirm that triphenylene was less reactive than corannulene and that pyrene, perylene and acenaphthene were more so. The stabilisation of a neighbouring carbocation by the various aromatic systems was investigated through consideration of the rates of methanolysis of a series of benzylic alcohols. The reactivity series was found to parallel that observed for the electrophilic aromatic substitutions and both series are supported by computational studies. As such, a reactivity scale was devised that showed that corannulene was less reactive than would be expected for an aromatic planar species of similar pi electron count.

Diversion of a thioglycoligase for the synthesis of 1-O-acyl arabinofuranoses.

PubMed

Pavic, Quentin; Tranchimand, Sylvain; Lemiègre, Loïc; Legentil, Laurent

2018-05-15

An arabinofuranosylhydrolase from the GH51 family was transformed into an acyl transferase by mutation of the catalytic acid/base amino acid. The resulting enzyme was able to transfer carboxylic acid onto the anomeric position of arabinose with complete chemo- and stereoselectivity. A wide range of acyl α-l-arabinofuranoses was obtained with yields ranging from 25 to 83%. Using this method, ibuprofen and N-Boc phenylalanine were successfully transformed into their corresponding acyl conjugates, expanding the scope of the reaction to drugs and amino acids.

Safety Assessment of Acyl Glucuronides-A Simplified Paradigm.

PubMed

Smith, Dennis A; Hammond, Timothy; Baillie, Thomas A

2018-06-01

While simple O - (ether-linked) and N -glucuronide drug conjugates generally are unreactive and considered benign from a safety perspective, the acyl glucuronides that derive from metabolism of carboxylic acid-containing xenobiotics can exhibit a degree of chemical reactivity that is dependent upon their molecular structure. As a result, concerns have arisen over the safety of acyl glucuronides as a class, several members of which have been implicated in the toxicity of their respective parent drugs. However, direct evidence in support of these claims remains sparse, and due to frequently encountered species differences in the systemic exposure to acyl glucuronides (both of the parent drug and oxidized derivatives thereof), coupled with their instability in aqueous media and potential to undergo chemical rearrangement (acyl migration), qualification of these conjugates by traditional safety assessment methods can be very challenging. In this Commentary, we discuss alternative (non-acyl glucuronide) mechanisms by which carboxylic acids may cause serious adverse reactions, and propose a novel, practical approach to compare systemic exposure to acyl glucuronide metabolites in humans to that in animal species used in preclinical safety assessment based on relative estimates of the total body burden of these circulating conjugates. Copyright © 2018 by The American Society for Pharmacology and Experimental Therapeutics.

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

Metabolic regulation of ghrelin O-acyl transferase (GOAT) expression in the mouse hypothalamus, pituitary, and stomach.

PubMed

Gahete, Manuel D; Córdoba-Chacón, Jose; Salvatori, Roberto; Castaño, Justo P; Kineman, Rhonda D; Luque, Raul M

2010-04-12

Ghrelin acts as an endocrine link connecting physiological processes regulating food intake, body composition, growth, and energy balance. Ghrelin is the only peptide known to undergo octanoylation. The enzyme mediating this process, ghrelin O-acyltransferase (GOAT), is expressed in the gastrointestinal tract (GI; primary source of circulating ghrelin) as well as other tissues. The present study demonstrates that stomach GOAT mRNA levels correlate with circulating acylated-ghrelin levels in fasted and diet-induced obese mice. In addition, GOAT was found to be expressed in both the pituitary and hypothalamus (two target tissues of ghrelin's actions), and regulated in response to metabolic status. Using primary pituitary cell cultures as a model system to study the regulation of GOAT expression, we found that acylated-ghrelin, but not desacyl-ghrelin, increased GOAT expression. In addition, growth-hormone-releasing hormone (GHRH) and leptin increased, while somatostatin (SST) decreased GOAT expression. The physiologic relevance of these later results is supported by the observation that pituitary GOAT expression in mice lacking GHRH, SST and leptin showed opposite changes to those observed after in vitro treatment with the corresponding peptides. Therefore, it seems plausible that these hormones directly contribute to the regulation of pituitary GOAT. Interestingly, in all the models studied, pituitary GOAT expression paralleled changes in the expression of a dominant spliced-variant of ghrelin (In2-ghrelin) and therefore this transcript may be a primary substrate for pituitary GOAT. Collectively, these observations support the notion that the GI tract is not the only source of acylated-ghrelin, but in fact locally produced des-acylated-ghrelin could be converted to acylated-ghrelin within target tissues by locally active GOAT, to mediate its tissue-specific effects.

Carbonyl atmospheric reaction products of aromatic hydrocarbons in ambient air

NASA Astrophysics Data System (ADS)

Obermeyer, Genevieve; Aschmann, Sara M.; Atkinson, Roger; Arey, Janet

To convert gaseous carbonyls to oximes during sampling, an XAD-4 resin denuder system pre-coated with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine and followed by analysis with methane positive chemical ionization gas chromatography/mass spectrometry was used to measure carbonyls in ambient air samples in Riverside, CA. In conjunction with similar analyses of environmental chamber OH radical-initiated reactions of o- and p-xylene, 1,2,4-trimethylbenzene, ethylbenzene, 4-hydroxy-2-butanone and 1,4-butanediol, we identified benzaldehyde, o-, m- and p-tolualdehyde and acetophenone and the dicarbonyls glyoxal, methylglyoxal, biacetyl, ethylglyoxal, 1,4-butenedial, 3-hexene-2,5-dione, 3-oxo-butanal, 1,4-butanedial and malonaldehyde in the ambient air samples. As discussed, these carbonyls and dicarbonyls can be formed from the OH radical-initiated reactions of aromatic hydrocarbons and other volatile organic compounds emitted into the atmosphere, and we conclude that in situ atmospheric formation is a major source of these carbonyls in our Riverside, CA, ambient air samples.

Sonochemical enzyme-catalyzed regioselective acylation of flavonoid glycosides.

PubMed

Ziaullah; Rupasinghe, H P Vasantha

2016-04-01

This work compares a highly efficient and alternative method of sonication-assisted lipase catalyzed acylation of quercetin-3-O-glucoside and phloretin-2'-glucoside, using Candida antarctica lipase B (Novozyme 435(®)), with a range of fatty acids. In this study, sonication-assisted irradiation coupled with stirring has been found to be more efficient and economical than conventional reaction conditions. Sonication-assisted acylation accelerated the reactions and reduced the time required by 4-5 folds. Copyright © 2016 Elsevier Inc. All rights reserved.

A new acylated isoflavone glucoside from Pterocarpus santalinus.

PubMed

Krishnaveni, K S; Srinivasa Rao, J V

2000-09-01

Phytochemical investigation on the constituents of heartwood of Pterocarpus santalinus resulted in the isolation of a new acylated isoflavone glucoside. The structure of the new compound was elucidated on the basis of spectral studies as 4',5-dihydroxy-7-O-methyl isoflavone 3'-O-D-(3''-E-cinnamoyl)glucoside.

(CF3CO)2O/CF3SO3H-mediated synthesis of 1,3-diketones from carboxylic acids and aromatic ketones

PubMed Central

Kim, JungKeun; Shokova, Elvira; Tafeenko, Victor

2014-01-01

Summary A very simple and convenient reaction for 1,3-diketone preparation from carboxylic acids and aromatic ketones in TFAA/TfOH system is described. When the β-phenylpropionic acids were used as starting materials, they initially gave 1-indanones and then underwent further acylation with the formation of 2-(β-phenylpropionyl)-1-indanones as the main reaction products. In addition, the application of the proposed protocol allowed for the synthesis of selected polysubstituted pyrazoles in a one-pot procedure directly from acids and ketones. PMID:25298794

A Novel Glucosylation Reaction on Anthocyanins Catalyzed by Acyl-Glucose–Dependent Glucosyltransferase in the Petals of Carnation and Delphinium[C][W

PubMed Central

Matsuba, Yuki; Sasaki, Nobuhiro; Tera, Masayuki; Okamura, Masachika; Abe, Yutaka; Okamoto, Emi; Nakamura, Haruka; Funabashi, Hisakage; Takatsu, Makoto; Saito, Mikako; Matsuoka, Hideaki; Nagasawa, Kazuo; Ozeki, Yoshihiro

2010-01-01

Glucosylation of anthocyanin in carnations (Dianthus caryophyllus) and delphiniums (Delphinium grandiflorum) involves novel sugar donors, aromatic acyl-glucoses, in a reaction catalyzed by the enzymes acyl-glucose–dependent anthocyanin 5(7)-O-glucosyltransferase (AA5GT and AA7GT). The AA5GT enzyme was purified from carnation petals, and cDNAs encoding carnation Dc AA5GT and the delphinium homolog Dg AA7GT were isolated. Recombinant Dc AA5GT and Dg AA7GT proteins showed AA5GT and AA7GT activities in vitro. Although expression of Dc AA5GT in developing carnation petals was highest at early stages, AA5GT activity and anthocyanin accumulation continued to increase during later stages. Neither Dc AA5GT expression nor AA5GT activity was observed in the petals of mutant carnations; these petals accumulated anthocyanin lacking the glucosyl moiety at the 5 position. Transient expression of Dc AA5GT in petal cells of mutant carnations is expected to result in the transfer of a glucose moiety to the 5 position of anthocyanin. The amino acid sequences of Dc AA5GT and Dg AA7GT showed high similarity to glycoside hydrolase family 1 proteins, which typically act as β-glycosidases. A phylogenetic analysis of the amino acid sequences suggested that other plant species are likely to have similar acyl-glucose–dependent glucosyltransferases. PMID:20971893

Head-group acylation of monogalactosyldiacylglycerol is a common stress response, and the acyl-galactose acyl composition varies with the plant species and applied stress

PubMed Central

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

2014-01-01

Formation of galactose-acylated monogalactosyldiacylglycerols has been shown to be induced by leaf homogenization, mechanical wounding, avirulent bacterial infection, and thawing after snap-freezing. Here, lipidomic analysis using mass spectrometry showed that galactose-acylated monogalactosyldiacylglycerols, formed in wheat (Triticum aestivum) and tomato (Solanum lycopersicum) leaves upon wounding, have acyl-galactose profiles that differ from those of wounded Arabidopsis thaliana, indicating that different plant species accumulate different acyl-galactose components in response to the same stress. Additionally, the composition of the acyl-galactose component of Arabidopsis acMGDG depends on the stress treatment. After sub-lethal freezing treatment, acMGDG contained mainly non-oxidized fatty acids esterified to galactose, whereas mostly oxidized fatty acids accumulated on galactose after wounding or bacterial infection. Compositional data are consistent with acMGDG being formed in vivo by transacylation with fatty acids from digalactosyldiacylglycerols. Oxophytodienoic acid, an oxidized fatty acid, was more concentrated on the galactosyl ring of acylated monogalactosyldiacylglycerols than in galactolipids in general. Also, oxidized fatty acid-containing acylated monogalactosyldiacylglycerols increased cumulatively when wounded Arabidopsis leaves were wounded again. These findings suggest that, in Arabidopsis, the pool of galactose-acylated monogalactosyldiacylglycerols may serve to sequester oxidized fatty acids during stress responses. PMID:24286212

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.

Non-methylene interrupted and hydroxy fatty acids in polar lipids of the alga Grateloupia turuturu over the four seasons.

PubMed

Kendel, Melha; Barnathan, Gilles; Fleurence, Joël; Rabesaotra, Vony; Wielgosz-Collin, Gaëtane

2013-05-01

Phospholipids (PL) and glycolipids (GL) FA in the edible Rhodophyta Grateloupia turuturu, from Brittany, France, were investigated over four seasons. The major lipid class was GL in all seasons (around 45 %). More than 80 FA occurred in polar lipids, with chains from C12 to C26, identified as methyl esters and N-acyl pyrrolidides by gas chromatography-mass spectrometry (GC-MS). PUFA occurred at up to 47.1 % (summer) in PL, and up to 43.6 % (summer) in GL. The major PUFA were 20:5n-3 (12.2 % in PL and 29.0 % in GL) and 20:4n-6 (25.6 % in PL and 10.4 % in GL). The unusual 18:3n-7 acid was identified in PL up to 2.2 %. Several minor unsaturated FA were identified in PL and are previously unreported in seaweeds, namely 14-tricosenoic, 15-tetracosenoic, 5,11-octadecadienoic and 5,9-nonadecadienoic. Also unprecedented in seaweeds, ten 2-hydroxy and three 3-hydroxy FA occurred mainly in PL, 13.9 % in spring with the 3-hydroxyhexadecanoic acid as the major one (8.1 % winter). Three n-9 monounsaturated 2-hydroxy FA occurred in PL. The 2-hydroxy-15-tetracosenoic acid was characterized as the dimethyl disulfide adduct of its methyl ester. The 2-hydroxy-16-pentacosenoic and 2-hydroxy-17-hexacosenoic acids were identified by comparison of mass spectra and GC mobilities with those of the 2-hydroxy-15-tetracosenoic acid, and of other homogeneous FA series. These rare n-9 monounsaturated 2-hydroxy FA are unprecedented in seaweeds.

Synthesis and mutagenicity of a ring-A-aromatized bile acid, 3-hydroxy-19-nor-1,3,5(10)-cholatrien-24-oic acid.

PubMed

Namba, T; Hirota, T; Hayakawa, S

1988-06-01

It has been presumed that ring-A-aromatized bile acids are produced from biliary bile acids by intestinal flora and the acids thus formed participate in the large bowel carcinogenesis. One of these acids is probably 3-hydroxy-19-nor-1,3,5(10)-cholatrien-24-oic acid, judged from the literatures. Consequently, this acid was synthesized from previously prepared 3-methoxy-19-nor-1,3,5(10)-cholatrien-24-ol. The phenolic ether was successively oxidized with pyridinium chlorochromate and wet silver oxide to give 3-methoxy-19-nor-1,3,5(10)-cholatrien-24-oic acid in high yield, which, after successive treatments with methanol containing a catalytic amount of p-toluenesulfonic acid, a combination of aluminum chloride and ethanethiol, and alkali, gave the desired compound in satisfactory yield. The compound was not mutagenic in Salmonella tester strains TA 98 and TA 100, but it increased the mutagenicity of 2-aminoanthracene when both were applied to plates together. When compared with cholic, deoxycholic, and lithocholic acids, the investigated compound exhibited about two to threefold increase of mutagenicity in the latter assay.

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…

Dual function catalysts. Dehydrogenation and asymmetric intramolecular Diels-Alder cycloaddition of N-hydroxy formate esters and hydroxamic acids: evidence for a ruthenium-acylnitroso intermediate.

PubMed

Chow, Chun P; Shea, Kenneth J

2005-03-23

The chiral ruthenium salen complex, 13b, functions as an efficient catalyst for the sequential oxidation and asymmetric Diels-Alder cycloaddition of hydroxamic acids and N-hydroxy formate esters. This result provides evidence for the formation of a ruthenium-nitroso formate (acyl nitroso) intermediate. The Diels-Alder precursors are prepared from simple building blocks, and the cycloadducts, bridged oxazinolactams, can serve as useful intermediates in organic synthesis.

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

Characterization of two acyl-acyl carrier protein thioesterases from developing Cuphea seeds specific for medium-chain- and oleoyl-acyl carrier protein.

PubMed

Dörmann, P; Spener, F; Ohlrogge, J B

1993-03-01

Two acyl-acyl carrier protein (ACP) thioesterases were partially purified from developing seeds of Cuphea lanceolata Ait., a plant with decanoic acid-rich triacylglycerols. The two enzymes differ markedly in their substrate specificity. One is specific for medium-chain acyl-ACPs, the other one for oleoyl-ACP. In addition, these enzymes are distinct with regard to molecular weight, pH optimum and sensitivity to salt. The thioesterases could be separated by Mono Q chromatography or gel filtration. The medium-chain acyl-ACP thioesterase and oleoyl-ACP thioesterase were purified from a crude extract 29- and 180-fold, respectively. In Cuphea wrightii A. Gray, which predominantly contains decanoic a nd lauric acid in the seeds, two different thioesterases were also found with a similar substrate specificity as in Cuphea lanceolata.

Acute effect of exercise intensity and duration on acylated ghrelin and hunger in men.

PubMed

Broom, David R; Miyashita, Masashi; Wasse, Lucy K; Pulsford, Richard; King, James A; Thackray, Alice E; Stensel, David J

2017-03-01

Acute exercise transiently suppresses the orexigenic gut hormone acylated ghrelin, but the extent to which exercise intensity and duration determine this response is not fully understood. The effects of manipulating exercise intensity and duration on acylated ghrelin concentrations and hunger were examined in two experiments. In experiment one, nine healthy males completed three, 4-h conditions (control, moderate-intensity running (MOD) and vigorous-intensity running (VIG)), with an energy expenditure of ~2.5 MJ induced in both MOD (55-min running at 52% peak oxygen uptake (V.O 2peak )) and VIG (36-min running at 75% V.O 2peak ). In experiment two, nine healthy males completed three, 9-h conditions (control, 45-min running (EX45) and 90-min running (EX90)). Exercise was performed at 70% V.O 2peak In both experiments, participants consumed standardised meals, and acylated ghrelin concentrations and hunger were quantified at predetermined intervals. In experiment one, delta acylated ghrelin concentrations were lower than control in MOD (ES = 0.44, P = 0.01) and VIG (ES = 0.98, P < 0.001); VIG was lower than MOD (ES = 0.54, P = 0.003). Hunger ratings were similar across the conditions (P = 0.35). In experiment two, delta acylated ghrelin concentrations were lower than control in EX45 (ES = 0.77, P < 0.001) and EX90 (ES = 0.68, P < 0.001); EX45 and EX90 were similar (ES = 0.09, P = 0.55). Hunger ratings were lower than control in EX45 (ES = 0.20, P = 0.01) and EX90 (ES = 0.27, P = 0.001); EX45 and EX90 were similar (ES = 0.07, P = 0.34). Hunger and delta acylated ghrelin concentrations remained suppressed at 1.5 h in EX90 but not EX45. In conclusion, exercise intensity, and to a lesser extent duration, are determinants of the acylated ghrelin response to acute exercise. © 2017 Society for Endocrinology.

Occurrence and metabolism of 7-hydroxy-2-indolinone-3-acetic acid in Zea mays

NASA Technical Reports Server (NTRS)

Lewer, P.; Bandurski, R. S.

1987-01-01

7-Hydroxy-2-indolinone-3-acetic acid was identified as a catabolite of indole-3-acetic acid in germinating kernels of Zea mays and found to be present in amounts of ca 3.1 nmol/kernel. 7-Hydroxy-2-indolinone-3-acetic acid was shown to be a biosynthetic intermediate between 2-indolinone-3-acetic acid and 7-hydroxy-2-indolinone-3-acetic acid-7'-O-glucoside in both kernels and roots of Zea mays. Further metabolism of 7-hydroxy-2-[5-3H]-indolinone-3-acetic acid-7'-O-glucoside occurred to yield tritiated water plus, as yet, uncharacterized products.

Acylated iridoids from the roots of Valeriana officinalis var. latifolia.

PubMed

Han, Zhu-zhen; Yan, Zhao-hui; Liu, Qing-xin; Hu, Xian-qing; Ye, Ji; Li, Hui-liang; Zhang, Wei-dong

2012-10-01

Phytochemical investigation of the roots of Valeriana officinalis var. latifolia resulted in the isolation and characterization of six new acylated iridoids, (5S,7S,8S,9S)-7-hydroxy-8-isovaleroyloxy-Δ⁴,¹¹-dihyronepetalactone (1), (5S,7S,8S,9S)-7-hydroxy-10-isovaleroyloxy-Δ⁴,¹¹-dihyronepetalactone (2), (5S,8S,9S)-10-isovaleroyloxy-Δ⁴,¹¹-dihyronepetalactone (3), (5S,6S,8S,9R)-6-isovaleroyloxy-Δ⁴,¹¹-1,3-diol (4), (5S,6S,8S,9R)-1,3-isovaleroxy-Δ4,11-1,3-diol (5), and (5S,6S,8S,9R)-3-isovaleroxy-6-isovaleroyloxy-Δ⁴,¹¹-1,3-diol (6). Their structures were determined mainly by 1D and 2D NMR spectroscopic techniques. We also report herein for the first time the single crystal X-ray structure of compound 1. In addition, the cytotoxic activities of compounds 1-6 were evaluated against A549 (human lung adenocarcinoma), HCT116 (human colon carcinoma), SK-BR-3 (human breast carcinoma), and HepG2 (human hepatoma) cell lines. Compound 6 showed weak cell growth inhibition of A549, HCT116, SK-BR-3, and HepG2 cells. Georg Thieme Verlag KG Stuttgart · New York.

Triazine-Substituted and Acyl Hydrazones: Experiment and Computation Reveal a Stability Inversion at Low pH.

PubMed

Ji, Kun; Lee, Changsuk; Janesko, Benjamin G; Simanek, Eric E

2015-08-03

Condensation of a hydrazine-substituted s-triazine with an aldehyde or ketone yields an equivalent to the widely used, acid-labile acyl hydrazone. Hydrolysis of these hydrazones using a formaldehyde trap as monitored using HPLC reveals that triazine-substituted hydrazones are more labile than acetyl hydrazones at pH>5. The reactivity trends mirror that of the corresponding acetyl hydrazones, with hydrolysis rates increasing along the series (aromatic aldehyde<aromatic ketone

Synthesis of 5-acyl-6-[2-hydroxy-3-(amino)propylamino]-1,3-dialkyl-1H-pyrimidine-2,4-diones.

PubMed

Singh, Palwinder; Paul, Kamaldeep; Holzer, Wolfgang

2005-11-07

A stepwise synthetic approach involving substitution of 6-chloro-1,3-dialkyluracils (5 and 6) with 3-(tert-amino)-2-hydroxypropylamines and subsequent acylation at C5 of uracil has been used to synthesize pyrimidinediones 27-33 in 61-89% overall yield. The conformational aspects of the new molecules based upon NMR data have been discussed.

Studies to further investigate the inhibition of human liver microsomal CYP2C8 by the acyl-β-glucuronide of gemfibrozil.

PubMed

Jenkins, S M; Zvyaga, T; Johnson, S R; Hurley, J; Wagner, A; Burrell, R; Turley, W; Leet, J E; Philip, T; Rodrigues, A D

2011-12-01

In previous studies, gemfibrozil acyl-β-glucuronide, but not gemfibrozil, was found to be a mechanism-based inhibitor of cytochrome P450 2C8. To better understand whether this inhibition is specific for gemfibrozil acyl-β-glucuronide or whether other glucuronide conjugates are potential substrates for inhibition of this enzyme, we evaluated several pharmaceutical compounds (as their acyl glucuronides) as direct-acting and metabolism-dependent inhibitors of CYP2C8 in human liver microsomes. Of 11 compounds that were evaluated as their acyl glucuronide conjugates, only gemfibrozil acyl-β-glucuronide exhibited mechanism-based inhibition, indicating that CYP2C8 mechanism-based inhibition is very specific to certain glucuronide conjugates. Structural analogs of gemfibrozil were synthesized, and their glucuronide conjugates were prepared to further examine the mechanism of inhibition. When the aromatic methyl groups on the gemfibrozil moiety were substituted with trifluoromethyls, the resulting glucuronide conjugate was a weaker inhibitor of CYP2C8 and mechanism-based inhibition was abolished. However, the glucuronide conjugates of monomethyl gemfibrozil analogs were mechanism-based inhibitors of CYP2C8, although not as potent as gemfibrozil acyl-β-glucuronide itself. The ortho-monomethyl analog was a more potent inhibitor than the meta-monomethyl analog, indicating that CYP2C8 favors the ortho position for oxidation and potential inhibition. Molecular modeling of gemfibrozil acyl-β-glucuronide in the CYP2C8 active site is consistent with the ortho-methyl position being the favored site of covalent attachment to the heme. Moreover, hydrogen bonding to four residues (Ser100, Ser103, Gln214, and Asn217) is implicated.

Peptide affinity labels for thrombin and other trypsin-like proteases

DOEpatents

Shaw, E.N.; Kettner, C.A.

1982-03-09

A peptide affinity label is disclosed of the formula (I): as given in the patent wherein X is a radical capable of acting as a leaving group in a nucleophilic substitution reaction; A is an aromatic amino acid residue; B is H, or a C[sub 1]--C[sub 4] alkyl group, or aryl; Y is selected from the group consisting of hydrogen, aroyl, C[sub 1]--C[sub 6] acyl, and Q--(A)--[sub n], wherein Q = hydrogen, aroyl, or C[sub 1]--C[sub 6] acyl, n = 1--10, A is an amino acid residue selected from the aliphatic, hydroxy-containing, carboxylic acid group, and amide-thereofcontaining, aromatic, sulfur-containing and imino-containing amino acids; and wherein J is selected from the group consisting of --CH[sub 2]--, --CH[sub 2]--CH[sub 2]--, --CH[sub 2]--CH[sub 2]--CH[sub 2]--, --CH[double bond]CH-- and --CH(OH)--CH[sub 2]. The affinity label is useful for irreversibly inactivating thrombin and trypsin-like enzymes and may be used as a potential anticlotting agent. 2 figs.

Peptide affinity labels for thrombin and other trypsin-like proteases

DOEpatents

Shaw, Elliott N.; Kettner, Charles A.

1982-03-09

A peptide affinity label of the formula (I): ##STR1## wherein X is a radical capable of acting as a leaving group in a nucleophilic substitution reaction; A is an aromatic amino acid residue; B is H, or a C.sub.1 -C.sub.4 alkyl group, or aryl; Y is selected from the group consisting of hydrogen, aroyl, C.sub.1 -C.sub.6 acyl, and Q--(A)--.sub.n, wherein Q=hydrogen, aroyl, or C.sub.1 -C.sub.6 acyl, n=1-10, A is an amino acid residue selected from the aliphatic, hydroxy-containing, carboxylic acid group, and amide-thereof-containing, aromatic, sulfur-containing and imino-containing amino acids; and wherein J is selected from the group consisting of --CH.sub.2 --, --CH.sub.2 --CH.sub.2 --,--CH.sub.2 --CH.sub.2 --CH.sub.2 --, --CH.dbd.CH-- and --CH(OH)--CH.sub.2. The affinity label is useful for irreversibly inactivating thrombin and trypsin-like enzymes and may be used as a potential anticlotting agent.

New parasite inhibitors encompassing novel conformationally-locked 5'-acyl sulfamoyl adenosines.

PubMed

Dixit, Shailesh S; Upadhayaya, Ram Shankar; Chattopadhyaya, Jyoti

2012-08-14

We describe the design, synthesis and biological evaluation of conformationally-locked 5'-acyl sulfamoyl adenosine derivatives as new parasitic inhibitors against Trypanosoma and Leishmania. The conformationally-locked (3'-endo, North-type) nucleosides have been synthesized by covalently attaching a 4'-CH(2)-O-2' bridge () across C2'-C4' of adenosine in order to reduce the conformational flexibility of the pentose ring. This is designed to decrease the entropic penalty for complex formation with the target protein, which may improve free-energy of stabilization of the complex leading to improved potency. Conformationally-locked 5'-acyl sulfamoyl adenosine derivatives (16-22) were tested against parasitic protozoans for the first time in this work, and showed potent inhibition of Trypanosoma cruzi, Trypanosoma brucei, Trypanosoma rhodesiense and Leishmania infantum with IC(50) = 0.25-0.51 μM. In particular, the potent 5'-pentanyl acyl sulfamoyl adenosine derivative 17 (IC(50) = 0.25 μM) against intracellular L. infantum amastigotes and Trypanosoma subspecies is interesting in view of its almost insignificant cytotoxicity in murine macrophage host cells (CC(50) >4 μM) and in diploid human fibroblasts MRC-5 cell lines (CC(50) 4 μM). This work also suggests that variable alkyl chain length of the acyl group on the acylsulfamoyl side chain at 5' can modulate the toxicity of 5'-O-sulfamoylnucleoside analogues. This conformationally-locked sulfamoyl adenosine scaffold presents some interesting possibilities for further drug design and lead optimization.

Raman spectroscopic study of a hydroxy-arsenate mineral containing bismuth-atelestite Bi 2O(OH)(AsO 4)

NASA Astrophysics Data System (ADS)

Frost, Ray L.; Čejka, Jiří; Sejkora, Jiří; Plášil, Jakub; Reddy, B. J.; Keeffe, Eloise C.

2011-01-01

The Raman spectrum of atelestite Bi 2O(OH)(AsO 4), a hydroxy-arsenate mineral containing bismuth, has been studied in terms of spectra-structure relations. The studied spectrum is compared with the Raman spectrum of atelestite downloaded from the RRUFF database. The sharp intense band at 834 cm -1 is assigned to the ν1 AsO 43- ( A1) symmetric stretching mode and the three bands at 767, 782 and 802 cm -1 to the ν3 AsO 43- antisymmetric stretching modes. The bands at 310, 324, 353, 370, 395, 450, 480 and 623 cm -1 are assigned to the corresponding ν4 and ν2 bending modes and Bi sbnd O sbnd Bi (vibration of bridging oxygen) and Bi sbnd O (vibration of non-bridging oxygen) stretching vibrations. Lattice modes are observed at 172, 199 and 218 cm -1. A broad low intensity band at 3095 cm -1 is attributed to the hydrogen bonded OH units in the atelestite structure. A weak band at 1082 cm -1 is assigned to δ(Bi sbnd OH) vibration.

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.

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

PubMed Central

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

2009-01-01

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

1-(Hydroxy­meth­yl)pyrene

PubMed Central

Gruber, Tobias; Seichter, Wilhelm; Weber, Edwin

2010-01-01

The asymmetric unit of the title compound, C17H12O, contains two molecules, in which the fused aromatic ring systems are almost planar [maximum deviations = 0.0529 (9) and 0.0256 (9) Å]. In the crystal, aromatic π–π stacking inter­actions (perpendicular distance of centroids of about 3.4 Å) and strong O—H⋯O hydrogen bonds result in a helical arrangement of pyrenyl dimers. PMID:21579858

Development and validation of a general derivatization HPLC method for the trace analysis of acyl chlorides in lipophilic drug substances.

PubMed

Zheng, Xiangyuan; Luo, Lan; Zhou, Jie; Ruan, Xiaoling; Liu, Wenyuan; Zheng, Feng

2017-06-05

Acyl chlorides are important acylating agents in the synthesis of active pharmaceutical ingredients. Determining the residual acyl chlorides in drug substances is a challenge due to their high reactivity and the matrix interferences from drug substances and their related impurities. This paper describes a general derivatization HPLC method for the determination of aromatic and aliphatic acyl chlorides in lipophilic drug substances. Since most drug substances have weak absorptions in the visible range (above 380nm), the nitro-substituted anilines and nitro-substituted phenylhydrazines were selected as the derivatization reagents due to their weak basicity and red-shift of UV absorption spectra. The maximum wavelength and absorption intensity of nitro-substituted anilines decreased after derivatization with acyl chlorides, whereas the derivatization products of nitro-substituted phenylhydrazines showed the slight increases of maximum wavelength and absorbance intensity. Hence, 2-nitrophenylhydrazine was selected as the suitable derivatization reagent because the derivatives have the maximum UV wavelength absorbance at 395nm, which could largely minimize the matrix interferences. The optimization of the concentration of 2-nitrophenylhydrazine is important for the sensitivity and stability of derivatives. Other reaction conditions including reaction temperature, time and the influence of three competitive solvents (water, methanol and ethanol) on the reaction efficiency were also studied. After derivatization with 100μgmL -1 2-nitrophenylhydrazine at room temperature for 30min, the method was validated for high specificity and sensitivity with the detection limits in the range of 0.01-0.03μgmL -1 . The proposed method was applied as a generic method to determine the residual acyl chlorides in lipophilic drug substances. Copyright © 2017 Elsevier B.V. All rights reserved.

Ribosomal synthesis and folding of peptide-helical aromatic foldamer hybrids

NASA Astrophysics Data System (ADS)

Rogers, Joseph M.; Kwon, Sunbum; Dawson, Simon J.; Mandal, Pradeep K.; Suga, Hiroaki; Huc, Ivan

2018-03-01

Translation, the mRNA-templated synthesis of peptides by the ribosome, can be manipulated to incorporate variants of the 20 cognate amino acids. Such approaches for expanding the range of chemical entities that can be produced by the ribosome may accelerate the discovery of molecules that can perform functions for which poorly folded, short peptidic sequences are ill suited. Here, we show that the ribosome tolerates some artificial helical aromatic oligomers, so-called foldamers. Using a flexible tRNA-acylation ribozyme—flexizyme—foldamers were attached to tRNA, and the resulting acylated tRNAs were delivered to the ribosome to initiate the synthesis of non-cyclic and cyclic foldamer-peptide hybrid molecules. Passing through the ribosome exit tunnel requires the foldamers to unfold. Yet foldamers encode sufficient folding information to influence the peptide structure once translation is completed. We also show that in cyclic hybrids, the foldamer portion can fold into a helix and force the peptide segment to adopt a constrained and stretched conformation.

Synthesis and Characterization of AlCl3 Impregnated Molybdenum Oxide as Heterogeneous Nano-Catalyst for the Friedel-Crafts Acylation Reaction in Ambient Condition.

PubMed

Jadhav, Arvind H; Chinnappan, Amutha; Hiremath, Vishwanath; Seo, Jeong Gil

2015-10-01

Aluminum trichloride (AlCl3) impregnated molybdenum oxide heterogeneous nano-catalyst was prepared by using simple impregnation method. The prepared heterogeneous catalyst was characterized by powder X-ray diffraction, FT-IR spectroscopy, solid-state NMR spectroscopy, SEM imaging, and EDX mapping. The catalytic activity of this protocol was evaluated as heterogeneous catalyst for the Friedel-Crafts acylation reaction at room temperature. The impregnated MoO4(AlCl2)2 catalyst showed tremendous catalytic activity in Friedel-Crafts acylation reaction under solvent-free and mild reaction condition. As a result, 84.0% yield of acyl product with 100% consumption of reactants in 18 h reaction time at room temperature was achieved. The effects of different solvents system with MoO4(AlCl2)2 catalyst in acylation reaction was also investigated. By using optimized reaction condition various acylated derivatives were prepared. In addition, the catalyst was separated by simple filtration process after the reaction and reused several times. Therefore, heterogeneous MoO4(AlCl2)2 catalyst was found environmentally benign catalyst, very convenient, high yielding, and clean method for the Friedel-Crafts acylation reaction under solvent-free and ambient reaction condition.

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

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

Acylated and unacylated ghrelin confer neuroprotection to mesencephalic neurons.

PubMed

Wagner, Johanna; Vulinović, Franca; Grünewald, Anne; Unger, Marcus M; Möller, Jens C; Klein, Christine; Michel, Patrick P; Ries, Vincent; Oertel, Wolfgang H; Alvarez-Fischer, Daniel

2017-12-04

The polypeptide ghrelin is an endogenous ligand at the growth hormone secretagogue receptor 1a. To ghrelin multiple functions have been ascribed including promotion of gastrointestinal motility. Postprandial ghrelin levels have been reported to be reduced in patients suffering from Parkinson disease (PD). Experimental studies revealed neuroprotective effects of ghrelin in different PD models. The purpose of the present study was (i) to further elucidate the mechanism underlying the neuroprotective action of ghrelin and (ii) to determine whether these effects occur with both the acylated and the unacylated form. The study was conducted in primary mesencephalic cultures treated with mitochondrial complex I and complex II inhibitors. We show that protective effects of ghrelin against complex I inhibition with MPP + were independent of the acylation status of ghrelin, although acylated ghrelin appeared to be more potent. Protection by both forms was also observed when neurons were exposed to the complex II inhibitor 3-NP. Both forms led to higher oxygen consumption rates upon electron transport chain uncoupling, indicating that the two peptides may exert uncoupling effects themselves. We demonstrate that the rescue provided by ghrelin required calcium influx through L-type voltage-gated calcium channels. Whereas the protective effects of acylated ghrelin required receptor binding, effects of the unacylated form remained unaffected by treatment with a ghrelin receptor antagonist. Importantly, inhibition of ghrelin O-acyltransferase failed to reduce the activity of unacylated ghrelin. Overall, our data suggest that both acylated and unacylated ghrelin afford protection to dopamine neurons but through mechanisms that only partially overlap. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Polybenzimidazole via aromatic nucleophilic displacement

NASA Technical Reports Server (NTRS)

Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor); Smith, Joseph G. (Inventor)

1994-01-01

Di(hydroxyphenyl)benzimidazole monomers were prepared from phenyl-4-hydroxybenzoate and aromatic bis(o-diamine)s. These monomers were used in the synthesis of soluble polybenzimidazoles. The reaction involved the aromatic nucleophilic displacement of various di(hydroxyphenyl)benzimidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds in the presence of an alkali metal base. These polymers exhibited lower glass transition temperatures, improved solubility, and better compression moldability over their commercial counterparts.

40 CFR 721.5288 - Chromate(2-), [3-hydroxy-4-[(2-hydroxy-1-naphthenyl)azo]-7-nitro-1-substituted][N-[7-hydroxy-8...

Code of Federal Regulations, 2010 CFR

2010-07-01

... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.5288 Chromate(2-), [3-hydroxy-4-[(2-hydroxy-1-naphthenyl)azo]-7-nitro-1-substituted][N-[7-hydroxy-8-[(2-hydroxy-5-nitrophenyl)azo]-1-substituted]-, salt (generic). (a) Chemical...

Identification of N-Acyl Phosphatidylserine Molecules in Eukaryotic Cells

PubMed Central

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

2008-01-01

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

Spectroscopic studies of the intramolecular hydrogen bonding in o-hydroxy Schiff bases, derived from diaminomaleonitrile, and their deprotonation reaction products

NASA Astrophysics Data System (ADS)

Szady-Chełmieniecka, Anna; Kołodziej, Beata; Morawiak, Maja; Kamieński, Bohdan; Schilf, Wojciech

2018-01-01

The structural study of five Schiff bases derived from diaminomaleonitrile (DAMN) and 2-hydroxy carbonyl compounds was performed using 1H, 13C and 15N NMR methods in solution and in the solid state as well. ATR-FTIR and X-Ray spectroscopies were used for confirmation of the results obtained by NMR method. The imine obtained from DAMN and benzaldehyde was synthesized as a model compound which lacks intramolecular hydrogen bond. Deprotonation of all synthesized compounds was done by treating with tetramethylguanidine (TMG). NMR data revealed that salicylidene Schiff bases in DMSO solution exist as OH forms without intramolecular hydrogen bonds and independent on the substituents in aromatic ring. In the case of 2-hydroxy naphthyl derivative, the OH proton is engaged into weak intramolecular hydrogen bond. Two of imines (salDAMN and 5-BrsalDAMN) exist in DMSO solution as equilibrium mixtures of two isomers (A and B). The structures of equilibrium mixture in the solid state have been studied by NMR, ATR-FTIR and X-Ray methods. The deprotonation of three studied compounds (salDAMN, 5-BrsalDAMN, and 5-CH3salDAMN) proceeded in two different ways: deprotonation of oxygen atom (X form) or of nitrogen atom of free primary amine group of DAMN moiety (Y form). For 5-NO2salDAMN and naphDAMN only one form (X) was observed.

Utilization of sophorolipids as biosurfactants for postemergence herbicides

USDA-ARS?s Scientific Manuscript database

Sophorolipids are carbohydrate-based, amphiphilic biosurfactants produced by several species of the Starmerella yeast clade. Most sophorolipids are partially acetylated sophorose sugars O-ß-glycosidically linked to 17-L-hydroxy-delta9-octadecenoic acid, where typically the acyl carboxyl group forms...

Acute aerobic exercise differentially alters acylated ghrelin and perceived fullness in normal-weight and obese individuals.

PubMed

Heden, Timothy D; Liu, Ying; Park, Youngmin; Dellsperger, Kevin C; Kanaley, Jill A

2013-09-01

Adiposity alters acylated ghrelin concentrations, but it is unknown whether adiposity alters the effect of exercise and feeding on acylated ghrelin responses. Therefore, the purpose of this study was to determine whether adiposity [normal-weight (NW) vs. obese (Ob)] influences the effect of exercise and feeding on acylated ghrelin, hunger, and fullness. Fourteen NW and 14 Ob individuals completed two trials in a randomized counterbalanced fashion, including a prior exercise trial (EX) and a no exercise trial (NoEX). During the EX trial, the participants performed 1 h of treadmill walking (55-60% peak O2 uptake) during the evening, 12 h before a 4-h standardized mixed meal test. Frequent blood samples were taken and analyzed for acylated ghrelin, and a visual analog scale was used to assess perceived hunger and fullness. In NW individuals, EX, compared with NoEX, reduced fasting acylated ghrelin concentrations by 18% (P = 0.03), and, in response to feeding, the change in acylated ghrelin (P = 0.02) was attenuated by 39%, but perceived hunger and fullness were unaltered. In Ob individuals, despite no changes in fasting or postprandial acylated ghrelin concentrations with EX, postprandial fullness was attenuated by 46% compared with NoEX (P = 0.05). In summary, exercise performed the night before a meal suppresses acylated ghrelin concentrations in NW individuals without altering perceived hunger or fullness. In Ob individuals, despite no changes in acylated ghrelin concentrations, EX reduced the fullness response to the test meal. Acylated ghrelin and perceived fullness responses are differently altered by acute aerobic exercise in NW and Ob individuals.

Copper-catalyzed, C-C coupling-based one-pot tandem reactions for the synthesis of benzofurans using o-iodophenols, acyl chlorides, and phosphorus ylides.

PubMed

Liu, Yunyun; Wang, Hang; Wan, Jie-Ping

2014-11-07

One-pot reactions involving acyl chlorides, phosphorus ylides, and o-iodophenols with copper catalysis have been established for the rapid synthesis of functionalized benzofurans. With all of these easily available and stable reactants, the construction of the target products has been accomplished via tandem transformations involving a key C-C coupling, leading to the formation of one C(sp(2))-C bond, one C(sp(2))-O bond, and one C ═ C bond.

The activities of acyl-CoA:1-acyl-lysophospholipid acyltransferase(s) in human platelets.

PubMed Central

Bakken, A M; Farstad, M

1992-01-01

The activities of acyl-CoA:1-acyl-lysophospholipid acyltransferases (EC 2.3.1.23) have been studied in human platelet lysates by using endogenously formed [14C]acyl-CoA from [14C]fatty acid, ATP and CoA in the presence of 1-acyl-lysophosphatidyl-choline (lysoPC), -ethanolamine (lysoPE), -serine (lysoPS) or -inositol (lysoPI). Linoleic acid as fatty acid substrate had the highest affinity to acyl-CoA:1-acyl-lysophospholipid acyltransferase with lysoPC as variable substrate, followed by eicosapentaenoic acid (EPA) and arachidonic acid (AA). The activity at optimal conditions was 7.4, 7.3 and 7.2 nmol/min per 10(9) platelets with lysoPC as substrate, with linoleic acid, AA and EPA respectively. EPA and AA were incorporated into all lyso-forms. Linoleic acid was also incorporated into lysoPE at a high rate, but less into lysoPS and lysoPI. DHA was incorporated into lysoPC and lysoPE, but only slightly into lysoPI and lysoPS. Whereas incorporation of all fatty acids tested was maximal for lysoPC and lysoPI at 200 and 80 microM respectively, maximal incorporation needed over 500 microM for lysoPE and lysoPS. The optimal concentration for [14C]fatty acid substrates was in the range 15-150 microM for all lysophospholipids. Competition experiments with equimolar concentrations of either lysoPC and lysoPI or lysoPE resulted in formation of [14C]PC almost as if lysoPI or lysoPE were not added to the assay medium. PMID:1471991

Catalytic conversion of isophorone to jet-fuel range aromatic hydrocarbons over a MoO(x)/SiO2 catalyst.

PubMed

Chen, Fang; Li, Ning; Wang, Wentao; Wang, Aiqin; Cong, Yu; Wang, Xiaodong; Zhang, Tao

2015-07-28

For the first time, jet fuel range C8-C9 aromatic hydrocarbons were synthesized in high carbon yield (∼80%) by the catalytic conversion of isophorone over MoO(x)/SiO2 at atmospheric pressure. A possible reaction pathway was proposed according to the control experiments and the intermediates generated during the reaction.

Two distinct domains contribute to the substrate acyl chain length selectivity of plant acyl-ACP thioesterase.

PubMed

Jing, Fuyuan; Zhao, Le; Yandeau-Nelson, Marna D; Nikolau, Basil J

2018-02-28

The substrate specificity of acyl-ACP thioesterase (TE) plays an essential role in controlling the fatty acid profile produced by type II fatty acid synthases. Here we identify two groups of residues that synergistically determine different substrate specificities of two acyl-ACP TEs from Cuphea viscosissima (CvFatB1 and CvFatB2). One group (V194, V217, N223, R226, R227, and I268 in CvFatB2) is critical in determining the structure and depth of a hydrophobic cavity in the N-terminal hotdog domain that binds the substrate's acyl moiety. The other group (255-RKLSKI-260 and 285-RKLPKL-289 in CvFatB2) defines positively charged surface patches that may facilitate binding of the ACP moiety. Mutagenesis of residues within these two groups results in distinct synthetic acyl-ACP TEs that efficiently hydrolyze substrates with even shorter chains (C4- to C8-ACPs). These insights into structural determinants of acyl-ACP TE substrate specificity are useful in modifying this enzyme for tailored fatty acid production in engineered organisms.

Regio- and Stereoselective Aliphatic-Aromatic Cross-Benzoin Reaction: Enzymatic Divergent Catalysis.

PubMed

Beigi, Maryam; Gauchenova, Ekaterina; Walter, Lydia; Waltzer, Simon; Bonina, Fabrizio; Stillger, Thomas; Rother, Dörte; Pohl, Martina; Müller, Michael

2016-09-19

The catalytic asymmetric synthesis of chiral 2-hydroxy ketones by using different thiamine diphosphate dependent enzymes, namely benzaldehyde lyase from Pseudomonas fluorescens (PfBAL), a variant of benzoylformate decarboxylase from Pseudomonas putida (PpBFD-L461A), branched-chain 2-keto acid decarboxylase from Lactococcus lactis (LlKdcA) and a variant of pyruvate decarboxylase from Acetobacter pasteurianus (ApPDC-E469G), was studied. Starting with the same set of substrates, substituted benzaldehydes in combination with different aliphatic aldehydes, PfBAL and PpBFD-L461A selectively deliver the (R)- and (S)-2-hydroxy-propiophenone derivatives, respectively. The (R)- and (S)-phenylacetylcarbinol (1-hydroxy-1-phenylacetone) derivatives are accessible in a similar way using LlKdcA and ApPDC-E469G, respectively. In many cases excellent stereochemical purities (>98 % enantiomeric excess) could be achieved. Hence, the regio- and stereochemistry of the product in the asymmetric aliphatic-aromatic cross-benzoin reaction can be controlled solely by choice of the appropriate enzyme or enzyme variant. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dose-response relationship between urinary polycyclic aromatic hydrocarbons metabolites and urinary 8-hydroxy-2'-deoxyguanosine in a Chinese general population.

PubMed

Sun, Huizhen; Hou, Jian; Zhou, Yun; Yang, Yuqing; Cheng, Juan; Xu, Tian; Xiao, Lili; Chen, Weihong; Yuan, Jing

2017-05-01

Association of exposure to polycyclic aromatic hydrocarbons (PAHs) with increased urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) formation has been reported in occupational population and children. However, studies on the association between them in general population are limited. A total of 1864 eligible subjects from the baseline Wuhan participants of the Wuhan-Zhuhai Cohort Study (n = 3053) were included in this study, after excluding individuals with certain disease and missing data on urinary monohydroxy PAHs (OH-PAHs) and 8-OHdG levels. Urinary monohydroxy PAHs and 8-OHdG levels were measured by gas chromatography-mass spectrometry and high performance liquid chromatography-electrochemical detection, respectively. Association of urinary OH-PAHs with urinary 8-OHdG was analyzed by multiple linear regression analysis. We found a dose-dependent relationship between urinary PAHs metabolites and urinary 8-OHdG (p < 0.05 for all). Furthermore, more evidence for the association of total concentrations of urinary OH-PAHs with 8-OHdG levels were observed in individuals with normal body mass index or central obesity (p < 0.01 for all). There was a dose-dependent relationship between urinary OH-PAHs levels and urinary 8-OHdG levels among a general Chinese population. Exposure to background PAHs may have a greater influence on urinary 8-OHdG levels in individuals with central obesity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of acyl donor chain length and substitutions pattern on the enzymatic acylation of flavonoids.

PubMed

Ardhaoui, M; Falcimaigne, A; Ognier, S; Engasser, J M; Moussou, P; Pauly, G; Ghoul, M

2004-06-10

Rutin and esculin were enzymatically acylated with different aliphatic acids as acyl donors (fatty acids, dicarboxylic acids and omega-substituted fatty acids) by an immobilized lipase from Candida antarctica. The effect of the water content and the acyl donors pattern on the flavonoid initial acylation rate and conversion yield were investigated. The obtained results indicated that the water content of the medium has a strong effect on the performance of these reactions. The best conversion yields were reached when the water content was kept lower than 200 ppm. At low water content of the medium, these syntheses are influenced by carbon chain length and substitution pattern of the acyl donors. Higher conversion yields of esculin and rutin (>70%) were obtained with aliphatic acids having high carbon chain length (>12). Moreover, it has been found that the amine and thiol groups on omega-substituted fatty acid chain were unfavourable to these reactions. The 1H NMR and 13C NMR analyses of some synthesized esters (esculin and rutin palmitate) show that only monoesters were produced and that the esterification takes place on the primary OH of glucose moiety of the esculin and on the secondary 4"'-OH of the rhamnose residue of rutin. Copyright 2004 Elsevier B.V.

Mutasynthesis of pyrrole spiroketal compound using calcimycin 3-hydroxy anthranilic acid biosynthetic mutant.

PubMed

Gou, Lixia; Wu, Qiulin; Lin, Shuangjun; Li, Xiangmei; Liang, Jingdan; Zhou, Xiufen; An, Derong; Deng, Zixin; Wang, Zhijun

2013-09-01

The five-membered aromatic nitrogen heterocyclic pyrrole ring is a building block for a wide variety of natural products. Aiming at generating new pyrrole-containing derivatives as well as to identify new candidates that may be of value in designing new anticancer, antiviral, and/or antimicrobial agents, we employed a strategy on pyrrole-containing compound mutasynthesis using the pyrrole-containing calcimycin biosynthetic gene cluster. We blocked the biosynthesis of the calcimycin precursor, 3-hydroxy anthranilic acid, by deletion of calB1-3 and found that two intermediates containing the pyrrole and the spiroketal moiety were accumulated in the culture. We then fed the mutant using the structurally similar compound of 3-hydroxy anthranilic acid. At least four additional new pyrrole spiroketal derivatives were obtained. The structures of the intermediates and the new pyrrole spiroketal derivatives were identified using LC-MS and NMR. One of them shows enhanced antibacterial activity. Our work shows a new way of pyrrole derivative biosynthetic mutasynthesis.

Chlamydia trachomatis Scavenges Host Fatty Acids for Phospholipid Synthesis via an Acyl-Acyl Carrier Protein Synthetase*

PubMed Central

Yao, Jiangwei; Dodson, V. Joshua; Frank, Matthew W.; Rock, Charles O.

2015-01-01

The obligate intracellular parasite Chlamydia trachomatis has a reduced genome but relies on de novo fatty acid and phospholipid biosynthesis to produce its membrane phospholipids. Lipidomic analyses showed that 8% of the phospholipid molecular species synthesized by C. trachomatis contained oleic acid, an abundant host fatty acid that cannot be made by the bacterium. Mass tracing experiments showed that isotopically labeled palmitic, myristic, and lauric acids added to the medium were incorporated into C. trachomatis-derived phospholipid molecular species. HeLa cells did not elongate lauric acid, but infected HeLa cell cultures elongated laurate to myristate and palmitate. The elongated fatty acids were incorporated exclusively into C. trachomatis-produced phospholipid molecular species. C. trachomatis has adjacent genes encoding the separate domains of the bifunctional acyl-acyl carrier protein (ACP) synthetase/2-acylglycerolphosphoethanolamine acyltransferase gene (aas) of Escherichia coli. The CT775 gene encodes an acyltransferase (LpaT) that selectively transfers fatty acids from acyl-ACP to the 1-position of 2-acyl-glycerophospholipids. The CT776 gene encodes an acyl-ACP synthetase (AasC) with a substrate preference for palmitic compared with oleic acid in vitro. Exogenous fatty acids were elongated and incorporated into phospholipids by Escherichia coli-expressing AasC, illustrating its function as an acyl-ACP synthetase in vivo. These data point to an AasC-dependent pathway in C. trachomatis that selectively scavenges host saturated fatty acids to be used for the de novo synthesis of its membrane constituents. PMID:26195634

Versatility of acyl-acyl carrier protein synthetases

DOE PAGES

Beld, Joris; Finzel, Kara; Burkart, Michael D.

2014-10-09

The acyl carrier protein (ACP) requires posttranslational modification with a 4'-phosphopantetheine arm for activity, and this thiol-terminated modification carries cargo between enzymes in ACP-dependent metabolic pathways. In this paper, we show that acyl-ACP synthetases (AasSs) from different organisms are able to load even, odd, and unnatural fatty acids onto E. coli ACP in vitro. Vibrio harveyi AasS not only shows promiscuity for the acid substrate, but also is active upon various alternate carrier proteins. AasS activity also extends to functional activation in living organisms. We show that exogenously supplied carboxylic acids are loaded onto ACP and extended by the E.more » coli fatty acid synthase, including unnatural fatty acid analogs. These analogs are further integrated into cellular lipids. Finally, in vitro characterization of four different adenylate-forming enzymes allowed us to disambiguate CoA-ligases and AasSs, and further in vivo studies show the potential for functional application in other organisms.« less

Polyphenylquinoxalines via aromatic nucleophilic displacement

NASA Technical Reports Server (NTRS)

Hergenrother, Paul M. (Inventor); Connell, John W. (Inventor)

1990-01-01

Polyphenylquinoxalines are prepared by the nucleophilic displacement reaction of di(hydroxyphenyl)quinoxaline monomers with activated aromatic dihalides or dinitro compounds. The reactions are carried out in polar aprotic solvents using alkali metal bases at elevated temperatures under nitrogen. The di(hydroxyphenyl)quinoxaline monomers are prepared either by reacting stoichiometric quantities of aromatic bis(o-diamines) with a hydroxybenzil or by reacting o-phenylenediamine with a dihydroxybenzil or bis(hydroxyphenylglyoxylyl)benzene.

Polyphenylquinoxalines via aromatic nucleophilic displacement

NASA Technical Reports Server (NTRS)

Hergenrother, Paul M. (Inventor); Connell, John W. (Inventor)

1991-01-01

Polyphenylquinoxalines are prepared by the nucleophilic displacement reaction of di(hydroxyphenyl)quinoxaline monomers with activated aromatic dihalides or dinitro compounds. The reactions are carried out in polar aprotic solvents during alkali metal bases at elevated temperatures under nitrogen. The di(hydroxyphenyl)quinoxaline monomers are prepared either by reacting stoichiometric quantities of aromatic bis(o-diamines) with a hydroxybenzil or by reacting o-phenylenediamine with a dihydroxybenzil or bis(hydroxyphenylglyoxylyl)benzene.

α-Amidoalkylating agents from N-acyl-α-amino acids: 1-(N-acylamino)alkyltriphenylphosphonium salts.

PubMed

Mazurkiewicz, Roman; Adamek, Jakub; Październiok-Holewa, Agnieszka; Zielińska, Katarzyna; Simka, Wojciech; Gajos, Anna; Szymura, Karol

2012-02-17

N-Acyl-α-amino acids were efficiently transformed in a two-step procedure into 1-N-(acylamino)alkyltriphenylphosphonium salts, new powerful α-amidoalkylating agents. The effect of the α-amino acid structure, the base used [MeONa or a silica gel-supported piperidine (SiO(2)-Pip)], and the main electrolysis parameters (current density, charge consumption) on the yield and selectivity of the electrochemical decarboxylative α-methoxylation of N-acyl-α-amino acids (Hofer-Moest reaction) was investigated. For most proteinogenic and all studied unproteinogenic α-amino acids, very good results were obtained using a substoichiometric amount of SiO(2)-Pip as the base. Only in the cases of N-acylated cysteine, methionine, and tryptophan, attempts to carry out the Hofer-Moest reaction in the applied conditions failed, probably because of the susceptibility of these α-amino acids to an electrochemical oxidation on the side chain. The methoxy group of N-(1-methoxyalkyl)amides was effectively displaced with the triphenylphosphonium group by dissolving an equimolar amount of N-(1-methoxyalkyl)amide and triphenylphosphonium tetrafluoroborate in CH(2)Cl(2) at room temperature for 30 min, followed by the precipitation of 1-N-(acylamino)alkyltriphenylphosphonium salt with Et(2)O.

A hydroxycinnamoyltransferase responsible for synthesizing suberin aromatics in Arabidopsis

PubMed Central

Gou, Jin-Ying; Yu, Xiao-Hong; Liu, Chang-Jun

2009-01-01

Suberin, a polyester polymer in the cell wall of terrestrial plants, controls the transport of water and nutrients and protects plant from pathogenic infections and environmental stresses. Structurally, suberin consists of aliphatic and aromatic domains; p-hydroxycinnamates, such as ferulate, p-coumarate, and/or sinapate, are the major phenolic constituents of the latter. By analyzing the “wall-bound” phenolics of mutant lines of Arabidopsis deficient in a family of acyl-CoA dependent acyltransferase (BAHD) genes, we discovered that the formation of aromatic suberin in Arabidopsis, primarily in seed and root tissues, depends on a member of the BAHD superfamily of enzymes encoded by At5g41040. This enzyme exhibits an ω-hydroxyacid hydroxycinnamoyltransferase activity with an in vitro kinetic preference for feruloyl-CoA and 16-hydroxypalmitic acid. Knocking down or knocking out the At5g41040 gene in Arabidopsis reduces specifically the quantity of ferulate in suberin, but does not affect the accumulation of p-coumarate or sinapate. The loss of the suberin phenolic differentially affects the aliphatic monomer loads and alters the permeability and sensitivity of seeds and roots to salt stress. This highlights the importance of suberin aromatics in the polymer's function. PMID:19846769

Photoinduced interaction studies on N-(2-methylthiophenyl)-2-hydroxy-1-naphthadiamine with TiO2 nanoparticles: a combined experimental and theoretical (DFT and spectroscopic) approach.

PubMed

Pushpam, S; Gayathri, S; Ramakrishnan, V

2014-12-10

Schiff base derivative synthesized by the reaction of 2-(methylthio) aniline and 2-hydroxy-1-naphthaldehyde exhibits keto-amine tautomerism in methanol solvent. The fluorescence quenching of N-(2-methyl thiophenyl)-2-hydroxy-1-naphthadiamine (NMTHN) by TiO2 nanoparticles in methanol has been studied. The excitation and emission peaks have been observed at 439 and 509nm respectively. The apparent association constant has been deduced from the absorption spectral changes of NMTHN-TiO2 nanoparticles using Bensi-Hildebrand equation. The number of binding sites and the binding constant have been calculated from the relevant fluorescence data. Quenching of fluorescence of NMTHN by TiO2 could be due to a dynamic mode. Density Functional Theory (DFT) calculations also have been performed to study the charge distribution of NMTHN-TiO2 both in ground and excited states. The HOMO-LUMO analysis of NMTHN-TiO2 in the ground state has been made. Copyright © 2014 Elsevier B.V. All rights reserved.

Increasing the Aromatic Selectivity of Quinoline Hydrogenolysis Using Pd/MOx–Al2O3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bachrach, Mark; Morlanes-Sanchez, Natalia; Canlas, Christian P.

2014-09-11

Catalysts consisting of Pd nanoparticles supported on highly dispersed TiOx–Al2O3, TaOx–Al2O3, and MoOx–Al2O3 are studied for catalytic quinoline hydrogenation and selective C–N bond cleavage at 275 °C and 20 bar H2. The Pd/MOx–Al2O3 materials exhibit significantly greater aromatic product selectivity and thus 10–15 % less required H2 for a given level of denitrogenation relative to an unmodified Pd/Al2O3 catalyst.

N-acyl-homoserine lactone-mediated quorum-sensing in Azospirillum: an exception rather than a rule.

PubMed

Vial, Ludovic; Cuny, Caroline; Gluchoff-Fiasson, Katia; Comte, Gilles; Oger, Phil M; Faure, Denis; Dessaux, Yves; Bally, René; Wisniewski-Dyé, Florence

2006-11-01

Forty Azospirillum strains were tested for their ability to synthesize N-acyl-homoserine lactones (AHLs). AHL production was detected for four strains belonging to the lipoferum species and isolated from a rice rhizosphere. AHL molecules were structurally identified for two strains: Azospirillum lipoferum TVV3 produces 3O,C(8)-HSL (N-3-oxo-octanoyl-homoserine-lactone), C(8)-HSL (N-3-octanoyl-homoserine-lactone), 3O,C(10)-HSL (N-3-oxo-decanoyl-homoserine-lactone), 3OH,C(10)-HSL (N-3-hydroxy-decanoyl-homoserine-lactone) and C(10)-HSL (N-3-decanoyl-homoserine-lactone), whereas A. lipoferum B518 produced 3O,C(6)-HSL (N-3-oxo-hexanoyl-homoserine-lactone), C(6)-HSL (N-3-hexanoyl-homoserine-lactone), 3O,C(8)-HSL, 3OH,C(8)-HSL and C(8)-HSL. Genes involved in AHL production were characterized for A. lipoferum TVV3 by generating a genomic library and complementing an AHL-deficient strain with sensor capabilities. Those genes, designated alpI and alpR, were found to belong to the luxI and luxR families, respectively. When cloned in a suitable heterologous host, alpI and alpR could direct the synthesis of the five cognate AHLs present in A. lipoferum TVV3. These two adjacent genes were found to be located on a 85 kb plasmid. Southern hybridization experiments with probes alpI/R indicated that genes involved in AHL production in the three other AHL-producing strains were not closely related to alpI and alpR. This study demonstrates that AHL-based quorum-sensing is not widespread among the genus Azospirillum and could be found only in some A. lipoferum strains.

Rabbit N-acetyltransferase 2 genotyping method to investigate role of acetylation polymorphism on N- and O-acetylation of aromatic and heterocyclic amine carcinogens.

PubMed

Hein, David W; Doll, Mark A

2017-09-01

The rabbit was the initial animal model to investigate the acetylation polymorphism expressed in humans. Use of the rabbit model is compromised by lack of a rapid non-invasive method for determining acetylator phenotype. Slow acetylator phenotype in the rabbit results from deletion of the N-acetyltransferase 2 (NAT2) gene. A relatively quick and non-invasive method for identifying the gene deletion was developed and acetylator phenotypes confirmed by measurement of N- and O-acetyltransferase activities in hepatic cytosols. Rabbit liver cytosols catalyzed the N-acetylation of sulfamethazine (p = 0.0014), benzidine (p = 0.0257), 4-aminobiphenyl (p = 0.0012), and the O-acetylation of N-hydroxy-2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (N-OH-PhIP; p = 0.002) at rates significantly higher in rabbits possessing NAT2 gene than rabbits with NAT2 gene deleted. In contrast, hepatic cytosols catalyzed the N-acetylation of p-aminobenzoic acid (an N-acetyltransferase 1 selective substrate) at rates that did not differ significantly (p > 0.05) between rabbits positive and negative for NAT2. The new NAT2 genotyping method facilitates use of the rabbit model to investigate the role of acetylator polymorphism in the metabolism of aromatic and heterocyclic amine drugs and carcinogens.

Identification, quantification and antioxidant activity of acylated flavonol glycosides from sea buckthorn (Hippophae rhamnoides ssp. sinensis).

PubMed

Chen, Chu; Xu, Xue-Min; Chen, Yang; Yu, Meng-Yao; Wen, Fei-Yan; Zhang, Hao

2013-12-01

A novel acylated flavonol glycoside: isorhamnetin (3-O-[(6-O-E-sinapoyl)-β-D-glucopyranosyl-(1→2)]-β-D-glucopyranosyl-7-O-α-L-rhamnopyranoside) (1), together with two known acylated flavonol glycosides: quercetin (3-O-[(6-O-E-sinapoyl)-β-D-glucopyranosyl-(1→2)]-β-D-glucopyranosyl-7-O-α-L-rhamnopyranoside) (2) and kaempferol (3-O-[(6-O-E-sinapoyl)-β-D-glucopyranosyl-(1→2)]-β-D-glucopyranosyl-7-O-α-L-rhamnopyranoside) (3) were isolated from the n-butanol fraction of sea buckthorn (Hippophae rhamnoides ssp. sinensis) berries for the first time by chromatographic methods, and their structures were elucidated using UV, MS, (1)H and (13)C NMR, and 2D NMR. Compounds 1-3 showed good scavenging activities, with respective IC50 values of 8.91, 4.26 and 30.90 μM toward the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical; respective Trolox equivalent antioxidant capacities of 2.89, 4.04 and 2.44 μM μM(-1) toward 2,2'-azino-bis-3-ethyl-benzothiazoline-6-sulphonate (ABTS) radical. The quantitative analysis of the isolated acylated flavonol glycosides was performed by HPLC-DAD method. The contents of compounds 1-3 were in the range of 12.2-31.4, 4.0-25.3, 7.5-59.7 mg/100 g dried berries and 9.1-34.5, 75.1-182.1, 29.2-113.4 mg/100 g dried leaves, respectively. Copyright © 2013. Published by Elsevier Ltd.

Spectroscopic studies of the intramolecular hydrogen bonding in o-hydroxy Schiff bases, derived from diaminomaleonitrile, and their deprotonation reaction products.

PubMed

Szady-Chełmieniecka, Anna; Kołodziej, Beata; Morawiak, Maja; Kamieński, Bohdan; Schilf, Wojciech

2018-01-15

The structural study of five Schiff bases derived from diaminomaleonitrile (DAMN) and 2-hydroxy carbonyl compounds was performed using 1 H, 13 C and 15 N NMR methods in solution and in the solid state as well. ATR-FTIR and X-Ray spectroscopies were used for confirmation of the results obtained by NMR method. The imine obtained from DAMN and benzaldehyde was synthesized as a model compound which lacks intramolecular hydrogen bond. Deprotonation of all synthesized compounds was done by treating with tetramethylguanidine (TMG). NMR data revealed that salicylidene Schiff bases in DMSO solution exist as OH forms without intramolecular hydrogen bonds and independent on the substituents in aromatic ring. In the case of 2-hydroxy naphthyl derivative, the OH proton is engaged into weak intramolecular hydrogen bond. Two of imines (salDAMN and 5-BrsalDAMN) exist in DMSO solution as equilibrium mixtures of two isomers (A and B). The structures of equilibrium mixture in the solid state have been studied by NMR, ATR-FTIR and X-Ray methods. The deprotonation of three studied compounds (salDAMN, 5-BrsalDAMN, and 5-CH 3 salDAMN) proceeded in two different ways: deprotonation of oxygen atom (X form) or of nitrogen atom of free primary amine group of DAMN moiety (Y form). For 5-NO 2 salDAMN and naphDAMN only one form (X) was observed. Copyright © 2017 Elsevier B.V. All rights reserved.

Inverse kinetic solvent isotope effect in TiO2 photocatalytic dehalogenation of non-adsorbable aromatic halides: a proton-induced pathway.

PubMed

Chang, Wei; Sun, Chunyan; Pang, Xibin; Sheng, Hua; Li, Yue; Ji, Hongwei; Song, Wenjing; Chen, Chuncheng; Ma, Wanhong; Zhao, Jincai

2015-02-09

An efficient redox reaction between organic substrates in solution and photoinduced h(+) vb /e(-) cb on the surface of photocatalysts requires the substrates or solvent to be adsorbed onto the surface, and is consequentially marked by a normal kinetic solvent isotope effect (KSIE ≥ 1). Reported herein is a universal inverse KSIE (0.6-0.8 at 298 K) for the reductive dehalogenation of aromatic halides which cannot adsorb onto TiO2 in a [D0 ]methanol/[D4 ]methanol solution. Combined with in situ ATR-FTIR spectroscopy investigations, a previously unknown pathway for the transformation of these aromatic halides in TiO2 photocatalysis was identified: a proton adduct intermediate, induced by released H(+) /D(+) from solvent oxidation, accompanies a change in hybridization from sp(2) to sp(3) at a carbon atom of the aromatic halides. The protonation event leads these aromatic halides to adsorb onto the TiO2 surface and an ET reaction to form dehalogenated products follows. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Increasing the Aromatic Selectivity of Quinoline Hydrogenolysis Using Pd/MO x–Al 2O 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bachrach, Mark; Morlanes-Sanchez, Natalia; Canlas, Christian P.

2014-09-11

Catalysts consisting of Pd nanoparticles supported on highly dispersed TiO x–Al 2O 3, TaO x–Al 2O 3, and MoO x–Al 2O 3 are studied for catalytic quinoline hydrogenation and selective C–N bond cleavage at 275 °C and 20 bar H 2. Lastly, the Pd/MO x–Al 2O 3 materials exhibit significantly greater aromatic product selectivity and thus 10–15 % less required H 2 for a given level of denitrogenation relative to an unmodified Pd/Al 2O 3 catalyst.

Novel approach in LC-MS/MS using MRM to generate a full profile of acyl-CoAs: discovery of acyl-dephospho-CoAs.

PubMed

Li, Qingling; Zhang, Shenghui; Berthiaume, Jessica M; Simons, Brigitte; Zhang, Guo-Fang

2014-03-01

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.

Regioselective and stereospecific acylation across oxirane- and silyloxy systems as a novel strategy to the synthesis of enantiomerically pure mono-, di- and triglycerides.

PubMed

Stamatov, Stephan D; Stawinski, Jacek

2007-12-07

A trifluoroacetate-catalyzed opening of the oxirane ring of glycidyl derivatives bearing allylic acyl or alkyl functionalities with trifluoroacetic anhydride (TFAA), provides an efficient entry to configurationally homogeneous 1(3)-acyl- or 1(3)-O-alkyl-sn-glycerols. Selective introduction of tert-butyldimethylsilyl- (TBDMS), or triisopropylsilyl- (TIPS) transient protections at the terminal sites within these key intermediates secures 1(3)-acyl- or 1(3)-O-alkyl-3(1)-O-TBDMS (or TIPS)-sn-glycerols as general bifunctional precursors to 1,2(2,3)-diacyl-, 1(3)-O-alkyl-2-acyl- and 1,3-diacyl-sn-glycerols and hence triester isosters. Incorporation of a requisite acyl residue at the central carbon of the silylated synthons with a subsequent Et(3)N.3HF-promoted, direct trichloroacetylation across the siloxy system by trichloroacetic anhydride (TCAA), followed by cleavage of the trichloroacetyl group, affords the respective 1,2(2,3)-diacyl- or 1(3)-O-alkyl-2-acyl-sn-glycerols. Alternatively, a reaction sequence involving: (i) attachment of a trichloroacetyl fragment at the stereogenic C2-centre of the monosilylated glycerides; (ii) replacement of the silyl moiety by a short- or long-chain carboxylic acid residue by means of the acylating agent: tetra-n-butylammonium bromide (TBABr)-carboxylic acid anhydride (CAA)-trimethylsilyl bromide (TMSBr); and (iii) removal of the trichloroacetyl replacement, provides pure 1,3-diacyl-sn-glycerols. The TBABr-CAA-TMSBr reagent system allows also a one-step conversion of 1,2-diacylglycerol silyl ethers into homochiral triglycerides with predefined asymmetry and degree of unsaturation. These compounds can also be accessed via a two-step one-pot approach where the trichloroacetyl derivatives of 1,2(2,3)- or 1,3-diacyl-sn-glycerols serve as triester building blocks for establishing the third ester bond at preselected C3(1)- or C2-positions within the glycerol skeleton at the very last synthetic stage. In all instances, the target compounds

Tandem Cu-catalyzed ketenimine formation and intramolecular nucleophile capture: Synthesis of 1,2-dihydro-2-iminoquinolines from 1-(o-acetamidophenyl)propargyl alcohols

PubMed Central

Kant, Ruchir

2014-01-01

Summary The copper-catalyzed ketenimine formation reaction of 1-(o-acetamidophenyl)propargyl alcohols with various sulfonyl azides is found to undergo a concomitant intramolecular nucleophile attack to generate 1,2-dihydro-2-iminoquinolines after aromatization (via elimination of acetyl and hydroxy groups) and tautomerization. The reaction produces 4-substituted and 3,4-unsubstituted title compounds in moderate to good yields under mild reaction conditions. PMID:24991276

40 CFR 721.10107 - Naphthalenedisulfonic acid, [amino-hydroxy-[(substituted)azo-sulfo-naphthaleneyl]azo]-hydroxy...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Naphthalenedisulfonic acid, [amino... Specific Chemical Substances § 721.10107 Naphthalenedisulfonic acid, [amino-hydroxy-[(substituted)azo-sulfo... naphthalenedisulfonic acid, [amino-hydroxy-[(substituted)azo-sulfo-naphthaleneyl]azo]-hydroxy-[(methoxy-sulfophenyl)azo...

40 CFR 721.10107 - Naphthalenedisulfonic acid, [amino-hydroxy-[(substituted)azo-sulfo-naphthaleneyl]azo]-hydroxy...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Naphthalenedisulfonic acid, [amino... Specific Chemical Substances § 721.10107 Naphthalenedisulfonic acid, [amino-hydroxy-[(substituted)azo-sulfo... naphthalenedisulfonic acid, [amino-hydroxy-[(substituted)azo-sulfo-naphthaleneyl]azo]-hydroxy-[(methoxy-sulfophenyl)azo...

Supramolecular aromaticity

NASA Astrophysics Data System (ADS)

Karabıyık, Hande; Sevinçek, Resul; Karabıyık, Hasan

2014-05-01

We report experimental and theoretical evidences for supramolecular aromaticity as a new concept to be widely used in researches about molecular crystals. CSD survey regarding frequently encountered resonance-assisted H-bonds (RAHBs) in formic acid, formamide, formimidamide, formic acid-formamide, and formamide-formimidamide dimers shows that supramolecular quasirings formed by RAHBs have remarkable electronic delocalization within themselves, which is reminiscent of aromaticity at supramolecular level. This study criticizes and reevaluates the validity of conventional judgment which states that ring systems formed by intermolecular H-bonds cannot be aromatic. Thus, the term aromaticity can be extended to supramolecular systems formed by RAHBs. Supramolecular aromaticity has a multi-fold nature involving both σ- and π-delocalization, and σ-delocalization through RAHBs takes on a task of compensating σ-deficiency within quasirings. Atomic composition in donor-acceptor set of the dimers is descriptive for supramolecular aromaticity. We revised bond-valence parameters for RAHBs and they suggest that hypervalent character of H atoms is more pronounced than their hypovalent character in RAHBs. The σ-delocalized bonding within H-bonded quasirings necessitates hypervalent character of H atoms. Quantum chemical calculations based on adiabatic Hydrogen Atom Transfer (HAT) between the monomers reveal that topological parameters at ring critical points (RCPs) of the quasirings correlate well with Shannon's entropic aromaticity index. The presence of additional LP orbital on O atoms implying more diffused LP-orbitals in donor-acceptor set leads to the formation of resonance-disabling states reducing supramolecular aromaticity of a quasiring and energetic cost of the electron transfer between the monomers. There is a nonignorable electron transfer between the monomers even in the cases where H atoms are close to donor or acceptor atom. NBO analyses have revealed that

4-[(E)-(2,4-Difluoro-phen-yl)(hydroxy-imino)meth-yl]piperidinium picrate.

PubMed

Jasinski, Jerry P; Butcher, Ray J; Yathirajan, H S; Mallesha, L; Mohana, K N

2009-09-05

The title compound, C(12)H(15)F(2)N(2)O(+)·C(6)H(2)N(3)O(7) (-), a picrate salt of 4-[(E)-(2,4-difluoro-phen-yl)(hydroxy-imino)meth-yl]piper-idine, crystallizes with two independent mol-ecules in a cation-anion pair in the asymmetric unit. In the cation, a methyl group is tris-ubstituted by hydroxy-imino, piperidin-4-yl and 2,4-difluoro-phenyl groups, the latter of which contains an F atom disordered over two positions in the ring [occupancy ratio 0.631 (4):0.369 (4)]. The mean plane of the hydr-oxy group is in a synclinical conformation nearly orthogonal [N-C-C-C = 72.44 (19)°] to the mean plane of the piperidine ring, which adopts a slightly distorted chair conformation. The dihedral angle between the mean plane of the 2,4-difluoro-phenyl and piperidin-4-yl groups is 60.2 (3)°. In the picrate anion, the mean planes of the two o-NO(2) and single p-NO(2) groups adopt twist angles of 5.7 (2), 25.3 (7) and 8.3 (6)°, respectively, with the attached planar benzene ring. The dihedral angle between the mean planes of the benzene ring in the picrate anion and those in the hydroxy-imino, piperidin-4-yl and 2,4-difluoro-phenyl groups in the cation are 84.9 (7), 78.9 (4) and 65.1 (1)°, respectively. Extensive hydrogen-bond inter-actions occur between the cation-anion pair, which help to establish the crystal packing in the unit cell. This includes dual three-center hydrogen bonds with the piperidin-4-yl group, the phenolate and o-NO(2) O atoms of the picrate anion at different positions in the unit cell, which form separate N-H⋯(O,O) bifurcated inter-molecular hydrogen-bond inter-actions. Also, the hydr-oxy group forms a separate hydrogen bond with a nearby piperidin-4-yl N atom, thus providing two groups of hydrogen bonds, which form an infinite two-dimensional network along (011).

Alkyl group effects on CO insertion into coordinatively unsaturated early-transition-metal alkyls. Preparations and the first structural characterizations of tantalum enolate-O and tantalum. eta. sup 2 -acyl complexes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meyer, T.Y.; Garner, L.R.; Baenziger, N.C.

1990-10-03

Low-pressure carbonylation of the mono(peralkylcyclopentadienyl)tantalum(V) alkyls ({eta}-C{sub 5}Me{sub 4}R)TaR{prime}Cl{sub 3} (R = Me, Et; R{prime} = CH{sub 2}C{sub 6}H{sub 4}-p-Me, CH{sub 2}CMe{sub 3}) yields either the O-bound enolate or the {eta}{sup 2}-acyl as shown by ir/NMR spectroscopy and x-ray diffractometry. The p-tolyl enolate ({eta}-C{sub 5}Me{sub 5})Ta(OCH{double bond}CHC{sub 6}H{sub 4}-p-Me)Cl{sub 3}, derived directly from carbonylation of the tantalum 4-methylbenzyl precursor, is shown to possess a cis configuration in solution and in the solid state. Key structural features from a single-crystal x-ray diffraction study of the tetrahydrofuran-ligated enolate complex are reported. The mechanism of formation of the enolate from carbonylation of themore » 4-methylbenzyl complex is discussed. The previously reported acyl ({eta}-C{sub 5}Me{sub 4}R)Ta(C(O)CH{sub 2}CMe{sub 3})Cl{sub 3} has been reexamined and found to possess a symmetric, strongly distorted {eta}{sup 2}-acyl coordination by solution {sup 1}H NMR spectroscopy and solid-state x-ray diffractometry. The molecular structures of ({eta}-C{sub 5}Me{sub 5})Ta(OCH{double bond}CHC{sub 6}H{sub 4}-p-Me)Cl{sub 3} and ({eta}-C{sub 5}Me{sub 5})Ta(C(O)CH{sub 2}CMe{sub 3})Cl{sub 3}, which are reported here, are the first structural determinations of a tantalum enolate and of a tantalum {eta}{sup 2}-acyl. 41 refs., 2 figs., 8 tabs.« less

Age-dependent decline in acyl-ghrelin concentrations and reduced association of acyl-ghrelin and growth hormone in healthy older adults.

PubMed

Nass, Ralf; Farhy, Leon S; Liu, Jianhua; Pezzoli, Suzan S; Johnson, Michael L; Gaylinn, Bruce D; Thorner, Michael O

2014-02-01

Acyl-ghrelin is thought to have both orexigenic effects and to stimulate GH release. A possible cause of the anorexia of aging is an age-dependent decrease in circulating acyl-ghrelin levels. The purpose of the study was to compare acyl-ghrelin and GH concentrations between healthy old and young adults and to examine the relationship of acyl-ghrelin and GH secretion in both age groups. Six healthy older adults (age 62-74 y, body mass index range 20.9-29 kg/m(2)) and eight healthy young men (aged 18-28 y, body mass index range 20.6-26.2 kg/m(2)) had frequent blood samples drawn for hormone measurements every 10 minutes for 24 hours. Ghrelin was measured in an in-house, two-site sandwich ELISA specific for full-length acyl-ghrelin. GH was measured in a sensitive assay (Immulite 2000), and GH peaks were determined by deconvolution analysis. The acyl-ghrelin/GH association was estimated from correlations between amplitudes of individual GH secretory events and the average acyl-ghrelin concentration in the 60-minute interval preceding each GH burst. Twenty-four-hour mean (±SEM) GH (0.48 ± 0.14 vs 2.2 ± 0.3 μg/L, P < .005) and acyl-ghrelin (14.7 ± 2.3 vs 27.8 ± 3.9 pg/mL, P < .05) levels were significantly lower in older adults compared with young adults. Twenty-four-hour cortisol concentrations were higher in the old than the young adults (15.1 ± 1.0 vs 10.6 ± 0.9 μg/dL, respectively, P < .01). The ghrelin/GH association was more than 3-fold lower in the older group compared with the young adults (0.16 ± 0.12 vs 0.69 ± 0.04, P < .001). These results provide further evidence of an age-dependent decline in circulating acyl-ghrelin levels, which might play a role both in the decline of GH and in the anorexia of aging. Our data also suggest that with normal aging, endogenous acyl-ghrelin levels are less tightly linked to GH regulation.

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

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

PubMed

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

1995-03-01

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.

Production of a Brassica napus low-molecular mass acyl-coenzyme A-binding protein in Arabidopsis alters the acyl-coenzyme A pool and acyl composition of oil in seeds

USDA-ARS?s Scientific Manuscript database

Low-molecular mass (10 kD) cytosolic acyl-coenzyme A-binding protein (ACBP) has a substantial influence over fatty acid (FA) composition in oilseeds, possibly via an effect on the partitioning of acyl groups between elongation and desaturation pathways. Previously, we demonstrated that the expressio...

Comparative study of n-hexane aromatization on Pt/KL, Pt/Mg(Al)O, and Pt/SiO{sub 2} catalysts: Clean and sulfur-containing feeds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacobs, G.; Padro, C.L.; Resasco, D.E.

The n-hexane aromatization has been studied on Pt/KL, Pt/Mg(Al)O, and Pt/SiO{sub 2} catalysts at 773 K using sulfur-free and 0.6 ppm sulfur containing feedstocks. Examination of the product distribution as a function of conversion suggests that the formation of benzene is preceded by the formation of hexenes. In contrast with previous reports, it has been found that the Pt/KL catalyst exhibits much higher aromatization activity than the Pt/Mg(Al)O catalyst. On Pt/KL the main product is benzene, with hexenes and lighter compounds as the principal by-products. By contrast, on the Pt/Mg(Al)O, the main products were hexenes. Since hexenes are primary productsmore » and benzene is a secondary product, the exceptional aromatization activity of Pt/KL is explained in terms of its ability to convert hexene into benzene. In the presence of sulfur, the Pt/KL exhibits a rapid loss in n-hexane conversion and benzene selectivity. Under these conditions, the sulfided Pt/KL catalyst presents a catalytic behavior typical of Pt/Mg(Al)O and Pt/SiO{sub 2}, generating larger amounts of hexenes. The observed results are consistent with the hypothesis that the most important role of the zeolite is to inhibit bimolecular interactions that lead to coke formation. The formation of coke has the net effect of selectively deactivating aromatization sites which require a large ensemble of atoms to constitute the active site but not affecting the dehydrogenation activity which is less ensemble-sensitive. Therefore, those particles that are not protected against coking inside the channels of the zeolite rapidly become unselective. In support of this hypothesis, the hydrogenolysis reaction which also requires a large ensemble of atoms, decreases in parallel with the aromatization reaction. The high sensitivity of Pt/KL to sulfur may be due to a combination of effects which may involve growth of metal particles outside the zeolite which would become unselective and partial poisoning of the

Polybenzimidazoles Via Aromatic Nucleophilic Displacement

NASA Technical Reports Server (NTRS)

Connell, John W. (Inventor); Hergerrother, Paul M. (Inventor); Smith, Joseph G., Jr. (Inventor)

1997-01-01

Novel molecular weight controlled and endcapped polybenzimidazoles (PBI) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenylbenzimidazole) monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The PBI are endcapped with mono(hydroxyphenyl)benzimidazoles. The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. Mono(hydroxyphenyl)benzimidazoles are synthesized by reacting phenyl-4-hydroxybenzoate with aromatic (o-diamine)s in diphenylsulfone. Molecular weight controlled and endcapped PBI of new chemical structures are prepared that exhibit a favorable combination of physical and mechanical properties.

Polybenzimidazoles via aromatic nucleophilic displacement

NASA Technical Reports Server (NTRS)

Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor); Smith, Joseph G., Jr. (Inventor)

1995-01-01

Novel molecular weight controlled and endcapped polybenzimidazoles (PBI) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl benzimidazole) monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The PBI are endcapped with mono(hydroxyphenyl) benzimidazoles. The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. Mono(hydroxyphenyl) benzimidazoles are synthesizedby reacting phenyl-4-hydroxybenzoate with aromatic (o-diamine)s in diphenylsulfone. Molecular weight controlled and endcapped PBI of new chemical structures are prepared that exhibit a favorable combination of physical and mechanical properties.

Metabolic Engineering for Enhanced Medium Chain Omega Hydroxy Fatty Acid Production in Escherichia coli

PubMed Central

Xiao, Kang; Yue, Xiu-Hong; Chen, Wen-Chao; Zhou, Xue-Rong; Wang, Lian; Xu, Lin; Huang, Feng-Hong; Wan, Xia

2018-01-01

Medium chain hydroxy fatty acids (HFAs) at ω-1, 2, or 3 positions (ω-1/2/3) are rare in nature but are attractive due to their potential applications in industry. They can be metabolically engineered in Escherichia coli, however, the current yield is low. In this study, metabolic engineering with P450BM3 monooxygenase was applied to regulate both the chain length and sub-terminal position of HFA products in E. coli, leading to increased yield. Five acyl-acyl carrier protein thioesterases from plants and bacteria were first evaluated for regulating the chain length of fatty acids. Co-expression of the selected thioesterase gene CcFatB1 with a fatty acid metabolism regulator fadR and monooxygenase P450BM3 boosted the production of HFAs especially ω-3-OH-C14:1, in both the wild type and fadD deficient strain. Supplementing renewable glycerol to reduce the usage of glucose as a carbon source further increased the HFAs production to 144 mg/L, representing the highest titer of such HFAs obtained in E. coli under the comparable conditions. This study illustrated an improved metabolic strategy for medium chain ω-1/2/3 HFAs production in E. coli. In addition, the produced HFAs were mostly secreted into culture media, which eased its recovery. PMID:29467747

Production of a Brassica napus Low-Molecular Mass Acyl-Coenzyme A-Binding Protein in Arabidopsis Alters the Acyl-Coenzyme A Pool and Acyl Composition of Oil in Seeds.

PubMed

Yurchenko, Olga; Singer, Stacy D; Nykiforuk, Cory L; Gidda, Satinder; Mullen, Robert T; Moloney, Maurice M; Weselake, Randall J

2014-06-01

Low-molecular mass (10 kD) cytosolic acyl-coenzyme A-binding protein (ACBP) has a substantial influence over fatty acid (FA) composition in oilseeds, possibly via an effect on the partitioning of acyl groups between elongation and desaturation pathways. Previously, we demonstrated that the expression of a Brassica napus ACBP (BnACBP) complementary DNA in the developing seeds of Arabidopsis (Arabidopsis thaliana) resulted in increased levels of polyunsaturated FAs at the expense of eicosenoic acid (20:1 cisΔ11 ) and saturated FAs in seed oil. In this study, we investigated whether alterations in the FA composition of seed oil at maturity were correlated with changes in the acyl-coenzyme A (CoA) pool in developing seeds of transgenic Arabidopsis expressing BnACBP. Our results indicated that both the acyl-CoA pool and seed oil of transgenic Arabidopsis lines expressing cytosolic BnACBP exhibited relative increases in linoleic acid (18:2 cisΔ9,12 ; 17.9%-44.4% and 7%-13.2%, respectively) and decreases in 20:1 cisΔ11 (38.7%-60.7% and 13.8%-16.3%, respectively). However, alterations in the FA composition of the acyl-CoA pool did not always correlate with those seen in the seed oil. In addition, we found that targeting of BnACBP to the endoplasmic reticulum resulted in FA compositional changes that were similar to those seen in lines expressing cytosolic BnACBP, with the most prominent exception being a relative reduction in α-linolenic acid (18:3 cisΔ9,12,15 ) in both the acyl-CoA pool and seed oil of the former (48.4%-48.9% and 5.3%-10.4%, respectively). Overall, these data support the role of ACBP in acyl trafficking in developing seeds and validate its use as a biotechnological tool for modifying the FA composition of seed oil. © 2014 American Society of Plant Biologists. All Rights Reserved.

Effect of alkali earth oxides on hydroxy-carbonated apatite nano layer formation for SiO2-BaO-CaO-Na2O-P2O5 glass system

NASA Astrophysics Data System (ADS)

Kiran, P.; Ramakrishna, V.; Shashikala, H. D.; Udayashankar, N. K.

2017-11-01

Barium soda lime phosphosilicate [(58SiO2-(32 - x)BaO- xCao-6Na2O-4P2O5 (where x = 15, 20, 25 and 30 mol%)] samples were synthesised using conventional sol-gel method at 700 °C sintering temperature. Thermal, structural properties were studied using thermo gravimetric analysis and differential thermal analysis, X-ray diffraction, scanning electron microscopy, fourier transform infrared and Raman spectroscopy. Using Raman spectra non-bridging oxygen concentrations were estimated. The hydroxy-carbonated apatite (HCA) layer formation on samples was analysed for 7 days using simulated body fluid (SBF) soaked samples. The growth of HCA layers self-assembled on the sample surface was discussed as a function of NBO/BO ratio. Results indicated that the number of Ca2+ ions released into SBF solution in dissolution process and weight loss of SB-treated samples vary with NBO/BO ratio. The changes in NBO/BO ratios were observed to be proportional to HCA forming ability of barium soda lime phosphosilicate glasses.

Crystal structure of the tri-ethyl-ammonium salt of 3-[(4-hy-droxy-3-meth-oxy-phen-yl)(4-hy-droxy-2-oxo-2H-chromen-3-yl)meth-yl]-2-oxo-2H-chromen-4-olate.

PubMed

Ikram, Muhammad; Rehman, Sadia; Khan, Afzal; Schulzke, Carola

2018-03-01

The reaction between 3,3'-[(3-meth-oxy-4-hy-droxy-phen-yl)methanedi-yl]bis-(4-hy-droxy-2 H -chromen-2-one) and tri-ethyl-amine in methanol yielded the title compound tri-ethyl-ammonium 3-[(4-hy-droxy-3-meth-oxy-phen-yl)(4-hy-droxy-2-oxo-2 H -chromen-3-yl)meth-yl]-2-oxo-2 H -chromen-4-olate, C 6 H 16 N + ·C 26 H 17 O 8 - or (NHEt 3 ) + (C 26 H 17 O 8 ) - , which crystallized directly from its methano-lic mother liquor. The non-deprotonated coumarol substituent shares its H atom with the deprotonated coumarolate substituent in a short negative charge-assisted hydrogen bond in which the freely refined H atom is moved from its parent O atom towards the acceptor O atom, elongating the covalent O-H bond to 1.18 (3) Å. The respective H atom can therefore be described as being shared by two alcohol O atoms, culminating in the formation of an eight-membered ring.

Hydroxy nitrate production in the OH-initiated oxidation of alkenes

NASA Astrophysics Data System (ADS)

Teng, A. P.; Crounse, J. D.; Lee, L.; St. Clair, J. M.; Cohen, R. C.; Wennberg, P. O.

2014-03-01

Alkenes generally react rapidly by addition of OH and subsequently O2 to form beta hydroxy peroxy radicals. These peroxy radicals react with NO to form beta hydroxy nitrates with a branching ratio α. We quantify α for C2-C8 alkenes at 296 K ±3 and 993 hPa. The branching ratio can be expressed as α = (0.042 ± 0.008) × N - (0.11 ± 0.04) where N is the number of heavy atoms (excluding the peroxy moiety), and listed errors are 2σ. These branching ratios are larger than previously reported and are similar to those for peroxy radicals formed from H abstraction from alkanes. We find the isomer distributions of beta hydroxy nitrates formed under NO-dominated peroxy radical chemistry to be similar to the isomer distribution of hydroxy hydroperoxides produced under HO2-dominated peroxy radical chemistry. With the assumption of unity yield for the hydroperoxides, this implies that the branching ratio to form beta hydroxy nitrates from primary, secondary, and tertiary RO2 are similar. Deuterium substitution enhances the branching ratio to form hydroxy nitrates in both propene and isoprene by a factor of ~1.5. These observations provide further evidence for importance of the ROONO lifetime in determining the branching ratio to form alkyl nitrates. We use these measurements to re-evaluate the role of alkene chemistry in the Houston region. We find that small alkenes play a larger role in oxidant formation than previously recognized.

The Functionality of Surface Hydroxy Groups on the Selectivity and Activity of Carbon Dioxide Reduction over Cuprous Oxide in Aqueous Solutions.

PubMed

Yang, Piaoping; Zhao, Zhi-Jian; Chang, Xiaoxia; Mu, Rentao; Zha, Shenjun; Zhang, Gong; Gong, Jinlong

2018-06-25

Carbon dioxide (CO 2 ) reduction in aqueous solutions is an attractive strategy for carbon capture and utilization. Cuprous oxide (Cu 2 O) is a promising catalyst for CO 2 reduction as it can convert CO 2 into valuable hydrocarbons and suppress the side hydrogen evolution reaction (HER). However, the nature of the active sites in Cu 2 O remains under debate because of the complex surface structure of Cu 2 O under reducing conditions, leading to limited guidance in designing improved Cu 2 O catalysts. This paper describes the functionality of surface-bonded hydroxy groups on partially reduced Cu 2 O(111) for the CO 2 reduction reaction (CO 2 RR) by combined density functional theory (DFT) calculations and experimental studies. We find that the surface hydroxy groups play a crucial role in the CO 2 RR and HER, and a moderate coverage of hydroxy groups is optimal for promotion of the CO 2 RR and suppression of the HER simultaneously. Electronic structure analysis indicates that the charge transfer from hydroxy groups to coordination-unsaturated Cu (Cu CUS ) sites stabilizes surface-adsorbed COOH*, which is a key intermediate during the CO 2 RR. Moreover, the CO 2 RR was evaluated over Cu 2 O octahedral catalysts with {111} facets and different surface coverages of hydroxy groups, which demonstrates that Cu 2 O octahedra with moderate coverage of hydroxy groups can indeed enhance the CO 2 RR and suppress the HER. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Oxidative cleavage of non-phenolic β-O-4 lignin model dimers by an extracellular aromatic peroxygenase

Treesearch

Matthias Kinne; Marzena Poraj-Kobielska; Rene Ullrich; Paula Nousiainen; Jussi Sipilä; Katrin Scheibner; Kenneth E. Hammel; Martin Hofrichter

2011-01-01

The extracellular aromatic peroxygenase of the agaric fungus Agrocybe aegerita catalyzed the H2O2-dependent cleavage of non-phenolic arylgiycerol-ß-aryl ethers (ß-O-4 ethers). For instance 1-(3,4-dimethoxyphenyl)-2-(2-methoxy-phenoxy)propane-1,3-diol, a recalcitrant dimeric lignin model compound that represents the major...

Photoaffinity Labeling of Developing Jojoba Seed Microsomal Membranes with a Photoreactive Analog of Acyl-Coenzyme A (Acyl-CoA) (Identification of a Putative Acyl-CoA:Fatty Alcohol Acyltransferase.

PubMed

Shockey, J. M.; Rajasekharan, R.; Kemp, J. D.

1995-01-01

Jojoba (Simmondsia chinensis, Link) is the only plant known that synthesizes liquid wax. The final step in liquid wax biosynthesis is catalyzed by an integral membrane enzyme, fatty acyl-coenzyme A (CoA):fatty alcohol acyltransferase, which transfers an acyl chain from acyl-CoA to a fatty alcohol to form the wax ester. To purify the acyltransferase, we have labeled the enzyme with a radioiodinated, photoreactive analog of acyl-CoA, 12-[N-(4-azidosalicyl)amino] dodecanoyl-CoA (ASD-CoA). This molecule acts as an inhibitor of acyltransferase activity in the dark and as an irreversible inhibitor upon exposure to ultraviolet light. Oleoyl-CoA protects enzymatic activity in a concentration-dependent manner. Photolysis of microsomal membranes with labeled ASD-CoA resulted in strong labeling of two polypeptides of 57 and 52 kD. Increasing concentrations of oleoyl-CoA reduced the labeling of the 57-kD polypeptide dramatically, whereas the labeling of the 52-kD polypeptide was much less responsive to oleoyl-CoA. Also, unlike the other polypeptide, the labeling of the 57-kD polypeptide was enhanced considerably when photolyzed in the presence of dodecanol. These results suggest that a 57-kD polypeptide from jojoba microsomes may be the acyl-CoA:fatty alcohol acyltransferase.

Nitroxyl-mediated oxidation of lignin and polycarboxylated products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stahl, Shannon S.; Rafiee, Mohammad

Methods of selectively modifying lignin, polycarboxylated products thereof, and methods of deriving aromatic compounds therefrom. The methods comprise electrochemically oxidizing lignin using stable nitroxyl radicals to selectively oxidize primary hydroxyls on .beta.-O-4 phenylpropanoid units to corresponding carboxylic acids while leaving the secondary hydroxyls unchanged. The oxidation results in polycarboxylated lignin in the form of a polymeric .beta.-hydroxy acid. The polymeric .beta.-hydroxy acid has a high loading of carboxylic acid and can be isolated in acid form, deprotonated, and/or converted to a salt. The .beta.-hydroxy acid, anion, or salt can also be subjected to acidolysis to generate various aromatic monomers ormore » oligomers. The initial oxidation of lignin to the polycarboxylated form renders the lignin more susceptible to acidolysis and thereby enhances the yield of aromatic monomers and oligomers obtained through acidolysis.« less

Studies on long chain cis- and trans-acyl-CoA esters and Acyl-CoA dehydrogenase from rat heart mitochondria.

PubMed

Korsrud, G O; Conacher, H B; Jarvis, G A; Beare-Rogers, J L

1977-02-01

The beta-oxidation of long chain fatty acids was investigated in a preparation of rat heart mitochondria. The acyl-CoA esters of the cis and trans isomers of delta9-hexadecenoic, delta9-octadecenoic, delta11-eicosenoic, and delta13-docosenoic acids were prepared. Rates of the acyl-CoA reaction were determined with an extract from rat heart mitochondria. The apparent Michaelis constant (Km) and maximum velocity (Vmax) were calculated for each substrate. In general, apparent Vmax values decreased with increasing chain length of the monoenoic substrates. Reduced activity of acyl-CoA dehydrogenase with long chain acyl-CoA esters could have contributed to accumulation of lipids in hearts of rats fed diets containing long chain fatty acids.

Identification, synthesis and regulatory function of the N-acylated homoserine lactone signals produced by Pseudomonas chlororaphis HT66.

PubMed

Peng, Huasong; Ouyang, Yi; Bilal, Muhammad; Wang, Wei; Hu, Hongbo; Zhang, Xuehong

2018-01-22

Pseudomonas chlororaphis HT66 isolated from the rice rhizosphere is an important plant growth-promoting rhizobacteria that produce phenazine-1-carboxamide (PCN) in high yield. Phenazine production is regulated by a quorum sensing (QS) system that involves the N-acylated homoserine lactones (AHLs)-a prevalent type of QS molecule. Three QS signals were detected by thin layer chromatography (TLC) and high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS), which identified to be N-(3-hydroxy hexanoyl)-L-homoserine lactone (3-OH-C6-HSL), N-(3-hydroxy octanoyl)-L-homoserine lactone (3-OH-C8-HSL) and N-(3-hydroxy decanoyl)-L-homoserine lactone (3-OH-C10-HSL). The signal types and methods of synthesis were different from that in other phenazine-producing Pseudomonas strains. By non-scar deletion and heterologous expression techniques, the biosynthesis of the AHL-signals was confirmed to be only catalyzed by PhzI, while other AHLs synthases i.e., CsaI and HdtS were not involved in strain HT66. In comparison to wild-type HT66, PCN production was 2.3-folds improved by over-expression of phzI, however, phzI or phzR mutant did not produce PCN. The cell growth of HT66∆phzI mutant was significantly decreased, and the biofilm formation in phzI or phzR inactivated strains of HT66 decreased to various extents. In conclusion, the results demonstrate that PhzI-PhzR system plays a critical role in numerous biological processes including phenazine production.

Inhibitors of glycogen synthase 3 kinase

DOEpatents

Schultz, Peter; Ring, David B.; Harrison, Stephen D.; Bray, Andrew M.

2000-01-01

Compounds of formula 1: ##STR1## wherein R.sub.1 is alkyl, cycloalkyl, aryl, aralkyl, heteroaryl, or heteroaralkyl, substituted with 0-3 substituents selected from lower alkyl, halo, hydroxy, lower alkoxy, amino, lower alkyl-amino, and nitro; R.sub.2 is hydroxy, amino, or lower alkoxy; R.sub.3 is H, lower alkyl, lower acyl, lower alkoxy-acyl, or amnino-acyl; R.sub.4 is H or lower alkyl; and pharmaceutically acceptable salts and esters thereof; are effective inhibitors of GSK3.

Inhibitors of glycogen synthase 3 kinase

DOEpatents

Schultz, Peter; Ring, David B.; Harrison, Stephen D.; Bray, Andrew M.

2006-05-30

Compounds of formula 1: ##STR00001## wherein R.sub.1 is alkyl, cycloalkyl, aryl, aralkyl, heteroaryl, or heteroaralkyl, substituted with 0 3 substituents selected from lower alkyl, halo, hydroxy, lower alkoxy, amino, lower alkyl-amino, and nitro; R.sub.2 is hydroxy, amino, or lower alkoxy; R.sub.3 is H, lower alkyl, lower acyl, lower alkoxy-acyl, or amino-acyl; R.sub.4 is H or lower alkyl; and pharmaceutically acceptable salts and esters thereof; are effective inhibitors of GSK3.

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

Polyketide family of novel antibacterial 7-O-methyl-5'-hydroxy-3'-heptenoate-macrolactin from seaweed-associated Bacillus subtilis MTCC 10403.

PubMed

Chakraborty, Kajal; Thilakan, Bini; Raola, Vamshi Krishna

2014-12-17

Seaweed-associated heterotrophic bacterial communities were screened to isolate potentially useful antimicrobial strains, which were characterized by phylogenetic analysis. The bacteria were screened for the presence of metabolite genes involved in natural product biosynthetic pathway, and the structural properties of secondary metabolites were correlated with the genes. Bioactivity-guided isolation of polyene antibiotic 7-O-methyl-5'-hydroxy-3'-heptenoate-macrolactin from Bacillus subtilis MTCC10403 associated with seaweed Anthophycus longifolius using mass spectrometry and extensive 2D-NMR studies was carried out. The newly isolated macrolactin compound is a bactericidal antibiotic with broad spectrum activity against human opportunistic clinical pathogens. The biosynthetic pathway of 7-O-methyl-5'-hydroxy-3'-heptenoate-macrolactin by means of a stepwise, decarboxylative condensation pathway established the PKS-assisted biosynthesis of the parent macrolactin and the side-chain 5-hydroxyhept-3-enoate moiety attached to the macrolactin ring system at C-7. Antimicrobial activity analysis combined with the results of amplifying genes encoding for polyketide synthetase and nonribosomal peptide synthetase showed that seaweed-associated bacteria had broad-spectrum antimicrobial activity. The present work may have an impact on the exploitation of macrolactins for pharmaceutical and biotechnological applications.

Photoaffinity Labeling of Developing Jojoba Seed Microsomal Membranes with a Photoreactive Analog of Acyl-Coenzyme A (Acyl-CoA) (Identification of a Putative Acyl-CoA:Fatty Alcohol Acyltransferase.

PubMed Central

Shockey, J. M.; Rajasekharan, R.; Kemp, J. D.

1995-01-01

Jojoba (Simmondsia chinensis, Link) is the only plant known that synthesizes liquid wax. The final step in liquid wax biosynthesis is catalyzed by an integral membrane enzyme, fatty acyl-coenzyme A (CoA):fatty alcohol acyltransferase, which transfers an acyl chain from acyl-CoA to a fatty alcohol to form the wax ester. To purify the acyltransferase, we have labeled the enzyme with a radioiodinated, photoreactive analog of acyl-CoA, 12-[N-(4-azidosalicyl)amino] dodecanoyl-CoA (ASD-CoA). This molecule acts as an inhibitor of acyltransferase activity in the dark and as an irreversible inhibitor upon exposure to ultraviolet light. Oleoyl-CoA protects enzymatic activity in a concentration-dependent manner. Photolysis of microsomal membranes with labeled ASD-CoA resulted in strong labeling of two polypeptides of 57 and 52 kD. Increasing concentrations of oleoyl-CoA reduced the labeling of the 57-kD polypeptide dramatically, whereas the labeling of the 52-kD polypeptide was much less responsive to oleoyl-CoA. Also, unlike the other polypeptide, the labeling of the 57-kD polypeptide was enhanced considerably when photolyzed in the presence of dodecanol. These results suggest that a 57-kD polypeptide from jojoba microsomes may be the acyl-CoA:fatty alcohol acyltransferase. PMID:12228351

Hydroxy nitrate production in the OH-initiated oxidation of alkenes

NASA Astrophysics Data System (ADS)

Teng, A. P.; Crounse, J. D.; Lee, L.; St. Clair, J. M.; Cohen, R. C.; Wennberg, P. O.

2015-04-01

Alkenes are oxidized rapidly in the atmosphere by addition of OH and subsequently O2 leading to the formation of β-hydroxy peroxy radicals. These peroxy radicals react with NO to form β-hydroxy nitrates with a branching ratio α. We quantify α for CM2-C8 alkenes at 295 K ± 3 and 993 hPa. The branching ratio can be expressed as α = (0.045 ± 0.016) × N - (0.11 ± 0.05) where N is the number of heavy atoms (excluding the peroxy moiety), and listed errors are 2σ. These branching ratios are larger than previously reported and are similar to those for peroxy radicals formed from H abstraction from alkanes. We find the isomer distributions of β-hydroxy nitrates formed under NO-dominated peroxy radical chemistry to be different than the isomer distribution of hydroxy hydroperoxides produced under HO2-dominated peroxy radical chemistry. Assuming unity yield for the hydroperoxides implies that the branching ratio to form β-hydroxy nitrates increases with substitution of RO2. Deuterium substitution enhances the branching ratio to form hydroxy nitrates in both propene and isoprene by a factor of ~ 1.5. The role of alkene chemistry in the Houston region is re-evaluated using the RONO2 branching ratios reported here. Small alkenes are found to play a significant role in present-day oxidant formation more than a decade (2013) after the 2000 Texas Air Quality Study identified these compounds as major contributors to photochemical smog in Houston.

Determining inhibition effects of some aromatic compounds on peroxidase enzyme purified from white and red cabbage

NASA Astrophysics Data System (ADS)

Öztekin, Aykut; Almaz, Züleyha; Özdemir, Hasan

2016-04-01

Peroxidases (E.C.1.11.1.7) catalyze the one electron oxidation of wide range of substrates. They are used in synthesis reaction, removal of peroxide from industrial wastes, clinical biochemistry and immunoassays. In this study, the white cabbage (Brassica Oleracea var. capitata f. alba) and red cabbage (Brassica oleracea L. var. capitata f. rubra) peroxidase enzymes were purified for investigation of inhibitory effect of some aromatic compounds on these enzymes. IC50 values and Ki constants were calculated for the molecules of 6-Amino nicotinic hydrazide, 6-Amino-5-bromo nicotinic hydrazide, 2-Amino-5-hydroxy benzohydrazide, 4-Amino-3-hydroxy benzohydrazide on purified enzymes and inhibition type of these molecules were determined. (This research was supported by Ataturk University. Project Number: BAP-2015/98).

Identification of products formed during the heterogeneous nitration and ozonation of polycyclic aromatic hydrocarbons

NASA Astrophysics Data System (ADS)

Cochran, Richard E.; Jeong, Haewoo; Haddadi, Shokouh; Fisseha Derseh, Rebeka; Gowan, Alexandra; Beránek, Josef; Kubátová, Alena

2016-03-01

The 3- and 4-ring polycyclic aromatic hydrocarbons (PAHs) are the most abundant of PAHs in air particulate matter (PM). Thus we have investigated heterogeneous oxidation of 3- and 4-ring PAHs in a small-scale flow reactor using quartz filter as a support. Four representative PAHs, anthracene, phenanthrene, pyrene, and fluoranthene, were exposed to either NO2, O3 or NO2+O3 (NO3/N2O5) with a goal to identify and attempt quantification of major product distribution. A combination of gas chromatography with mass spectrometry (GC-MS) with/without derivatization and liquid chromatography with high resolution MS (LC-HRMS) was used for identification. For the first time, a comprehensive characterization of a broad range of products enabled identifying ketone/diketone, aldehyde, hydroxyl, and carboxylic acid PAH derivatives. Exposure to NO3/N2O5 (formed by reacting NO2 with O3, a more powerful reactant than either O3 or NO2) produced additional compounds not observed with either oxidant alone. Multiple isomers of nitrofluoranthene and, for the first time, nitrophenanthrene were identified. In addition hydroxy-nitro-PAH derivatives were observed for the reaction of anthracene with NO3/N2O5. Monitoring of specific common ions such as those of 176 and 205 m/z attributed to carbonyl phenanthrene and deprotonated phenanthrene ions respectively was shown to be a useful tool for identification of multiple pyrene oxidation products.

Plasma levels of acylated ghrelin in patients with functional dyspepsia

PubMed Central

Kim, Yeon Soo; Lee, Joon Seong; Lee, Tae Hee; Cho, Joo Young; Kim, Jin Oh; Kim, Wan Jung; Kim, Hyun Gun; Jeon, Seong Ran; Jeong, Hoe Su

2012-01-01

AIM: To investigate the relationship between plasma acylated ghrelin levels and the pathophysiology of functional dyspepsia. METHODS: Twenty-two female patients with functional dyspepsia and twelve healthy volunteers were recruited for the study. The functional dyspepsia patients were each diagnosed based on the Rome III criteria. Eligible patients completed a questionnaire concerning the severity of 10 symptoms. Plasma acylated ghrelin levels before and after a meal were determined in the study participants using a commercial human acylated enzyme immunoassay kit; electrogastrograms were performed for 50 min before and after a standardized 10-min meal containing 265 kcal. RESULTS: There were no significant differences in plasma acylated ghrelin levels between healthy volunteers and patients with functional dyspepsia. However, in patients with functional dyspepsia, there was a negative correlation between fasting plasma acylated ghrelin levels and the sum score of epigastric pain (r = -0.427, P = 0.047) and a positive correlation between the postprandial/fasting plasma acylated ghrelin ratio and the sum score of early satiety (r = 0.428, P =0.047). Additionally, there was a negative correlation between fasting acylated ghrelin plasma levels and fasting normogastria (%) (r = -0.522, P = 0.013). Interestingly, two functional dyspepsia patients showed paradoxically elevated plasma acylated ghrelin levels after the meal. CONCLUSION: Abnormal plasma acylated ghrelin levels before or after a meal may be related to several of the dyspeptic symptoms seen in patients with functional dyspepsia. PMID:22611317

Transgenic rice seed expressing flavonoid biosynthetic genes accumulate glycosylated and/or acylated flavonoids in protein bodies

PubMed Central

Ogo, Yuko; Mori, Tetsuya; Nakabayashi, Ryo; Saito, Kazuki; Takaiwa, Fumio

2016-01-01

Plant-specialized (or secondary) metabolites represent an important source of high-value chemicals. In order to generate a new production platform for these metabolites, an attempt was made to produce flavonoids in rice seeds. Metabolome analysis of these transgenic rice seeds using liquid chromatography-photodiode array-quadrupole time-of-flight mass spectrometry was performed. A total of 4392 peaks were detected in both transgenic and non-transgenic rice, 20–40% of which were only detected in transgenic rice. Among these, 82 flavonoids, including 37 flavonols, 11 isoflavones, and 34 flavones, were chemically assigned. Most of the flavonols and isoflavones were O-glycosylated, while many flavones were O-glycosylated and/or C-glycosylated. Several flavonoids were acylated with malonyl, feruloyl, acetyl, and coumaroyl groups. These glycosylated/acylated flavonoids are thought to have been biosynthesized by endogenous rice enzymes using newly synthesized flavonoids whose biosynthesis was catalysed by exogenous enzymes. The subcellular localization of the flavonoids differed depending on the class of aglycone and the glycosylation/acylation pattern. Therefore, flavonoids with the intended aglycones were efficiently produced in rice seeds via the exogenous enzymes introduced, while the flavonoids were variously glycosylated/acylated by endogenous enzymes. The results suggest that rice seeds are useful not only as a production platform for plant-specialized metabolites such as flavonoids but also as a tool for expanding the diversity of flavonoid structures, providing novel, physiologically active substances. PMID:26438413

Determination of hydroxy metabolites of cocaine from hair samples and comparison with street cocaine samples.

PubMed

Franz, Thomas; Scheufler, Frank; Stein, Klaus; Uhl, Michael; Dame, Torsten; Schwarz, Gerlinde; Sachs, Hans; Skopp, Gisela; Musshoff, Frank

2018-07-01

Drugs which are commonly smoked or sniffed (e.g. cocaine), can contaminate hair through smoke or dust; therefore testing for metabolites, especially hydroxy metabolites, is highly recommended. The presence of hydroxy metabolites in street-cocaine (COC) has been discussed. To check if detection of hydroxy metabolites definitely proves ingestion, the presence of these metabolites in street COC samples has to be checked. It is expected that the more hydrophilic hydroxy metabolites of COC are incorporated into the hair-matrix to a lesser extent. For this study 576 COC positive hair samples (≥0.1ng COC/mg hair) were analysed by LC-MS/MS for benzoylecgonine (BE), norcocaine (NC), cocaethylene (CE), ortho-, meta- and para-hydroxy COC (o-, m-, p-OH-COC), meta- and para-hydroxy BE (m-, p-OH-BE), and meta- and para-hydroxy NC (m-, p-OH-NC). The results were compared with the respective metabolite/COC concentration ratios in 146 street COC samples, confiscated by the Bavarian police. Peak areas were used to estimate BE/COC, NC/COC, CE/COC and hydroxy metabolites/COC. Similar metabolic ratios were found for o-OH-COC in 88% of the samples, but for p-OH-COC and m-OH-COC only in 5.1% and 6.8%, respectively. Notably, p- and m-OH-BE as well as p- and m-OH-NC could not be identified from seized samples. We propose that area ratios exceeding the ratios of street COC more than twice or identification of OH-BE and OH-NC enable to differentiate COC consumption from contamination. Using these criteria, consumption of the drug could be proven in 92% of COC positive samples. As detection of meta- and para-hydroxy metabolites using the above mentioned criteria is a reliable tool to distinguish between ingestion and external contamination, it is recommended to implement their measurement into daily routine work. Copyright © 2018 Elsevier B.V. All rights reserved.

Global and Phylogenetic Distribution of Quorum Sensing Signals, Acyl Homoserine Lactones, in the Family of Vibrionaceae

PubMed Central

Barker Rasmussen, Bastian; Fog Nielsen, Kristian; Machado, Henrique; Melchiorsen, Jette; Gram, Lone; Sonnenschein, Eva C.

2014-01-01

Bacterial quorum sensing (QS) and the corresponding signals, acyl homoserine lactones (AHLs), were first described for a luminescent Vibrio species. Since then, detailed knowledge has been gained on the functional level of QS; however, the abundance of AHLs in the family of Vibrionaceae in the environment has remained unclear. Three hundred and one Vibrionaceae strains were collected on a global research cruise and the prevalence and profile of AHL signals in this global collection were determined. AHLs were detected in 32 of the 301 strains using Agrobacterium tumefaciens and Chromobacterium violaceum reporter strains. Ethyl acetate extracts of the cultures were analysed by ultra-high performance liquid chromatography-high resolution mass spectrometry (MS) with automated tandem MS confirmation for AHLs. N-(3-hydroxy-hexanoyl) (OH-C6) and N-(3-hydroxy-decanoyl) (OH-C10) homoserine lactones were the most common AHLs found in 17 and 12 strains, respectively. Several strains produced a diversity of different AHLs, including N-heptanoyl (C7) HL. AHL-producing Vibrionaceae were found in polar, temperate and tropical waters. The AHL profiles correlated with strain phylogeny based on gene sequence homology, however not with geographical location. In conclusion, a wide range of AHL signals are produced by a number of clades in the Vibrionaceae family and these results will allow future investigations of inter- and intra-species interactions within this cosmopolitan family of marine bacteria. PMID:25419995

Enzymatic Acylation of Anthocyanins Isolated from Alpine Bearberry ( Arctostaphylos alpina) and Lipophilic Properties, Thermostability, and Antioxidant Capacity of the Derivatives.

PubMed

Yang, Wei; Kortesniemi, Maaria; Yang, Baoru; Zheng, Jie

2018-03-21

Cyanidin-3- O-galactoside (cy-gal) isolated from alpine bearberry ( Arctostaphylos alpine L.) was enzymatically acylated with saturated fatty acids of different chain lengths with Candida antarctica lipase immobilized on acrylic resin (Novozyme 435). The acylation reaction was optimized by considering the reaction medium, acyl donor, substrate molar ratio, reaction temperature, and reaction time. The highest conversion yield of 73% was obtained by reacting cy-gal with lauric acid (molar ratio of 1:10) in tert-butanol at 60 °C for 72 h. A novel compound was synthesized, which was identified as cyanidin-3- O-(6″-dodecanoyl)galactoside by mass spectrometry and nuclear magnetic resonance. Introducing lauric acid into cy-gal significantly improved both the lipophilicity and thermostability and substantially preserved the ultraviolet-visible absorbance and antioxidant properties. The research provides important insight in expanding the application of natural anthocyanins in the cosmetic and food industries.

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

Benzoyl radicals from (hetero)aromatic aldehydes. Decatungstate photocatalyzed synthesis of substituted aromatic ketones.

PubMed

Ravelli, Davide; Zema, Michele; Mella, Mariella; Fagnoni, Maurizio; Albini, Angelo

2010-09-21

Benzoyl radicals are generated directly from (hetero)aromatic aldehydes upon tetrabutylammonium decatungstate ((n-Bu(4)N)(4)W(10)O(32)), TBADT) photocatalysis under mild conditions. In the presence of alpha,beta-unsaturated esters, ketones and nitriles radical conjugate addition ensues and gives the corresponding beta-functionalized aryl alkyl ketones in moderate to good yields (stereoselectively in the case of 3-methylene-2-norbornanone). Due to the mild reaction conditions the presence of various functional groups on the aromatic ring is tolerated (e.g. methyl, methoxy, chloro). The method can be applied to hetero-aromatic aldehydes whether electron-rich (e.g. thiophene-2-carbaldehyde) or electron-poor (e.g. pyridine-3-carbaldehyde).

Genetic studies on the ghrelin, growth hormone secretagogue receptor (GHSR) and ghrelin O-acyl transferase (GOAT) genes.

PubMed

Liu, Boyang; Garcia, Edwin A; Korbonits, Márta

2011-11-01

Ghrelin is a 28 amino acid peptide hormone that is produced both centrally and peripherally. Regulated by the ghrelin O-acyl transferase enzyme, ghrelin exerts its action through the growth hormone secretagogue receptor, and is implicated in a diverse range of physiological processes. These implications have placed the ghrelin signaling pathway at the center of a large number of candidate gene and genome-wide studies which aim to identify the genetic basis of human heterogeneity. In this review we summarize the available data on the genetic variability of ghrelin, its receptor and its regulatory enzyme, and their association with obesity, stature, type 2 diabetes, cardiovascular disease, eating disorders, and reward seeking behavior. Copyright © 2011 Elsevier Inc. All rights reserved.

Oxonitriles: A Grignard Addition-Acylation Route to Enamides

PubMed Central

Wei, Guoqing; Zhang, Zhiyu; Steward, Omar W.

2008-01-01

Sequential addition of three different Grignard reagents and pivaloyl chloride to 3-oxo-1-cyclohexene-1-carbonitrile installs four new bonds to generate a diverse array of cyclic enamides. Remarkably, formation of the C-magnesiated nitrile intermediate is followed by preferential acylation by pivaloyl chloride rather than consumption by in situ Grignard reagent. Rapid N-acylation of the C-magnesiated nitrile generates an acyl ketenimine that reacts readily with Grignard reagents, or a trialkyl zincate, effectively assembling highly substituted, cyclic enamides. PMID:17020332

Analogies between Vanadoborates and Planar Aromatic Hydrocarbons: A High-Spin Analogue of Aromaticity.

PubMed

King, R Bruce

2017-12-23

The vanadium-vanadium interactions in the polygonal aggregates of d¹ vanadium(IV) atoms, with a total of 4 k + 2 vanadium electrons ( k an integer) imbedded in an electronically inactive borate matrix in certain vanadoborate structures are analogous to the ring carbon-carbon interactions in diamagnetic planar cyclic hydrocarbons. They thus represent a high-spin analogue of aromaticity. Thus, the vanadoborate anion [V₆B 20 O 50 H₈] 8- with six V(IV) electrons (i.e., 4 k + 2 for k = 1) contains a macrohexagon of d¹ V(IV) atoms with four unpaired electrons. This high-spin system is related to the low-spin aromaticity in the diamagnetic benzene having six π electrons. Similarly, the vanadoborate anion [V 10 B 28 O 74 H₈] 16- with ten V(IV) electrons (i.e., 4 k + 2 for k = 2) contains a macrodecagon of d¹ V(IV) atoms with eight unpaired electrons. Again, this high-spin system is related to the aromaticity in the diamagnetic 1,6-methanol[10]annulene, having ten π electrons.

Oxonitriles: a grignard addition-acylation route to enamides.

PubMed

Fleming, Fraser F; Wei, Guoqing; Zhang, Zhiyu; Steward, Omar W

2006-10-12

[reaction: see text] Sequential addition of three different Grignard reagents and pivaloyl chloride to 3-oxo-1-cyclohexene-1-carbonitrile installs four new bonds to generate a diverse array of cyclic enamides. Remarkably, formation of the C-magnesiated nitrile intermediate is followed by preferential acylation by pivaloyl chloride rather than consumption by an in situ Grignard reagent. Rapid N-acylation of the C-magnesiated nitrile generates an acyl ketenimine that reacts readily with Grignard reagents or a trialkylzincate, effectively assembling highly substituted, cyclic enamides.

Glycogen phosphorylase as a target for type 2 diabetes: synthetic, biochemical, structural and computational evaluation of novel N-acyl-N´-(β-D-glucopyranosyl) urea inhibitors.

PubMed

Kantsadi, Anastassia L; Parmenopoulou, Vanessa; Bakalov, Dimitar N; Snelgrove, Laura; Stravodimos, George A; Chatzileontiadou, Demetra S M; Manta, Stella; Panagiotopoulou, Angeliki; Hayes, Joseph M; Komiotis, Dimitri; Leonidas, Demetres D

2015-01-01

Glycogen phosphorylase (GP), a validated target for the development of anti-hyperglycaemic agents, has been targeted for the design of novel glycopyranosylamine inhibitors. Exploiting the two most potent inhibitors from our previous study of N-acyl-β-D-glucopyranosylamines (Parmenopoulou et al., Bioorg. Med. Chem. 2014, 22, 4810), we have extended the linking group to -NHCONHCO- between the glucose moiety and the aliphatic/aromatic substituent in the GP catalytic site β-cavity. The N-acyl-N´-(β-D-glucopyranosyl) urea inhibitors were synthesized and their efficiency assessed by biochemical methods, revealing inhibition constant values of 4.95 µM and 2.53 µM. Crystal structures of GP in complex with these inhibitors were determined and analyzed, providing data for further structure based design efforts. A novel Linear Response - Molecular Mechanics Coulomb Surface Area (LR-MM-CBSA) method has been developed which relates predicted and experimental binding free energies for a training set of N-acyl-N´-(β-D-glucopyranosyl) urea ligands with a correlation coefficient R(2) of 0.89 and leave-one-out cross-validation (LOO-cv) Q(2) statistic of 0.79. The method has significant applications to direct future lead optimization studies, where ligand entropy loss on binding is revealed as a key factor to be considered. ADMET property predictions revealed that apart from potential permeability issues, the synthesized N-acyl-N´-(β-D-glucopyranosyl) urea inhibitors have drug-like potential without any toxicity warnings.

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.

Determining inhibition effects of some aromatic compounds on peroxidase enzyme purified from white and red cabbage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Öztekin, Aykut, E-mail: aoztekin@agri.edu.tr; Agri Ibrahim Cecen University Faculty of Arts and Sciences, Department of Chemistry, 04100-Agri; Almaz, Züleyha, E-mail: zturkoglu-2344@hotmail.com

2016-04-18

Peroxidases (E.C.1.11.1.7) catalyze the one electron oxidation of wide range of substrates. They are used in synthesis reaction, removal of peroxide from industrial wastes, clinical biochemistry and immunoassays. In this study, the white cabbage (Brassica Oleracea var. capitata f. alba) and red cabbage (Brassica oleracea L. var. capitata f. rubra) peroxidase enzymes were purified for investigation of inhibitory effect of some aromatic compounds on these enzymes. IC{sub 50} values and Ki constants were calculated for the molecules of 6-Amino nicotinic hydrazide, 6-Amino-5-bromo nicotinic hydrazide, 2-Amino-5-hydroxy benzohydrazide, 4-Amino-3-hydroxy benzohydrazide on purified enzymes and inhibition type of these molecules were determined. (Thismore » research was supported by Ataturk University. Project Number: BAP-2015/98).« less

Transgenic rice seed expressing flavonoid biosynthetic genes accumulate glycosylated and/or acylated flavonoids in protein bodies.

PubMed

Ogo, Yuko; Mori, Tetsuya; Nakabayashi, Ryo; Saito, Kazuki; Takaiwa, Fumio

2016-01-01

Plant-specialized (or secondary) metabolites represent an important source of high-value chemicals. In order to generate a new production platform for these metabolites, an attempt was made to produce flavonoids in rice seeds. Metabolome analysis of these transgenic rice seeds using liquid chromatography-photodiode array-quadrupole time-of-flight mass spectrometry was performed. A total of 4392 peaks were detected in both transgenic and non-transgenic rice, 20-40% of which were only detected in transgenic rice. Among these, 82 flavonoids, including 37 flavonols, 11 isoflavones, and 34 flavones, were chemically assigned. Most of the flavonols and isoflavones were O-glycosylated, while many flavones were O-glycosylated and/or C-glycosylated. Several flavonoids were acylated with malonyl, feruloyl, acetyl, and coumaroyl groups. These glycosylated/acylated flavonoids are thought to have been biosynthesized by endogenous rice enzymes using newly synthesized flavonoids whose biosynthesis was catalysed by exogenous enzymes. The subcellular localization of the flavonoids differed depending on the class of aglycone and the glycosylation/acylation pattern. Therefore, flavonoids with the intended aglycones were efficiently produced in rice seeds via the exogenous enzymes introduced, while the flavonoids were variously glycosylated/acylated by endogenous enzymes. The results suggest that rice seeds are useful not only as a production platform for plant-specialized metabolites such as flavonoids but also as a tool for expanding the diversity of flavonoid structures, providing novel, physiologically active substances. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Association of atmospheric concentrations of polycyclic aromatic hydrocarbons with their urinary metabolites in children and adolescents.

PubMed

Poursafa, Parinaz; Amin, Mohammad Mehdi; Hajizadeh, Yaghoub; Mansourian, Marjan; Pourzamani, Hamidreza; Ebrahim, Karim; Sadeghian, Babak; Kelishadi, Roya

2017-07-01

This study aims to determine the atmospheric concentrations of particulate matter 2.5 (PM 2.5 )-bounded polycyclic aromatic hydrocarbons (PAHs) and their association with their urinary metabolites in children and adolescents. This study was conducted from October 2014 to March 2016 in Isfahan, Iran. We measured 16 species of PAHs bounded to PM 2.5 by gas chromatography mass spectrometry (GC/MS) from 7 parts of the city. Moreover, PAH urinary metabolites were measured in 186 children and adolescents, randomly selected from households. Urinary metabolites consisted of 1-hydroxy naphthalene (1-naphthol), 2-hydroxy naphthalene (2-naphthol), 9-hydroxy phenanthrene (9-phenanthrol), and 1-hydroxy pyrene using GC/MS. Considering the short half-lives of PAHs, we measured the metabolites twice with 4 to 6 months of time interval. We found that the ambient concentrations of PAHs were significantly associated with their urinary metabolites. 1-hydroxy naphthalene and 2-hydroxy naphthalene concentrations showed an increase of 1.049 (95% CI: 1.030, 1.069) and 1.047 (95% CI: 1.025, 1.066) for each unit increase (1 ng/m 3 ) in ambient naphthalene. Similarly, 1-hydroxy pyrene showed an increase of 1.009 (95% CI: 1.006-1.011) for each unit increase (1 ng/m 3 ) in ambient pyrene concentration after adjustment for body mass index, physical activity level, urinary creatinine, age, and sex. The association of urinary 9-hydroxyphenanthrene and ambient phenantherene was significant in the crude model; however after adjustment for the abovementioned covariates, it was no more significant. We found significant correlations between exposure to ambient PM 2.5 -bounded PAHs and their urinary excretion. Considering the adverse health effects of PAHs in the pediatric age group, biomonitoring of PAHs should be underscored; preventive measures need to be intensified.

α-melanocyte stimulating hormone modulates the central acyl ghrelin-induced stimulation of feeding, gastrointestinal motility, and colonic secretion.

PubMed

Huang, Hsien-Hao; Chen, Liang-Yu; Doong, Ming-Luen; Chang, Shi-Chuan; Chen, Chih-Yen

2017-01-01

Acyl ghrelin-induced intake depends on hypothalamic neuropeptide Y and agouti-related protein (AgRP) neurotransmitters. Intracerebroventricular (ICV) injection of AgRP increases feeding through competitive antagonism at melanocortin receptors. ICV administration of α-melanocyte stimulating hormone (α-MSH), a natural antagonist of AgRP, may modulate the acyl ghrelin-induced orexigenic effect. This study aimed to investigate the modulating effect of α-MSH on the central acyl ghrelin-induced food intake, gastrointestinal motility, and colonic secretion in rats. We examined the effects of α-MSH and acyl ghrelin on food intake, gastric emptying, small intestinal transit, colonic motility, and secretion in conscious rats with a chronic implant of ICV catheters. ICV injection of O - n -octanoylated ghrelin (0.1 nmol/rat) significantly increased the cumulative food intake up to 8 h ( P <0.01), enhanced non-nutrient semi-liquid gastric emptying ( P <0.001), increased the geometric center and running percentage of small intestinal transit ( P <0.001), accelerated colonic transit time ( P <0.05), and increased fecal pellet output ( P <0.01) and total fecal weight ( P <0.01). Pretreatment with ICV injection of α-MSH (1.0 and 2.0 nmol/rat) attenuated the acyl ghrelin-induced hyperphagic effect, fecal pellet output, and total fecal weight, while higher dose of α-MSH (2.0 nmol/rat) attenuated the increase in the geometric center of small intestinal transit ( P <0.01). However, neither dose of α-MSH altered acyl ghrelin-stimulated gastroprokinetic effect, increase in the running percentage of small intestinal transit, nor accelerated colonic transit time. α-MSH is involved in central acyl ghrelin-elicited feeding, small intestinal transit, fecal pellet output, and fecal weight. α-MSH does not affect central acyl ghrelin-induced acceleration of gastric emptying and colonic transit time in rats.

Catalytic ethanolysis and gasification of kraft lignin into aromatic alcohols and H2-rich gas over Rh supported on La2O3/CeO2-ZrO2.

PubMed

Yang, Jing; Zhao, Liang; Liu, Chunze; Wang, Yuanyuan; Dai, Liyi

2016-10-01

Efficient catalytic ethanolysis and gasification of kraft lignin were conducted over a versatile supported catalyst Rh/La2O3/CeO2-ZrO2 to give high-value aromatic alcohols and H2-rich gas. The removal of phenolic hydroxyl group was the most prevalent reaction, and importantly, almost no phenols, undesired char and saturating the aromatic ring were detected. Meanwhile, the feedstock and solvent both played key roles in H2 generation that contributed to the hydrodeoxygenation of liquid components and made the whole catalytic process out of H2 supply. Reusability tests of catalyst indicated that the crystalline phase transition and agglomeration of support, the loss of noble metal Rh and carbon deposition were the possible reasons for its deactivation in supercritical ethanol. Comparing with water, methanol and isopropanol system, ethanol was the only effective solvent for the depolymerization process. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

Understanding Acyl Chain and Glycerolipid Metabolism in Plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

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.

Carbamoyl anion-initiated cascade reaction for stereoselective synthesis of substituted α-hydroxy-β-amino amides.

PubMed

Lin, Chao-Yang; Ma, Peng-Ju; Sun, Zhao; Lu, Chong-Dao; Xu, Yan-Jun

2016-01-18

A carbamoyl anion-initiated cascade reaction with acylsilanes and imines has been used to rapidly construct substituted α-hydroxy-β-amino amides. The Brook rearrangement-mediated cascade allows the formation of two C-C bonds and one O-Si bond in a single pot. Using this approach, a range of α-aryl α-hydroxy-β-amino amides has been synthesized in high yields with excellent diastereoselectivities.

In silico and experimental methods revealed highly diverse bacteria with quorum sensing and aromatics biodegradation systems--a potential broad application on bioremediation.

PubMed

Huang, Yili; Zeng, Yanhua; Yu, Zhiliang; Zhang, Jing; Feng, Hao; Lin, Xiuchun

2013-11-01

Phylogenetic overlaps between aromatics-degrading bacteria and acyl-homoserine-lactone (AHL) or autoinducer (AI) based quorum-sensing (QS) bacteria were evident in literatures; however, the diversity of bacteria with both activities had never been finely described. In-silico searching in NCBI genome database revealed that more than 11% of investigated population harbored both aromatic ring-hydroxylating-dioxygenase (RHD) gene and AHL/AI-synthetase gene. These bacteria were distributed in 10 orders, 15 families, 42 genus and 78 species. Horizontal transfers of both genes were common among them. Using enrichment and culture dependent method, 6 Sphingomonadales and 4 Rhizobiales with phenanthrene- or pyrene-degrading ability and AHL-production were isolated from marine, wetland and soil samples. Thin-layer-chromatography and gas-chromatography-mass-spectrum revealed that these Sphingomonads produced various AHL molecules. This is the first report of highly diverse bacteria that harbored both aromatics-degrading and QS systems. QS regulation may have broad impacts on aromatics biodegradation, and would be a new angle for developing bioremediation technology. Copyright © 2013 Elsevier Ltd. All rights reserved.

Lanthanide complexes with aromatic o-phosphorylated ligands: synthesis, structure elucidation and photophysical properties.

PubMed

Shuvaev, Sergey; Utochnikova, Valentina; Marciniak, Łukasz; Freidzon, Alexandra; Sinev, Ilya; Van Deun, Rik; Freire, Ricardo O; Zubavichus, Yan; Grünert, Wolfgang; Kuzmina, Natalia

2014-02-28

Lanthanide complexes LnL3 (Ln = Sm, Eu, Tb, Dy, Tm, Yb, Lu) with aromatic o-phosphorylated ligands (HL(1) and HL(2)) have been synthesized and identified. Their molecular structure was proposed on the basis of a new complex approach, including DFT calculations, Sparkle/PM3 modelling, EXAFS spectroscopy and luminescent probing. The photophysical properties of all of the complexes were investigated in detail to obtain a deeper insight into the energy transfer processes.

Acyl donors for native chemical ligation.

PubMed

Yan, Bingjia; Shi, Weiwei; Ye, Linzhi; Liu, Lei

2018-04-11

Native chemical ligation (NCL) has become one of the most important methods in chemical syntheses of proteins. Recently, in order to expand its scope, considerable effort has been devoted to tuning the C-terminal acyl donor thioesters used in NCL. This article reviews the recent advances in the design of C-terminal acyl donors, their precursors and surrogates, and highlights some noteworthy progress that may lead the future direction of protein chemical synthesis. Copyright © 2018 Elsevier Ltd. All rights reserved.

Disruption of plastid acyl:acyl carrier protein synthetases increases medium chain fatty acid accumulation in seeds of transgenic Arabidopsis.

PubMed

Tjellström, Henrik; Strawsine, Merissa; Silva, Jillian; Cahoon, Edgar B; Ohlrogge, John B

2013-04-02

Engineering transgenic plants that accumulate high levels of medium-chain fatty acids (MCFA) has been least successful for shorter chain lengths (e.g., C8). We demonstrate that one limitation is the activity of acyl-ACP synthetase (AAE) that re-activates fatty acids released by acyl-ACP thioesterases. Seed expression of Cuphea pulcherrima FATB acyl-ACP thioesterase in a double mutant lacking AAE15/16 increased 8:0 accumulation almost 2-fold compared to expression in wild type. These results also provide an in planta demonstration that AAE enzymes participate not only in activation of exogenously added MCFA but also in activation of MCFA synthesized in plastids. Copyright © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Anatomy of the β-branching enzyme of polyketide biosynthesis and its interaction with an acyl-ACP substrate.

PubMed

Maloney, Finn P; Gerwick, Lena; Gerwick, William H; Sherman, David H; Smith, Janet L

2016-09-13

Alkyl branching at the β position of a polyketide intermediate is an important variation on canonical polyketide natural product biosynthesis. The branching enzyme, 3-hydroxy-3-methylglutaryl synthase (HMGS), catalyzes the aldol addition of an acyl donor to a β-keto-polyketide intermediate acceptor. HMGS is highly selective for two specialized acyl carrier proteins (ACPs) that deliver the donor and acceptor substrates. The HMGS from the curacin A biosynthetic pathway (CurD) was examined to establish the basis for ACP selectivity. The donor ACP (CurB) had high affinity for the enzyme (Kd = 0.5 μM) and could not be substituted by the acceptor ACP. High-resolution crystal structures of HMGS alone and in complex with its donor ACP reveal a tight interaction that depends on exquisite surface shape and charge complementarity between the proteins. Selectivity is explained by HMGS binding to an unusual surface cleft on the donor ACP, in a manner that would exclude the acceptor ACP. Within the active site, HMGS discriminates between pre- and postreaction states of the donor ACP. The free phosphopantetheine (Ppant) cofactor of ACP occupies a conserved pocket that excludes the acetyl-Ppant substrate. In comparison with HMG-CoA (CoA) synthase, the homologous enzyme from primary metabolism, HMGS has several differences at the active site entrance, including a flexible-loop insertion, which may account for the specificity of one enzyme for substrates delivered by ACP and the other by CoA.

Dehalogenation of aromatics by nucleophilic aromatic substitution.

PubMed

Sadowsky, Daniel; McNeill, Kristopher; Cramer, Christopher J

2014-09-16

Nucleophilic aromatic substitution has been implicated as a mechanism for both the biotic and abiotic hydrodehalogenation of aromatics. Two mechanisms for the aqueous dehalogenation of aromatics involving nucleophilic aromatic substitution with hydride as a nucleophile are investigated using a validated density functional and continuum solvation protocol. For chlorinated and brominated aromatics, nucleophilic addition ortho to carbon-halogen bonds via an anionic intermediate is predicted to be the preferred mechanism in the majority of cases, while concerted substitution is predicted to be preferred for most fluorinated aromatics. Nucleophilic aromatic substitution reactions with the hydroxide and hydrosulfide anions as nucleophiles are also investigated and compared.

Acyl-CoA:Lysophosphatidylethanolamine Acyltransferase Activity Regulates Growth of Arabidopsis1

PubMed Central

Jasieniecka-Gazarkiewicz, Katarzyna; Lager, Ida; Carlsson, Anders S.; Gutbrod, Katharina; Peisker, Helga; Dörmann, Peter; Stymne, Sten; Banaś, Antoni

2017-01-01

Arabidopsis (Arabidopsis thaliana) contains two enzymes (encoded by the At1g80950 and At2g45670 genes) preferentially acylating lysophosphatidylethanolamine (LPE) with acyl-coenzyme A (CoA), designated LYSOPHOSPHATIDYLETHANOLAMINE ACYLTRANSFERASE1 (LPEAT1) and LPEAT2. The transfer DNA insertion mutant lpeat2 and the double mutant lpeat1 lpeat2 showed impaired growth, smaller leaves, shorter roots, less seed setting, and reduced lipid content per fresh weight in roots and seeds and large increases in LPE and lysophosphatidylcholine (LPC) contents in leaves. Microsomal preparations from leaves of these mutants showed around 70% decrease in acylation activity of LPE with 16:0-CoA compared with wild-type membranes, whereas the acylation with 18:1-CoA was much less affected, demonstrating that other lysophospholipid acyltransferases than the two LPEATs could acylate LPE. The above-mentioned effects were less pronounced in the single lpeat1 mutant. Overexpression of either LPEAT1 or LPEAT2 under the control of the 35S promotor led to morphological changes opposite to what was seen in the transfer DNA mutants. Acyl specificity studies showed that LPEAT1 utilized 16:0-CoA at the highest rate of 11 tested acyl-CoAs, whereas LPEAT2 utilized 20:0-CoA as the best acyl donor. Both LPEATs could acylate either sn position of ether analogs of LPC. The data show that the activities of LPEAT1 and LPEAT2 are, in a complementary way, involved in growth regulation in Arabidopsis. It is shown that LPEAT activity (especially LPEAT2) is essential for maintaining adequate levels of phosphatidylethanolamine, LPE, and LPC in the cells. PMID:28408542

40 CFR 721.6485 - Hydroxy terminated polyester.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Hydroxy terminated polyester. 721.6485... Substances § 721.6485 Hydroxy terminated polyester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a hydroxy terminated polyester...

40 CFR 721.6485 - Hydroxy terminated polyester.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Hydroxy terminated polyester. 721.6485... Substances § 721.6485 Hydroxy terminated polyester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a hydroxy terminated polyester...

Novel analogues of degarelix incorporating hydroxy-, methoxy-, and pegylated-urea moieties at positions 3, 5, 6 and the N-terminus. Part III.

PubMed

Samant, Manoj P; Hong, Doley J; Croston, Glenn; Rivier, Catherine; Rivier, Jean

2006-06-15

Novel degarelix (Fe200486) analogues were screened for antagonism of GnRH-induced response (IC(50)) in a reporter gene assay. Inhibition of luteinizing hormone release over time was measured in the castrated male rat. N(omega)-Hydroxy- and N(omega)-methoxy-carbamoylation of Dab and Dap at position 3 (3-6), and N(omega)-hydroxy-,N(omega)-methoxy-carbamoylation and pegylation of 4Aph at positions 5 and 6 (7-10, 15-17, 22-25) were carried out. Modulation of hydrophobicity was achieved using different acylating groups at the N-terminus (11-14, 18-21, 26-28). Analogues 8, 15-17, 22, and 23 were equipotent to acyline (IC(50) = 0.69 nM) and degarelix (IC(50) = 0.58 nM) in vitro. Analogues 7, 17, and 23 were shorter acting than acyline, when 9, 11, 13, 15, 16, and 22 were longer acting. Only 9 and 14 were inactive at releasing histamine. No analogue exhibited a duration of action comparable to that of degarelix. Analogues with shorter and longer retention times on HPLC (a measure of hydrophilicity) than degarelix were identified.

Deactivation of Ceria Supported Palladium through C–C Scission during Transfer Hydrogenation of Phenol with Alcohols

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nelson, Nicholas C.; Manzano, J. Sebastián; Slowing, Igor I.

The stability of palladium supported on ceria (Pd/CeO 2) was studied during liquid flow transfer hydrogenation using primary and secondary alcohols as hydrogen donors. For primary alcohols, the ceria support was reduced to cerium hydroxy carbonate within 14 h and was a contributing factor toward catalyst deactivation. For secondary alcohols, cerium hydroxy carbonate was not observed during the same time period and the catalyst was stable upon prolonged reaction. Regeneration through oxidation/reduction does not restore initial activity likely due to irreversible catalyst restructuring. Lastly, a deactivation mechanism involving C–C scission of acyl and carboxylate intermediates is proposed.

Deactivation of Ceria Supported Palladium through C–C Scission during Transfer Hydrogenation of Phenol with Alcohols

DOE PAGES

Nelson, Nicholas C.; Manzano, J. Sebastián; Slowing, Igor I.

2016-11-21

The stability of palladium supported on ceria (Pd/CeO 2) was studied during liquid flow transfer hydrogenation using primary and secondary alcohols as hydrogen donors. For primary alcohols, the ceria support was reduced to cerium hydroxy carbonate within 14 h and was a contributing factor toward catalyst deactivation. For secondary alcohols, cerium hydroxy carbonate was not observed during the same time period and the catalyst was stable upon prolonged reaction. Regeneration through oxidation/reduction does not restore initial activity likely due to irreversible catalyst restructuring. Lastly, a deactivation mechanism involving C–C scission of acyl and carboxylate intermediates is proposed.

Biomonitoring of polycyclic aromatic hydrocarbon exposure in pregnant women in Trujillo, Peru — Comparison of different fuel types used for cooking☆

PubMed Central

Adetona, Olorunfemi; Li, Zheng; Sjödin, Andreas; Romanoff, Lovisa C.; Aguilar-Villalobos, Manuel; Needham, Larry L.; Hall, Daniel B.; Cassidy, Brandon E.; Naeher, Luke P.

2016-01-01

Women and children in developing countries are often exposed to high levels of air pollution including polycyclic aromatic hydrocarbons (PAHs), which may negatively impact their health, due to household combustion of biomass fuel for cooking and heating. We compared creatinine adjusted hydroxy-PAH (OH-PAH) concentrations in pregnant women in Trujillo, Peru who cook with wood to levels measured in those who cook with kerosene, liquefied petroleum gas or a combination of fuels. Seventy-nine women were recruited for the study between May and July 2004 in the first trimester of their pregnancy. Urine samples were collected from the subjects in the first, second and third trimesters for OH-PAH analyses. The concentrations of the OH-PAHs were compared across the type of fuel used for cooking and pregnancy trimesters. The relationships between OH-PAHs levels in the first trimester and concurrently measured personal exposures to PM2.5, carbon monoxide and nitrogen dioxide together with their indoor and outdoor air concentrations were also investigated. Women cooking with wood or kerosene had the highest creatinine adjusted OH-PAH concentrations compared with those using gas, coal briquette or a combination of fuels. Concentrations of creatinine adjusted 2-hydroxy-fluorene, 3-hydroxy-fluorene, 1-hydroxy-fluorene, 2-hydroxy-phenanthrene and 4-hydroxy-phenanthrene were significantly higher (p<0.05) in women who used wood or kerosene alone compared with women who used liquefied petroleum gas (LPG), coal briquette or a combination of fuels. An increase in the concentrations of creatinine adjusted 9-hydroxy-fluorene, 1-hydroxy-phenanthrene, 2-hydroxy-phenanthrene, 4-hydroxy-phenanthrene and 1-hydroxy-pyrene in the third trimesters was also observed. Weak positive correlation (Spearman correlation coefficient, ρ<0.4; p<0.05) was observed between all first trimester creatinine adjusted OH-PAHs and indoor (kitchen and living room), and personal 48-h TWA PM2.5. Women who cooked

Reduction of N-hydroxy-sulfonamides, including N-hydroxy-valdecoxib, by the molybdenum-containing enzyme mARC.

PubMed

Havemeyer, Antje; Grünewald, Sanja; Wahl, Bettina; Bittner, Florian; Mendel, Ralf; Erdélyi, Péter; Fischer, János; Clement, Bernd

2010-11-01

Purification of the mitochondrial enzyme responsible for reduction of N-hydroxylated amidine prodrugs led to the identification of two newly discovered mammalian molybdenum-containing proteins, the mitochondrial amidoxime reducing components mARC-1 and mARC-2 (Gruenewald et al., 2008). These 35-kDa proteins represent a novel group of molybdenum proteins in eukaryotes as they form a molybdenum cofactor-dependent enzyme system consisting of three separate proteins (Havemeyer et al., 2006). Each mARC protein reduces N-hydroxylated compounds after reconstitution with the electron transport proteins cytochrome b(5) and b(5) reductase. In continuation of our drug metabolism investigations (Havemeyer et al., 2006; Gruenewald et al., 2008), we present data from reconstituted enzyme systems with recombinant human and native porcine enzymes showing the reduction of N-hydroxy-sulfonamides (sulfohydroxamic acids) to sulfonamides: the N-hydroxy-sulfonamide N-hydroxy-valdecoxib (N-hydroxy-4-[5-methyl-3-phenyl-4-isoxazolyl]-benzenesulfonamide) represents a novel cyclooxygenase (COX)-2 inhibitor and is therefore a drug candidate in the treatment of diseases associated with rheumatic inflammation, pain, and fever. It was synthesized as an analog of the known COX-2 inhibitor valdecoxib (4-[5-methyl-3-phenyl-4-isoxazolyl]-benzenesulfonamide) (Talley et al., 2000). N-Hydroxy-valdecoxib had low in vitro COX-2 activity but showed significant analgesic activity in vivo and a prolonged therapeutic effect compared with valdecoxib (Erdélyi et al., 2008). In this report, we demonstrate that N-hydroxy-valdecoxib is enzymatically reduced to its pharmacologically active metabolite valdecoxib. Thus, N-hydroxy-valdecoxib acts as prodrug that is activated by the molybdenum-containing enzyme mARC.

Domino Acylation/Diels-Alder Synthesis of N-Alkyl-octahydroisoquinolin-1-one-8-carboxylic Acids under Low-Solvent Conditions.

PubMed

Slauson, Stephen R; Pemberton, Ryan; Ghosh, Partha; Tantillo, Dean J; Aubé, Jeffrey

2015-05-15

The development of the domino reaction between an aminoethyl-substituted diene and maleic anhydride to afford an N-substituted octahydroisoquinolin-1-one is described. A typical procedure involves the treatment of a 1-aminoethyl-substituted butadiene with maleic anhydride at 0 °C to room temperature for 20 min under low-solvent conditions, which affords a series of isoquinolinone carboxylic acids in moderate to excellent yields. NMR monitoring suggested that the reaction proceeded via an initial acylation step followed by an intramolecular Diels-Alder reaction. For the latter step, a significant rate difference was observed depending on whether the amino group was substituted by a phenyl or an alkyl (usually benzyl) substituent, with the former noted by NMR to be substantially slower. The Diels-Alder step was studied by density functional theory (DFT) methods, leading to the conclusion that the degree of preorganization in the starting acylated intermediate had the largest effect on the reaction barriers. In addition, the effect of electronics on the aromatic ring in N-phenyl substrates was studied computationally and experimentally. Overall, this protocol proved considerably more amenable to scale up compared to earlier methods by eliminating the requirement of microwave batch chemistry for this reaction as well as significantly reducing the quantity of solvent.

Design and synthesis of 2-nitroimidazoles with variable alkylating and acylating functionality.

PubMed

Winters, Thomas; Sercel, Anthony; Suto, Carla; Elliott, William; Leopold, Wilbur; Leopold, Judith; Showalter, Hollis

2014-01-01

The synthesis of a small series of 2-nitroimidazoles in which the β-amino alcohol side chain was amidated with a range of alkylating/acylating functionality is described. Synthetic methodologies were developed that generally provided for selective N-acyl versus N,O-bisacyl products. In vitro, target analogs showed minimal radiosensitization activity, with only a few exhibiting a sensitizer enhancement ratio (SER) >2.0 and C(1.6) values comparable to reference agents RB-6145 and RSU-1069. In an assay to determine potential to alkylate biomolecules, representative analogs showed <1% of the alkylating activity of RSU-1069. In vivo, one analog showed an enhancement ratio of 1.6 relative to vehicle control when tested in B6C3F1 mice with an implanted KHT sarcoma. The data reinforce prior findings that there is a correlation between alkylation potential and in vivo activity.

Effects of covalent modification by 4-hydroxy-2-nonenal on the noncovalent oligomerization of ubiquitin.

PubMed

Grasso, Giuseppe; Axelsen, Paul H

2017-01-01

When lipid membranes containing ω-6 polyunsaturated fatty acyl chains are subjected to oxidative stress, one of the reaction products is 4-hydroxy-2-nonenal (HNE)-a chemically reactive short chain alkenal that can covalently modify proteins. The ubiquitin proteasome system is involved in the clearing of proteins modified by oxidation products such as HNE, but the chemical structure, stability and function of ubiquitin may be impaired by HNE modification. To evaluate this possibility, the susceptibility of ubiquitin to modification by HNE has been characterized over a range of concentrations where ubiquitin forms non-covalent oligomers. Results indicate that HNE modifies ubiquitin at only two of the many possible sites, and that HNE modification at these two sites alters the ubiquitin oligomerization equilibrium. These results suggest that any role ubiquitin may have in clearing proteins damaged by oxidative stress may itself be impaired by oxidative lipid degradation products. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

A synthesis of 4-hydroxy-2-trans-nonenal and 4-(3H) 4-hydroxy-2-trans-nonenal.

PubMed

Chandra, A; Srivastava, S K

1997-07-01

4-Hydroxy-2-trans-nonenal, the most abundant and toxic unsaturated aldehyde generated during membrane lipid peroxidation, was synthesized starting from fumaraldehyde dimethyl acetal. In the first step of the synthesis, the fumaraldehyde dimethyl acetal was partially hydrolyzed using amberlyst catalyst to obtain the monoacetal. The 4-hydroxy-2-trans-nonenal was synthesized by the Grignard reaction of the fumaraldehyde monoacetal with 1-bromopentane. 4-Hydroxy-2-trans-nonenal, obtained as its dimethylacetal, was oxidized to its corresponding 4-keto derivative using pyridinium chlorochromate buffered with sodium acetate as the oxidizing agent. 4-(3H) 4-Hydroxy-2-trans-nonenal was obtained in one step by the sodium borotriteride reduction of the 4-keto derivative.

Unexpected solvent effects on the UV/Vis absorption spectra of o-cresol in toluene and benzene: in contrast with non-aromatic solvents

PubMed Central

Zheng, Dong; Yuan, Xiang-Ai; Ma, Haibo; Li, Xiaoxiong; Wang, Xizhang; Liu, Ziteng

2018-01-01

Cresol is a prototype molecule in understanding intermolecular interactions in material and biological systems, because it offers different binding sites with various solvents and protonation states under different pH values. It is found that the UV/Vis absorption spectra of o-cresol in aromatic solvents (benzene, toluene) are characterized by a sharp peak, unlike the broad double-peaks in 11 non-aromatic solvents. Both molecular dynamics simulations and electronic structure calculations revealed the formation of intermolecular π-complexation between o-cresol and aromatic solvents. The thermal movements of solvent and solute molecules render the conformations of o-cresol changing between trans and cis isomers. The π-interaction makes the cis configuration a dominant isomer, hence leading to the single keen-edged UV/Vis absorption peak at approximately 283 nm. The free conformation changes between trans and cis in aqueous solution rationalize the broader absorption peaks in the range of 260–280 nm. The pH dependence of the UV/Vis absorption spectra in aqueous solutions is also rationalized by different protonation states of o-cresol. The explicit solvent model with long-ranged interactions is vital to describe the effects of π-complexation and electrostatic interaction on the UV/Vis absorption spectra of o-cresol in toluene and alkaline aqueous (pH > 10.3) solutions, respectively. PMID:29657794

Unexpected solvent effects on the UV/Vis absorption spectra of o-cresol in toluene and benzene: in contrast with non-aromatic solvents.

PubMed

Zheng, Dong; Yuan, Xiang-Ai; Ma, Haibo; Li, Xiaoxiong; Wang, Xizhang; Liu, Ziteng; Ma, Jing

2018-03-01

Cresol is a prototype molecule in understanding intermolecular interactions in material and biological systems, because it offers different binding sites with various solvents and protonation states under different pH values. It is found that the UV/Vis absorption spectra of o -cresol in aromatic solvents (benzene, toluene) are characterized by a sharp peak, unlike the broad double-peaks in 11 non-aromatic solvents. Both molecular dynamics simulations and electronic structure calculations revealed the formation of intermolecular π-complexation between o -cresol and aromatic solvents. The thermal movements of solvent and solute molecules render the conformations of o -cresol changing between trans and cis isomers. The π-interaction makes the cis configuration a dominant isomer, hence leading to the single keen-edged UV/Vis absorption peak at approximately 283 nm. The free conformation changes between trans and cis in aqueous solution rationalize the broader absorption peaks in the range of 260-280 nm. The pH dependence of the UV/Vis absorption spectra in aqueous solutions is also rationalized by different protonation states of o -cresol. The explicit solvent model with long-ranged interactions is vital to describe the effects of π-complexation and electrostatic interaction on the UV/Vis absorption spectra of o -cresol in toluene and alkaline aqueous (pH > 10.3) solutions, respectively.

Stress-related alterations of acyl and desacyl ghrelin circulating levels: mechanisms and functional implications

PubMed Central

Stengel, Andreas; Wang, Lixin; Taché, Yvette

2011-01-01

Ghrelin is the only known peripherally produced and centrally acting peptide hormone that stimulates food intake and digestive functions. Ghrelin circulates as acylated and desacylated forms and recently the acylating enzyme, ghrelin-O-acyltransferase (GOAT) and the de-acylating enzyme, thioesterase 1/lysophospholipase 1 have been identified adding new layers of complexity to the regulation of ghrelin. Stress is known to alter gastrointestinal motility and food intake and was recently shown to modify circulating ghrelin and GOAT levels with differential responses related to the type of stressors including a reduction induced by physical stressors (abdominal surgery and immunological/endotoxin injection, exercise) and elevation by metabolic (cold exposure, fasting and caloric restriction) and psychological stressors. However, the pathways underlying the alterations of ghrelin under these various stress conditions are still largely to be defined and may relate to stress-associated autonomic changes. There is evidence that alterations of circulating ghrelin may contribute to the neuroendocrine and behavioral responses along with sustaining the energetic requirement needed upon repeated exposure to stressors. A better understanding of these mechanisms will allow targeting components of ghrelin signaling that may improve food intake and gastric motility alterations induced by stress. PMID:21782868

Stress-related alterations of acyl and desacyl ghrelin circulating levels: mechanisms and functional implications.

PubMed

Stengel, Andreas; Wang, Lixin; Taché, Yvette

2011-11-01

Ghrelin is the only known peripherally produced and centrally acting peptide hormone that stimulates food intake and digestive functions. Ghrelin circulates as acylated and desacylated forms and recently the acylating enzyme, ghrelin-O-acyltransferase (GOAT) and the de-acylating enzyme, thioesterase 1/lysophospholipase 1 have been identified adding new layers of complexity to the regulation of ghrelin. Stress is known to alter gastrointestinal motility and food intake and was recently shown to modify circulating ghrelin and GOAT levels with differential responses related to the type of stressors including a reduction induced by physical stressors (abdominal surgery and immunological/endotoxin injection, exercise) and elevation by metabolic (cold exposure, acute fasting and caloric restriction) and psychological stressors. However, the pathways underlying the alterations of ghrelin under these various stress conditions are still largely to be defined and may relate to stress-associated autonomic changes. There is evidence that alterations of circulating ghrelin may contribute to the neuroendocrine and behavioral responses along with sustaining the energetic requirement needed upon repeated exposure to stressors. A better understanding of these mechanisms will allow targeting components of ghrelin signaling that may improve food intake and gastric motility alterations induced by stress. Published by Elsevier Inc.

Gas-phase cationic benzoylation of ambient aromatic substrates studied with the decay technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Occhiucci, G.; Cacace, F.; Speranza, M.

1986-03-05

The gas-phase benzoylation of typical ambient aromatic substrates PhY (Y = OH, OMe, and NH/sub 2/) has been investigated by a combination of the decay technique and of FT ICR mass spectrometry. Labeled phenylium ions, C/sub 6/X/sub 5//sup +/ (X = H and T), from the decay of multiply tritiated benzene, C/sub 6/X/sub 6/, have been allowed to react with excess CO-containing traces of PhY (Y = OH, OMe, and NH/sub 2/), in the pressure range from 90 to 650 torr. Radio GLC and HPLC of the tritiated products demonstrate two competitive reaction channels, i.e., phenylation and benzoylation of themore » aromatic substrates. The results indicate a sharp kinetic bias of the gaseous phenylium ions for the aromatic substrates, measured by an apparent k/sub CO//k/sub PhY/ ratio of 0.12 (Y = OH), 0.13 (Y = OMe), and 0.04 (Y = NH/sub 2/) in the systems at nearly atmospheric pressure. Gas-phase benzoylation displays a high intramolecular selectivity, occurring exclusively at the n-type center of PhOH and PhNH/sub 2/. In the case of PhOMe, appreciable ring benzoylation is observed, characterized by a remarkably high (up to 30:1) bias for the para position. The mechanistic features of the gas-phase benzoylation and phenylation processes, deduced from the decay and the ICR experiments, are discussed and compared with those of related aromatic acylation and alkylation reactions occurring in the dilute gas state. 30 references, 2 tables.« less

Metal-metal bonding and aromaticity in [M2(NHCHNH)3]2 (μ-E)2 (E = O, S; M = Nb, Mo, Tc, Ru, Rh).

PubMed

Yan, Xiuli; Meng, Lingpeng; Sun, Zheng; Li, Xiaoyan

2016-02-01

The nature of M-M bonding and aromaticity of [M2(NHCHNH)3]2(μ-E)2 (E = O, S; M = Nb, Mo, Tc, Ru, Rh) was investigated using atoms in molecules (AIM) theory, electron localization function (ELF), natural bond orbital (NBO) and molecular orbital analysis. These analyses led to the following main conclusions: in [M2(NHCHNH)3]2(μ-E)2 (E = O, S; M = Nb, Mo, Tc, Ru, Rh), the Nb-Nb, Ru-Ru, and Rh-Rh bonds belong to "metallic" bonds, whereas Mo-Mo and Tc-Tc drifted toward the "dative" side; all these bonds are partially covalent in character. The Nb-Nb, Mo-Mo, and Tc-Tc bonds are stronger than Ru-Ru and Rh-Rh bonds. The M-M bonds in [M2(NHCHNH)3]2(μ-S)2 are stronger than those in [M2(NHCHNH)3]2(μ-O)2 for M = Nb, Mo, Tc, and Ru. The NICS(1)ZZ values show that all of the studied molecules, except [Ru2(NHCHNH)3]2(μ-O)2, are aromaticity molecules. O-bridged compounds have more aromaticity than S-bridged compounds. Graphical Abstract Left Molecular graph, and right electron localization function (ELF) isosurface of [M2(NHCHNH)3]2(μ-E)2(E = O, S; M = Nb, Mo, Tc, Ru, Rh).

Suzuki-miyaura cross-coupling in acylation reactions, scope and recent developments.

PubMed

Blangetti, Marco; Rosso, Heléna; Prandi, Cristina; Deagostino, Annamaria; Venturello, Paolo

2013-01-17

Since the first report and due to its handiness and wide scope, the Suzuki-Miyaura (SM) cross coupling reaction has become a routine methodology in many laboratories worldwide. With respect to other common transition metal catalyzed cross couplings, the SM reaction has been so far less exploited as a tool to introduce an acyl function into a specific substrate. In this review, the various approaches found in the literature will be considered, starting from the direct SM acylative coupling to the recent developments of cross coupling between boronates and acyl chlorides or anhydrides. Special attention will be dedicated to the use of masked acyl boronates, alkoxy styryl and alkoxy dienyl boronates as coupling partners. A final section will be then focused on the acyl SM reaction as key synthetic step in the framework of natural products synthesis.

Evaluation of Feruloylated and p-Coumaroylated Arabinosyl Units in Grass Arabinoxylans by Acidolysis in Dioxane/Methanol.

PubMed

Lapierre, Catherine; Voxeur, Aline; Karlen, Steven D; Helm, Richard F; Ralph, John

2018-05-30

The arabinosyl side chains of grass arabinoxylans are partially acylated by p-coumarate ( pCA) and ferulate (FA). These aromatic side chains can cross-couple wall polymers resulting in modulation of cell wall physical properties. The determination of p-coumaroylated and feruloylated arabinose units has been the target of analytical efforts with trifluoroacetic acid hydrolysis the standard method to release feruloylated and p-coumaroylated arabinose units from arabinoxylans. Herein, we report on a more robust method to measure these acylated units. Acidolysis of extractive-free grass samples in a dioxane/methanol/aqueous 2 M HCl mixture provided the methyl 5- O- p-coumaroyl- and 5- O-feruloyl-l-arabinofuranoside anomers ( pCA-MeAra and FA-MeAra). These conjugates were readily analyzed by liquid chromatography combined with both UV and MS detection. The method revealed the variability of the relative acylation of arabinose units by pCA or FA in grass cell walls. This methodology will permit delineation of hydroxycinnamate acylation patterns in arabinoxylans.

Analysis of the impregnation of ZnO:Mn2+ nanoparticles on cigarette filters for trapping polycyclic aromatic hydrocarbons (PAHs)

NASA Astrophysics Data System (ADS)

Estrada-Izquierdo, Irma; Sánchez-Espindola, Esther; Uribe-Hernández, Raúl; Ramón-Gallegos, Eva

2012-10-01

Each cigarette can generate 1149 ng of a mixture of 14 polycyclic aromatic hydrocarbons, of which there are a lot of information about its harmful effects on the environment and human health, they are considered mutagenic, teratogenic and carcinogenic. In this paper we tested ZnO:Mn2+ nanoparticles, attached to the filters of cigarettes. The first results showed that the filtration system was able to catch the Benzo(a)pyrene contained in cigarette smoke; but more tests are needed to quantify the efficiency with greater accuracy over other polycyclic aromatic hydrocarbons.

Adsorbed States of phosphonate derivatives of N-heterocyclic aromatic compounds, imidazole, thiazole, and pyridine on colloidal silver: comparison with a silver electrode.

PubMed

Podstawka, Edyta; Olszewski, Tomasz K; Boduszek, Bogdan; Proniewicz, Leonard M

2009-09-03

Here, we report a systematic surface-enhanced Raman spectroscopy (SERS) study of the structures of phosphonate derivatives of the N-heterocyclic aromatic compounds imidazole (ImMeP ([hydroxy(1H-imidazol-5-yl)methyl]phosphonic acid) and (ImMe)(2)P (bis[hydroxy-(1H-imidazol-4-yl)-methyl]phosphinic acid)), thiazole (BAThMeP (butylaminothiazol-2-yl-methyl)phosphonic acid) and BzAThMeP (benzylaminothiazol-2-yl-methyl)phosphonic acid)), and pyridine ((PyMe)(2)P (bis[(hydroxypyridin-3-yl-methyl)]phosphinic acid)) adsorbed on nanometer-sized colloidal particles. We compared these structures to those on a roughened silver electrode surface to determine the relationship between the adsorption strength and the geometry. For example, we showed that all of these biomolecules interact with the colloidal surface through aromatic rings. However, for BzAThMeP, a preferential interaction between the benzene ring and the colloidal silver surface is observed more so than that between the thiazole ring and this substrate. The PC(OH)C fragment does not take part in the adsorption process, and the phosphonate moiety of ImMeP and (ImMe)(2)P, being removed from the surface, only assists in this process.

Aliphatic C-C Bond Cleavage in α-Hydroxy Ketones by a Dioxygen-Derived Nucleophilic Iron-Oxygen Oxidant.

PubMed

Bhattacharya, Shrabanti; Rahaman, Rubina; Chatterjee, Sayanti; Paine, Tapan K

2017-03-17

A nucleophilic iron-oxygen oxidant, formed in situ in the reaction between an iron(II)-benzilate complex and O 2 , oxidatively cleaves the aliphatic C-C bonds of α-hydroxy ketones. In the cleavage reaction, α-hydroxy ketones without any α-C-H bond afford a 1:1 mixture of carboxylic acid and ketone. Isotope labeling studies established that one of the oxygen atoms from dioxygen is incorporated into the carboxylic acid product. Furthermore, the iron(II) complex cleaves an aliphatic C-C bond of 17-α-hydroxyprogesterone affording androstenedione and acetic acid. The O 2 -dependent aliphatic C-C bond cleavage of α-hydroxy ketones containing no α-C-H bond bears similarity to the lyase activity of the heme enzyme, cytochrome P450 17A1 (CYP17A1). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Fatty acyl-CoA reductases of birds

PubMed Central

2011-01-01

Background Birds clean and lubricate their feathers with waxes that are produced in the uropygial gland, a holocrine gland located on their back above the tail. The type and the composition of the secreted wax esters are dependent on the bird species, for instance the wax ester secretion of goose contains branched-chain fatty acids and unbranched fatty alcohols, whereas that of barn owl contains fatty acids and alcohols both of which are branched. Alcohol-forming fatty acyl-CoA reductases (FAR) catalyze the reduction of activated acyl groups to fatty alcohols that can be esterified with acyl-CoA thioesters forming wax esters. Results cDNA sequences encoding fatty acyl-CoA reductases were cloned from the uropygial glands of barn owl (Tyto alba), domestic chicken (Gallus gallus domesticus) and domestic goose (Anser anser domesticus). Heterologous expression in Saccharomyces cerevisiae showed that they encode membrane associated enzymes which catalyze a NADPH dependent reduction of acyl-CoA thioesters to fatty alcohols. By feeding studies of transgenic yeast cultures and in vitro enzyme assays with membrane fractions of transgenic yeast cells two groups of isozymes with different properties were identified, termed FAR1 and FAR2. The FAR1 group mainly synthesized 1-hexadecanol and accepted substrates in the range between 14 and 18 carbon atoms, whereas the FAR2 group preferred stearoyl-CoA and accepted substrates between 16 and 20 carbon atoms. Expression studies with tissues of domestic chicken indicated that FAR transcripts were not restricted to the uropygial gland. Conclusion The data of our study suggest that the identified and characterized avian FAR isozymes, FAR1 and FAR2, can be involved in wax ester biosynthesis and in other pathways like ether lipid synthesis. PMID:22151413

Antioxidant activity of phenolic acids and their metabolites: synthesis and antioxidant properties of the sulfate derivatives of ferulic and caffeic acids and of the acyl glucuronide of ferulic acid.

PubMed

Piazzon, A; Vrhovsek, U; Masuero, D; Mattivi, F; Mandoj, F; Nardini, M

2012-12-19

The main metabolites of caffeic and ferulic acids (ferulic acid-4'-O-sulfate, caffeic acid-4'-O-sulfate, and caffeic acid-3'-O-sulfate), the most representative phenolic acids in fruits and vegetables, and the acyl glucuronide of ferulic acid were synthesized, purified, and tested for their antioxidant activity in comparison with those of their parent compounds and other related phenolics. Both the ferric reducing antioxidant power (FRAP) assay and the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging method were used. Ferulic acid-4'-O-sulfate and ferulic acid-4'-O-glucuronide exhibited very low antioxidant activity, while the monosulfate derivatives of caffeic acid were 4-fold less efficient as the antioxidant than caffeic acid. The acyl glucuronide of ferulic acid showed strong antioxidant action. The antioxidant activity of caffeic acid-3'-O-glucuronide and caffeic acid-4'-O-glucuronide was also studied. Our results demonstrate that some of the products of phenolic acid metabolism still retain strong antioxidant properties. Moreover, we first demonstrate the ex vivo synthesis of the acyl glucuronide of ferulic acid by mouse liver microsomes, in addition to the phenyl glucuronide.

Isoniazid cocrystals with anti-oxidant hydroxy benzoic acids

NASA Astrophysics Data System (ADS)

Mashhadi, Syed Muddassir Ali; Yunus, Uzma; Bhatti, Moazzam Hussain; Tahir, Muhammad Nawaz

2014-11-01

Isoniazid is the primary constituent of “triple therapy” used to effectively treat tuberculosis. In tuberculosis and other diseases, tissue inflammation and free radical burst from macrophages results in oxidative stress. These free radicals cause pulmonary inflammation if not countered by anti-oxidants. Therefore, in the present study cocrystals of isoniazid with four anti-oxidant hydroxy benzoic acids have been reported. Gallic acid, 2,3-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, and 3-hydroxybenzoic acid resulted in the formation of cocrystals when reacted with isoniazid. Cocrystal structure analysis confirmed the existence of pyridine-carboxylic acid synthon in the cocrystals of isoniazid with Gallic acid, 2,3-dihydroxybenzoic acid and 3-hydroxybenzoic acid. While cocrystal of 3,5-dihydroxybenzoic acid formed the pyridine-hydroxy group synthon. Other synthons of different graph sets are formed between hydrazide group of isoniazid and coformers involving Nsbnd H⋯O and Osbnd H⋯N bonds. All the cocrystals were in 1:1 stoichiometric ratio.

Acyl-protein thioesterase 2 catalyzes the deacylation of peripheral membrane-associated GAP-43.

PubMed

Tomatis, Vanesa M; Trenchi, Alejandra; Gomez, Guillermo A; Daniotti, Jose L

2010-11-30

An acylation/deacylation cycle is necessary to maintain the steady-state subcellular distribution and biological activity of S-acylated peripheral proteins. Despite the progress that has been made in identifying and characterizing palmitoyltransferases (PATs), much less is known about the thioesterases involved in protein deacylation. In this work, we investigated the deacylation of growth-associated protein-43 (GAP-43), a dually acylated protein at cysteine residues 3 and 4. Using fluorescent fusion constructs, we measured in vivo the rate of deacylation of GAP-43 and its single acylated mutants in Chinese hamster ovary (CHO)-K1 and human HeLa cells. Biochemical and live cell imaging experiments demonstrated that single acylated mutants were completely deacylated with similar kinetic in both cell types. By RT-PCR we observed that acyl-protein thioesterase 1 (APT-1), the only bona fide thioesterase shown to mediate deacylation in vivo, is expressed in HeLa cells, but not in CHO-K1 cells. However, APT-1 overexpression neither increased the deacylation rate of single acylated GAP-43 nor affected the steady-state subcellular distribution of dually acylated GAP-43 both in CHO-K1 and HeLa cells, indicating that GAP-43 deacylation is not mediated by APT-1. Accordingly, we performed a bioinformatic search to identify putative candidates with acyl-protein thioesterase activity. Among several candidates, we found that APT-2 is expressed both in CHO-K1 and HeLa cells and its overexpression increased the deacylation rate of single acylated GAP-43 and affected the steady-state localization of diacylated GAP-43 and H-Ras. Thus, the results demonstrate that APT-2 is the protein thioesterase involved in the acylation/deacylation cycle operating in GAP-43 subcellular distribution.

BAHD or SCPL acyltransferase? What a dilemma for acylation in the world of plant phenolic compounds.

PubMed

Bontpart, Thibaut; Cheynier, Véronique; Ageorges, Agnès; Terrier, Nancy

2015-11-01

Phenolic compounds are secondary metabolites involved in several plant growth and development processes, including resistance to biotic and abiotic stresses. The biosynthetic pathways leading to the vast diversity of plant phenolic products often include an acylation step, with phenolic compounds being the donor or acceptor molecules. To date, two acyltransferase families using phenolic compounds as acceptor or donor molecules have been described, with each using a different 'energy-rich' acyl donor. BAHD-acyltransferases, named after the first four biochemically characterized enzymes of the group, use acyl-CoA thioesters as donor molecules, whereas SCPL (Serine CarboxyPeptidase Like)-acyltransferases use 1-O-β-glucose esters. Here, common and divergent specifications found in the literature for both enzyme families were analyzed to answer the following questions. Are both acyltransferases involved in the synthesis of the same molecule (or same group of molecules)? Are both acyltransferases recruited in the same plant? How does the subcellular localization of these enzymes impact metabolite trafficking in plant cells? © 2015 INRA. New Phytologist © 2015 New Phytologist Trust.

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

ClinicalTrials.gov

2018-06-01

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

Acyl carrier proteins from sunflower (Helianthus annuus L.) seeds and their influence on FatA and FatB acyl-ACP thioesterase activities.

PubMed

Aznar-Moreno, Jose A; Venegas-Calerón, Mónica; Martínez-Force, Enrique; Garcés, Rafael; Salas, Joaquín J

2016-08-01

The kinetics of acyl-ACP thioesterases from sunflower importantly changed when endogenous ACPs were used. Sunflower FatB was much more specific towards saturated acyl-ACPs when assayed with them. Acyl carrier proteins (ACPs) are small (~9 kDa), soluble, acidic proteins involved in fatty acid synthesis in plants and bacteria. ACPs bind to fatty acids through a thioester bond, generating the acyl-ACP lipoproteins that are substrates for fatty acid synthase (FAS) complexes, and that are required for fatty acid chain elongation, acting as important intermediates in de novo fatty acid synthesis in plants. Plants, usually express several ACP isoforms with distinct functionalities. We report here the cloning of three ACPs from developing sunflower seeds: HaACP1, HaACP2, and HaACP3. These proteins were plastidial ACPs expressed strongly in seeds, and as such they are probably involved in the synthesis of sunflower oil. The recombinant sunflower ACPs were expressed in bacteria but they were lethal to the prokaryote host. Thus, they were finally produced using the GST gene fusion system, which allowed the apo-enzyme to be produced and later activated to the holo form. Radiolabelled acyl-ACPs from the newly cloned holo-ACP forms were also synthesized and used to characterize the activity of recombinant sunflower FatA and FatB thioesterases, important enzymes in plant fatty acids synthesis. The activity of these enzymes changed significantly when the endogenous ACPs were used. Thus, FatA importantly increased its activity levels, whereas FatB displayed a different specificity profile, with much high activity levels towards saturated acyl-CoA derivatives. All these data pointed to an important influence of the ACP moieties on the activity of enzymes involved in lipid synthesis.

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.

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

Insight into Coenzyme A cofactor binding and the mechanism of acyl-transfer in an acylating aldehyde dehydrogenase from Clostridium phytofermentans.

PubMed

Tuck, Laura R; Altenbach, Kirsten; Ang, Thiau Fu; Crawshaw, Adam D; Campopiano, Dominic J; Clarke, David J; Marles-Wright, Jon

2016-02-22

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.

N-Methylpyrrolidone Hydroperoxide/Cs2 CO3 as an Excellent Reagent System for the Hydroxy-Directed Diastereoselective Epoxidation of Electron-Deficient Olefins.

PubMed

Victor, Napoleon John; Gana, Janardhanan; Muraleedharan, Kannoth Manheri

2015-10-12

This report introduces N-methylpyrrolidone hydroperoxide (NMPOOH)/base as an excellent reagent system for hydroxy-directed syn selective epoxidation of electron-deficient olefins, characterized by high diastereoselectivity, short reaction times and remarkable chemoselectivity, especially in presence of oxidatively labile nitrogen or sulfur atoms. NMPOOH also proves efficient in the oxidation of electron-deficient aromatic aldehydes, in the removal of oxazolidinone chiral auxiliary, and in the functionalization of alkenes and alkynes, showing wide application potential. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

ClinicalTrials.gov

2018-06-19

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

Rapid Acyl-Homoserine Lactone Quorum Signal Biodegradation in Diverse Soils†

PubMed Central

Wang, Ya-Juan; Leadbetter, Jared Renton

2005-01-01

Signal degradation impacts all communications. Although acyl-homoserine lactone (acyl-HSL) quorum-sensing signals are known to be degraded by defined laboratory cultures, little is known about their stability in nature. Here, we show that acyl-HSLs are biodegraded in soils sampled from diverse U.S. sites and by termite hindgut contents. When amended to samples at physiologically relevant concentrations, 14C-labeled acyl-HSLs were mineralized to 14CO2 rapidly and, at most sites examined, without lag. A lag-free turf soil activity was characterized in further detail. Heating or irradiation of the soil prior to the addition of radiolabel abolished mineralization, whereas protein synthesis inhibitors did not. Mineralization exhibited an apparent Km of 1.5 μM acyl-HSL, ca. 1,000-fold lower than that reported for a purified acyl-HSL lactonase. Under optimal conditions, acyl-HSL degradation proceeded at a rate of 13.4 nmol · h−1 · g of fresh weight soil−1. Bioassays established that the final extent of signal inactivation was greater than for its full conversion to CO2 but that the two processes were well coupled kinetically. A most probable number of 4.6 × 105 cells · g of turf soil−1 degraded physiologically relevant amounts of hexanoyl-[1-14C]HSL to 14CO2. It would take chemical lactonolysis months to match the level of signal decay achieved in days by the observed biological activity. Rapid decay might serve either to quiet signal cross talk that might otherwise occur between spatially separated microbial aggregates or as a full system reset. Depending on the context, biological signal decay might either promote or complicate cellular communications and the accuracy of population density-based controls on gene expression in species-rich ecosystems. PMID:15746331

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 phenotypesmore » 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.« less

SIMULTANEOUS DTERMINATION OF CHROMATE AND AROMATIC HYDROCARBONS IN ENVIRONMENTAL SAMPLES BY CAPILLARY ELECTROPHORESIS

EPA Science Inventory

An analytical method was developed to determine simultaneously, the inorganic anion CrO2-4, and organic aromatic compounds including benzoate, 2-Cl-benzoate, phenol, m-cresol and o-/p-cresol by capillary electrophoresis (CE). Chromate and the aromatics were separated in a relativ...

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…

Biotransformation of petroleum asphaltenes and high molecular weight polycyclic aromatic hydrocarbons by Neosartorya fischeri.

PubMed

Hernández-López, E Lorena; Perezgasga, Lucia; Huerta-Saquero, Alejandro; Mouriño-Pérez, Rosa; Vazquez-Duhalt, Rafael

2016-06-01

Neosartorya fischeri, an Aspergillaceae fungus, was evaluated in its capacity to transform high molecular weight polycyclic aromatics hydrocarbons (HMW-PAHs) and the recalcitrant fraction of petroleum, the asphaltenes. N. fischeri was able to grow in these compounds as sole carbon source. Coronene, benzo(g,h,i)perylene, and indeno(1,2,3-c,d)pyrene, together with the asphaltenes, were assayed for fungal biotransformation. The transformation of the asphaltenes and HMW-PAHs was confirmed by reverse-phase high-performance liquid chromatography (HPLC), nano-LC mass spectrometry, and IR spectrometry. The formation of hydroxy and ketones groups on the PAH molecules suggest a biotransformation mediated by monooxygenases such as cytochrome P450 system (CYP). A comparative microarray with the complete genome from N. fischeri showed three CYP monooxygenases and one flavin monooxygenase genes upregulated. These findings, together with the internalization of aromatic substrates into fungal cells and the microsomal transformation of HMW-PAHs, strongly support the role of CYPs in the oxidation of these recalcitrant compounds.

Nature of the water/aromatic parallel alignment interactions.

PubMed

Mitoraj, Mariusz P; Janjić, Goran V; Medaković, Vesna B; Veljković, Dušan Ž; Michalak, Artur; Zarić, Snežana D; Milčić, Miloš K

2015-01-30

The water/aromatic parallel alignment interactions are interactions where the water molecule or one of its O-H bonds is parallel to the aromatic ring plane. The calculated energies of the interactions are significant, up to ΔE(CCSD)(T)(limit) = -2.45 kcal mol(-1) at large horizontal displacement, out of benzene ring and CH bond region. These interactions are stronger than CH···O water/benzene interactions, but weaker than OH···π interactions. To investigate the nature of water/aromatic parallel alignment interactions, energy decomposition methods, symmetry-adapted perturbation theory, and extended transition state-natural orbitals for chemical valence (NOCV), were used. The calculations have shown that, for the complexes at large horizontal displacements, major contribution to interaction energy comes from electrostatic interactions between monomers, and for the complexes at small horizontal displacements, dispersion interactions are dominant binding force. The NOCV-based analysis has shown that in structures with strong interaction energies charge transfer of the type π → σ*(O-H) between the monomers also exists. © 2014 Wiley Periodicals, Inc.

Aromatic proteinaceous surfactants stabilize long-lived gas microbubbles from natural sources

NASA Technical Reports Server (NTRS)

Darrigo, J. S.

1981-01-01

Three different types of protein-specific chemical tests were performed on long-lived gas microbubbles derived from aqueous solutions of agarose powder and from filtered aqueous extracts of Hawaiian forest soil. The separate protein-specific tests involved use of either 0.3% (w/v) ninhydrin, 100 microM methylene blue dye, or 0.7-1.0 M 2-hydroxy-5-nitrobenzyl bromide. The chemical test results obtained with each of the two natural substances, i.e., agarose powder and Hawaiian forest soil, were very similar and indicate that the biological surfactants which surround and stabilize long-lived gas microbubbles are proteinaceous compounds that contain, and whose surface activity depends upon, aromatic amino acid residues, particularly tryptophan.

Analysis of protein prenylation and S-acylation using gas chromatography-coupled mass spectrometry.

PubMed

Sorek, Nadav; Akerman, Amir; Yalovsky, Shaul

2013-01-01

Lipid modifications play a key role in protein targeting and function. The two Arabidopsis Gγ subunits, AGG1 and AGG2, have been shown to undergo prenylation (AGG1) and S-acylation (AGG2). Prenylation involves covalent nonreversible attachment of either farnesyl (15 carbons) or geranylgeranyl (20 carbons) isoprenoids to conserved cysteine residues at or near the C-terminus of proteins. S-acylation, frequently referred to as palmitoylation, involves the attachment of acyl fatty acids to thiol groups of cysteine residues through a reversible thioester bond. The procedures described below allow direct analysis of the prenyl and acyl moieties using gas chromatography-coupled mass spectrometry (GC-MS). These methods are based on (1) cleavage of prenyl groups with the Raney nickel catalyst and (2) analysis of protein S-acylation following cleavage of the acyl fatty acids from proteins by hydrogenation with platinum (IV) oxide. The hydrogenation under these conditions causes an acid transesterification of the acyl moieties, adding an ethyl group to the carboxyl head of the fatty acid. The addition of the ethyl group reduces the polarity of the fatty acids, allowing their efficient separation by gas chromatography.

Evaluation of 8-hydroxy-2'-deoxyguanosine (8-OHdG) adduct levels and DNA strand breaks in human peripheral blood lymphocytes exposed in vitro to polycyclic aromatic hydrocarbons with or without animal metabolic activation.

PubMed

Isabel, Rodríguez-Romero María; Sandra, Gómez-Arroyo; Rafael, Villalobos-Pietrini; Carmen, Martínez-Valenzuela; Josefina, Cortés-Eslava; del Carmen, Calderón-Ezquerro María; Rocío, García-Martínez; Francisco, Arenas-Huertero; Elena, Calderón-Segura María

2012-04-01

The polycyclic aromatic hydrocarbons (PAHs) dibenzo(a,h)anthracene, benzo(ghi)perylene, benzo(b)fluoranthene and benzo(a)pyrene have been identified in urban air from Mexico City and some of them are classified as human carcinogens. In the present study, human peripheral blood lymphocytes were exposed in vitro to different concentrations of PAHs with (+S9) or without (-S9) metabolic activation. The genotoxic and cytotoxic effects of each PAH were examined with an alkaline comet assay and trypan blue dye exclusion, and oxidative DNA damage was determined via the detection of 8-hydroxy-2'-deoxyguanosine (8-OhdG) adduct levels by enzyme-linked immunosorbent assay (ELISA). The DNA damage was evaluated with two genotoxicity parameters: the frequency of comets and the comet tail length. Concentrations of 20, 40, 80, 160 and 320 µM DB(a,h)A-S9; 20, 40, 80, 160 and 240 µM B(ghi)P-S9; 20, 30, 40, 60 and 80 µM B(b)F-S9; and 80 µM B(a)P-S9 for 24 h induced a small but significant increase in the means of comet frequency, in the tail length and in the 8-oHDg levels in relation to the control (0.5% DMSO-S9). However, all PAHs+S9 produced a more significant increase in DNA strand breaks and the level of 8-OHdG compared with the control (0.5% DMSO+S9), with a concentration-effect relationship. The viability of lymphocytes exposed to all PAHs-S9 and PAHs+S9 was not modified compared with the control. The results of this study demonstrate that the comet and ELISA are rapid, suitable and sensitive methods to detect in vitro PAH-induced DNA damage in human peripheral lymphocytes.

rac-6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide from synchrotron data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brzezinski, Krzysztof; Dauter, Zbigniew; Baj, Aneta

2012-05-29

The crystal structure of the title water-soluble analogue of vitamin E, trolox amide, C{sub 14}H{sub 19}NO{sub 3}, solved and refined against synchrotron diffraction data, contains two molecules in the asymmetric unit. In both molecules, the heterocyclic ring is in a half-chair conformation. The crystal packing features a herring-bone pattern generated by N-H...O hydrogen bonds between the hydroxy and amide groups. O-H...O hydrogen bonds also occur.

Breslow Intermediates from Aromatic N-Heterocyclic Carbenes (Benzimidazolin-2-ylidenes, Thiazolin-2-ylidenes).

PubMed

Berkessel, Albrecht; Paul, Mathias; Sudkaow, Panyapon; Wessels, Alina; Schlörer, Nils E; Neudörfl, Jörg M

2018-04-12

We report the first generation and characterization of the elusive Breslow intermediates derived from aromatic N-heterocyclic carbenes (NHCs), namely benzimidazolin-2-ylidenes (NMR, X-ray) and thiazolin-2-ylidenes (NMR). In the former case, the diaminoenols were generated by reaction of the free N,N-bis-Dipp- and N,N-bis-Mes-benzimidazolin-2-ylidenes with aldehydes, while the dimer of 3,4,5-trimethylthiazolin-2-ylidene served as the starting material in the latter case. The unambiguous NMR-identification of the first thiazolin-2-ylidene based Breslow intermediate rests on double 13C labeling of both the NHC and the aldehyde component. Acyl anion reactivity was proven by benzoin formation with excess aldehyde. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Head-group acylation of monogalactosyldiacylglycerol is a common stress response, but the acyl-galactose acyl composition varies with the plant species and applied stress

USDA-ARS?s Scientific Manuscript database

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...

Acyl transfer from membrane lipids to peptides is a generic process.

PubMed

Dods, Robert H; Bechinger, Burkhard; Mosely, Jackie A; Sanderson, John M

2013-11-15

The generality of acyl transfer from phospholipids to membrane-active peptides has been probed using liquid chromatography-mass spectrometry analysis of peptide-lipid mixtures. The peptides examined include melittin, magainin II, PGLa, LAK1, LAK3 and penetratin. Peptides were added to liposomes with membrane lipid compositions ranging from pure phosphatidylcholine (PC) to mixtures of PC with phosphatidylethanolamine, phosphatidylserine or phosphatidylglycerol. Experiments were typically conducted at pH7.4 at modest salt concentrations (90 mM NaCl). In favorable cases, lipidated peptides were further characterized by tandem mass spectrometry methods to determine the sites of acylation. Melittin and magainin II were the most reactive peptides, with significant acyl transfer detected under all conditions and membrane compositions. Both peptides were lipidated at the N-terminus by transfer from PC, phosphatidylethanolamine, phosphatidylserine or phosphatidylglycerol, as well as at internal sites: lysine for melittin; serine and lysine for magainin II. Acyl transfer could be detected within 3h of melittin addition to negatively charged membranes. The other peptides were less reactive, but for each peptide, acylation was found to occur in at least one of the conditions examined. The data demonstrate that acyl transfer is a generic process for peptides bound to membranes composed of diacylglycerophospholipids. Phospholipid membranes cannot therefore be considered as chemically inert toward peptides and by extension proteins. © 2013. Published by Elsevier Ltd. All rights reserved.

Acyl Chain Preference in Foam Cell Formation from Mouse Peritoneal Macrophages.

PubMed

Fujiwara, Yuko; Hama, Kotaro; Tsukahara, Makoto; Izumi-Tsuzuki, Ryosuke; Nagai, Toru; Ohe-Yamada, Mihoko; Inoue, Keizo; Yokoyama, Kazuaki

2018-01-01

Macrophage foam cells play critical roles in the initiation and development of atherosclerosis by synthesizing and accumulating cholesteryl ester (CE) in lipid droplets. However, in analyzing lipid metabolism in foam cell formation, studies have focused on the sterol group, and little research has been done on the acyl chains. Therefore, we adapted a model system using liposomes containing particular acyl chains and examined the effect of various acyl chains on foam cell formation. Of the phosphatidylserine (PS) liposomes tested containing PS, phosphatidylcholine, and cholesterol, we found that unsaturated (C18:1), but not saturated (C16:0 and C18:0), PS liposomes induced lipid droplet formation, indicating that foam cell formation depends on the nature of the acyl chain of the PS liposomes. Experiments on the uptake and accumulation of cholesterol from liposomes by adding [ 14 C]cholesterol suggested that foam cell formation could be induced only when cholesterol was converted to CE in the case of C18:1 PS liposomes. Both microscopic observations and metabolic analysis suggest that cholesterol incorporated into either C16:0 or C18:0 PS liposomes may stay intact after being taken in by endosomes. The [ 14 C]C18:1 fatty acyl chain in the C18:1 PS liposome was used to synthesize CE and triacylglycerol (TG). Interestingly, the [ 14 C]C16:0 in the C18:1 PS liposome was metabolized to sphingomyelin rather than being incorporated into either CE or TG, which could be because of enzymatic acyl chain selectivity. In conclusion, our results indicate that the acyl chain preference of macrophages could have some impact on their progression to foam cells.

Influence of lipophilicity in O-acyl and O-alkyl derivatives of juglone and lawsone: a structure-activity relationship study in the search for natural herbicide models.

PubMed

Durán, Alexandra G; Chinchilla, Nuria; Molinillo, José Mg; Macías, Francisco A

2018-03-01

Naphthoquinones are known for their broad range of biological activities. Given the increasing demands of consumers in relation to food quality and growing concerns about the impact of synthetic herbicides, it is necessary to search for new agrochemicals. Natural products and allelopathy provide new alternatives for the development of pesticides with lower toxicity and greater environmental compatibility. A structure-activity relationship to evaluate the effect of bioavailability was performed. A total of 44 O-acyl and O-alkyl derivatives of juglone and lawsone with different linear chain lengths were prepared. These compounds were tested on etiolated wheat coleoptiles, standard target species (STS) and four weeds, Echinochloa crus-galli L., Lolium rigidum Gaud., Lolium perenne L. and Avena fatua L. The results showed a strong influence of lipophilicity and, in most cases, the data fitted a logP-dependent quadratic mathematical model. The effects produced were mostly stunting and necrosis caused by growth inhibition. The potential structure and activity behaviour is described. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Structural Basis for Substrate Fatty Acyl Chain Specificity

PubMed Central

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

2008-01-01

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-Å resolution. The overall fold of the N-terminal ∼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 α-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 12Å and permitting substrate acyl chain lengths as long as 24 carbons to bind. VLCAD deficiency is among the more common defects of mitochondrial β-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. PMID:18227065

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

PubMed

Jing, Fuyuan; Cantu, David C; Tvaruzkova, Jarmila; Chipman, Jay P; Nikolau, Basil J; Yandeau-Nelson, Marna D; Reilly, Peter J

2011-08-10

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. 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. These acyl-ACP TEs can potentially be used to diversify the fatty acid biosynthesis pathway to produce novel fatty acids.

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

Aromatic thiol-mediated cleavage of N-O bonds enables chemical ubiquitylation of folded proteins

NASA Astrophysics Data System (ADS)

Weller, Caroline E.; Dhall, Abhinav; Ding, Feizhi; Linares, Edlaine; Whedon, Samuel D.; Senger, Nicholas A.; Tyson, Elizabeth L.; Bagert, John D.; Li, Xiaosong; Augusto, Ohara; Chatterjee, Champak

2016-09-01

Access to protein substrates homogenously modified by ubiquitin (Ub) is critical for biophysical and biochemical investigations aimed at deconvoluting the myriad biological roles for Ub. Current chemical strategies for protein ubiquitylation, however, employ temporary ligation auxiliaries that are removed under harsh denaturing conditions and have limited applicability. We report an unprecedented aromatic thiol-mediated N-O bond cleavage and its application towards native chemical ubiquitylation with the ligation auxiliary 2-aminooxyethanethiol. Our interrogation of the reaction mechanism suggests a disulfide radical anion as the active species capable of cleaving the N-O bond. The successful semisynthesis of full-length histone H2B modified by the small ubiquitin-like modifier-3 (SUMO-3) protein further demonstrates the generalizability and compatibility of our strategy with folded proteins.

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

2017-04-01

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 whose subunit composition and physiological roles have not yet been clearly established. Inconclusive data in the literature refer to the exact protein composition and substrate specificity of the enzyme complex that produces the long-chain α-carboxy-acyl-CoAs, which are substrates involved in the last step of condensation mediated by the polyketide synthase 13 to synthesize mature mycolic acids. Here we have successfully reconstituted the long-chain acyl-CoA carboxylase (LCC) complex 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 activity. Furthermore, we also showed by substrate competition experiments and the use of a specific inhibitor that the AccD5 subunit's 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-C 24-26 -CoA, used as condensing units for the biosynthesis of all the lipids present in this pathogen. © 2017 Federation of European Biochemical Societies.

The R117A variant of the Escherichia coli transacylase FabD synthesizes novel acyl-(acyl carrier proteins).

PubMed

Marcella, Aaron M; Barb, Adam W

2017-12-01

The commercial impact of fermentation systems producing novel and biorenewable chemicals will flourish with the expansion of enzymes engineered to synthesize new molecules. Though a small degree of natural variability exists in fatty acid biosynthesis, the molecular space accessible through enzyme engineering is fundamentally limitless. Prokaryotic fatty acid biosynthesis enzymes build carbon chains on a functionalized acyl carrier protein (ACP) that provides solubility, stability, and a scaffold for interactions with the synthetic enzymes. Here, we identify the malonyl-coenzyme A (CoA)/holo-ACP transacylase (FabD) from Escherichia coli as a platform enzyme for engineering to diversify microbial fatty acid biosynthesis. The FabD R117A variant produced novel ACP-based primer and extender units for fatty acid biosynthesis. Unlike the wild-type enzyme that is highly specific for malonyl-CoA to produce malonyl-ACP, the R117A variant synthesized acetyl-ACP, succinyl-ACP, isobutyryl-ACP, 2-butenoyl-ACP, and β-hydroxybutyryl-ACP among others from holo-ACP and the corresponding acyl-CoAs with specific activities from 3.7 to 120 nmol min -1  mg -1 . FabD R117A maintained K M values for holo-ACP (~ 40 μM) and displayed small changes in K M for acetoacetyl-CoA (110 ± 30 μM) and acetyl-CoA (200 ± 70 μM) when compared to malonyl-CoA (80 ± 30 μM). FabD R117A represents a novel catalyst that synthesizes a broad range of acyl-acyl-ACPs.

Total and acylated ghrelin in liver cirrhosis: correlation with clinical and nutritional status.

PubMed

El-Shehaby, Amal M; Obaia, Eman M; Alwakil, Sahar S; Hiekal, Ahmed A

2010-07-01

The pathogenesis of anorexia in cirrhotic patients is complex and the appetite-modulating hormone ghrelin could be involved. Acylated ghrelin is the biologically active form that modifies insulin sensitivity and body composition. The aim of the present study was to compare acylated and total ghrelin concentration in patients with liver cirrhosis and to investigate the possible relationship between ghrelin and clinical and nutritional parameters. Sixty patients with viral liver cirrhosis who did not have hepatocellular carcinoma or acute infections were studied. Twenty healthy volunteers were recruited after matching for age, gender, and body mass index with the patients and served as controls. Fasting levels of total, acylated ghrelin, leptin, TNF-alpha and insulin were measured in all subjects, in addition, clinical and nutrition parameters were assessed. In cirrhotic patients, plasma levels of both acylated and total ghrelin were significantly higher than those in the controls. The mean plasma acylated ghrelin levels were significantly higher in Child C cirrhosis compared to Child A and B. Ghrelin (total and acylated) were negatively correlated with leptin in cirrhotic patients confirming the fact that leptin acts as a physiological counterpart of ghrelin. Nutritional and metabolic abnormalities in cirrhotic patients may be dependent on the changes in the ghrelin/leptin systems, mainly the acylated form of ghrelin.

Chlorogenic acids and the acyl-quinic acids: discovery, biosynthesis, bioavailability and bioactivity.

PubMed

Clifford, Michael N; Jaganath, Indu B; Ludwig, Iziar A; Crozier, Alan

2017-12-13

Covering: 2000 up to late 2017This review is focussed upon the acyl-quinic acids, the most studied group within the ca. 400 chlorogenic acids so far reported. The acyl-quinic acids, the first of which was characterised in 1846, are a diverse group of plant-derived compounds produced principally through esterification of an hydroxycinnamic acid and 1l-(-)-quinic acid. Topics addressed in this review include the confusing nomenclature, quantification and characterisation by NMR and MS, biosynthesis and role in planta, and the occurrence of acyl-quinic acids in coffee, their transformation during roasting and delivery to the beverage. Coffee is the major human dietary source world-wide of acyl-quinic acids and consideration is given to their absorption and metabolism in the upper gastrointestinal tract, and the colon where the microbiota play a key role in the formation of catabolites. Evidence on the potential of the in vivo metabolites and catabolites of acyl-quinic acids to promote the consumer's health is evaluated.

Engineered short branched-chain acyl-CoA synthesis in E. coli and acylation of chloramphenicol to branched-chain derivatives.

PubMed

Bi, Huiping; Bai, Yanfen; Cai, Tao; Zhuang, Yibin; Liang, Xiaomei; Zhang, Xueli; Liu, Tao; Ma, Yanhe

2013-12-01

Short branched-chain acyl-CoAs are important building blocks for a wide variety of pharmaceutically valuable natural products. Escherichia coli has been used as a heterologous host for the production of a variety of natural compounds for many years. In the current study, we engineered synthesis of isobutyryl-CoA and isovaleryl-CoA from glucose in E. coli by integration of the branched-chain α-keto acid dehydrogenase complex from Streptomyces avermitilis. In the presence of the chloramphenicol acetyltransferase (cat) gene, chloramphenicol was converted to both chloramphenicol-3-isobutyrate and chloramphenicol-3-isovalerate by the recombinant E. coli strains, which suggested successful synthesis of isobutyryl-CoA and isovaleryl-CoA. Furthermore, we improved the α-keto acid precursor supply by overexpressing the alsS gene from Bacillus subtilis and the ilvC and ilvD genes from E. coli and thus enhanced the synthesis of short branched-chain acyl-CoAs. By feeding 25 mg/L chloramphenicol, 2.96 ± 0.06 mg/L chloramphenicol-3-isobutyrate and 3.94 ± 0.06 mg/L chloramphenicol-3-isovalerate were generated by the engineered E. coli strain, which indicated efficient biosynthesis of short branched-chain acyl-CoAs. HPLC analysis showed that the most efficient E. coli strain produced 80.77 ± 3.83 nmol/g wet weight isovaleryl-CoA. To our knowledge, this is the first report of production of short branched-chain acyl-CoAs in E. coli and opens a way to biosynthesize various valuable natural compounds based on these special building blocks from renewable carbon sources.

Jejunal administration of glucose enhances acyl ghrelin suppression in obese humans

PubMed Central

Sidani, Reem M.; Garcia, Anna E.; Antoun, Joseph; Isbell, James M.; Abumrad, Naji N.

2016-01-01

Ghrelin is a gastric hormone that stimulates hunger and worsens glucose metabolism. Circulating ghrelin is decreased after Roux-en-Y gastric bypass (RYGB) surgery; however, the mechanism(s) underlying this change is unknown. We tested the hypothesis that jejunal nutrient exposure plays a significant role in ghrelin suppression after RYGB. Feeding tubes were placed in the stomach or jejunum in 13 obese subjects to simulate pre-RYGB or post-RYGB glucose exposure to the gastrointestinal (GI) tract, respectively, without the confounding effects of caloric restriction, weight loss, and surgical stress. On separate study days, the plasma glucose curves obtained with either gastric or jejunal administration of glucose were replicated with intravenous (iv) infusions of glucose. These “isoglycemic clamps” enabled us to determine the contribution of the GI tract and postabsorptive plasma glucose to acyl ghrelin suppression. Plasma acyl ghrelin levels were suppressed to a greater degree with jejunal glucose administration compared with gastric glucose administration (P < 0.05). Jejunal administration of glucose also resulted in a greater suppression of acyl ghrelin than the corresponding isoglycemic glucose infusion (P ≤ 0.01). However, gastric and isoglycemic iv glucose infusions resulted in similar degrees of acyl ghrelin suppression (P > 0.05). Direct exposure of the proximal jejunum to glucose increases acyl ghrelin suppression independent of circulating glucose levels. The enhanced suppression of acyl ghrelin after RYGB may be due to a nutrient-initiated signal in the jejunum that regulates ghrelin secretion. PMID:27279247

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.

2017-06-01

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. [Figure not available: see fulltext.

Acyl hydrazides as acyl donors for the synthesis of diaryl and aryl alkyl ketones.

PubMed

Akhbar, Ahmed R; Chudasama, Vijay; Fitzmaurice, Richard J; Powell, Lyn; Caddick, Stephen

2014-01-21

In this communication we describe a novel strategy for the formation of valuable diaryl and aryl alkyl ketones from acyl hydrazides. A wide variety of ketones are prepared and the mild reaction conditions allow for the use of a range of functionalities, especially in the synthesis of diaryl ketones.

Commelinid Monocotyledon Lignins Are Acylated by p-Coumarate.

PubMed

Karlen, Steven D; Free, Heather C A; Padmakshan, Dharshana; Smith, Bronwen G; Ralph, John; Harris, Philip J

2018-06-01

Commelinid monocotyledons are a monophyletic clade differentiated from other monocotyledons by the presence of cell wall-bound ferulate and p -coumarate. The Poaceae, or grass family, is a member of this group, and most of the p -coumarate in the cell walls of this family acylates lignin. Here, we isolated and examined lignified cell wall preparations from 10 species of commelinid monocotyledons from nine families other than Poaceae, including species from all four commelinid monocotyledon orders (Poales, Zingiberales, Commelinales, and Arecales). We showed that, as in the Poaceae, lignin-linked p -coumarate occurs exclusively on the hydroxyl group on the γ-carbon of lignin unit side chains, mostly on syringyl units. Although the mechanism of acylation has not been studied directly in these species, it is likely to be similar to that in the Poaceae and involve BAHD acyl-coenzyme A:monolignol transferases. © 2018 American Society of Plant Biologists. All rights reserved.

(E)-3-[3,4-Bis(meth-oxy-methoxy)phen-yl]-1-(7-hy-droxy-5-meth-oxy-2,2-dimethyl-chroman-8-yl)prop-2-en-1-one.

PubMed

Hashim, Nur Athirah; Ahmad, Farediah; Basar, Norazah; Awang, Khalijah; Ng, Seik Weng

2011-09-01

The reaction of 5,6-(2,2-dimethyl-chroman-yl)-2-hy-droxy-4-meth-oxy-acetophenone and 3,4-bis-(meth-oxy-meth-yloxy)benzaldehyde affords the intense orange title chalcone derivative, C(25)H(30)O(8). The two benzene rings are connected through a -C(=O)-CH=CH- (propenone) unit, which is in an E conformation; the ring with the hy-droxy substitutent is aligned at 19.5 (2)° with respect to this unit, whereas the ring with the meth-oxy-meth-yloxy substituent is aligned at 9.3 (3)°. The dihedral angle between the rings is 19.38 (10)°. The hy-droxy group engages in an intra-molecular O-H⋯O hydrogen bond with the carbonyl O atom of the propenone unit, generating an S(5) ring.

SIRT2 and lysine fatty acylation regulate the transforming activity of K-Ras4a

PubMed Central

Wisner, Stephanie A; Chen, Xiao; Spiegelman, Nicole A; Linder, Maurine E

2017-01-01

Ras proteins play vital roles in numerous biological processes and Ras mutations are found in many human tumors. Understanding how Ras proteins are regulated is important for elucidating cell signaling pathways and identifying new targets for treating human diseases. Here we report that one of the K-Ras splice variants, K-Ras4a, is subject to lysine fatty acylation, a previously under-studied protein post-translational modification. Sirtuin 2 (SIRT2), one of the mammalian nicotinamide adenine dinucleotide (NAD)-dependent lysine deacylases, catalyzes the removal of fatty acylation from K-Ras4a. We further demonstrate that SIRT2-mediated lysine defatty-acylation promotes endomembrane localization of K-Ras4a, enhances its interaction with A-Raf, and thus promotes cellular transformation. Our study identifies lysine fatty acylation as a previously unknown regulatory mechanism for the Ras family of GTPases that is distinct from cysteine fatty acylation. These findings highlight the biological significance of lysine fatty acylation and sirtuin-catalyzed protein lysine defatty-acylation. PMID:29239724

Identification of N-acyl-fumonisin B1 as new cytotoxic metabolites of fumonisin mycotoxins.

PubMed

Harrer, Henning; Laviad, Elad L; Humpf, Hans Ulrich; Futerman, Anthony H

2013-03-01

Fumonisins are mycotoxins produced by Fusarium species. The predominant derivative, fumonisin B1 (FB1), occurs in food and feed and is of health concern due to its hepatotoxic and carcinogenic effects. However, the role of FB1 metabolites on the mechanism of the toxicity, the inhibition of the ceramide synthesis, is unknown. The aim of this study was to identify new fumonisin metabolites and to evaluate their cytotoxic potential. MS, molecular biology, and in vitro enzyme assays were used to investigate fumonisin metabolism in mammalian cells overexpressing human ceramide synthase (CerS) genes. N-acyl-FB1 derivatives were detected as new metabolites in cultured cells at levels of up to 10 pmol/mg of protein. The N-acylation of FB1 and hydrolyzed FB1 was analyzed in several cell lines, including cells overexpressing CerS. The acyl-chain length of the N-acyl fumonisins depends on the CerS isoform acylating them. The N-acyl fumonisins are more cytotoxic than the parent fumonisin B1. The identification of N-acyl fumonisins with various acyl chain lengths together with the observed cytotoxicity of these compounds is a new aspect of fumonisin-related toxicity. Therefore, these new metabolites might play an important role in the mode of action of fumonisins. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interactions of acylated methylglucoside derivatives with CO2: simulation and calculations.

PubMed

Chang, H H; Cao, R X; Yang, C C; Wei, W L; Pang, X Y; Qiao, Y

2016-01-01

Carbohydrates have drawn considerable interest from researchers recently due to their affinity for CO2. However, most of the research in this field has focused on peracetylated derivatives. Compared with acetylated carbohydrates, which have already been studied in depth, methyl D-glucopyranoside derivatives are more stable and could have additional applications. Thus, in the present work, ab initio calculations were performed to elucidate the characteristics of the interactions of methylglucoside derivatives with CO2, and to investigate how the binding energy (ΔE) is affected by isomerization or the introduction of various acyl groups. Four methyl D-glucopyranosides (each with two anomers) bearing acetyl, propionyl, butyryl, and isobutyryl moieties, respectively, were designed as substrates, and the 1:1 complexes of a CO2 molecule with each of these sugar substrates were modeled. The results indicate that ΔE is mainly influenced by interaction distance and the number of negatively charged donors or interacting pairs in the complex; the structure of the acyl group present in the substrate is a secondary influence. Except in the case of methyl 2-O-acetyl-D-glucopyranose, the ΔE values of the α- and β-anomers of each methylglucoside were found to be almost the same. Therefore, we would expect the CO2 affinities of the four derivatives studied here to be as strong as or even stronger than that of peracetylated D-glucopyranose. Graphical Abstract The binding energy between methyl D-glucopyranoside derivatives with various substituted acyl groups and CO2 are evaluated by ab initio calculations. The strong interaction between these methyl dglucopyranoside derivatives and CO2 showed the potential of their application for CO2 capture.

LOCATION OF ACYL GROUPS ON TWO PARTLY ACYLATED GLYCOLIPIDS FROM STRAINS OF USTILAGO (SMUT FUNGI),

DTIC Science & Technology

erythritol from Ustilago sp. (probably U. nuda (Jens.) Rostr. = U. tritici (Pers.) Rostr.) PRL-627 were acetalated with methyl vinyl ether, deacylated...Partly acylated ustilagic acids 8 (from Ustilago maydis (DC) Corda (= U. zeae Unger) PRL-119), consisting of partially esterified beta-cellobiosyl

Metabolism of 4-N-Hydroxy-Cytidine in Escherichia coli

PubMed Central

Trimble, R. B.; Maley, Frank

1971-01-01

4-N-hydroxy-cytidine was found to substitute for uridine as a pyrimidine supplement for the growth of Escherichia coli Bu−. Measurement of the incorporation of 4-N-hydroxy-cytidine-2-14C into ribonucleic acid and deoxyribonucleic acid revealed that this compound was converted to cytidine or uridine before utilization. Two pathways for metabolism were considered: (i) the reduction of 4-N-hydroxy-cytidine to cytidine followed by deamination, (ii) the direct hydrolysis of hydroxylamine from 4-N-hydroxy-cytidine to yield uridine. A threefold increase in cytidine (deoxycytidine) deaminase (EC 3.5.4.5) activity, when the cells were grown on 4-N-hydroxy-cytidine, suggested the involvement of this enzyme. More direct proof was obtained by purifying the deaminase 185-fold and finding that it released hydroxylamine from 4-N-hydroxy-cytidine at one-fiftieth the rate at which ammonia was removed from cytidine. This result is consistent with the slower rate of growth of the Bu− cells on 4-N-hydroxy-cytidine than cytidine and suggests that the second pathway is the major route for utilization of this compound. PMID:4941553

Acylation-dependent protein export in Leishmania.

PubMed

Denny, P W; Gokool, S; Russell, D G; Field, M C; Smith, D F

2000-04-14

The surface of the protozoan parasite Leishmania is unusual in that it consists predominantly of glycosylphosphatidylinositol-anchored glycoconjugates and proteins. Additionally, a family of hydrophilic acylated surface proteins (HASPs) has been localized to the extracellular face of the plasma membrane in infective parasite stages. These surface polypeptides lack a recognizable endoplasmic reticulum secretory signal sequence, transmembrane spanning domain, or glycosylphosphatidylinositol-anchor consensus sequence, indicating that novel mechanisms are involved in their transport and localization. Here, we show that the N-terminal domain of HASPB contains primary structural information that directs both N-myristoylation and palmitoylation and is essential for correct localization of the protein to the plasma membrane. Furthermore, the N-terminal 18 amino acids of HASPB, encoding the dual acylation site, are sufficient to target the heterologous Aequorea victoria green fluorescent protein to the cell surface of Leishmania. Mutagenesis of the predicted acylated residues confirms that modification by both myristate and palmitate is required for correct trafficking. These data suggest that HASPB is a representative of a novel class of proteins whose translocation onto the surface of eukaryotic cells is dependent upon a "non-classical" pathway involving N-myristoylation/palmitoylation. Significantly, HASPB is also translocated on to the extracellular face of the plasma membrane of transfected mammalian cells, indicating that the export signal for HASPB is recognized by a higher eukaryotic export mechanism.

Structure of YciA from Haemophilus influenzae (HI0827), a Hexameric Broad Specificity Acyl-Coenzyme A Thioesterase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Willis, Mark A.; Zhuang, Zhihao; Song, Feng

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 occupiedmore » 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.« less

Evolution of the acyl-CoA binding protein (ACBP)

PubMed Central

Burton, Mark; Rose, Timothy M.; Færgeman, Nils J.; Knudsen, Jens

2005-01-01

Acyl-CoA-binding protein (ACBP) is a 10 kDa protein that binds C12–C22 acyl-CoA esters with high affinity. In vitro and in vivo experiments suggest that it is involved in multiple cellular tasks including modulation of fatty acid biosynthesis, enzyme regulation, regulation of the intracellular acyl-CoA pool size, donation of acyl-CoA esters for β-oxidation, vesicular trafficking, complex lipid synthesis and gene regulation. In the present study, we delineate the evolutionary history of ACBP to get a complete picture of its evolution and distribution among species. ACBP homologues were identified in all four eukaryotic kingdoms, Animalia, Plantae, Fungi and Protista, and eleven eubacterial species. ACBP homologues were not detected in any other known bacterial species, or in archaea. Nearly all of the ACBP-containing bacteria are pathogenic to plants or animals, suggesting that an ACBP gene could have been acquired from a eukaryotic host by horizontal gene transfer. Many bacterial, fungal and higher eukaryotic species only harbour a single ACBP homologue. However, a number of species, ranging from protozoa to vertebrates, have evolved two to six lineage-specific paralogues through gene duplication and/or retrotransposition events. The ACBP protein is highly conserved across phylums, and the majority of ACBP genes are subjected to strong purifying selection. Experimental evidence indicates that the function of ACBP has been conserved from yeast to humans and that the multiple lineage-specific paralogues have evolved altered functions. The appearance of ACBP very early on in evolution points towards a fundamental role of ACBP in acyl-CoA metabolism, including ceramide synthesis and in signalling. PMID:16018771

Preparation of 7-hydroxy-2-oxoindolin-3-ylacetic acid and its [13C2], [5-n-3H], and [5-n-3H]-7-O-glucosyl analogues for use in the study of indol-3-ylacetic acid catabolism

NASA Technical Reports Server (NTRS)

Lewer, P.; Bandurski, R. S. (Principal Investigator)

1987-01-01

An improved synthesis of 7-hydroxy-2-oxoindolin-3-ylacetic acid via the base-induced condensation reaction between oxalate esters and 7-benzyloxyindolin-2-one is described. 7-Benzyloxyindolin-2-one was prepared in four steps and 50% overall yield from 3-hydroxy-2-nitrotoluene. The yield of the title compound from 7-benzyloxyindolin-2-one was 56%. This route was used to prepare 7-hydroxy-2-oxoindolin-3-yl[13C2]acetic acid in 30% yield from [13C2]oxalic acid dihydrate. The method could not be extended to the preparation of the corresponding [14C2]-compound. However, an enzyme preparation from Zea mays roots catalysed the conversion of carrier-free [5-n-3H]indol-3-ylacetic acid with a specific activity of 16.7 Ci mmol-1 to a mixture of 7-hydroxy-2-oxo[5-n-3H]indolin-3-ylacetic acid and its [5-n-3H]-7-O-glucoside in ca. 3 and 40% radiochemical yield respectively. The glucoside was converted into the 7-hydroxy compound in 80% yield by means of beta-glucosidase.

LC-mS analysis of human urine specimens for 2-oxo-3-hydroxy LSD: method validation for potential interferants and stability study of 2-oxo-3-hydroxy LSD under various storage conditions.

PubMed

Klette, Kevin L; Horn, Carl K; Stout, Peter R; Anderson, Cynthia J

2002-01-01

2-Oxo-3-hydroxy lysergic acid diethylamide (O-H-LSD), a major LSD metabolite, has previously been demonstrated to be a superior marker for identifying LSD use compared with the parent drug, LSD. Specifically, O-H-LSD analyzed using liquid chromatography-mass spectrometry has been reported to be present in urine at concentrations 16 to 43 times greater than LSD. To further support forensic application of this procedure, the specificity of the assay was assessed using compounds that have structural and chemical properties similar to O-H-LSD, common over-the-counter products, prescription drugs and some of their metabolites, and other drugs of abuse. Of the wide range of compounds studied, none were found to interfere with the detection of O-H-LSD or the internal standard 2-oxo-3-hydroxy lysergic acid methyl propylamide. The stability of O-H-LSD was investigated from 0 to 9 days at various temperatures, pH conditions, and exposures to fluorescent light. Additionally, the effect of long-term frozen storage and pH was investigated from 0 to 60 days. There was no significant loss of O-H-LSD under both refrigerated and frozen conditions within the normal human physiological pH range of urine (4.6-8.4). However, significant loss of O-H-LSD was observed in samples prepared at pH 4.6-8.4 and stored at room temperature or higher (24-50 degrees C).

40 CFR 721.10164 - Benzenecarboximidamide, N-hydroxy-4-nitro-.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzenecarboximidamide, N-hydroxy-4... Specific Chemical Substances § 721.10164 Benzenecarboximidamide, N-hydroxy-4-nitro-. (a) Chemical substance... benzenecarboximidamide, N-hydroxy-4-nitro- (PMN P-08-36; CAS No. 1613-86-1) is subject to reporting under this section...

40 CFR 721.10164 - Benzenecarboximidamide, N-hydroxy-4-nitro-.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Benzenecarboximidamide, N-hydroxy-4... Specific Chemical Substances § 721.10164 Benzenecarboximidamide, N-hydroxy-4-nitro-. (a) Chemical substance... benzenecarboximidamide, N-hydroxy-4-nitro- (PMN P-08-36; CAS No. 1613-86-1) is subject to reporting under this section...

Bond cleavage of lignin model compounds into aromatic monomers using supported metal catalysts in supercritical water

PubMed Central

Yamaguchi, Aritomo; Mimura, Naoki; Shirai, Masayuki; Sato, Osamu

2017-01-01

More efficient use of lignin carbon is necessary for carbon-efficient utilization of lignocellulosic biomass. Conversion of lignin into valuable aromatic compounds requires the cleavage of C–O ether bonds and C–C bonds between lignin monomer units. The catalytic cleavage of C–O bonds is still challenging, and cleavage of C–C bonds is even more difficult. Here, we report cleavage of the aromatic C–O bonds in lignin model compounds using supported metal catalysts in supercritical water without adding hydrogen gas and without causing hydrogenation of the aromatic rings. The cleavage of the C–C bond in bibenzyl was also achieved with Rh/C as a catalyst. Use of this technique may greatly facilitate the conversion of lignin into valuable aromatic compounds. PMID:28387304

Acyl spermidines in inflorescence extracts of elder (Sambucus nigra L., Adoxaceae) and elderflower drinks.

PubMed

Kite, Geoffrey C; Larsson, Sonny; Veitch, Nigel C; Porter, Elaine A; Ding, Ning; Simmonds, Monique S J

2013-04-10

LC-UV-MS analyses of inflorescence extracts of Sambucus nigra L. (elder, Adoxaceae) revealed the presence of numerous acyl spermidines, with isomers of N,N-diferuloylspermidine and N-acetyl-N,N-diferuloylspermidine being most abundant. Pollen was the main source of the acyl spermidines in the inflorescence. Three of the major acyl spermidines were isolated and their structures determined by NMR spectroscopy as N⁵,N¹⁰-di-(E,E)-feruloylspermidine and the new compounds N¹-acetyl-N⁵,N¹⁰-di-(Z,E)-feruloylspermidine and N¹-acetyl-N⁵,N¹⁰-di-(E,E)-feruloylspermidine. An isomer of N,N,N-triferuloylspermidine was also obtained and identified as N¹,N⁵,N¹⁰-tri-(E,E,E)-feruloylspermidine. In addition to stereoisomers of the isolated acyl spermidines, other acyl spermidines detected by the positive ion LC-UV-MS were isomers of N-caffeoyl-N,N-diferuloylspermidine, N-coumaroyl-N,N-diferuloylspermidine, N-caffeoyl-N-feruloylspermidine, N-coumaroyl-N-feruloylspermidine, N-acetyl-N-caffeoyl-N-feruloylspermidine, and N-acetyl-N-coumaroyl-N-feruloylspermidine. Analysis of commercial elderflower drinks showed that acyl spermidines were persistent in these processed elderflower products. Examination of inflorescence extracts from Sambucus canadensis L. (American elder) revealed the presence of acyl spermidines that were different from those of S. nigra.

Design of N-acyl homoserine lactonase with high substrate specificity by a rational approach.

PubMed

Kyeong, Hyun-Ho; Kim, Jin-Hyun; Kim, Hak-Sung

2015-06-01

N-Acyl homoserine lactone (AHL) is a major quorum-sensing signaling molecule in many bacterial species. Quorum-quenching (QQ) enzymes, which degrade such signaling molecules, have attracted much attention as an approach to controlling and preventing bacterial virulence and pathogenesis. However, naturally occurring QQ enzymes show a broad substrate spectrum, raising the concern of unintentionally attenuating beneficial effects by symbiotic bacteria. Here we report the rational design of acyl homoserine lactonase with high substrate specificity. Through docking analysis, we identified three key residues which play a key role in the substrate preference of the enzyme. The key residues were changed in a way that increases hydrophobic contact with a substrate having a short acyl chain (C4-AHL) while generating steric clashes with that containing a long acyl chain (C12-AHL). The resulting mutants exhibited a significantly shifted preference toward a substrate with a short acyl chain. Molecular dynamics simulations suggested that the mutations affect the behavior of a flexible loop, allowing tighter binding of a substrate with a short acyl chain.

Shifting Native Chemical Ligation into Reverse through N→S Acyl Transfer

PubMed Central

Macmillan, Derek; Adams, Anna; Premdjee, Bhavesh

2011-01-01

Peptide thioester synthesis by N→S acyl transfer is being intensively explored by many research groups the world over. Reasons for this likely include the often straightforward method of precursor assembly using Fmoc-based chemistry and the fundamentally interesting acyl migration process. In this review we introduce recent advances in this exciting area and discuss, in more detail, our own efforts towards the synthesis of peptide thioesters through N→S acyl transfer in native peptide sequences. We have found that several peptide thioesters can be readily prepared and, what’s more, there appears to be ample opportunity for further development and discovery. PMID:22347724

Exploring Cooperative Effects in Oxidative NHC Catalysis: Regioselective Acylation of Carbohydrates.

PubMed

Cramer, David L; Bera, Srikrishna; Studer, Armido

2016-05-23

The utility of oxidative NHC catalysis for both the regioselective and chemoselective functionalization of carbohydrates is explored. Chiral NHCs allow for the highly regioselective oxidative esterification of various carbohydrates using aldehydes as acylation precursors. The transformation was also shown to be amenable to both cis/trans diol isomers, free amino groups, and selective for specific sugar epimers in competition experiments. Efficiency and regioselectivity of the acylation can be improved upon using two different NHC catalysts that act cooperatively. The potential of the method is documented by the regioselective acylation of an amino-linked neodisaccharide. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel chemoselective hydrogenation of aromatic nitro compounds over ferric hydroxide supported nanocluster gold in the presence of CO and H2O.

PubMed

Liu, Lequan; Qiao, Botao; Chen, Zhengjian; Zhang, Juan; Deng, Youquan

2009-02-14

Chemoselective hydrogenation of aromatic nitro compounds were first efficiently achieved over Au/Fe(OH)(x) at 100-120 degrees C for 1.5-6 h (depending on different substrates) in the presence of CO and H(2)O.

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

PubMed Central

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

2017-01-01

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-13C]glucose, 13CO2, 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. PMID:27903654

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 CO 2 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 CO 2 , or D 2 O 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. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

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.

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

Isomerization of 1-O-indol-3-ylacetyl-beta-D-glucose. Enzymatic hydrolysis of 1-O, 4-O, and 6-O-indol-3-ylacetyl-beta-D-glucose and the enzymatic synthesis of indole-3-acetyl glycerol by a hormone metabolizing complex

NASA Technical Reports Server (NTRS)

Kowalczyk, S.; Bandurski, R. S.

1990-01-01

The first compound in the series of reactions leading to the ester conjugates of indole-3-acetic acid (IAA) in kernels of Zea mays sweet corn is the acyl alkyl acetal, 1-O-indol-3-ylacetyl-beta-D-glucose (1-O-IAGlu). The enzyme catalyzing the synthesis of this compound is UDP-glucose:indol-3-ylacetate glucosyl-transferase (IAGlu synthase). The IAA moiety of the high energy compound 1-O-IAGlu may be enzymatically transferred to myo-inositol or to glycerol or the 1-O-IAGlu may be enzymatically hydrolyzed. Alternatively, nonenzymatic acyl migration may occur to yield the 2-O, 4-O, and 6-O esters of IAA and glucose. The 4-O and 6-O esters may then be enzymatically hydrolyzed to yield free IAA and glucose. This work reports new enzymatic activities, the transfer of IAA from 1-O-IAGlu to glycerol, and the enzyme-catalyzed hydrolysis of 4-O and 6-O-IAGlu. Data is also presented on the rate of non-enzymatic acyl migration of IAA from the 1-O to the 4-O and 6-O positions of glucose. We also report that enzymes catalyzing the synthesis of 1-O-IAGlu and the hydrolysis of 1-O, 4-O, and 6-O-IAGlu fractionate as a hormone metabolizing complex. The association of synthetic and hydrolytic capabilities in enzymes which cofractionate may have physiological significance.

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.

Anorexia in hemodialysis patients: the possible role of des-acyl ghrelin.

PubMed

Muscaritoli, Maurizio; Molfino, Alessio; Chiappini, Maria Grazia; Laviano, Alessandro; Ammann, Thomas; Spinsanti, Paola; Melchiorri, Daniela; Inui, Akio; Alegiani, Filippo; Rossi Fanelli, Filippo

2007-01-01

Anorexia is frequently found in end-stage renal disease and is a reliable predictor of morbidity and mortality in hemodialysis (HD) patients. The pathogenesis of anorexia is complex and the appetite-modulating hormone ghrelin could be involved. Two forms of circulating ghrelin have been described: acylated ghrelin (<10% of circulating ghrelin) which promotes food intake, and des-acyl ghrelin which induces a negative energy balance. The aim of this cross-sectional study is to clarify whether anorexia and body weight change in HD patients relate to plasma des-acyl ghrelin levels. 34 HD patients and 15 healthy controls were studied. The presence of anorexia was assessed by a questionnaire. Serum des-acyl ghrelin was measured in HD patients and in 15 body mass index-, sex- and age-matched controls by ELISA. Energy intake was assessed by a 3-day dietary diary, and fat-free mass (FFM) was evaluated by body impedance analysis. Data have been statistically analyzed and are presented as mean +/- SD. 14 patients (41%) were found to be anorexic, and 20 patients (59%) non-anorexic. Energy intake (kcal/day) was significantly lower in anorexic than in non-anorexic patients (1,682 +/- 241 vs. 1,972.50 +/- 490; p < 0.05). FFM (%) was lower in anorexic than in non-anorexic patients (65.8 +/- 4.4 vs. 70.9 +/- 8.7; p = 0.05). Plasma des-acyl ghrelin levels (fmol/ml) were significantly higher in HD patients than in controls (214.88 +/- 154.24 vs. 128.93 +/- 51.07; p < 0.05), and in anorexic HD patients than in non-anorexic (301.7 +/- 162.4 vs. 159.1 +/- 115.5; p < 0.01). Anorexia is highly prevalent among HD patients and des-acyl ghrelin could be involved in its pathogenesis. Copyright 2007 S. Karger AG, Basel.

S-acylation dependent post-translational cross-talk regulates large conductance calcium- and voltage- activated potassium (BK) channels

PubMed Central

Shipston, Michael J.

2014-01-01

Mechanisms that control surface expression and/or activity of large conductance calcium-activated potassium (BK) channels are important determinants of their (patho)physiological function. Indeed, BK channel dysfunction is associated with major human disorders ranging from epilepsy to hypertension and obesity. S-acylation (S-palmitoylation) represents a major reversible, post-translational modification controlling the properties and function of many proteins including ion channels. Recent evidence reveals that both pore-forming and regulatory subunits of BK channels are S-acylated and control channel trafficking and regulation by AGC-family protein kinases. The pore-forming α-subunit is S-acylated at two distinct sites within the N- and C-terminus, each site being regulated by different palmitoyl acyl transferases (zDHHCs) and acyl thioesterases (APTs). S-acylation of the N-terminus controls channel trafficking and surface expression whereas S-acylation of the C-terminal domain determines regulation of channel activity by AGC-family protein kinases. S-acylation of the regulatory β4-subunit controls ER exit and surface expression of BK channels but does not affect ion channel kinetics at the plasma membrane. Furthermore, a significant number of previously identified BK-channel interacting proteins have been shown, or are predicted to be, S-acylated. Thus, the BK channel multi-molecular signaling complex may be dynamically regulated by this fundamental post-translational modification and thus S-acylation likely represents an important determinant of BK channel physiology in health and disease. PMID:25140154

Intracerebroventricular urocortin 3 counteracts central acyl ghrelin-induced hyperphagic and gastroprokinetic effects via CRF receptor 2 in rats

PubMed Central

Yeh, Chun; Ting, Ching-Heng; Doong, Ming-Luen; Chi, Chin-Wen; Lee, Shou-Dong; Chen, Chih-Yen

2016-01-01

Purpose Urocortin 3 is a key neuromodulator in the regulation of stress, anxiety, food intake, gut motility, and energy homeostasis, while ghrelin elicits feeding behavior and enhances gastric emptying, adiposity, and positive energy balance. However, the interplays between urocortin 3 and ghrelin on food intake and gastric emptying remain uninvestigated. Methods We examined the differential effects of central O-n-octanoylated ghrelin, des-Gln14-ghrelin, and urocortin 3 on food intake, as well as on charcoal nonnutrient semiliquid gastric emptying in conscious rats that were chronically implanted with intracerebroventricular (ICV) catheters. The functional importance of corticotropin-releasing factor (CRF) receptor 2 in urocortin 3-induced responses was examined by ICV injection of the selective CRF receptor 2 antagonist, astressin2-B. Results ICV infusion of urocortin 3 opposed central acyl ghrelin-elicited hyperphagia via CRF receptor 2 in satiated rats. ICV injection of O-n-octanoylated ghrelin and des-Gln14-ghrelin were equally potent in accelerating gastric emptying in fasted rats, whereas ICV administration of urocortin 3 delayed gastric emptying. In addition, ICV infusion of urocortin 3 counteracted central acyl ghrelin-induced gastroprokinetic effects via CRF receptor 2 pathway. Conclusion ICV-infused urocortin 3 counteracts central acyl ghrelin-induced hyperphagic and gastroprokinetic effects via CRF receptor 2 in rats. Our results clearly showed that enhancing ghrelin and blocking CRF receptor 2 signaling in the brain accelerated gastric emptying, which provided important clues for a new therapeutic avenue in ameliorating anorexia and gastric ileus found in various chronic wasting disorders. PMID:27757017

Complete structural characterization of ceramides as [M – H]− ions by multiple-stage linear ion trap mass spectrometry

PubMed Central

Hsu, Fong-Fu

2016-01-01

Ceramide is a huge lipid family consisting of diversified structures including various modifications in the fatty acyl chain and the long chain base (LCB). In this contribution, negative-ion ESI linear ion-trap multiple-stage mass spectrometric method (LIT MSn) towards complete structural determination of ceramides in ten major families characterized as the [M – H]− ions is described. Multiple sets of fragment ions reflecting the fatty acyl chain and LCB were observed in the CID MS2 spectrum, while the sequential MS3 and MS4 spectra contain structural information for locating the double bond and the functional groups, permitting realization of the fragmentation processes. Thereby, differentiation of ceramide molecules varied by chain length, the LCB (sphingosine, phytosphigosine, 6-hydroxy-sphingosine), and by the modification (α-hydroxy-, β-hydroxy-, ω-hydroxy-FA) can be achieved; and many isomeric structures in the biological specimen can be revealed in detail. PMID:27523779

Infrared spectroscopy of hydrated polycyclic aromatic hydrocarbon cations: naphthalene+-water.

PubMed

Chatterjee, Kuntal; Dopfer, Otto

2017-12-13

Polycyclic aromatic hydrocarbons (PAHs) are suggested to occur in interstellar media and ice grains. It is important to characterize hydrated PAHs and their cations to explore their stability in interstellar and biological media. Herein, the infrared photodissociation (IRPD) spectrum of the naphthalene + -H 2 O radical cation (Np + -H 2 O) recorded in the O-H and C-H stretch range is analysed by dispersion-corrected density functional theory calculations at the B3LYP-D3/aug-cc-pVTZ level to determine its structure and intermolecular bonding. Monohydration of Np + in its 2 A u ground electronic state leads to the formation of a bifurcated CHO ionic hydrogen bond (H-bond), in which the lone pairs of H 2 O bind to two adjacent CH proton donors of the two aromatic rings. The frequency-dependent branching ratios observed for IRPD of cold Np + -H 2 O-Ar clusters allows the estimation of the dissociation energy of Np + -H 2 O as D 0 ∼ 2800 ± 300 cm -1 . The monohydration motif of Np + differs qualitatively from that of the benzene cation in both structure and binding energy, indicating the strong influence of the multiple aromatic rings on the hydration of PAH + cations. This difference is rationalized by natural bond orbital analysis of the ionic H-bond motif. Comparison with neutral Np-H 2 O reveals the large change in structure and bond strength of the hydrated PAHs upon ionization. While neutral Np-H 2 O is stabilized by weak π H-bonds (OHπ, π-stacking), strong cation-dipole forces favour a planar bifurcated CHO ionic H-bond in Np + -H 2 O.

Effects of ghrelin and des-acyl ghrelin on neurogenesis of the rat fetal spinal cord

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sato, Miho; Nakahara, Keiko; Goto, Shintaro

Expressions of the growth hormone secretagogue receptor (GHS-R) mRNA and its protein were confirmed in rat fetal spinal cord tissues by RT-PCR and immunohistochemistry. In vitro, over 3 nM ghrelin and des-acyl ghrelin induced significant proliferation of primary cultured cells from the fetal spinal cord. The proliferating cells were then double-stained using antibodies against the neuronal precursor marker, nestin, and the cell proliferation marker, 5-bromo-2'-deoxyuridine (BrdU), and the nestin-positive cells were also found to be co-stained with antibody against GHS-R. Furthermore, binding studies using [{sup 125}I]des-acyl ghrelin indicated the presence of a specific binding site for des-acyl ghrelin, and confirmedmore » that the binding was displaced with unlabeled des-acyl ghrelin or ghrelin. These results indicate that ghrelin and des-acyl ghrelin induce proliferation of neuronal precursor cells that is both dependent and independent of GHS-R, suggesting that both ghrelin and des-acyl ghrelin are involved in neurogenesis of the fetal spinal cord.« less

Synthesis of 3-Methyl-4-(4-methylbenzoyl)-1-phenyl-pyrazol-5-One: How to Avoid O-Acylation

ERIC Educational Resources Information Center

Kurteva, Vanya B.; Petrova, Maria A.

2015-01-01

In this laboratory experiment, students synthesize 3-methyl-4-(4-methylbenzoyl)-1-phenyl-pyrazol-5-one by selective C-acylation of 3-methyl-1-phenyl-1H-pyrazol-5-one. Calcium hydroxide is used to push the tautomeric equilibrium toward the enol form, to protect the hydroxyl functionality as a complex, to trap the liberated hydrogen chloride, and to…

40 CFR 721.10050 - Disubstituted-N′- hydroxy-benzenecarboximidamide (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... Specific Chemical Substances § 721.10050 Disubstituted-N′- hydroxy-benzenecarboximidamide (generic). (a... generically as disubstituted-N′- hydroxy-benzenecarboximidamide (PMN P-02-929) is subject to reporting under...

40 CFR 721.10050 - Disubstituted-N′- hydroxy-benzenecarboximidamide (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... Specific Chemical Substances § 721.10050 Disubstituted-N′- hydroxy-benzenecarboximidamide (generic). (a... generically as disubstituted-N′- hydroxy-benzenecarboximidamide (PMN P-02-929) is subject to reporting under...

Oxidative decomposition of aromatic hydrocarbons by electron beam irradiation

NASA Astrophysics Data System (ADS)

Han, Do-Hung; Stuchinskaya, Tatiana; Won, Yang-Soo; Park, Wan-Sik; Lim, Jae-Kyong

2003-05-01

Decomposition of aromatic volatile organic compounds (VOCs) under electron beam irradiation was studied in order to examine the kinetics of the process, to characterize the reaction product distribution and to develop a process of waste gas control technology. Toluene, ethylbenzene, o-, m-, p-xylenes and chlorobenzene were used as target materials. The experiments were carried out at doses ranging from 0.5 to 10 kGy, using a flow reactor utilized under electron beam irradiation. Maximum degrees of decomposition carried out at 10 kGy in air environment were 55-65% for “non-chlorinated” aromatic VOC and 85% for chlorobenzene. It was found that a combination of aromatic pollutants with chlorobenzene would considerably increase the degradation value up to nearly 50% compared to the same compounds in the absence of chlorine groups. Based on our experimental observation, the degradation mechanism of the aromatic compounds combined with chloro-compound suggests that a chlorine radical, formed from EB irradiation, induces a chain reaction, resulting in an accelerating oxidative destruction of aromatic VOCs.

Dihydropyranone Formation by Ipso C–H Activation in a Glucal 3-Carbamate-Derived Rhodium Acyl Nitrenoid

PubMed Central

Hurlocker, Brisa; Abascal, Nadia C.; Repka, Lindsay M.; Santizo-Deleon, Elsy; Smenton, Abigail L.; Baranov, Victoria; Gupta, Ritu; Bernard, Sarah E.; Chowdhury, Shenjuti; Rojas, Christian M.

2011-01-01

By using (N-tosyloxy)-3-O-carbamoyl-D-glucal 10, which removes the need for a hypervalent iodine(III) oxidant, we provide evidence for rhodium nitrenoid-mediated ipso C–H activation as the origin of a C3-oxidized dihydropyranone product 3. This system may be especially susceptible to such a pathway due to the ease of forming a cation upon hydride transfer to the rhodium-complexed acyl nitrene. PMID:21381715

Bis(6-meth-oxy-2-{[tris-(hydroxy-meth-yl)-meth-yl]-imino-meth-yl}phenolato)-copper(II) dihydrate.

PubMed

Zhang, Xiutang; Wei, Peihai; Dou, Jianmin; Li, Bin; Hu, Bo

2009-01-08

In the title compound, [Cu(C(12)H(16)NO(5))(2)]·2H(2)O, the Cu(II) ion adopts a trans-CuN(2)O(4) octa-hedral geometry arising from two N,O,O'-tridentate 6-meth-oxy-2-{[tris-(hydroxy-meth-yl)meth-yl]-imino-meth-yl}phenolate ligands. The Jahn-Teller distortion of the copper centre is unusally small. In the crystal structure, O-H⋯O hydrogen bonds, some of which are bifurcated, link the component species.

Assembly of N,N-disubstituted hydrazines and 1-aryl-1H-indazoles via copper-catalyzed coupling reactions.

PubMed

Xiong, Xiaodong; Jiang, Yongwen; Ma, Dawei

2012-05-18

CuI-catalyzed coupling of N-acyl-N'-substituted hydrazines with aryl iodides takes place at 60-90 °C to afford N-acyl-N',N'-disubstituted hydrazines regioselectively and thereby gives a facile method for assembling N,N-diaryl hydrazines. N-Acyl-N'-substituted hydrazines can also react with 2-bromoarylcarbonylic compounds at 60-125 °C under the catalysis of CuI/4-hydroxy-l-proline to provide 1-aryl-1H-indazoles.

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

PubMed

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

2011-10-04

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

Process for the preparation of benozotriazoles and their polymers, and 2(2-hydroxy-5-isopropenylphenyl)2H-benzotriazole produced thereby

DOEpatents

Vogl, Otto; Nir, Zohar

1989-03-14

The compound 2(2-hydroxy-5-isopropenylphenyl)2H-benzotriazole (2H5P) is produced by azo coupling of o-nitrophenyl diazonium chloride with p-hydroxyacetophenone, subjecting the resulting isolated azo compound to reductive cyclization with zinc in the presence of sodium hydroxide at a temperature of about 50.degree.-70.degree. C., acidifying the resulting mixture so as to produce (2(2-hydroxy-5-acetylphenyl)2H-benzotriazole (2H5A), acetylating the isolated 2(2-hydroxy-5-acetylphenyl)2H-benzotriazole (2H5A), so as to produce 2(2-acetoxy-5-acetylphenyl)2H-benzotriazole (2A5A), methylating the isolated 2(2-acetoxy-5-acetylphenyl(2H-benzotriazole (2A5A) with a methyl Grignard reagent and dehydrating the isolated reaction product with potassium hydrogen sulfate so as to produce 2(2-hydroxy-5-isopropenylphenyl)2H-benzotriazole (2H5P). The compound is used as a polymerizable ultra violet light stabilizer.

Toward Green Acylation of (Hetero)arenes: Palladium-Catalyzed Carbonylation of Olefins to Ketones

PubMed Central

2017-01-01

Green Friedel–Crafts acylation reactions belong to the most desired transformations in organic chemistry. The resulting ketones constitute important intermediates, building blocks, and functional molecules in organic synthesis as well as for the chemical industry. Over the past 60 years, advances in this topic have focused on how to make this reaction more economically and environmentally friendly by using green acylating conditions, such as stoichiometric acylations and catalytic homogeneous and heterogeneous acylations. However, currently well-established methodologies for their synthesis either produce significant amounts of waste or proceed under harsh conditions, limiting applications. Here, we present a new protocol for the straightforward and selective introduction of acyl groups into (hetero)arenes without directing groups by using available olefins with inexpensive CO. In the presence of commercial palladium catalysts, inter- and intramolecular carbonylative C–H functionalizations take place with good regio- and chemoselectivity. Compared to classical Friedel–Crafts chemistry, this novel methodology proceeds under mild reaction conditions. The general applicability of this methodology is demonstrated by the direct carbonylation of industrial feedstocks (ethylene and diisobutene) as well as of natural products (eugenol and safrole). Furthermore, synthetic applications to drug molecules are showcased. PMID:29392174

Des-acyl ghrelin prevents heatstroke-like symptoms in rats exposed to high temperature and high humidity.

PubMed

Inoue, Yoshiyuki; Hayashi, Yujiro; Kangawa, Kenji; Suzuki, Yoshihiro; Murakami, Noboru; Nakahara, Keiko

2016-02-26

We have shown previously that des-acyl ghrelin decreases body temperature in rats through activation of the parasympathetic nervous system. Here we investigated whether des-acyl ghrelin ameliorates heatstroke in rats exposed to high temperature. Peripheral administration of des-acyl ghrelin significantly attenuated hyperthermia induced by exposure to high-temperature (35°C) together with high humidity (70-80%). Although biochemical analysis revealed that exposure to high temperature significantly increased hematocrit and the serum levels of aspartate amino transferase (AST), alanine transaminase (ALT), blood urea nitrogen (BUN), creatinine and electrolytes (Na(+), K(+), Cl(-)), most of these heatstroke-associated reactions were significantly reduced by treatment with des-acyl ghrelin. The level of des-acyl ghrelin in plasma was also found to be significantly increased under high-temperature conditions. These results suggest that des-acyl ghrelin could be useful for preventing heatstroke under high temperature condition. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Deacylation transition states of a bacterial DD-peptidase.

PubMed

Adediran, S A; Kumar, I; Pratt, R F

2006-10-31

Beta-lactam antibiotics restrict bacterial growth by inhibiting DD-peptidases. These enzymes catalyze the final transpeptidation step in bacterial cell wall biosynthesis. Although much structural information is now available for these enzymes, the mechanism of the actual transpeptidation reaction has not been studied in detail. The reaction is known to involve a double-displacement mechanism with an acyl-enzyme intermediate, which can be attacked by water, specific amino acids, peptides, and other acyl acceptors. We describe in this paper an investigation of acyl acceptor specificity and assess the need for general base catalysis in the deacylation transition state of the Streptomyces R61 DD-peptidase. We show, by the criterion of solvent deuterium kinetic isotope effect measurements and proton inventories, that the transition states of specific and nonspecific substrates are very similar, at least with respect to proton motion. The transition states for attack (tetrahedral intermediate formation) by d-amino acids and Gly-l-Xaa dipeptides do not include a general base catalyst, while such catalysis is essential for reaction with water and d-alpha-hydroxy acids. D-Alpha-hydroxy acids act as acyl acceptors for glycyl substrates but not for more specific d-alanyl substrates; hydroxy acids actually behave, more generally, as mixed inhibitors of the DD-peptidase. The structural and mechanistic bases of these observations are discussed; they should inform transition state analogue design.

Formation of highly oxygenated organic molecules from aromatic compounds

NASA Astrophysics Data System (ADS)

Molteni, Ugo; Bianchi, Federico; Klein, Felix; El Haddad, Imad; Frege, Carla; Rossi, Michel J.; Dommen, Josef; Baltensperger, Urs

2018-02-01

Anthropogenic volatile organic compounds (AVOCs) often dominate the urban atmosphere and consist to a large degree of aromatic hydrocarbons (ArHCs), such as benzene, toluene, xylenes, and trimethylbenzenes, e.g., from the handling and combustion of fuels. These compounds are important precursors for the formation of secondary organic aerosol. Here we show that the oxidation of aromatics with OH leads to a subsequent autoxidation chain reaction forming highly oxygenated molecules (HOMs) with an O : C ratio of up to 1.09. This is exemplified for five single-ring ArHCs (benzene, toluene, o-/m-/p-xylene, mesitylene (1,3,5-trimethylbenzene) and ethylbenzene), as well as two conjugated polycyclic ArHCs (naphthalene and biphenyl). We report the elemental composition of the HOMs and show the differences in the oxidation patterns of these ArHCs. A potential pathway for the formation of these HOMs from aromatics is presented and discussed. We hypothesize that AVOCs may contribute substantially to new particle formation events that have been detected in urban areas.

A new acylated flavonol from the aerial parts of Asteriscus maritimus (L.) Less (Asteraceae).

PubMed

Ezzat, Marwa I; Ezzat, Shahira M; El Deeb, Kadriya S; El Fishawy, Ahlam M; El-Toumy, Sayed A

2016-08-01

Phytochemical investigation of the flowering aerial parts of Asteriscus maritimus (L.) Less (Asteraceae) led to the isolation of a new compound: patuletin 7-O-β-D-[(2″'S) 6″(3″'-hydroxy-2″'-methyl-propanoyl)] glucopyranoside, together with five known metabolites; β-sitosterol 2, chlorogenic acid 3, P-hydroxy -methylbenzoate 4, luteolin 5 and protocatechuic acid 6. The structures of the isolated compounds were determined by comprehensive analyses of its 1D and 2D NMR, HRMS and compared with previously known analogues. The ethanolic extract of the flowering aerial parts of A. maritimus was found to be safe (LD50 = 4.6 mg/kg) and possess significant antioxidant and anti-inflammatory activities and this was in accordance with its high phenolic content (107.36 ± 0.051 mg GAE/g extract).

Enhanced adsorbability and photocatalytic activity of TiO2-graphene composite for polycyclic aromatic hydrocarbons removal in aqueous phase.

PubMed

Bai, Hongzhen; Zhou, Jun; Zhang, Hongjian; Tang, Guping

2017-02-01

Photodegradation via titanium dioxide (TiO 2 ) has been used to remove polycyclic aromatic hydrocarbons (PAHs) from environmental media broadly. In this study, a series of TiO 2 -graphene composites (P25-GR) with different GR weight ratios were synthesized via hydrothermal reaction of graphene oxide (GO) and P25. Their structures were characterized and the proprieties were tested in aqueous phase. Phenanthrene (PHE), fluoranthene (FLAN), and benzo[a]pyrene (BaP) were selected as models of PAHs. The experiment indicated that P25-2.5%GR exhibited enhancement in both adsorption and photodegradation, ∼80% of PAHs were removed after 2h photocatalysis. The influence of photodegradation rate was studied, including PAHs initial concentration and pH. Aromatic intermediates were identified during the reaction process and the degradation pathways were portrayed. This work explored the enhanced photocatalysis performance was attributed to the PAH-selective adsorbability and the strong electron transfer ability of the composite. The analysis of the degradation intermediates confirmed that the reaction proceeded with the formation of free radicals, leading to the gradual PAH mineralization. Copyright © 2016 Elsevier B.V. All rights reserved.

Commelinid Monocotyledon Lignins Are Acylated by p-Coumarate1[OPEN

PubMed Central

Free, Heather C.A.; Smith, Bronwen G.

2018-01-01

Commelinid monocotyledons are a monophyletic clade differentiated from other monocotyledons by the presence of cell wall-bound ferulate and p-coumarate. The Poaceae, or grass family, is a member of this group, and most of the p-coumarate in the cell walls of this family acylates lignin. Here, we isolated and examined lignified cell wall preparations from 10 species of commelinid monocotyledons from nine families other than Poaceae, including species from all four commelinid monocotyledon orders (Poales, Zingiberales, Commelinales, and Arecales). We showed that, as in the Poaceae, lignin-linked p-coumarate occurs exclusively on the hydroxyl group on the γ-carbon of lignin unit side chains, mostly on syringyl units. Although the mechanism of acylation has not been studied directly in these species, it is likely to be similar to that in the Poaceae and involve BAHD acyl-coenzyme A:monolignol transferases. PMID:29724771

Spectroscopic, computational and electrochemical studies on the formation of the copper complex of 1-amino-4-hydroxy-9,10-anthraquinone and effect of it on superoxide formation by NADH dehydrogenase.

PubMed

Roy, Sanjay; Mondal, Palash; Sengupta, Partha Sarathi; Dhak, Debasis; Santra, Ramesh Chandra; Das, Saurabh; Guin, Partha Sarathi

2015-03-28

A 1 : 2 copper(II) complex of 1-amino-4-hydroxy-9,10-anthraquinone (QH) having the molecular formula CuQ2 was prepared and characterized by elemental analysis, NMR, FTIR, UV-vis and mass spectroscopy. The powder diffraction of the solid complex, magnetic susceptibility and ESR spectra were also recorded. The presence of the planar anthraquinone moiety in the complex makes it extremely difficult to obtain a single crystal suitable for X-ray diffraction studies. To overcome this problem, density functional theory (DFT) was used to evaluate an optimized structure of CuQ2. In the optimized structure, it was found that there is a tilt of the two planar aromatic anthraquinone rings of the complex with respect to each other in the two planes containing the O-Cu(II)-O plane. The present study is an important addition to the understanding of the structural aspects of metal-anthracyclines because there are only a few reports on the actual structures of metal-anthracyclines. The theoretical vibrational spectrum of the complex was assigned with the help of vibrational energy distribution analysis (VEDA) using potential energy distribution (PED) and compared with experimental results. Being important in producing the biochemical action of this class of molecules, the electrochemical behavior of the complex was studied in aqueous and non-aqueous solvents to find certain electrochemical parameters. In aqueous media, reduction involves a kinetic effect during electron transfer at an electrode surface, which was characterized very carefully using cyclic voltammetry. Electrochemical studies showed a significant modification in the electrochemical properties of 1-amino-4-hydroxy-9,10-anthraquinone (QH) when bound to Cu(II) in the complex compared to those observed for free QH. This suggests that the copper complex might be a good choice as a biologically active molecule, which was reflected in the lack of stimulated superoxide generation by the complex.

Multicomponent hydrogen-bonding organic solids constructed from 6-hydroxy-2-naphthoic acid and N-heterocycles: Synthesis, structural characterization and synthon discussion

NASA Astrophysics Data System (ADS)

Zong, Yingxia; Shao, Hui; Pang, Yanyan; Wang, Debao; Liu, Kang; Wang, Lei

2016-07-01

Seven novel multicomponent crystals involving various substituted organic amine molecules and 6-hydroxy-2-naphthoic acid were prepared and characterized by using single crystal X-ray diffraction, infrared and thermogravimetric analyses (TGA). Crystal structures with 1,4-bis(imidazol) butane (L1) 1, 1,4-bis(imidazol-1-ylmethyl)benzene (L2) 2, 1-phenyl piperazine 3, 2-amino-4-hydroxy-6-methyl pyrimidine 4, 4,4'-bipyridine 5, 5,5'-dimethyl-2,2'-dipyridine 6, 2-amino-4,6-dimethyl pyrimidine 7 were determined. Among the seven molecular complexes, total proton transfer from 6-hydroxy-2-naphthoic acid to coformer has occurred in crystals 1-4, while the remaining were cocrystals. X-ray single-crystal structures of these complexes reveal that strong hydrogen bonding O-H···O/N-H···O/O-H···N and weak C-H···O/C-H···π/π···π intermolecular interactions direct the packing modes of molecular crystals together. The analysis of supramolecular synthons in the present structures shows that some classical supramolecular synthons like pyridine-carboxylic acid heterosynthon R22 (7) and aminopyridine-carboxylic acid heterosynthon R22 (8), are again observed in constructing the hydrogen-bonding networks in this paper. Besides, we noticed that water molecules act as a significant hydrogen-bonding connector in constructing supramolecular architectures of 3, 4, 6, and 7.

3-hydroxy-2(1H)-pyridinone chelating agents

DOEpatents

Raymond, K.N.; Xu, J.

1997-04-29

Disclosed is a series of improved metal chelating agents, which are highly effective upon both injection and oral administration; several of the most effective are of low toxicity. These chelating agents incorporate within their structure 1-hydroxy-2-pyridinone (1,2-HOPO) and 3-hydroxy-2-pyridinone (3,2-HOPO) moieties with a substituted carbamoyl group ortho to the hydroxy or oxo groups of the hydroxypyridinone ring. The electron-withdrawing carbamoyl group increases the acidity of the hydroxypyridinones. In the metal complexes of the chelating agents, the amide protons form very strong hydrogen bonds with its adjacent HOPO oxygen donor, making these complexes very stable at physiological conditions. The terminal N-substituents provides a certain degree of lipophilicity to the 3,2-HOPO, increasing oral activity. Also disclosed is a method of making the chelating agents and a method of producing a known compound, 3-hydroxy-1-alkyl-2(1H)pyridinone, used as a precursor to the chelating agent, safely and in large quantities. 2 figs.

3-hydroxy-2(1H)-pyridinone chelating agents

DOEpatents

Raymond, Kenneth N.; Xu, Jide

1997-01-01

Disclosed is a series of improved metal chelating agents, which are highly effective upon both injection and oral administration; several of the most effective are of low toxicity. These chelating agents incorporate within their structure 1-hydroxy-2-pyridinone (1,2-HOPO) and 3-hydroxy-2-pyridinone (3,2-HOPO) moieties with a substituted carbamoyl group ortho to the hydroxy or oxo groups of the hydroxypyridinone ring. The electron-withdrawing carbamoyl group increases the acidity of the hydroxypyridinones. In the metal complexes of said chelating agents, the amide protons form very strong hydrogen bonds with its adjacent HOPO oxygen donor, making these complexes very stable at physiological conditions. The terminal N-substituents provides a certain degree of lipophilicity to said 3,2-HOPO, increasing oral activity. Also disclosed is a method of making the chelating agents and a method of producing a known compound, 3-hydroxy-1-alkyl-2(1H)pyridinone, used as a precursor to the chelating agent, safely and in large quantities.

N-Acyl derivatives of Asn, new bacterial N-acyl D-amino acids with surfactant activity.

PubMed

Peypoux, F; Laprévote, O; Pagadoy, M; Wallach, J

2004-03-01

New N-acyl D-amino acids were isolated from Bacillus pumilus IM 1801. Their structures were determined by chemical analysis and mass spectrometry. The lipid part was identified as a mixture of fatty acids with 11, 12, 13, 15, and 16 carbon atoms in the iso, anteiso or n configuration linked by an amide bond with a D-asparagine. They exhibited surfactant properties.

Bivalent transition metal complexes of o-hydroxyacetophenone [N-(3-hydroxy-2-naphthoyl)] hydrazone: Spectroscopic, antibacterial, antifungal activity and thermogravimetric studies

NASA Astrophysics Data System (ADS)

Zaky, R. R.; Ibrahim, K. M.; Gabr, I. M.

2011-10-01

Schiff base complexes of Cu(II), Ni(II) and Zn(II) with the o-hydroxyacetophenone [N-(3-hydroxy-2-naphthoyl)] hydrazone (H 2o-HAHNH) containing N and O donor sites have been synthesized. Both ligand and its metal complexes were characterized by different physicochemical methods, elemental analysis, molar conductivity ( 1H NMR, 13C NMR, IR, UV-visible, ESR, MS spectra) and also thermal analysis (TG and DTG) techniques. The discussion of the outcome data of the prepared complexes indicates that the ligand behave as a bidentate and/or tridentate ligand. The electronic spectra of the complexes as well as their magnetic moments suggest octahedral geometries for all isolated complexes. The room temperature solid state ESR spectrum of the Cu(II) complex shows d x2- y2 as a ground state, suggesting tetragonally distorted octahedral geometry around Cu(II) centre. The molar conductance measurements proved that the complexes are non-electrolytes. The kinetic thermodynamic parameters such as: E#, Δ H#, Δ G#, Δ S# are calculated from the DTG curves, for the [Ni(H O-HAHNH) 2] and [Zn(H 2 O-HAHNH)(OAc) 2]·H 2O complexes using the Coats-Redfern equation. Also, the antimicrobial properties of all compounds were studied using a wide spectrum of bacterial and fungal strains. The [Cu(H o-HAHNH)(OAc)(H 2O) 2] complex was the most active against all strains, including Aspergillus sp., Stemphylium sp. and Trichoderma sp. Fungi; E. coli and Clostridium sp. Bacteria.

40 CFR 721.10056 - Benzenemethanaminium, N-(3-aminopropyl)-N,N-dimethyl-, N-soya acyl derivs., chlorides.

Code of Federal Regulations, 2014 CFR

2014-07-01

...)-N,N-dimethyl-, N-soya acyl derivs., chlorides. 721.10056 Section 721.10056 Protection of Environment...-aminopropyl)-N,N-dimethyl-, N-soya acyl derivs., chlorides. (a) Chemical substance and significant new uses...-dimethyl-, N-soya acyl derivs., chlorides (PMN P-03-47; CAS No. 90194-13-1) is subject to reporting under...

40 CFR 721.10056 - Benzenemethanaminium, N-(3-aminopropyl)-N,N-dimethyl-, N-soya acyl derivs., chlorides.

Code of Federal Regulations, 2013 CFR

2013-07-01

...)-N,N-dimethyl-, N-soya acyl derivs., chlorides. 721.10056 Section 721.10056 Protection of Environment...-aminopropyl)-N,N-dimethyl-, N-soya acyl derivs., chlorides. (a) Chemical substance and significant new uses...-dimethyl-, N-soya acyl derivs., chlorides (PMN P-03-47; CAS No. 90194-13-1) is subject to reporting under...

40 CFR 721.10056 - Benzenemethanaminium, N-(3-aminopropyl)-N,N-dimethyl-, N-soya acyl derivs., chlorides.

Code of Federal Regulations, 2012 CFR

2012-07-01

...)-N,N-dimethyl-, N-soya acyl derivs., chlorides. 721.10056 Section 721.10056 Protection of Environment...-aminopropyl)-N,N-dimethyl-, N-soya acyl derivs., chlorides. (a) Chemical substance and significant new uses...-dimethyl-, N-soya acyl derivs., chlorides (PMN P-03-47; CAS No. 90194-13-1) is subject to reporting under...

Comparison of hydroxy naphthoquinone from North Qinglongyi with different storage times

NASA Astrophysics Data System (ADS)

Xin, G. S.; Ji, Y. B.; Wei, C.

2017-12-01

Objective: To determine the appropriate solvent for the extraction of hydroxy naphthoquinone, and to establish a method for the determination of the content of hydroxy naphthoquinone in the North Qinglongyi, and compare the changes of the content of hydroxy naphthoquinone in North Qinglongyi with different storage times. Methods: According to the nature of hydroxy naphthoquinone in alkaline solution will be discolored, so this experiment for Juglone as the standard reagent, 5% KOH solution as a developer, and the absorbance was measured by UV-spectrophotometry at the wavelength of 515 nm. The content of hydroxy naphthoquinone in North Qinglongyi was determined by colorimetric method, and the contents of hydroxy naphthoquinone in North Qinglongyi of different storage times were compared. Results: The optimum extraction solvent was ethyl acetate. The recoveries were 97.73%±1.11% and the RSD was 1.14% (n = 6). The contents of hydroxy naphthoquinone in the North Qinglunyi were 0.0141%, 0.0104% and 0.0073%, respectively, for one year, two years and three years. The content of hydroxy naphthoquinone decreased with the storage time prolonged. Conclusion This experimental method was stability, high recovery rate, simple and reliable. According to the results of this experiment, we can see that the storage time of North Qinglunyi should not be too long. Should try to choose this year’s North Qinglunyi for experimental research.

Enantioselective N-Heterocyclic Carbene Catalysis via the Dienyl Acyl Azolium.

PubMed

Gillard, Rachel M; Fernando, Jared E M; Lupton, David W

2018-04-16

Herein we report the enantioselective N-heterocyclic carbene catalyzed (4+2) annulation of the dienyl acyl azolium with enolates. The reaction exploits readily accessible acyl fluorides and TMS enol ethers to give a range of highly enantio- and diastereo-enriched cyclohexenes (most >97:3 er and >20:1 dr). The reaction was found to require high nucleophilicity NHC catalysts with mechanistic studies supporting a stepwise 1,6-addition/β-lactonization. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Modified Acyl-ACP desaturase

DOEpatents

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

1999-03-30

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

Modified acyl-ACP desaturase

DOEpatents

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

1998-01-06

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

(E)-1-[2-Hy-droxy-4,6-bis-(meth-oxy-meth-oxy)phen-yl]-3-phenyl-prop-2-en-1-one.

PubMed

Niu, Chao; Liu, Y Q; He, Y W; Aisa, H A

2013-05-01

The title compound, C19H20O6, consists of a tetra-substituted benzene ring with one substituent being an α,β-unsaturated cinnamoyl group, which forms an extended conjugated system in the mol-ecule. In addition, two meth-oxy-meth-oxy and one hy-droxy group are bonded to the central benzene ring. The dihedral angle between eh rings is 10.22 (10)°. An intra-molecular hydrogen bond is observed between the hy-droxy group and the carbonyl O atom. One of the meth-oxy-meth-oxy substituents is conformationally disordered over two sets of sites with site-occupation factors of 0.831 (3) and 0.169 (3).

Anti-cancer agents based on N-acyl-2, 3-dihydro-1H-pyrrolo[2,3-b] quinoline derivatives and a method of making

DOEpatents

Gakh, Andrei; Krasavin, Mikhail; Karapetian, Ruben; Rufanov, Konstantin A; Konstantinov, Igor; Godovykh, Elena; Soldatkina, Olga; Sosnov, Andrey V

2013-04-16

The present disclosure relates to novel compounds that can be used as anti-cancer agents in the prostate cancer therapy. In particular, the invention relates to N-acyl derivatives of 2,3-dihydro-1H-pyrrolo[2,3-b]quinolines having the structural Formula (I), ##STR00001## stereoisomers, tautomers, racemics, prodrugs, metabolites thereof, or pharmaceutically acceptable salt and/or solvate thereof. The meaning of R1 is independently selected from H; C1-C6 Alkyl, cyclo-Alkyl or iso-Alkyl substituents; R2 is selected from C1-C6 Alkyl, cyclo-Alkyl or iso-Alkyl; substituted or non-substituted, fused or non-fused to substituted or non-substituted aromatic ring, aryl or heteroaryl groups. The invention also relates to methods for preparing said compounds, and to pharmaceutical compositions comprising said compounds.

Investigation of acyl migration in mono- and dicaffeoylquinic acids under aqueous basic, aqueous acidic, and dry roasting conditions.

PubMed

Deshpande, Sagar; Jaiswal, Rakesh; Matei, Marius Febi; Kuhnert, Nikolai

2014-09-17

Acyl migration in chlorogenic acids describes the process of migration of cinnamoyl moieties from one quinic acid alcohol group to another, thus interconverting chlorogenic acid regioisomers. It therefore constitutes a special case of transesterification reaction. Acyl migration constitutes an important reaction pathway in both coffee roasting and brewing, altering the structure of chlorogenic acid initially present in the green coffee bean. In this contribution we describe detailed and comprehensive mechanistic studies comparing inter- and intramolecular acyl migration involving the seven most common chlorogenic acids in coffee. We employe aqueous acidic and basic conditions mimicking the brewing of coffee along with dry roasting conditions. We show that under aqueous basic conditions intramolecular acyl migration is fully reversible with basic hydrolysis competing with acyl migration. 3-Caffeoylquinic acid was shown to be most labile to basic hydrolysis. We additionally show that the acyl migration process is strongly pH dependent with increased transesterification taking place at basic pH. Under dry roasting conditions acyl migration competes with dehydration to form lactones. We argue that acyl migration precedes lactonization, with 3-caffeoylquinic acid lactone being the predominant product.

Characterization of acyl-coenzyme A:diacylglycerol acyltransferase (DGAT) enzyme of human small intestine.

PubMed

Hiramine, Yasushi; Tanabe, Toshizumi

2011-06-01

Acyl-coenzyme A:diacylglycerol acyltransferase (DGAT) enzyme plays a significant role in dietary triacylglycerol (TAG) absorption in the small intestine. However, the characteristics of human intestinal DGAT enzyme have not been examined in detail. The aim of our study was to characterize the human intestinal DGAT enzyme by examining acyl-CoA specificity, temperature dependency, and selectivity for 1,2-diacylglycerol (DAG) or 1,3-DAG. We detected DGAT activity of human intestinal microsome and found that the acyl-CoA specificity and temperature dependency of intestinal DGAT coincided with those of recombinant human DGAT1. To elucidate the selectivity of human intestinal DGAT to 1,2-DAG or 1,3-DAG, we conducted acyl-coenzyme A:monoacylglycerol acyltransferase assays using 1- or 2-monoacylglycerol (MAG) as substrates. When 2-MAG was used as acyl acceptor, both 1,2-DAG and TAG were generated; however, when 1-MAG was used, 1,3-DAG was predominantly observed and little TAG was detected. These findings suggest that human small intestinal DGAT, which is mainly encoded by DGAT1, utilizes 1,2-DAG as the substrate to form TAG. This study will contribute to understand the lipid absorption profile in the small intestine.

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

PubMed Central

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

2011-01-01

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

Preparation of ω-hydroxy pelargonic acid

NASA Astrophysics Data System (ADS)

Hadi, Siti Faieza Abd; Salimon, Jumat

2018-04-01

Utilization of plant oil as renewable raw material for monomers and polymers in bioplastic industry has a great potential to replace conventional petroleum-based plastic usage especially in packaging and adhesive applications. One of useful monomer is ω-hydroxy pelargonic acid that can be polymerizing as biodegradable polyester. In this study, the aim is to synthesis ω-hydroxy pelargonic acid from oleic acid based on oxidation/ esterification/ saponification and reduction methodology. The yield obtained after aqueous workup is 53% and the compound structure is determined by FT-IR and 1H and 13C NMR.

Metabolism of lysergic acid diethylamide (LSD) to 2-oxo-3-hydroxy LSD (O-H-LSD) in human liver microsomes and cryopreserved human hepatocytes.

PubMed

Klette, K L; Anderson, C J; Poch, G K; Nimrod, A C; ElSohly, M A

2000-10-01

The metabolism of lysergic acid diethylamide (LSD) to 2-oxo-3-hydroxy lysergic acid diethylamide (O-H-LSD) was investigated in liver microsomes and cyropreserved hepatocytes from humans. Previous studies have demonstrated that O-H-LSD is present in human urine at concentrations 16-43 times greater than LSD, the parent compound. Additionally, these studies have determined that O-H-LSD is not generated during the specimen extraction and analytical processes or due to parent compound degradation in aqueous urine samples. However, these studies have not been conclusive in demonstrating that O-H-LSD is uniquely produced during in vivo metabolism. Phase I drug metabolism was investigated by incubating human liver microsomes and cryopreserved human hepatocytes with LSD. The reaction was quenched at various time points, and the aliquots were extracted using liquid partitioning and analyzed by liquid chromatography-mass spectrometry. O-H-LSD was positively identified in all human liver microsomal and human hepatocyte fractions incubated with LSD. In addition, O-H-LSD was not detected in any microsomal or hepatocyte fraction not treated with LSD nor in LSD specimens devoid of microsomes or hepatocytes. This study provides definitive evidence that O-H-LSD is produced as a metabolic product following incubation of human liver microsomes and hepatocytes with LSD.

Association of acylated ghrelin profiles with chronic inflammatory markers in overweight and obese postmenopausal women: a MONET study.

PubMed

St-Pierre, David H; Bastard, Jean-Philippe; Coderre, Lise; Brochu, Martin; Karelis, Antony D; Lavoie, Marie-Eve; Malita, Florin; Fontaine, Jonathan; Mignault, Diane; Cianflone, Katherine; Imbeault, Pascal; Doucet, Eric; Rabasa-Lhoret, Rémi

2007-10-01

Recent reports have suggested that the existence of associations between hormonal dysregulation and chronic upregulation of inflammatory markers, which may cause obesity-related disturbances. Thus, we examined whether acylated ghrelin (AcylG) and total ghrelin (TotG) levels could be associated with the following inflammatory markers: C-reactive protein (CRP), tumor necrosis factor alpha (TNF-alpha), and soluble TNF receptor 1 (sTNF-R1). Cross-sectional study consisting of 50 overweight and obese postmenopausal women. AcylG and TotG levels were assessed at 0, 60, 160, 170, and 180 min of the euglycemic/hyperinsulinemic clamp (EHC). We evaluated insulin sensitivity, body composition, and blood lipid profiles as well as fasting concentrations of CRP, TNF-alpha, and sTNF-R1. In fasting conditions, sTNF-R1 was negatively correlated with AcylG (r = -0.48, P < 0.001) levels. In addition, AcylG/TotG was associated negatively with sTNF-R1 (r = -0.44, P = 0.002) and positively with TNF-alpha (r = 0.38, P = 0.009) values. During the EHC, TotG (at all time points) and AcylG (at 60 and 160 min) values were significantly decreased from fasting concentrations. AcylG maximal reduction and area under the curve (AUC) values were correlated to sTNF-R1 (r = -0.35, P = 0.02 and r = -0.34, P = 0.02, respectively). Meanwhile, the AcylG/TotG AUC ratio was associated negatively with sTNF-R1 (r = -0.29, P < 0.05) and positively with TNF-alpha (r = 0.36, P = 0.02). Following adjustments for total adiposity, sTNF-R1 remained correlated with fasting and maximal reduction AcylG values. Similarly, AcylG/TotG ratios remained significantly correlated with sTNF-R1 and TNF-alpha. Importantly, 23% of the variation in sTNF-R1 was independently predicted by fasting AcylG. These results are the first to suggest that both fasting and EHC-induced AcylG profiles are correlated with fasting values of sTNF-R1, a component of the TNF-alpha system. Thus, AcylG may act, at least in part, as one mediator of

4-Hydroxy cinnamic acid as mushroom preservation: Anti-tyrosinase activity kinetics and application.

PubMed

Hu, Yong-Hua; Chen, Qing-Xi; Cui, Yi; Gao, Huan-Juan; Xu, Lian; Yu, Xin-Yuan; Wang, Ying; Yan, Chong-Ling; Wang, Qin

2016-05-01

Tyrosinase is a key enzyme in post-harvest browning of fruit and vegetable. To control and inhibit its activity is the most effective method for delaying the browning and extend the shelf life. In this paper, the inhibitory kinetics of 4-hydroxy cinnamic acid on mushroom tyrosinase was investigated using the kinetics method of substrate reaction. The results showed that the inhibition of tyrosinase by 4-hydroxy cinnamic acid was a slow, reversible reaction with fractional remaining activity. The microscopic rate constants were determined for the reaction on 4-hydroxy cinnamic acid with tyrosinase. Furthermore, the molecular docking was used to simulate 4-hydroxy cinnamic acid dock with tyrosinase. The results showed that 4-hydroxy cinnamic acid interacted with the enzyme active site mainly through the hydroxy competed with the substrate hydroxy group. The cytotoxicity study of 4-hydroxy cinnamic acid indicated that it had no effects on the proliferation of normal liver cells. Moreover, the results of effects of 4-hydroxy cinnamic acid on the preservation of mushroom showed that it could delay the mushroom browning. These results provide a comprehensive underlying the inhibitory mechanisms of 4-hydroxy cinnamic acid and its delaying post-harvest browning, that is beneficial for the application of this compound. Copyright © 2016 Elsevier B.V. All rights reserved.

Spectroscopic Diagnosis of Excited-State Aromaticity: Capturing Electronic Structures and Conformations upon Aromaticity Reversal.

PubMed

Oh, Juwon; Sung, Young Mo; Hong, Yongseok; Kim, Dongho

2018-03-06

Aromaticity, the special energetic stability derived from cyclic [4 n + 2]π-conjugated electronic structures, has been the topic of intense interest in chemistry because it plays a critical role in rationalizing molecular stability, reactivity, and physical/chemical properties. Recently, the pioneering work by Colin Baird on aromaticity reversal, postulating that aromatic (antiaromatic) character in the ground state reverses to antiaromatic (aromatic) character in the lowest excited triplet state, has attracted much scientific attention. The completely reversed aromaticity in the excited state provides direct insight into understanding the photophysical/chemical properties of photoactive materials. In turn, the application of aromatic molecules to photoactive materials has led to numerous studies revealing this aromaticity reversal. However, most studies of excited-state aromaticity have been based on the theoretical point of view. The experimental evaluation of aromaticity in the excited state is still challenging and strenuous because the assessment of (anti)aromaticity with conventional magnetic, energetic, and geometric indices is difficult in the excited state, which practically restricts the extension and application of the concept of excited-state aromaticity. Time-resolved optical spectroscopies can provide a new and alternative avenue to evaluate excited-state aromaticity experimentally while observing changes in the molecular features in the excited states. Time-resolved optical spectroscopies take advantage of ultrafast laser pulses to achieve high time resolution, making them suitable for monitoring ultrafast changes in the excited states of molecular systems. This can provide valuable information for understanding the aromaticity reversal. This Account presents recent breakthroughs in the experimental assessment of excited-state aromaticity and the verification of aromaticity reversal with time-resolved optical spectroscopic measurements. To

Cloning and characterization of a novel amidase from Paracoccus sp. M-1, showing aryl acylamidase and acyl transferase activities.

PubMed

Shen, Weiliang; Chen, Honghong; Jia, Kaizhi; Ni, Jun; Yan, Xin; Li, Shunpeng

2012-05-01

A novel amidase gene, designated pamh, was cloned from Paracoccus sp. M-1. Site-directed mutagenesis and bioinformatic analysis showed that the PamH protein belonged to the amidase signature enzyme family. PamH was expressed in Escherichia coli, purified, and characterized. The molecular mass of PamH was determined to be 52 kDa with an isoelectric point of 5.13. PamH displayed its highest enzymatic activity at 45°C and at pH 8.0 and was stable within a pH range of 5.0-10.0. The PamH enzyme exhibited amidase activity, aryl acylamidase activity, and acyl transferase activity, allowing it to function across a very broad substrate spectrum. PamH was highly active on aromatic and short-chain aliphatic amides (benzamide and propionamide), moderately active on amino acid amides, and possessed weak urease activity. Of the anilides examined, only propanil was a good substrate for PamH. For propanil, the k (cat) and K (m) were 2.8 s(-1) and 158 μM, respectively, and the catalytic efficiency value (k (cat)/K (m)) was 0.018 μM(-1) s(-1). In addition, PamH was able to catalyze the acyl transfer reaction to hydroxylamine for both amide and anilide substrates, including acetamide, propanil, and 4-nitroacetanilide; the highest reaction rate was shown with isobutyramide. These characteristics make PamH an excellent candidate for environmental remediation and an important enzyme for the biosynthesis of novel amides.

40 CFR 721.7270 - 1-propanaminium, 3-amino-, N,N,N-trimethyl-N-soya acyl derivs., chloride.

Code of Federal Regulations, 2013 CFR

2013-07-01

...-trimethyl-N-soya acyl derivs., chloride. 721.7270 Section 721.7270 Protection of Environment ENVIRONMENTAL...-soya acyl derivs., chloride. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as 1-propanaminium, 3-amino-, N,N,N-trimethyl-N-soya acyl derivs...

40 CFR 721.7270 - 1-propanaminium, 3-amino-, N,N,N-trimethyl-N-soya acyl derivs., chloride.

Code of Federal Regulations, 2012 CFR

2012-07-01

...-trimethyl-N-soya acyl derivs., chloride. 721.7270 Section 721.7270 Protection of Environment ENVIRONMENTAL...-soya acyl derivs., chloride. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as 1-propanaminium, 3-amino-, N,N,N-trimethyl-N-soya acyl derivs...

40 CFR 721.7270 - 1-propanaminium, 3-amino-, N,N,N-trimethyl-N-soya acyl derivs., chloride.

Code of Federal Regulations, 2014 CFR

2014-07-01

...-trimethyl-N-soya acyl derivs., chloride. 721.7270 Section 721.7270 Protection of Environment ENVIRONMENTAL...-soya acyl derivs., chloride. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as 1-propanaminium, 3-amino-, N,N,N-trimethyl-N-soya acyl derivs...

21 CFR 582.5477 - Methionine hydroxy analog and its calcium salts.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Methionine hydroxy analog and its calcium salts... Nutrients and/or Dietary Supplements 1 § 582.5477 Methionine hydroxy analog and its calcium salts. (a) Product. Methionine hydroxy analog and its calcium salts. (b) [Reserved] (c) Limitations, restrictions, or...

21 CFR 582.5477 - Methionine hydroxy analog and its calcium salts.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Methionine hydroxy analog and its calcium salts... Nutrients and/or Dietary Supplements 1 § 582.5477 Methionine hydroxy analog and its calcium salts. (a) Product. Methionine hydroxy analog and its calcium salts. (b) [Reserved] (c) Limitations, restrictions, or...

Human caspase-4 detects tetra-acylated LPS and cytosolic Francisella and functions differently from murine caspase-11.

PubMed

Lagrange, Brice; Benaoudia, Sacha; Wallet, Pierre; Magnotti, Flora; Provost, Angelina; Michal, Fanny; Martin, Amandine; Di Lorenzo, Flaviana; Py, Bénédicte F; Molinaro, Antonio; Henry, Thomas

2018-01-16

Caspase-4/5 in humans and caspase-11 in mice bind hexa-acylated lipid A, the lipid moeity of lipopolysaccharide (LPS), to induce the activation of non-canonical inflammasome. Pathogens such as Francisella novicida express an under-acylated lipid A and escape caspase-11 recognition in mice. Here, we show that caspase-4 drives inflammasome responses to F. novicida infection in human macrophages. Caspase-4 triggers F. novicida-mediated, gasdermin D-dependent pyroptosis and activates the NLRP3 inflammasome. Inflammasome activation could be recapitulated by transfection of under-acylated LPS from different bacterial species or synthetic tetra-acylated lipid A into cytosol of human macrophage. Our results indicate functional differences between human caspase-4 and murine caspase-11. We further establish that human Guanylate-binding proteins promote inflammasome responses to under-acylated LPS. Altogether, our data demonstrate a broader reactivity of caspase-4 to under-acylated LPS than caspase-11, which may have important clinical implications for management of sepsis.

o-Fluorination of aromatic azides yields improved azido-based fluorescent probes for hydrogen sulfide: synthesis, spectra, and bioimaging.

PubMed

Wei, Chao; Wang, Runyu; Wei, Lv; Cheng, Longhuai; Li, Zhifei; Xi, Zhen; Yi, Long

2014-12-01

Hydrogen sulfide (H2S) is an endogenously produced gaseous signaling molecule with multiple biological functions. To visualize the endogenous in situ production of H2S in real time, new coumarin- and boron-dipyrromethene-based fluorescent turn-on probes were developed for fast sensing of H2S in aqueous buffer and in living cells. Introduction of a fluoro group in the ortho position of the aromatic azide can lead to a greater than twofold increase in the rate of reaction with H2S. On the basis of o-fluorinated aromatic azides, fluorescent probes with high sensitivity and selectivity toward H2S over other biologically relevant species were designed and synthesized. The probes can be used to in situ to visualize exogenous H2S and D-cysteine-dependent endogenously produced H2S in living cells, which makes them promising tools for potential applications in H2S biology. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Precise through-space control of an abiotic electrophilic aromatic substitution reaction

NASA Astrophysics Data System (ADS)

Murphy, Kyle E.; Bocanegra, Jessica L.; Liu, Xiaoxi; Chau, H.-Y. Katharine; Lee, Patrick C.; Li, Jianing; Schneebeli, Severin T.

2017-04-01

Nature has evolved selective enzymes for the efficient biosynthesis of complex products. This exceptional ability stems from adapted enzymatic pockets, which geometrically constrain reactants and stabilize specific reactive intermediates by placing electron-donating/accepting residues nearby. Here we perform an abiotic electrophilic aromatic substitution reaction, which is directed precisely through space. Ester arms--positioned above the planes of aromatic rings--enable it to distinguish between nearly identical, neighbouring reactive positions. Quantum mechanical calculations show that, in two competing reaction pathways, both [C-H...O]-hydrogen bonding and electrophile preorganization by coordination to a carbonyl group likely play a role in controlling the reaction. These through-space-directed mechanisms are inspired by dimethylallyl tryptophan synthases, which direct biological electrophilic aromatic substitutions by preorganizing dimethylallyl cations and by stabilizing reactive intermediates with [C-H...N]-hydrogen bonding. Our results demonstrate how the third dimension above and underneath aromatic rings can be exploited to precisely control electrophilic aromatic substitutions.

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.

Modified Acyl-ACP desaturase

DOEpatents

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

1999-03-30

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

Coexistence of Cu, Fe, Pb, and Zn oxides and chlorides as a determinant of chlorinated aromatics generation in municipal solid waste incinerator fly ash.

PubMed

Fujimori, Takashi; Tanino, Yuta; Takaoka, Masaki

2014-01-01

We investigated chemical determinants of the generation of chlorinated aromatic compounds (aromatic-Cls), such as polychlorinated biphenyls (PCBs) and chlorobenzenes (CBzs), in fly ash from municipal solid waste incineration. The influences of the following on aromatic-Cls formation in model fly ash (MFA) were systematically examined quantitatively and statistically: (i) inorganic chlorides (KCl, NaCl, CaCl2), (ii) base materials (SiO2, Al2O3, CaCO3), (iii) metal oxides (CuO, Fe2O3, PbO, ZnO), (iv) metal chlorides (CuCl2, FeCl3, PbCl2, ZnCl2), and (v) "coexisting multi-models." On the basis of aromatic-Cls concentrations, the ∑CBzs/∑PCBs ratio, and the similarity between distribution patterns, MFAs were categorized into six groups. The results and analysis indicated that the formation of aromatic-Cls depended strongly on the "coexistence condition", namely multimodels composed of not only metal chlorides, but also of metal oxides. The precise replication of metal chloride to oxide ratios, such as the precise ratios of Cu-, Fe-, Pb-, and Zn-chlorides and oxides, may be an essential factor in changing the thermochemical formation patterns of aromatic-Cls. Although CuCl2 acted as a promoter of aromatic-Cls generation, statistical analyses implied that FeCl3 also largely influenced the generation of aromatic-Cls under mixture conditions. Various additional components of fly ash were also comprehensively analyzed.

Anaerobic biodegradation of aromatic compounds.

PubMed

Jothimani, P; Kalaichelvan, G; Bhaskaran, A; Selvaseelan, D Augustine; Ramasamy, K

2003-09-01

Many aromatic compounds and their monomers are existing in nature. Besides they are introduced into the environment by human activity. The conversion of these aromatic compounds is mainly an aerobic process because of the involvement of molecular oxygen in ring fission and as an electron acceptor. Recent literatures indicated that ring fission of monomers and obligomers mainly occurs in anaerobic environments through anaerobic respiration with nitrate, sulphate, carbon dioxide or carbonate as electron acceptors. These anaerobic processes will help to work out the better situation for bioremediation of contaminated environments. While there are plenty of efforts to reduce the release of these chemicals to the environment, already contaminated sites need to be remediated not only to restore the sites but to prevent the leachates spreading to nearby environment. Basically microorganisms are better candidates for breakdown of these compounds because of their wider catalytic mechanisms and the ability to act even in the absence of oxygen. These microbes can be grouped based on their energy mechanisms. Normally, the aerobic counterparts employ the enzymes like mono-and-dioxygenases. The end product is basically catechol, which further may be metabolised to CO2 by means of quinones reductases cycles. In the absense of reductases compounds, the reduced catechols tend to become oxidised to form many quinone compounds. The quinone products are more recalcitrant and lead to other aesthetic problems like colour in water, unpleasant odour, etc. On the contrary, in the reducing environment this process is prevented and in a cascade of pathways, the cleaved products are converted to acetyl co-A to be integrated into other central metabolite paths. The central metabolite of anaerobic degradation is invariably co-A thio-esters of benzoic acid or hydroxy benzoic acid. The benzene ring undergoes various substitution and addition reactions to form chloro-, nitro-, methyl- compounds

Structure, vibrations and quantum chemical investigations of hydrogen bonded complex of bis(1-hydroxy-2-methylpropan-2-aminium)selenate

NASA Astrophysics Data System (ADS)

Thirunarayanan, S.; Arjunan, V.; Marchewka, M. K.; Mohan, S.

2017-04-01

The hydrogen bonded molecular complex bis(1-hydroxy-2-methylpropan-2-aminium)selenate (C8H24N2O6Se) has been prepared by the reaction of 2-amino-2-methyl propanol and selenic acid. The X-ray diffraction analysis revealed that the intermolecular proton transfer from selenic acid (SeO4H2) to 2-amino-2-methylpropanol results in the formation of bis(1-hydroxy-2-methylpropan-2-aminium)selenate (HMPAS) salt and the fragments are connected through H-bonding and ion pairing. The N-H⋯O and O-H⋯O interactions between 2-amino-2-methylpropanol and selenic acid determine the supramolecular arrangement in three-dimensional space. The salt crystallises in the space group P121/n1 of monoclinic system. The complete vibrational assignments of HMPAS have been performed by FTIR and FT-Raman spectroscopy. The experimental data are correlated with the structural properties namely the energy, thermodynamic parameters, atomic charges, hybridization concepts and vibrational frequencies determined by quantum chemical studies performed with B3LYP method using 6-311++G*, 6-31+G* and 6-31G** basis sets.

Physical characterisation of high amylose maize starch and acylated high amylose maize starches.

PubMed

Lim, Ya-Mei; Hoobin, Pamela; Ying, DanYang; Burgar, Iko; Gooley, Paul R; Augustin, Mary Ann

2015-03-06

The particle size, water sorption properties and molecular mobility of high amylose maize starch (HAMS) and high amylose maize starch acylated with acetate (HAMSA), propionate (HAMSP) and butyrate (HAMSB) were investigated. Acylation increased the mean particle size (D(4,3)) and lowered the specific gravity (G) of the starch granules with an inverse relationship between the length of the fatty acid chain and particle size. Acylation of HAMS with fatty acids lowered the monolayer moisture content with the trend being HAMSBacylated starches and that drying and storage of the starch granules further reduced T2 long. Analysis of the Free Induction Decay (FID) focussing on the short components of T2 (correlated to the solid matrix), indicated that drying and subsequent storage resulted in alterations of starch at 0.33a(w) and that these changes were reduced with acylation. In vitro enzymatic digestibility of heated starch dispersions by bacterial α-amylase was increased by acylation (HAMS

Biodegradation of trichloroethylene and involvement of an aromatic biodegradative pathway.

PubMed Central

Nelson, M J; Montgomery, S O; Mahaffey, W R; Pritchard, P H

1987-01-01

Biodegradation of trichloroethylene (TCE) by bacterial strain G4 resulted in complete dechlorination of the compound, as indicated by the production of inorganic chloride. A component of the water from which strain G4 was isolated that was required for TCE degradation was identified as phenol. Strain G4 degraded TCE in the presence of chloramphenicol only when preinduced with phenol. Toluene, o-cresol. and m-cresol could replace the phenol requirement. Two of the inducers of TCE metabolism, phenol and toluene, apparently induced the same aromatic degradative pathway that cleaved the aromatic ring by meta fission. Cells induced with either phenol or toluene had similar oxidation rates for several aromatic compounds and had similar levels of catechol-2,3-dioxygenase. The results indicate that one or more enzymes of an inducible pathway for aromatic degradation in strain G4 are responsible for the degradation of TCE. PMID:3606099

Evaluation of Environmentally Benign New Chemical Rust Removing Agent- Hydroxy Ethane Diphosphonic Acid (HEDPA)

DTIC Science & Technology

2012-12-15

Removing Agent – Hydroxy Ethane Diphosphonic Acid (HEDPA) 1, A. Sarada Rao, 2, A. Yashodhara Rao, 3, Appajosula S. Rao Naval Surface Warfare...Abstract------------------------------------------------------------ In order to evaluate the adaptability of hydroxyethane diphosphonic acid (HEDPA...function of acid concentration in the range 2-20 vol. % and at different temperatures in the temperature range 23 o C -55°C. The results suggest

8-Hydroxy-5-deazaflavin-reducing hydrogenase from Methanobacterium thermoautotrophicum: 2. Kinetic and hydrogen-transfer studies.

PubMed

Livingston, D J; Fox, J A; Orme-Johnson, W H; Walsh, C T

1987-07-14

Steady-state kinetic parameters have been obtained for the pure 8-hydroxy-5-deazaflavin-reducing hydrogenase. With H2 and 8-hydroxy-5-deazariboflavin (F0) as substrates, Km (H2) = 12 microM, Km (F0) = 26 microM, and Kcat = 225 s-1. In the back-direction, F0H2 is reoxidized (anaerobically) at 225 s-1. Initial velocity patterns, product inhibition patterns, dead-end inhibition by carbon monoxide, and transhydrogenation to Procion Red HE-3B suggest a two-site hybrid ping-pong mechanism. A kinetic derivation for the rate equation is provided in the Appendix. Studies with D2 and with D2O reveal that no steps involving D transfer are substantially rate determining. Further, D2 yields F0H2 with no deuterium at C5 while in D2O a 5-monodeuterio F0H2 product is formed, indicating complete exchange of hydrogens from H2 with solvent before final transfer of a hydride ion out from reduced enzyme to C5 of F0.

Synthesis and emulsifying properties of carbohydrate fatty acid esters produced from Agave tequilana fructans by enzymatic acylation.

PubMed

Casas-Godoy, Leticia; Arrizon, Javier; Arrieta-Baez, Daniel; Plou, Francisco J; Sandoval, Georgina

2016-08-01

Carbohydrate fatty acid esters are non-ionic surfactants with a broad spectrum of applications. These molecules are generally synthesized using short carbohydrates or linear fructans; however in this research carbohydrate fatty acid esters were produced for the first time with branched fructans from Agave tequilana. Using immobilized lipases we successfully acylated A. tequilana fructans with vinyl laurate, obtaining products with different degrees of polymerization (DP). Lipozyme 435 was the most efficient lipase to catalyze the transesterification reaction. HPLC and ESI-MS analysis proved the presence of a mixture of acylated products as a result of the chemical complexity of fructans in the A. tequilana. The ESI-MS spectra showed a molecular mass shift between 183 and 366g/mol for fructooligosaccharides with a DP lower than 6, which indicated the presence of Agave fructans that had been mono- and diacylated with lauric acid. The carbohydrate fatty acid esters (CFAE) obtained showed good emulsifying properties in W/O emulsions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Aromatic Polyimide Foam

NASA Technical Reports Server (NTRS)

Weiser, Erik S. (Inventor); St.Clair, Terry L. (Inventor); Echigo, Yoshiaki (Inventor); Kaneshiro, Hisayasu (Inventor)

2000-01-01

A mechanically undensified aromatic polyimide foam is made from an aromatic polyimide precursor solid residuum and has the following combination of properties: a density according to ASTM D-3574A of about 0.5 pounds/cu.ft to about 20 pounds/cu.ft; a compression strength according to ASTM D-3574C of about 1.5 psi to about 1500 psi; and a limiting oxygen index according to ASTM D-2863 of about 35% oxygen to about 75% oxygen at atmospheric pressure. The aromatic polyimide foam has no appreciable solid inorganic contaminants which are residues of inorganic blowing agents. The aromatic polyimide which constitutes the aromatic polyimide foam has a glass transition temperature (Tg) by differential scanning calorimetry of about 235 C to about 400 C; and a thermal stability of 0 to about 1% weight loss at 204 C as determined by thermogravinietric analysis (TGA). The aromatic polyimide foam has utility as foam insulation and as structural foam, for example, for aeronautical, aerospace and maritime applications.

Interaction of gamma-glutamyltranspeptidase with clofibryl-S-acyl-glutathione in vitro and in vivo in rat.

PubMed

Grillo, M P; Benet, L Z

2001-08-01

Clofibric acid (CA) is metabolized to chemically reactive acylating products that can transacylate glutathione to form clofibryl-S-acyl-glutathione (CA-SG) in vitro and in vivo. We investigated the first step in the degradation of CA-SG to the mercapturic acid conjugate, clofibryl-S-acyl-N-acetylcysteine (CA-SNAC), which is catalyzed by gamma-glutamyltranspeptidase (gamma-GT). After gamma-GT mediated cleavage of glutamate from CA-SG, the product clofibryl-S-acyl-cysteinylglycine (CA-S-CG) should undergo an intramolecular rearrangement reaction [Tate, S. S. (1975) FEBS Lett. 54, 319-322] to form clofibryl-N-acyl-cysteinylglycine (CA-N-CG). We performed in vitro studies incubating CA-SG with gamma-GT to determine the products formed, and in vivo studies examining the products excreted in urine after dosing rats with CA-SG or CA. Thus, CA-SG (0.1 mM) was incubated with gamma-GT (0.1 unit/mL) in buffer (pH 7.4, 25 degrees C) and analyzed for products formed by reversed-phase HPLC and electrospray mass spectrometry (ESI/MS). Results showed that CA-SG is degraded completely after 6 h of incubation leading to the formation of two products, CA-N-CG and its disulfide, with no detection of CA-S-CG thioester. After 36 h of incubation, only the disulfide remained in the incubation. Treatment of the disulfide with dithiothreitol led to the reappearance of CA-N-CG. ESI/LC/MS analysis of urine (16 h) extracts of CA-SG-dosed rats (200 mg/kg, iv) showed that CA-SG is degraded to CA-N-CG, CA-N-acyl-cysteine (CA-N-C) and their respective S-methylated products. The mercapturic acid conjugate (CA-SNAC) was found as a minor product. Analysis of urine extracts from CA-dosed rats (200 mg/kg, ip) resulted in the detection of clofibryl-N-acyl-cysteine (CA-N-C), but no evidence for the formation of CA-SNAC was obtained. These in vitro and in vivo experiments indicate that gamma-GT mediated degradation of clofibryl-S-acyl-glutathione leads primarily to the formation and excretion of clofibryl-N-acyl

New fatty acid and acyl glycoside from the aerial parts of Phyllanthus fraternus Webster.

PubMed

Ali, Abuzer; Jameel, Mohammad; Ali, Mohammed

2016-01-01

Phyllanthus fraternus Webster (Euphorbiaceae) is used to treat dyspepsia, indigestion, jaundice, dysentery, diabetes, influenza, kidney stones, urinary tract diseases, vaginitis, and skin eruptions in traditional systems of medicine. The methanol extract of aerial parts of P. fraternus was obtained by soxhlation method. Isolation of compounds was done by silica gel column chromatography. Analytical thin layer chromatography was used to check the homogeneity of eluted fractions. The structures of isolated compounds were established on the basis of spectral studies and chemical reactions. Phytochemical investigation of a methanolic extract of the aerial parts yielded a new fatty acid characterized as cis-n-octacos-17-enoic acid (5) and a new acyl tetraglycoside formulated as n-dodecanoyl-O-β-D-glucopyranosyl-(2'→1'')-O-β-D-glucopyranosyl-(2''→1''')-O-β-D-glucopyranosyl-(2'''→1'''')-O-β-D-glucopyranoside (7) along with known compounds 1-pentacosanol (1), β-sitosteryl oleate (2), β-sitosteryl linoleate (3), stigmasterol (4) and palmityl glucuronoside (6).

Synthesis of g-C3N4/Fe3O4 nanocomposites and application as a new sorbent for solid phase extraction of polycyclic aromatic hydrocarbons in water samples.

PubMed

Wang, Man; Cui, Shihai; Yang, Xiaodi; Bi, Wentao

2015-01-01

An easy preparation of g-C3N4/Fe3O4 nanocomposites by chemical co-precipitation has been demonstrated. The as-prepared materials were characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. The high affinity of g-C3N4 toward polycyclic aromatic hydrocarbons and the magnetic behavior of Fe3O4 were combined to provide an efficient and simple magnetic solid phase extraction (MSPE). The adsorption and desorption of polycyclic aromatic hydrocarbons on g-C3N4/Fe3O4 were examined. Different factors affecting the magnetic solid phase extraction of polycyclic aromatic hydrocarbons were assessed in terms of adsorption, desorption, and recovery. Under the optimized conditions, the proposed method showed good limits of detection (LOD, S/N=3) in the range of 0.05-0.1 ng mL(-1) and precision in the range of 1.8-5.3% (RSDs, n=3). This method was also successfully applied to the analysis of real water samples; good spiked recoveries over the range of 80.0-99.8% were obtained. Copyright © 2014 Elsevier B.V. All rights reserved.

Targeted Lipidomics in Drosophila melanogaster Identifies Novel 2-Monoacylglycerols and N-acyl Amides

PubMed Central

Takacs, Sara M.; Stuart, Jordyn M.; Basnet, Arjun; Raboune, Siham; Widlanski, Theodore S.; Doherty, Patrick; Bradshaw, Heather B.

2013-01-01

Lipid metabolism is critical to coordinate organ development and physiology in response to tissue-autonomous signals and environmental cues. Changes to the availability and signaling of lipid mediators can limit competitiveness, adaptation to environmental stressors, and augment pathological processes. Two classes of lipids, the N-acyl amides and the 2-acyl glycerols, have emerged as important signaling molecules in a wide range of species with important signaling properties, though most of what is known about their cellular functions is from mammalian models. Therefore, expanding available knowledge on the repertoire of these lipids in invertebrates will provide additional avenues of research aimed at elucidating biosynthetic, metabolic, and signaling properties of these molecules. Drosophila melanogaster is a commonly used organism to study intercellular communication, including the functions of bioactive lipids. However, limited information is available on the molecular identity of lipids with putative biological activities in Drosophila. Here, we used a targeted lipidomics approach to identify putative signaling lipids in third instar Drosophila larvae, possessing particularly large lipid mass in their fat body. We identified 2-linoleoyl glycerol, 2-oleoyl glycerol, and 45 N-acyl amides in larval tissues, and validated our findings by the comparative analysis of Oregon-RS, Canton-S and w1118 strains. Data here suggest that Drosophila represent another model system to use for the study of 2-acyl glycerol and N-acyl amide signaling. PMID:23874457

In Situ Hydrothermally Grown TiO2@C Core-Shell Nanowire Coating for Highly Sensitive Solid Phase Microextraction of Polycyclic Aromatic Hydrocarbons.

PubMed

Wang, Fuxin; Zheng, Juan; Qiu, Junlang; Liu, Shuqin; Chen, Guosheng; Tong, Yexiang; Zhu, Fang; Ouyang, Gangfeng

2017-01-18

Nanostructured materials have great potential for solid phase microextraction (SPME) on account of their tiny size, distinct architectures and superior physical and chemical properties. Herein, a core-shell TiO 2 @C fiber for SPME was successfully fabricated by the simple hydrothermal reaction of a titanium wire and subsequent amorphous carbon coating. The readily hydrothermal procedure afforded in situ synthesis of TiO 2 nanowires on a titanium wire and provided a desirable substrate for further coating of amorphous carbon. Benefiting from the much larger surface area of subsequent TiO 2 and good adsorption property of the amorphous carbon coating, the core-shell TiO 2 @C fiber was utilized for the SPME device for the first time and proved to have better performance in extraction of polycyclic aromatic hydrocarbons. In comparison to the polydimethylsiloxane (PDMS) and PDMS/divinylbenzene (DVB) fiber for commercial use, the TiO 2 @C fiber obtained gas chromatography responses 3-8 times higher than those obtained by the commercial 100 μm PDMS and 1-9 times higher than those obtained by the 65 μm PDMS/DVB fiber. Under the optimized extraction conditions, the low detection limits were obtained in the range of 0.4-7.1 ng L -1 with wider linearity in the range of 10-2000 ng L -1 . Moreover, the fiber was successfully used for the determination of polycyclic aromatic hydrocarbons in Pearl River water, which demonstrated the applicability of the core-shell TiO 2 @C fiber.

One-Pot Catalyst-Free Synthesis of β- and γ-Hydroxy Sulfides using Diaryliodonium Salts and Microwave Irradiation

EPA Science Inventory

A facile one-pot high-yield protocol is described for the preparation of β- and γ-hydroxy sulfides directly from diaryliodonium salts, potassium thiocyanate, and ethane-1,2-diol (ethylene glycol)/propane-1,3-diol (β-propylene glycol) without the need for any additional catalyst o...

Lanthanum tricyanide-catalyzed acyl silane-ketone benzoin additions.

PubMed

Tarr, James C; Johnson, Jeffrey S

2009-09-03

Lanthanum tricyanide efficiently catalyzes a benzoin-type coupling between acyl silanes and ketones. Yields range from moderate to excellent over a broad substrate scope encompassing aryl, alkyl, electron-rich, and sterically hindered ketones.

Natural separation of the acyl-CoA ligase reaction results in a non-adenylating enzyme.

PubMed

Wang, Nan; Rudolf, Jeffrey D; Dong, Liao-Bin; Osipiuk, Jerzy; Hatzos-Skintges, Catherine; Endres, Michael; Chang, Chin-Yuan; Babnigg, Gyorgy; Joachimiak, Andrzej; Phillips, George N; Shen, Ben

2018-06-04

Acyl-coenzyme A (CoA) ligases catalyze the activation of carboxylic acids via a two-step reaction of adenylation followed by thioesterification. Here, we report the discovery of a non-adenylating acyl-CoA ligase PtmA2 and the functional separation of an acyl-CoA ligase reaction. Both PtmA1 and PtmA2, two acyl-CoA ligases from the biosynthetic pathway of platensimycin and platencin, are necessary for the two steps of CoA activation. Gene inactivation of ptmA1 and ptmA2 resulted in the accumulation of free acid and adenylate intermediates, respectively. Enzymatic and structural characterization of PtmA2 confirmed its ability to only catalyze thioesterification. Structural characterization of PtmA2 revealed it binds both free acid and adenylate substrates and undergoes the established mechanism of domain alternation. Finally, site-directed mutagenesis restored both the adenylation and complete CoA activation reactions. This study challenges the currently accepted paradigm of adenylating enzymes and inspires future investigations on functionally separated acyl-CoA ligases and their ramifications in biology.

Thermochemical and kinetic analysis on the reactions of O2 with products from OH addition to isobutene, 2-hydroxy-1,1-dimethylethyl, and 2-hydroxy-2-methylpropyl radicals: HO2 formation from oxidation of neopentane, Part II.

PubMed

Sun, Hongyan; Bozzelli, Joseph W; Law, Chung K

2007-06-14

Unimolecular dissociation of a neopentyl radical to isobutene and methyl radical is competitive with the neopentyl association with O2 ((3)Sigma(g)-) in thermal oxidative systems. Furthermore, both isobutene and the OH radical are important primary products from the reactions of neopentyl with O2. Consequently, the reactions of O2 with the 2-hydroxy-1,1-dimethylethyl and 2-hydroxy-2-methylpropyl radicals resulting from the OH addition to isobutene are important to understanding the oxidation of neopentane and other branched hydrocarbons. Reactions that correspond to the association of radical adducts with O2((3)Sigma(g)-) involve chemically activated peroxy intermediates, which can isomerize and react to form one of several products before stabilization. The above reaction systems were analyzed with ab initio and density functional calculations to evaluate the thermochemistry, reaction paths, and kinetics that are important in neopentyl radical oxidation. The stationary points of potential energy surfaces were analyzed based on the enthalpies calculated at the CBS-Q level. The entropies, S(degrees)298, and heat capacities, C(p)(T), (0

Acylated ghrelin concentrations are markedly decreased during pregnancy in mothers with and without gestational diabetes: relationship with cholinesterase.

PubMed

Tham, Elaine; Liu, Jianhua; Innis, Sheila; Thompson, David; Gaylinn, Bruce D; Bogarin, Roberto; Haim, Alon; Thorner, Michael O; Chanoine, Jean-Pierre

2009-05-01

Acylated (octanoylated) ghrelin stimulates food intake and growth hormone secretion and is deacylated into desacyl ghrelin by butyrylcholinesterase. Acylated and desacyl ghrelin both promote adipogenesis. Ghrelin concentrations decrease with hyperglycemia and hyperinsulinism. We hypothesized that 1) acylated ghrelin increases during pregnancy, contributing positively to energy balance, but is lower in women with gestational diabetes and 2) butyrylcholinesterase activity is inversely correlated with acylated ghrelin concentrations. In a first group of subjects, using two-site sandwich ghrelin assays that specifically detect full-length forms, we investigated women with and without gestational diabetes (n = 14/group) during pregnancy and after delivery. We examined whether changes in ghrelin during a test meal were correlated with changes in pituitary growth hormone [assessed through calculation of the area under the curve (AUC) during the test meal]. In postpartum subjects, the percent of total ghrelin that is acylated was four to five times higher than previously observed using single antibody assays. During pregnancy, acylated ghrelin concentrations (mean +/- SE) were lower compared with the postpartum period throughout the meal (AUC 1.2 +/- 0.2 vs. 10.2 +/- 1.9 ng.ml(-1).90 min(-1), P < 0.001). In the postpartum, acylated ghrelin and growth hormone were positively correlated (r = 0.50, P = 0.007). Desacyl (but not acylated) ghrelin was increased in subjects with gestational diabetes during and after pregnancy (AUC 15.4 +/- 1.9 vs. 8.6 +/- 1.2 ng.ml(-1).90 min(-1), P = 0.005). In a second group of subjects (n = 13), acylated ghrelin was similarly suppressed during pregnancy. Circulating octanoate concentrations (3.1 +/- 0.5 vs. 4.5 +/- 0.6 microg/ml, P = 0.029) and cholinesterase activity (705 +/- 33 vs. 1,013 +/- 56 U/ml, P < 0.001) were lower during pregnancy compared with the postpartum period. In conclusion, acylated ghrelin markedly decreases during pregnancy

Mechanism and regulation of mycobactin fatty acyl-AMP ligase FadD33.

PubMed

Vergnolle, Olivia; Xu, Hua; Blanchard, John S

2013-09-27

Mycobacterial siderophores are critical components for bacterial virulence in the host. Pathogenic mycobacteria synthesize iron chelating siderophores named mycobactin and carboxymycobactin to extract intracellular macrophage iron. The two siderophores differ in structure only by a lipophilic aliphatic chain attached on the ε-amino group of the lysine mycobactin core, which is transferred by MbtK. Prior to acyl chain transfer, the lipophilic chain requires activation by a specific fatty acyl-AMP ligase FadD33 (also known as MbtM) and is then loaded onto phosphopantetheinylated acyl carrier protein (holo-MbtL) to form covalently acylated MbtL. We demonstrate that FadD33 prefers long chain saturated lipids and initial velocity studies showed that FadD33 proceeds via a Bi Uni Uni Bi ping-pong mechanism. Inhibition experiments suggest that, during the first half-reaction (adenylation), fatty acid binds first to the free enzyme, followed by ATP and the release of pyrophosphate to form the adenylate intermediate. During the second half-reaction (ligation), holo-MbtL binds to the enzyme followed by the release of products AMP and acylated MbtL. In addition, we characterized a post-translational regulation mechanism of FadD33 by the mycobacterial protein lysine acetyltransferase in a cAMP-dependent manner. FadD33 acetylation leads to enzyme inhibition, which can be reversed by the NAD(+)-dependent deacetylase, MSMEG_5175 (DAc1). To the best of our knowledge, this is the first time that bacterial siderophore synthesis has been shown to be regulated via post-translational protein acetylation.

Inverse association of des-acyl ghrelin with worksite blood pressure in overweight/obese male workers.

PubMed

Narisada, Akihiko; Hasegawa, Tomomi; Nakahigashi, Maki; Hirobe, Takaaki; Ikemoto, Tatsunori; Ushida, Takahiro; Kobayashi, Fumio

2015-05-01

Job strain, defined as a combination of high job demands and low job control, has been reported to elevate blood pressure (BP) during work. Meanwhile, a recent experimental study showed that ghrelin blunted the BP response to such mental stress. In the present study, we examined the hypothesis that des-acyl ghrelin may have some beneficial effects on worksite BP through modulating the BP response to work-related mental stress, i.e., job strain. Subjects were 34 overweight/obese male day-shift workers (mean age 41.7 ± 6.7 years). No subjects had received any anti-hypertensive medication. A 24-h ambulatory BP monitoring was recorded every 30 min on a regular working day. The average BP was calculated for Work BP, Morning BP, and Home BP. Job strain was assessed using the short version of the Japanese Job Content Questionnaire. Des-acyl ghrelin showed significant inverse correlations with almost all BPs except Morning SBP, Morning DBP, and Home DBP. In multiple regression analysis, des-acyl ghrelin inversely correlated with Work SBP after adjusting for confounding factors. Des-acyl ghrelin was also negatively associated with BP changes from Sleep to Morning, Sleep to Work, and Sleep to Home. Des-acyl ghrelin was inversely associated with Worksite BP, suggesting a unique beneficial effect of des-acyl ghrelin on Worksite BP in overweight/obese male day-shift workers.

Extreme halophilic alcohol dehydrogenase mediated highly efficient syntheses of enantiopure aromatic alcohols.

PubMed

Alsafadi, Diya; Alsalman, Safaa; Paradisi, Francesca

2017-11-07

Enzymatic synthesis of enantiopure aromatic secondary alcohols (including substituted, hetero-aromatic and bicyclic structures) was carried out using halophilic alcohol dehydrogenase ADH2 from Haloferax volcanii (HvADH2). This enzyme showed an unprecedented substrate scope and absolute enatioselectivity. The cofactor NADPH was used catalytically and regenerated in situ by the biocatalyst, in the presence of 5% ethanol. The efficiency of HvADH2 for the conversion of aromatic ketones was markedly influenced by the steric and electronic factors as well as the solubility of ketones in the reaction medium. Furthermore, carbonyl stretching band frequencies ν (C[double bond, length as m-dash]O) have been measured for different ketones to understand the effect of electron withdrawing or donating properties of the ketone substituents on the reaction rate catalyzed by HvADH2. Good correlation was observed between ν (C[double bond, length as m-dash]O) of methyl aryl-ketones and the reaction rate catalyzed by HvADH2. The enzyme catalyzed the reductions of ketone substrates on the preparative scale, demonstrating that HvADH2 would be a valuable biocatalyst for the preparation of chiral aromatic alcohols of pharmaceutical interest.

Kinetics of acyl transfer reactions in organic media catalysed by Candida antarctica lipase B.

PubMed

Martinelle, M; Hult, K

1995-09-06

The acyl transfer reactions catalysed by Candida antartica lipase B in organic media followed a bi-bi ping-pong mechanism, with competitive substrate inhibition by the alcohols used as acyl acceptors. The effect of organic solvents on Vm and Km was investigated. The Vm values in acetonitrile was 40-50% of those in heptane. High Km values in acetonitrile compared to those in heptane could partly be explained by an increased solvation of the substrates in acetonitrile. Substrate solvation caused a 10-fold change in substrate specificity, defined as (Vm/Km)ethyl octanoate/(Vm/Km)octanoic acid, going from heptane to acetonitrile. Deacylation was the rate determining step for the acyl transfer in heptane with vinyl- and ethyl octanoate as acyl donors and (R)-2-octanol as acyl acceptor. With 1-octanol, a rate determining deacylation step in heptane was indicated using the same acyl donors. Using 1-octanol as acceptor in heptane, S-ethyl thiooctanoate had a 25- to 30-fold lower Vm/Km value and vinyl octanoate a 4-fold higher Vm/Km value than that for ethyl octanoate. The difference showed to be a Km effect for vinyl octanoate and mainly a Km effect for S-ethyl thiooctanoate. The Vm values of the esterification of octanoic acid with different alcohols was 10-30-times lower than those for the corresponding transesterification of ethyl octanoate. The low activity could be explained by a low pH around the enzyme caused by the acid or a withdrawing of active enzyme by nonproductive binding by the acid.

Engineering acyl carrier protein to enhance production of shortened fatty acids.

PubMed

Liu, Xueliang; Hicks, Wade M; Silver, Pamela A; Way, Jeffrey C

2016-01-01

The acyl carrier protein (ACP) is an essential and ubiquitous component of microbial synthesis of fatty acids, the natural precursor to biofuels. Natural fatty acids usually contain long chains of 16 or more carbon atoms. Shorter carbon chains, with increased fuel volatility, are desired for internal combustion engines. Engineering the length specificity of key proteins in fatty acid metabolism, such as ACP, may enable microbial synthesis of these shorter chain fatty acids. We constructed a homology model of the Synechococcus elongatus ACP, showing a hydrophobic pocket harboring the growing acyl chain. Amino acids within the pocket were mutated to increase steric hindrance to the acyl chain. Certain mutant ACPs, when over-expressed in Escherichia coli, increased the proportion of shorter chain lipids; I75 W and I75Y showed the strongest effects. Expression of I75 W and I75Y mutant ACPs also increased production of lauric acid in E. coli that expressed the C12-specific acyl-ACP thioesterase from Cuphea palustris. We engineered the specificity of the ACP, an essential protein of fatty acid metabolism, to alter the E. coli lipid pool and enhance production of medium-chain fatty acids as biofuel precursors. These results indicate that modification of ACP itself could be combined with enzymes affecting length specificity in fatty acid synthesis to enhance production of commodity chemicals based on fatty acids.

The oxidation degradation of aromatic compounds

NASA Technical Reports Server (NTRS)

Brezinsky, Kenneth; Glassman, Irvin

1987-01-01

A series of experiments were conducted which focused on understanding the role that the O atom addition to aromatic rings plays in the oxidation of benzene and toluene. Flow reactor studies of the oxidation of toluene gave an indication of the amount of O atoms available during an oxidation and the degree to which the O atom adds to the ring. Flow reactor studies of the oxidation of toluene and benzene to which NO2 was added, have shown that NO2 appears to suppress the formation of O atoms and consequently reduce the amount of phenols and cresols formed by O atom addition. A high temperature pyrolysis study of phenol has confirmed that the major decomposition products are carbon monoxide and cyclopentadiene. A preliminary value for the overall decomposition rate constant was also obtained.

Enzyme-like catalysis via ternary complex mechanism: alkoxy-bridged dinuclear cobalt complex mediates chemoselective O-esterification over N-amidation.

PubMed

Hayashi, Yukiko; Santoro, Stefano; Azuma, Yuki; Himo, Fahmi; Ohshima, Takashi; Mashima, Kazushi

2013-04-24

Hydroxy group-selective acylation in the presence of more nucleophilic amines was achieved using acetates of first-row late transition metals, such as Mn, Fe, Co, Cu, and Zn. Among them, cobalt(II) acetate was the best catalyst in terms of reactivity and selectivity. The combination of an octanuclear cobalt carboxylate cluster [Co4(OCOR)6O]2 (2a: R = CF3, 2b: R = CH3, 2c: R = (t)Bu) with nitrogen-containing ligands, such as 2,2'-bipyridine, provided an efficient catalytic system for transesterification, in which an alkoxide-bridged dinuclear complex, Co2(OCO(t)Bu)2(bpy)2(μ2-OCH2-C6H4-4-CH3)2 (10), was successfully isolated as a key intermediate. Kinetic studies and density functional theory calculations revealed Michaelis-Menten behavior of the complex 10 through an ordered ternary complex mechanism similar to dinuclear metallo-enzymes, suggesting the formation of alkoxides followed by coordination of the ester.

Lanthanum Tricyanide-Catalyzed Acyl Silane-Ketone Benzoin Additions

PubMed Central

Tarr, James C.; Johnson, Jeffrey S.

2009-01-01

Lanthanum tricyanide efficiently catalyzes a benzoin-type coupling between acyl silanes and ketones. Yields range from moderate to excellent over a broad substrate scope encompassing aryl, alkyl, electron-rich, and sterically hindered ketones. PMID:19655731

Enhanced Antibacterial Activity of Ent-Labdane Derivatives of Salvic Acid (7α-Hydroxy-8(17)-ent-Labden-15-Oic Acid): Effect of Lipophilicity and the Hydrogen Bonding Role in Bacterial Membrane Interaction.

PubMed

Echeverría, Javier; Urzúa, Alejandro; Sanhueza, Loreto; Wilkens, Marcela

2017-06-23

In the present study, the antibacterial activity of several ent -labdane derivatives of salvic acid (7α-hydroxy-8(17)- ent -labden-15-oic acid) was evaluated in vitro against the Gram-negative bacterium Escherichia coli and the Gram-positive bacteria Staphylococcus aureus and Bacillus cereus . For all of the compounds, the antibacterial activity was expressed as the minimum inhibitory concentration (MIC) in liquid media and minimum inhibitory amount (MIA) in solid media. Structure activity relationships (SAR) were employed to correlate the effect of the calculated lipophilicity parameters (logP ow ) on the inhibitory activity. Employing a phospholipidic bilayer (POPG) as a bacterial membrane model, ent -labdane-membrane interactions were simulated utilizing docking studies. The results indicate that (i) the presence of a carboxylic acid in the C-15 position, which acted as a hydrogen-bond donor (HBD), was essential for the antibacterial activity of the ent -labdanes; (ii) an increase in the length of the acylated chain at the C-7 position improved the antibacterial activity until an optimum length of five carbon atoms was reached; (iii) an increase in the length of the acylated chain by more than five carbon atoms resulted in a dramatic decrease in activity, which completely disappeared in acyl chains of more than nine carbon atoms; and (iv) the structural factors described above, including one HBD at C-15 and a hexanoyloxi moiety at C-7, had a good fit to a specific lipophilic range and antibacterial activity. The lipophilicity parameter has a predictive characteristic feature on the antibacterial activity of this class of compounds, to be considered in the design of new biologically active molecules.

Metabolism of the 18O-methoxy substituent of 3-methoxybenzoic acid and other unlabeled methoxybenzoic acids by anaerobic bacteria.

PubMed Central

DeWeerd, K A; Saxena, A; Nagle, D P; Suflita, J M

1988-01-01

O-methyl substituents of aromatic compounds can provide C1 growth substrates for facultative and strict anaerobic bacteria isolated from diverse environments. The mechanism of the bioconversion of methoxylated benzoic acids to the hydroxylated derivatives was investigated with a model substrate and cultures of one anaerobic consortium, eight strict anaerobic bacteria, and one facultative anaerobic microorganism. Using high-pressure liquid chromatography and gas chromatography-mass spectral analysis, we found that a haloaromatic dehalogenating consortium, a dehalogenating isolate from that consortium, Eubacterium limosum, and a strain of Acetobacterium woodii metabolized 3-[methoxy-18O]methoxybenzoic acid (3-anisic acid) to 3-[hydroxy-18O]hydroxybenzoic acid stoichiometrically at rates of 1.5, 3.2, 52.4, and 36.7 nmol/min per mg of protein, respectively. A different strain of Acetobacterium and strains of Syntrophococcus, Clostridium, Desulfotomaculum, Enterobacter, and an anaerobic bacterium, strain TH-001, were unable to transform this compound. The O-demethylating ability of E. limosum was induced only with appropriate methoxylated benzoates but not with D-glucose, lactate, isoleucine, or methanol. Cross-acclimation and growth experiments with E. limosum showed a rate of metabolism that was an order of magnitude slower and showed no growth with either 4-methoxysalicylic acid (2-hydroxy-4-methoxybenzoic acid) or 4-anisic acid (4-methoxybenzoic acid) when adapted to 3-anisic acid. However, A. woodii NZva-16 showed slower rates and no growth with 3- or 4-methoxysalicylic acid when adapted to 3-anisic acid in similar experiments. The results clearly indicate a methyl rather than methoxy group removal mechanism for such reactions. PMID:3389815

Mechanism-based inhibitors of MenE, an acyl-CoA synthetase involved in bacterial menaquinone biosynthesis†

PubMed Central

Lu, Xuequan; Zhang, Huaning; Tonge, Peter J.; Tan, Derek S.

2008-01-01

Menaquinone (vitamin K2) is an essential component of the electron transfer chain in many pathogens, including Mycobacterium tuberculosis and Staphylococcus aureus, and menaquinone biosynthesis is a potential target for antibiotic drug discovery. We report herein a series of mechanism-based inhibitors of MenE, an acyl-CoA synthetase that catalyzes adenylation and thioesterification of o-succinylbenzoic acid (OSB) during menaquinone biosynthesis. The most potent compound inhibits MenE with an IC50 value of 5.7 μM. PMID:18762421

Synthesis of 2-Amino-3-hydroxy-3H-indoles via Palladium-Catalyzed One-Pot Reaction of Isonitriles, Oxygen, and N-Tosylhydrazones Derived from 2-Acylanilines.

PubMed

Chu, Haoke; Dai, Qiang; Jiang, Yan; Cheng, Jiang

2017-08-04

A cyanide-free one-pot procedure was developed to access 2-amino-3-hydroxy-3H-indoles, which involved: (1) in situ formation of ketenimines by the reaction of N'-(1-(2-aminophenyl)ethylidene)-p-tosylhydrazones with isonitriles; (2) the intramolecular nucleophilic attack of ketenimines by the amino in phenyl furnishing the ring closure leading to 2-aminoindoles; (3) the oxidation of 2-aminoindoles by O 2 leading to 2-amino-3-hydroxy-3H-indoles. This strategy represents not only a key compliment to the sporadic synthetic methods toward 2-amino-3-hydroxy-3H-indoles but also progress in N-tosylhydrazone, isonitrile, and ketenimine chemistry.

Detection of the anaerobic dechlorinating microorganism Desulfomonile tiedjei in environmental matrices by its signature lipopolysacchride branched-long-chain hydroxy fatty acids

USGS Publications Warehouse

Ringleberg, D.B.; Townsend, G.T.; DeWeerd, K.A.; Suflita, J.M.; White, D.C.

1994-01-01

Desulfomonile tiedjei is a Gram-negative sulfate-reducing bacterium capable of catalyzing aryl reductive dehalogenation reactions. Since many toxic and persistent contaminants in the subsurface are halogenated aromatic compounds, the detection and enumeration of dehalogenating microorganisms in the environment may be a useful tool for planning and evaluating bioremediation efforts. In this study, we show that D. tiedjei contains unique lipopolysaccharide branched 3-hydroxy fatty acids, unknown as yet in other bacteria, and that it is possible to detect the bacterium in inoculated aquifer sediments based on these signature lipid biomarkers. The detection of D. tiedjeiand other dehalogenating microorganisms possessing similar cellular properties in environmental matrices may be possible by this technique. Additionally, the effect of such inoculation on dehalogenation activity is examined.

pHP-Tethered N-Acyl Carbamate: A Photocage for Nicotinamide.

PubMed

Salahi, Farbod; Purohit, Vatsal; Ferraudi, Guillermo; Stauffacher, Cynthia; Wiest, Olaf; Helquist, Paul

2018-05-04

The synthesis of a new photocaged nicotinamide having an N-acyl carbamate linker and a p-hydroxyphenacyl (pHP) chromophore is described. The photophysical and photochemical studies showed an absorption maximum at λ = 330 nm and a quantum yield for release of 11% that are dependent upon both pH and solvent. While the acyl carbamate releases nicotinamide efficiently, a simpler amide linker was inert to photocleavage. This photocaged nicotinamide has significant advantages with respect to quantum yield, absorbance wavelength, rate of release, and solubility that make it the first practical example of a photocaged amide.

Mechanism of the mutagenic action of hydroxylamine. IX. The UV-induced cleavage of the N-O bond in N4-hydroxy-and N4-methoxycytidine and N6-methoxyadenosine.

PubMed Central

Simukova, N A; Yakovlev, D Y; Budowsky, E I

1975-01-01

The principal UV-induced (lambda = 2546nm) reaction of N4-hydroxy- and N4methoxycytidines and N6-methoxyadenosine in neutral aqueous solutions is cleavage of the exocyclic N-O bond with the respective formation of cytidine and adenosine. Quantum yields are 2.8x10(-3) and 2.2x10(-3) M/E for the first two compounds and 9.1x10(-3) M/E for N6-methoxyadenosine. PMID:1052542

Characterization of the transacylase activity of rat liver 60-kDa lysophospholipase-transacylase. Acyl transfer from the sn-2 to the sn-1 position.

PubMed

Sugimoto, H; Yamashita, S

1999-05-18

Rat liver 60-kDa lysophospholipase-transacylase catalyzes not only the hydrolysis of 1-acyl-sn-glycero-3-phosphocholine, but also the transfer of its acyl chain to a second molecule of 1-acyl-sn-glycero-3-phosphocholine to form phosphatidylcholine (H. Sugimoto, S. Yamashita, J. Biol. Chem. 269 (1994) 6252-6258). Here we report the detailed characterization of the transacylase activity of the enzyme. The enzyme mediated three types of acyl transfer between donor and acceptor lipids, transferring acyl residues from: (1) the sn-1 to -1(3); (2) sn-1 to -2; and (3) sn-2 to -1 positions. In the sn-1 to -1(3) transfer, the sn-1 acyl residue of 1-acyl-sn-glycero-3-phosphocholine was transferred to the sn-1(3) positions of glycerol and 2-acyl-sn-glycerol, producing 1(3)-acyl-sn-glycerol and 1,2-diacyl-sn-glycerol, respectively. In the sn-1 to -2 transfer, the sn-1 acyl residue of 1-acyl-sn-glycero-3-phosphocholine was transferred to not only the sn-2 positions of 1-acyl-sn-glycero-3-phosphocholine, but also 1-acyl-sn-glycero-3-phosphoethanolamine, producing phosphatidylcholine and phosphatidylethanolamine, respectively. 1-Acyl-sn-glycero-3-phospho-myo-inositol and 1-acyl-sn-glycero-3-phosphoserine were much less effectively transacylated by the enzyme. In the sn-2 to -1 transfer, the sn-2 acyl residue of 2-acyl-sn-glycero-3-phosphocholine was transferred to the sn-1 position of 2-acyl-sn-glycero-3-phosphocholine and 2-acyl-sn-glycero-3-phosphoethanolamine, producing phosphatidylcholine and phosphatidylethanolamine, respectively. Consistently, the enzyme hydrolyzed the sn-2 acyl residue from 2-acyl-sn-glycero-3-phosphocholine. By the sn-2 to -1 transfer activity, arachidonic acid was transferred from the sn-2 position of donor lipids to the sn-1 position of acceptor lipids, thus producing 1-arachidonoyl phosphatidylcholine. When 2-arachidonoyl-sn-glycero-3-phosphocholine was used as the sole substrate, diarachidonoyl phosphatidylcholine was synthesized at a rate of 0

Microhydration effects on the electronic spectra of protonated polycyclic aromatic hydrocarbons: [naphthalene-(H2O)n = 1,2]H+

NASA Astrophysics Data System (ADS)

Alata, Ivan; Broquier, Michel; Dedonder-Lardeux, Claude; Jouvet, Christophe; Kim, Minho; Sohn, Woon Yong; Kim, Sang-su; Kang, Hyuk; Schütz, Markus; Patzer, Alexander; Dopfer, Otto

2011-02-01

Vibrational and electronic spectra of protonated naphthalene (NaphH+) microsolvated by one and two water molecules were obtained by photofragmentation spectroscopy. The IR spectrum of the monohydrated species is consistent with a structure with the proton located on the aromatic molecule, NaphH+-H2O. Similar to isolated NaphH+, the first electronic transition of NaphH+-H2O (S1) occurs in the visible range near 500 nm. The doubly hydrated species lacks any absorption in the visible range (420-600 nm) but absorbs in the UV range, similar to neutral Naph. This observation is consistent with a structure, in which the proton is located on the water moiety, Naph-(H2O)2H+. Ab initio calculations for [Naph-(H2O)n]H+ confirm that the excess proton transfers from Naph to the solvent cluster upon attachment of the second water molecule.

Sites of intermolecular crosslinking of fatty acyl chains in phospholipids carrying a photoactivable carbene precursor

PubMed Central

Gupta, Chhitar M.; Costello, Catherine E.; Khorana, H. Gobind

1979-01-01

Sonicated vesicles of 1-fatty acyl-2-ω-(2-diazo-3,3,3-trifluoropropionoxy) fatty acyl sn-glycero-3-phosphoryl-cholines were shown recently to form intermolecular crosslinks by insertion of the photogenerated carbene into a C—H bond of a neighboring hydrocarbon chain. We now report that photolysis of multilamellar dispersions gives a second series of products in which carbene insertion is accompanied by elimination of a molecule of hydrogen fluoride. The sites of crosslinking in the latter compounds have been studied by mass spectrometry using phospholipids with varying chain lengths of the fatty acyl groups carrying the carbene precursor. The patterns observed show that the point of maximum crosslinking is consistent with the recent conclusion that in phospholipids the sn-2 fatty acyl chain trails the sn-1 chain by 2-4 atoms. Images PMID:16592675

Acylated ghrelin concentrations are markedly decreased during pregnancy in mothers with and without gestational diabetes: relationship with cholinesterase

PubMed Central

Tham, Elaine; Liu, Jianhua; Innis, Sheila; Thompson, David; Gaylinn, Bruce D.; Bogarin, Roberto; Haim, Alon; Thorner, Michael O.; Chanoine, Jean-Pierre

2009-01-01

Acylated (octanoylated) ghrelin stimulates food intake and growth hormone secretion and is deacylated into desacyl ghrelin by butyrylcholinesterase. Acylated and desacyl ghrelin both promote adipogenesis. Ghrelin concentrations decrease with hyperglycemia and hyperinsulinism. We hypothesized that 1) acylated ghrelin increases during pregnancy, contributing positively to energy balance, but is lower in women with gestational diabetes and 2) butyrylcholinesterase activity is inversely correlated with acylated ghrelin concentrations. In a first group of subjects, using two-site sandwich ghrelin assays that specifically detect full-length forms, we investigated women with and without gestational diabetes (n = 14/group) during pregnancy and after delivery. We examined whether changes in ghrelin during a test meal were correlated with changes in pituitary growth hormone [assessed through calculation of the area under the curve (AUC) during the test meal]. In postpartum subjects, the percent of total ghrelin that is acylated was four to five times higher than previously observed using single antibody assays. During pregnancy, acylated ghrelin concentrations (mean ± SE) were lower compared with the postpartum period throughout the meal (AUC 1.2 ± 0.2 vs. 10.2 ± 1.9 ng·ml−1·90 min−1, P < 0.001). In the postpartum, acylated ghrelin and growth hormone were positively correlated (r = 0.50, P = 0.007). Desacyl (but not acylated) ghrelin was increased in subjects with gestational diabetes during and after pregnancy (AUC 15.4 ± 1.9 vs. 8.6 ± 1.2 ng·ml−1·90 min−1, P = 0.005). In a second group of subjects (n = 13), acylated ghrelin was similarly suppressed during pregnancy. Circulating octanoate concentrations (3.1 ± 0.5 vs. 4.5 ± 0.6 μg/ml, P = 0.029) and cholinesterase activity (705 ± 33 vs. 1,013 ± 56 U/ml, P < 0.001) were lower during pregnancy compared with the postpartum period. In conclusion, acylated ghrelin markedly decreases during pregnancy, likely

Newer mixed ligand Schiff base complexes from aquo-N-(2‧-hydroxy acetophenone) glycinatocopper(II) as synthon: DFT, antimicrobial activity and molecular docking study

NASA Astrophysics Data System (ADS)

Pramanik, Harun A. R.; Das, Dharitri; Paul, Pradip C.; Mondal, Paritosh; Bhattacharjee, Chira R.

2014-02-01

Synthesis of a series of newer mixed ligand copper(II) complexes of aminoacid Schiff base of the type [CuL(X)] (L = N-(2‧-hydroxy acetophenone) glycinate, X = imidazole (im) 2, benzimidazole (benz) 3, pyridine (py) 4, hydrazine (hz) 5,8-hydroxyquinoline (8-hq) 6, pyrrolidine (pyrr) 7, piperidine (pip) 8, and nicotinamide (nic) 9) have been accomplished from the interaction of an aquated Schiff base complex, [CuL(H2O)]·H2O, 1 with some selected neutral nitrogen-donor ligands. The copper(II) Schiff base complex, [CuL(H2O)]·H2O, L = N-(2‧-hydroxy acetophenone) glycinate was synthesized from the reaction of glycine and 2‧ hydroxy acetophenone and copper(II) acetate. The compounds were characterised by elemental analysis, spectral, magnetic and thermal studies. The density functional theory calculations were performed using LANL2DZ and 6-311 G(d, p) basis sets with B3LYP correlation functional to ascertain the stable electronic structure, HOMO-LUMO energy gap, chemical hardness and dipole moment of the mixed ligand complexes. A distorted square planar geometry has been conjectured for the complexes. Antibacterial activities of the ligand and its metal complexes have been tested against selected gram-positive and gram-negative strains and correlated with computational docking scores.

Determination of hydroxylated polycyclic aromatic hydrocarbons by HPLC-photoionization tandem mass spectrometry in wood smoke particles and soil samples.

PubMed

Avagyan, Rozanna; Nyström, Robin; Boman, Christoffer; Westerholm, Roger

2015-06-01

A simple and fast method for analysis of hydroxylated polycyclic aromatic hydrocarbons using pressurized liquid extraction and high performance liquid chromatography utilizing photoionization tandem mass spectrometry was developed. Simultaneous separation and determination of nine hydroxylated polycyclic aromatic hydrocarbons and two hydroxy biphenyls could be performed in negative mode with a run time of 12 min, including equilibration in 5 min. The calibration curves were in two concentration ranges; 1-50 ng/mL and 0.01-50 μg/mL, with coefficients of correlation R (2) > 0.997. The limits of detection and method quantification limits were in the range of 9-56 pg and 5-38 ng/g, respectively. A two-level full factorial experimental design was used for screening of conditions with the highest impact on the extraction. The extraction procedure was automated and suitable for a large number of samples. The extraction recoveries ranged from 70 to 102 % and the matrix effects were between 92 and 104 %. The overall method was demonstrated on wood smoke particles and soil samples with good analytical performance, and five OH-PAHs were determined in the concentration range of 0.19-210 μg/g. As far as we know, hydroxylated polycyclic aromatic hydrocarbons were determined in wood smoke and soil samples using photoionization mass spectrometry for the first time in this present study. Accordingly, this study shows that high performance liquid chromatography photoionization tandem mass spectrometry can be a good option for the determination of hydroxylated polycyclic aromatic hydrocarbons in complex environmental samples. Graphical Abstract The method developed in this study was used to determine hydroxylated polycyclic aromatic hydrocarbons in wood smoke and soil.

Rhenium(VII) Catalysis of Prins Cyclization Reactions

PubMed Central

Tadpetch, Kwanruthai; Rychnovsky, Scott D.

2009-01-01

The rhenium(VII) complex O3ReOSiPh3 are particularly effective catalyst for Prins cyclizations using aromatic and α,β-unsaturated aldehydes. The reaction conditions are mild and the highly substituted 4-hydroxy tetrahydropyran products are formed stereoselectively. Rhenium(VII) complexes appear to spontaneously form esters with alcohols and to directly activate electron rich alcohols for solvolysis. Re2O7 and perrhenic acid were equally effective in catalyzing these cyclizations. PMID:18816133

Identification of keto- and hydroxy-dicarboxylic acids in remote marine aerosols from the western North Pacific: GC and GC/TOF-MS measurements

NASA Astrophysics Data System (ADS)

Vani, D.; Kawamura, K.; Tachibana, E.; Boreddy, S. K. R.

2015-12-01

Dicarboxylic acids (diacids) are dominant components of organic aerosols in the atmosphere. They contribute significantly to the total aerosol mass and have a serious impacts on global climate changes. However, studies on keto- and hydroxy-diacids in marine aerosols are limited. Compare to diacids, keto- and hydroxy-diacids are more hygroscopic due to the additional polar groups (OH and CO) and, hence, acts as cloud condensation nuclei (CCN). Molecular characterization of these compounds provides insight into organic aerosols sources and transformation pathways. We collected marine aerosols from remote Chichijima Island in the western North Pacific from December 2010 to November 2011 and studied for water-soluble keto- and hydroxy-diacids. Carboxyl groups were derivatized to dibutyl esters with 14% boron trifluoride/n-butanol, whereas hydroxyl groups were derivatized to trimethylsilyl ethers using N,O-Bis (trimethylsilyl) trifluoroacetamide (BSTFA). After two-step derivatization, samples were injected to GC, GC/MS and GC/TOF-MS. In the GC chromatogram, we detected several new peaks after BSTFA derivatization of dibutyl ester fraction. Based on mass spectral interpretation, we found these peaks as homologues series of hydroxy-diacids and keto-diacids. Some of these hydroxy-diacids have been individually reported in literature in the laboratory photo-oxidation experiments and forest environments samples. But, there are no evidences to prove their sources and formation mechanism in the atmosphere. Here, we report for the first time homologous series of hydroxy-diacids (hC3di-hC6di) and keto-diacid (oxaloacetic acid, enol and keto forms) in remote marine atmosphere. Molecular distributions of hydroxy-diacids generally showed the predominance of malic acid followed by tartronic acid. Both hydroxy- and keto-diacids show significant positive correlation with oxalic acid and SO42-, suggesting that they are generated in the atmosphere and play an important role in the

Prenatal exposure to polycyclic aromatic hydrocarbons/aromatics, BDNF and child development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perera, Frederica, E-mail: fpp1@columbia.edu; Columbia Center for Children's Environmental Health, Columbia University, 722 W. 168th St., New York, NY 10032; Phillips, David H.

Objectives: Within a New York City (NYC) birth cohort, we assessed the associations between polycyclic aromatic hydrocarbon (PAH) and other aromatic DNA adducts and brain derived neurotrophic factor (BDNF) concentrations in umbilical cord blood, and neurodevelopment at age 2 years and whether BDNF is a mediator of the associations between PAH/aromatic-DNA adducts and neurodevelopment. Methods: PAH/aromatic-DNA adduct concentrations in cord blood were measured in 505 children born to nonsmoking African-American and Dominican women residing in NYC, and a subset was assessed for neurodevelopment at 2 years using the Bayley Scales of Infant Development Mental Development Index (MDI). A spectrum ofmore » PAH/aromatic-DNA adducts was measured using the {sup 32}P-postlabeling assay; DNA adducts formed by benzo[a]pyrene (B[a]P), a representative PAH, were measured by High Performance Liquid Chromatography (HPLC)/fluorescence. BDNF mature protein in cord blood plasma was quantified by an ELISA. Multivariate regression analysis, adjusting for potential confounders, was conducted. Results: PAH/aromatic-DNA adduct concentration measured by postlabeling was inversely associated with BDNF concentration (p=0.02) and with MDI scores at 2 years (p=0.04). BDNF level was positively associated with MDI scores (p=0.003). Restricting to subjects having all three measures (PAH/aromatic-DNA adducts by postlabeling, MDI, and BDNF), results were similar but attenuated (p=0.13, p=0.05, p=0.01, respectively). Associations between B[a]P-DNA adducts and BDNF and B[a]P-DNA adducts and MDI at age 2 years were not significant. At age 3 years, the positive association of BDNF with MDI was not observed. Conclusions: The results at age 2 suggest that prenatal exposure to a spectrum of PAH/aromatic pollutants may adversely affect early neurodevelopment, in part by reducing BDNF levels during the fetal period. However, the same relationship was not seen at age 3. - Highlights: • Cord blood

Hydroxy protons as structural probes to reveal hydrogen bonding properties of polyols in aqueous solution by NMR spectroscopy

NASA Astrophysics Data System (ADS)

Oruc, Gizem; Varnali, Tereza; Bekiroglu, Somer

2018-05-01

The solution properties of ethylene glycol (ethane-1,2-diol), glycerol (propane-1,2,3-triol), erythritol ((2R,3S)-butane-1,2,3,4-tetraol), D-xylitol ((2R,3r,4S)-pentane-1,2,3,4,5-pentaol), D-mannitol ((2R,3R,4R,5R)-hexane-1,2,3,4,5,6-hexaol), and D-sorbitol ((2S,3R,4R,5R)-hexane-1,2,3,4,5,6-hexaol), constituting a subgroup of polyalcohols/polyols of maximum six carbon atoms have been investigated using 1H NMR chemical shifts, coupling constants, temperature coefficients, and chemical exchange rates of hydroxy protons in aqueous medium. Relative within a molecule, minimum two-fold difference in rate of exchange values and higher temperature dependence of chemical shifts of the hydroxy protons on terminal carbon atoms confirm that sustainable hydrogen bonding interactions is accentuated for the hydroxyl groups on secondary carbons. Compared to the primary carbons i.e. terminal ones, the hydroxy protons on second and third carbon atoms exhibit much lower rate of exchange and smaller temperature coefficients, indicating that they are further involved in transient hydrogen bonding interactions. Scalar 3JOH,CH-couplings ranging between 3.9 and 7.2 Hz imply that the hydroxyl groups are practically in free rotation regime. Examination of the chemical shift differences with respect to the shift of glycol hydroxy proton reveals that the disparity between terminal and inner hydroxyl groups disclosed by the exchange rates and temperature coefficients is sustained with the exception of 0.003 and 0.053 ppm for O(3)H of mannitol and O(5)H of sorbitol respectively. The experimental findings have been augmented by quantum chemical calculations targeting theoretical NMR chemical shifts, as well as the conformational analysis of the structures.

Density functional theory studies on the nano-scaled composites consisted of graphene and acyl hydrazone molecules

NASA Astrophysics Data System (ADS)

Ren, J. L.; Zhou, L.; Lv, Z. C.; Ding, C. H.; Wu, Y. H.; Bai, H. C.

2016-07-01

Graphene, which is the first obtained single atomic layer 2D materials, has drawn a great of concern in nano biotechnology due to the unique property. On one hand, acyl hydrazone compounds belonging to the Schif bases have aroused considerable attention in medicine, pharmacy, and analytical reagent. However, few understanding about the interaction between graphene and acyl hydrazone molecules is now available. And such investigations are much crucial for the applications of these new nano-scaled composites. The current work revealed theoretical investigations on the nano-scaled composites built by acyl hydrazone molecules loaded on the surface of graphene. The relative energy, electronic property and the interaction between the counterparts of graphene/acyl hydrazone composites are investigated based on the density functional theory calculations. According to the obtained adsorption energy, the formation of the nano-scaled composite from the isolated graphene and acyl hydrazone molecule is exothermic, and thus it is energetically favorable to form these nano composites in viewpoint of total energy change. The frontier molecular orbital for the nano composite is mainly distributed at the graphene part, leading to that the energy levels of the frontier molecular orbital of the nano composites are very close to that of isolated graphene. Moreover, the counterpart interaction for the graphene/acyl hydrazone composites is also explored based on the discussions of orbital hybridization, charge redistribution and Van der Waals interaction.

Acyl carrier protein structural classification and normal mode analysis

PubMed Central

Cantu, David C; Forrester, Michael J; Charov, Katherine; Reilly, Peter J

2012-01-01

All acyl carrier protein primary and tertiary structures were gathered into the ThYme database. They are classified into 16 families by amino acid sequence similarity, with members of the different families having sequences with statistically highly significant differences. These classifications are supported by tertiary structure superposition analysis. Tertiary structures from a number of families are very similar, suggesting that these families may come from a single distant ancestor. Normal vibrational mode analysis was conducted on experimentally determined freestanding structures, showing greater fluctuations at chain termini and loops than in most helices. Their modes overlap more so within families than between different families. The tertiary structures of three acyl carrier protein families that lacked any known structures were predicted as well. PMID:22374859

Atypical cleavage of protonated N-fatty acyl amino acids derived from aspartic acid evidenced by sequential MS3 experiments.

PubMed

Boukerche, Toufik Taalibi; Alves, Sandra; Le Faouder, Pauline; Warnet, Anna; Bertrand-Michel, Justine; Bouchekara, Mohamed; Belbachir, Mohammed; Tabet, Jean-Claude

2016-12-01

Lipidomics calls for information on detected lipids and conjugates whose structural elucidation by mass spectrometry requires to rationalization of their gas phase dissociations toward collision-induced dissociation (CID) processes. This study focused on activated dissociations of two lipoamino acid (LAA) systems composed of N-palmitoyl acyl coupled with aspartic and glutamic acid mono ethyl esters (as LAA (*D) and LAA (*E) ). Although in MS/MS, their CID spectra show similar trends, e.g., release of water and ethanol, the [(LAA (*D/*E) +H)-C 2 H 5 OH] + product ions dissociate via distinct pathways in sequential MS 3 experiments. The formation of all the product ions is rationalized by charge-promoted cleavages often involving stepwise processes with ion isomerization into ion-dipole prior to dissociation. The latter explains the maleic anhydride or ketene neutral losses from N-palmitoyl acyl aspartate and glutamate anhydride fragment ions, respectively. Consequently, protonated palmitoyl acid amide is generated from LAA (*D), whereas LAA (*E) leads to the [*E+H-H 2 O] + anhydride. The former releases ammonia to provide acylium, which gives the C n H (2n-1) and C n H (2n-3) carbenium series. This should offer structural information, e.g., to locate either unsaturation(s) or alkyl group branching present on the various fatty acyl moieties of lipo-aspartic acid in further studies based on MS n experiments.

Heteropoly acid encapsulated into zeolite imidazolate framework (ZIF-67) cage as an efficient heterogeneous catalyst for Friedel–Crafts acylation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ammar, Muhammad; Jiang, Sai; Ji, Shengfu, E-mail: jisf@mail.buct.edu.cn

2016-01-15

A new strategy has been developed for the encapsulation of the phosphotungstic heteropoly acid (H{sub 3}PW{sub 12}O{sub 40} denoted as PTA) into zeolite imidazolate framework (ZIF-67) cage and the PTA@ZIF-67(ec) catalysts with different PTA content were prepared. The structure of the catalysts was characterized by XRD, BET, SEM, FT-IR, ICP-AES and TG. The catalytic activity and recovery properties of the catalysts for the Friedel-Crafts acylation of anisole with benzoyl chloride were evaluated. The results showed that 14.6–31.7 wt% PTA were encapsulated in the ZIF-67 cage. The PTA@ZIF-67(ec) catalysts had good catalytic activity for Friedel-Crafts acylation. The conversion of anisole canmore » reach ~100% and the selectivity of the production can reach ~94% over 26.5 wt% PTA@ZIF-67(ec) catalyst under the reaction condition of 120 °C and 6 h. After reaction, the catalyst can be easily separated from the reaction mixture by the centrifugation. The recovered catalyst can be reused five times and the selectivity can be kept over 90%. - Graphical abstract: The PTA@ZIF-67 catalysts with different PTA content were prepared by encapsulating the PTA into ZIF-67 cage and the as-synthesized catalysts exhibited good catalytic activity for the Friedel–Craft acylation of anisole with benzoyl chloride.« less

Deuterium enrichment of polycyclic aromatic hydrocarbons by photochemically induced exchange with deuterium-rich cosmic ices

NASA Technical Reports Server (NTRS)

Sandford, S. A.; Bernstein, M. P.; Allamandola, L. J.; Gillette, J. S.; Zare, R. N.

2000-01-01

The polycyclic aromatic hydrocarbon (PAH) coronene (C24H12) frozen in D2O ice in a ratio of less than 1 part in 500 rapidly exchanges its hydrogen atoms with the deuterium in the ice at interstellar temperatures and pressures when exposed to ultraviolet radiation. Exchange occurs via three different chemical processes: D atom addition, D atom exchange at oxidized edge sites, and D atom exchange at aromatic edge sites. Observed exchange rates for coronene (C24H12)-D2O and d12-coronene (C24D12)-H2O isotopic substitution experiments show that PAHs in interstellar ices could easily attain the D/H levels observed in meteorites. These results may have important consequences for the abundance of deuterium observed in aromatic materials in the interstellar medium and in meteorites. These exchange mechanisms produce deuteration in characteristic molecular locations on the PAHs that may distinguish them from previously postulated processes for D enrichment of PAHs.

Discovering Targets of Non-enzymatic Acylation by Thioester Reactivity Profiling | Center for Cancer Research

Cancer.gov

The cover image illuminates the non-enzymatic “ghost writers” of lysine acylation. Meier et al. detail the development of a chemoproteomic strategy that harnesses thioester reactivity to discover candidate cellular targets of non-enzymatic acylation. Application of this approach reveals that glycolytic enzymes can be strongly inhibited by reactive thioesters, including the

Ene reaction of singlet oxygen, triazolinedione, and nitrosoarene with chiral deuterium-labeled allylic alcohols: the interdependence of diastereoselectivity and regioselectivity discloses mechanistic insights into the hydroxy-group directivity.

PubMed

Adam, Waldemar; Bottke, Nils; Krebs, Oliver; Lykakis, Ioannis; Orfanopoulos, Michael; Stratakis, Manolis

2002-12-04

The ene reaction of singlet oxygen ((1)O(2)), triazolinedione (TAD), and nitrosoarene, specifically 4-nitronitrosobenzene (ArNO), with the tetrasubstituted 1,3-allylically strained, chiral allylic alcohol 3,4-dimethylpent-3-en-2-ol (2) leads to the threo-configured ene products in high diastereoselectivity, a consequence of the hydroxy-group directivity. Hydrogen bonding favors formation of the threo-configured encounter complex threo-EC in the early stage of ene reaction. For the analogous twix deuterium-labeled allylic alcohol Z-2-d(3), a hitherto unrecognized dichotomy between (1)O(2) and the ArNO and TAD enophiles is disclosed in the regioselectivity of the tetrasubstituted alcohol: Whereas for ArNO and TAD, hydrogen bonding with the allylic hydroxy group dictates the regioselectivity (twix selectivity), for (1)O(2), the cis effect dominates (twin/trix selectivity). From the interdependence between the twix/twin regioselectivity and the threo/erythro diastereoselectivity, it has been recognized that the enophile also attacks the allylic alcohol from the erythro pi face without assistance by hydrogen bonding with the allylic hydroxy functionality.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kishino, Hideyuki; Eguchi, Hiroki; Takagi, Keiko

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 phospholipidmore » 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.« less

Synthesis of 4-hydroxy-3-methylchalcone from Reimer-Tiemann reaction product and its antibacterial activity test

NASA Astrophysics Data System (ADS)

Hapsari, M.; Windarti, T.; Purbowatiningrum; Ngadiwiyana; Ismiyarto

2018-04-01

A 4-hydroxy-3-methylchalcone has been synthesized from 4-hydroxy-3-methylbenzaldehyde as the Reimer-Tiemann reaction product. This research consists of three steps involve synthesize of 4-hydroxy-3-methylbenzaldehyde from ortho-cresol, synthesize of chalcone derivatives from 4-hydroxy-3-methylbenzaldehyde and 4-hydroxy-3-methoxybenzaldehyde or vanillin for the comparison, the last is antibacterial activity test of both chalcone derivatives against Escherichia coli (negative gram) and Staphylococcus aureus (positive gram) bacteria using disc diffusion method. Results of Reimer-Tiemann reaction is 4-hydroxy-3-methylbenzaldehyde compound in an orange colour solid form which has 43% yields and melting point 110-114°C. A 4-hydroxy-3-methylbenzaldehyde then reacted with acetophenone in a base condition and form 4-hydroxy-3-methylchalcone compound in a yellow colour solid form which has 40% yields and melting point 83-86°C. The antibacterial activity of the 4-hydroxy-3-methylchalcone against gram-positive bacteria Staphylococcus aureus is better than the 4-hydroxy-3-methoxychalcone.

Cyp7b, a novel brain cytochrome P450, catalyzes the synthesis of neurosteroids 7α-hydroxy dehydroepiandrosterone and 7α-hydroxy pregnenolone

PubMed Central

Rose, Ken A.; Stapleton, Genevieve; Dott, Karin; Kieny, Marie Paule; Best, Ruth; Schwarz, Margrit; Russell, David W.; Björkhem, Ingemar; Seckl, Jonathan; Lathe, Richard

1997-01-01

Steroids produced locally in brain (neurosteroids), including dehydroepiandrosterone (DHEA), influence cognition and behavior. We previously described a novel cytochrome P450, Cyp7b, strongly expressed in rat and mouse brain, particularly in hippocampus. Cyp7b is most similar to steroidogenic P450s and potentially could play a role in neurosteroid metabolism. To examine the catalytic activity of the enzyme mouse Cyp7b cDNA was introduced into a vaccinia virus vector. Extracts from cells infected with the recombinant showed NADPH-dependent conversion of DHEA (Km, 13.6 μM) and pregnenolone (Km, 4.0 μM) to slower migrating forms on thin layer chromatography. The expressed enzyme was less active against 25-hydroxycholesterol, 17β-estradiol and 5α-androstane-3β,17β-diol, with low to undetectable activity against progesterone, corticosterone, and testosterone. On gas chromatography and mass spectrometry of the Cyp7b metabolite of DHEA the retention time and fragmentation patterns were identical to those obtained with authentic 7α-hydroxy DHEA. The reaction product also comigrated on thin layer chromatography with 7α-hydroxy DHEA but not with 7β-hydroxy DHEA; when [7α-3H]pregnenolone was incubated with Cyp7b extracts the extent of release of radioactivity into the medium suggested that hydroxylation was preferentially at the 7α position. Brain extracts also efficiently liberated tritium from [7α-3H]pregnenolone and converted DHEA to a product with a chromatographic mobility indistinguishable from 7α-hydroxy DHEA. We conclude that Cyp7b is a 7α-hydroxylase participating in the synthesis, in brain, of neurosteroids 7α-hydroxy DHEA, and 7α-hydroxy pregnenolone. PMID:9144166

CONTROL OF AROMATIC WASTE AIR STREAMS BY SOIL BIOREACTORS

EPA Science Inventory

Three soils were examined for the ability to degrade hydrocarbon vapors of benzene, toluene, ethylbenzene, and o-xylene (BTEX). Each of these compounds are major aromatic constituents of gasolines. The soils examined were Rubicon Sand from Traverse City, Michigan, Durant Loam fro...

40 CFR 721.10063 - Halo substituted hydroxy nitrophenyl amide (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... amide (generic). 721.10063 Section 721.10063 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10063 Halo substituted hydroxy nitrophenyl amide (generic). (a) Chemical... as halo substituted hydroxy nitrophenyl amide (PMN P-04-792) is subject to reporting under this...

Aromatic Borozene

PubMed Central

2009-01-01

Based on our comprehensive theoretical investigation and known experimental results for small boron clusters, we predict the existence of a novel aromatic inorganic molecule, B12H6. This molecule, which we refer to as borozene, has remarkably similar properties to the well-known benzene. Borozene is planar, possesses a large first excitation energy, D3hsymmetry, and more importantly is aromatic. Furthermore, the calculated anisotropy of the magnetic susceptibility of borozene is three times larger in absolute value than for benzene. Finally, we show that borozene molecules may be fused together to give larger aromatic compounds with even larger anisotropic susceptibilities. PMID:20596438

Enzymatic acylation of flavonoid glycosides by a carbohydrate esterase of family 16.

PubMed

Biely, Peter; Cziszárová, Mária; Wong, Ken K Y; Fernyhough, Alan

2014-11-01

The acetyl esterase of Trichoderma reesei belonging to carbohydrate esterase (CE) family 16 catalyzes transacylations to carbohydrate moieties of flavonoid glycosides, esculin and rutin. The enzyme recognizes as acyl donors vinyl esters of short carboxylic acids. Esculin was acylated at position 3 of the glucosyl residue in aqueous solutions saturated with vinyl acetate and vinyl propionate. The yields of esculin monoacetate and monopropionate of esculin in aqueous medium (esculin 40 mM, enzyme 40 µg/ml, 40 °C, 3 days) were 67 and 55 %, respectively. Replacement of water by 2-propanol was required for a similar acylation of rutin at 4 mM concentration. The yields of rutin monoacetate and propionate were 60 and 30 %, respectively. The results indicate that the enzyme could be used for an easy modification of solubility and hydrophobicity of glycosylated compounds, including drugs and functional food additives.

Serum Levels of Acyl-Carnitines along the Continuum from Normal to Alzheimer's Dementia.

PubMed

Cristofano, Adriana; Sapere, Nadia; La Marca, Giancarlo; Angiolillo, Antonella; Vitale, Michela; Corbi, Graziamaria; Scapagnini, Giovanni; Intrieri, Mariano; Russo, Claudio; Corso, Gaetano; Di Costanzo, Alfonso

2016-01-01

This study aimed to determine the serum levels of free L-carnitine, acetyl-L-carnitine and 34 acyl-L-carnitine in healthy subjects and in patients with or at risk of Alzheimer's disease. Twenty-nine patients with probable Alzheimer's disease, 18 with mild cognitive impairment of the amnestic type, 24 with subjective memory complaint and 46 healthy subjects were enrolled in the study, and the levels of carnitine and acyl-carnitines were measured by tandem mass spectrometry. The concentrations of acetyl-L-carnitine progressively decreased passing from healthy subjects group (mean±SD, 5.6±1.3 μmol/L) to subjective memory complaint (4.3±0.9 μmol/L), mild cognitive impairment (4.0±0.53 μmol/L), up to Alzheimer's disease (3.5±0.6 μmol/L) group (p<0.001). The differences were significant for the comparisons: healthy subjects vs. subjective memory complaint, mild cognitive impairment or Alzheimer's disease group; and subjective memory complaint vs. Alzheimer's disease group. Other acyl-carnitines, such as malonyl-, 3-hydroxyisovaleryl-, hexenoyl-, decanoyl-, dodecanoyl-, dodecenoyl-, myristoyl-, tetradecenoyl-, hexadecenoyl-, stearoyl-, oleyl- and linoleyl-L-carnitine, showed a similar decreasing trend, passing from healthy subjects to patients at risk of or with Alzheimer's disease. These results suggest that serum acetyl-L-carnitine and other acyl-L-carnitine levels decrease along the continuum from healthy subjects to subjective memory complaint and mild cognitive impairment subjects, up to patients with Alzheimer's disease, and that the metabolism of some acyl-carnitines is finely connected among them. These findings also suggest that the serum levels of acetyl-L-carnitine and other acyl-L-carnitines could help to identify the patients before the phenotype conversion to Alzheimer's disease and the patients who would benefit from the treatment with acetyl-L-carnitine. However, further validation on a larger number of samples in a longitudinal study is needed

Serum Levels of Acyl-Carnitines along the Continuum from Normal to Alzheimer's Dementia

PubMed Central

Sapere, Nadia; La Marca, Giancarlo; Angiolillo, Antonella; Vitale, Michela; Corbi, Graziamaria; Scapagnini, Giovanni; Intrieri, Mariano; Russo, Claudio

2016-01-01

This study aimed to determine the serum levels of free L-carnitine, acetyl-L-carnitine and 34 acyl-L-carnitine in healthy subjects and in patients with or at risk of Alzheimer’s disease. Twenty-nine patients with probable Alzheimer’s disease, 18 with mild cognitive impairment of the amnestic type, 24 with subjective memory complaint and 46 healthy subjects were enrolled in the study, and the levels of carnitine and acyl-carnitines were measured by tandem mass spectrometry. The concentrations of acetyl-L-carnitine progressively decreased passing from healthy subjects group (mean±SD, 5.6±1.3 μmol/L) to subjective memory complaint (4.3±0.9 μmol/L), mild cognitive impairment (4.0±0.53 μmol/L), up to Alzheimer’s disease (3.5±0.6 μmol/L) group (p<0.001). The differences were significant for the comparisons: healthy subjects vs. subjective memory complaint, mild cognitive impairment or Alzheimer’s disease group; and subjective memory complaint vs. Alzheimer’s disease group. Other acyl-carnitines, such as malonyl-, 3-hydroxyisovaleryl-, hexenoyl-, decanoyl-, dodecanoyl-, dodecenoyl-, myristoyl-, tetradecenoyl-, hexadecenoyl-, stearoyl-, oleyl- and linoleyl-L-carnitine, showed a similar decreasing trend, passing from healthy subjects to patients at risk of or with Alzheimer’s disease. These results suggest that serum acetyl-L-carnitine and other acyl-L-carnitine levels decrease along the continuum from healthy subjects to subjective memory complaint and mild cognitive impairment subjects, up to patients with Alzheimer’s disease, and that the metabolism of some acyl-carnitines is finely connected among them. These findings also suggest that the serum levels of acetyl-L-carnitine and other acyl-L-carnitines could help to identify the patients before the phenotype conversion to Alzheimer’s disease and the patients who would benefit from the treatment with acetyl-L-carnitine. However, further validation on a larger number of samples in a longitudinal

Bond Length Equalization with molecular aromaticity-A new measurement of aromaticity.

PubMed

Shen, Chen-Fei; Liu, Zi-Zhong; Liu, Hong-Xia; Zhang, Hui-Qing

2018-05-08

A new method to measure the amount of aromaticity is presented through the process of Bond Length Equalization (BLE). Degree of Aromaticity (DOA), a two-dimensional intensive quantity including geometric and energetic factors, as a new measurement of aromaticity is proposed. The unique characteristic of DOA and the formation of DOA will be displayed. The calculation of the geometrical optimization, DOA, Nucleus Independent Chemical Shifts (NICS) and Ring Stretching Vibration Raman Spectroscopy Frequency (RSVRSF) for the aromatic ring molecules - G n H n m (G = C, Si, Ge, n = 3, 5-8, m = +1, -1, 0, +1, +2) were calculated using the method of Density Functional Theory (DFT). The correlation between radius angle and molecular energy is absolute quadratic in the process of BLE. As the increasing of the number of ring atoms, the value of DOA decreasing gradually, the aromaticity decreased gradually, which was a same conclusion as NICS and RSVRSF concluded. Copyright © 2018 Elsevier B.V. All rights reserved.

Synthesis of 2-acyl-1,4-diketones via the diacylation of {alpha},{beta}-unsaturated ketones

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, N.S.; Yu, S.; Kabalka, G.W.

1998-08-17

The first example of a diacylation of the carbon-carbon double bond in {alpha},{beta}-unsaturated ketones is described. The reaction of acylcyanocuprate reagents with {alpha},{beta}-unsaturated ketones, followed by C-acylation, produces 2-acyl-1,4-diketones in good yields (50--89%). The 1,4-addition of organocuprate reagents to conjugated enones, followed by trapping of the enolate intermediates with various electrophiles, is one of the most useful synthetic reactions. However, to the best of the authors` knowledge, 1,4-acylation followed by trapping of the enolate intermediates with acid chloride has not been reported.

New Molecular Detections in TMC-1 with the Green Bank Telescope: Carbon-Chain and Aromatic Molecules

NASA Astrophysics Data System (ADS)

Burkhardt, Andrew Michael

2018-01-01

Polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic nitrogen heterocycles PA(N)Hs are believed to be widespread throughout the Universe, and are likely responsible for the unidentified infrared bands. However, the individual detection of aromatic molecules has been limited to a single weak absorption feature of an infrared bending mode of benzene (c-C6H6). The cold core TMC-1 has long been a source of new molecular detections, particularly for unsaturated carbon-rich molecules that are appealing potential precursors of PA(N)Hs. Through deep observations with the Green Bank Telescope of TMC-1, we report the first rotational detection of an aromatic molecule, benzonitrile (c-C6H5CN), along with 8 new isotopologues of HC5N and HC7N and an entirely new molecular family (HC5O, HC7O). These new detections provide crucial insights to the formation of PAHs and the underlying carbon-chain chemistry of dark clouds.

The 1:1 co-crystal of 2-bromo-naphthalene-1,4-dione and 1,8-di-hydroxy-anthracene-9,10-dione: crystal structure and Hirshfeld surface analysis.

PubMed

Tonin, Marlon D L; Garden, Simon J; Jotani, Mukesh M; Wardell, Solange M S V; Wardell, James L; Tiekink, Edward R T

2017-05-01

The asymmetric unit of the title co-crystal, C 10 H 5 BrO 2 ·C 14 H 8 O 4 [systematic name: 2-bromo-1,4-di-hydro-naphthalene-1,4-dione-1,8-dihy-droxy-9,10-di-hydro-anthracene-9,10-dione (1/1)], features one mol-ecule of each coformer. The 2-bromo-naphtho-quinone mol-ecule is almost planar [r.m.s deviation of the 13 non-H atoms = 0.060 Å, with the maximum deviations of 0.093 (1) and 0.099 (1) Å being for the Br atom and a carbonyl-O atom, respectively]. The 1,8-di-hydroxy-anthra-quinone mol-ecule is planar (r.m.s. deviation for the 18 non-H atoms is 0.022 Å) and features two intra-molecular hy-droxy-O-H⋯O(carbon-yl) hydrogen bonds. Dimeric aggregates of 1,8-di-hydroxy-anthra-quinone mol-ecules assemble through weak inter-molecular hy-droxy-O-H⋯O(carbon-yl) hydrogen bonds. The mol-ecular packing comprises stacks of mol-ecules of 2-bromo-naphtho-quinone and dimeric assembles of 1,8-di-hydroxy-anthra-quinone with the shortest π-π contact within a stack of 3.5760 (9) Å occurring between the different rings of 2-bromo-naphtho-quinone mol-ecules. The analysis of the Hirshfeld surface reveals the importance of the inter-actions just indicated but, also the contribution of additional C-H⋯O contacts as well as C=O⋯π inter-actions to the mol-ecular packing.

Role of methyl group number on SOA formation from aromatic hydrocarbons photooxidation under low NOx conditions

NASA Astrophysics Data System (ADS)

Li, L.; Tang, P.; Nakao, S.; Chen, C.-L.; Cocker, D. R., III

2015-11-01

Substitution of methyl groups onto the aromatic ring determines the SOA formation from the aromatic hydrocarbon precursor. This study links the number of methyl groups on the aromatic ring to SOA formation from aromatic hydrocarbons photooxidation under low NOx conditions (HC / NO > 10 ppb C : ppb). Aromatic hydrocarbons with increasing numbers of methyl groups are systematically studied. SOA formation from pentamethylbenzene and hexamethylbenzene are reported for the first time. A decreasing SOA yield with increasing number of methyl groups is observed. Linear trends are found in both f44 vs. f43 and O / C vs. H / C for SOA from aromatic hydrocarbons with zero to six methyl groups. An SOA oxidation state predictive method based on benzene is used to examine the effect of added methyl groups on aromatic oxidation under low NOx conditions. Further, the impact of methyl group number on density and volatility of SOA from aromatic hydrocarbons is explored. Finally, a mechanism for methyl group impact on SOA formation is suggested. Overall, this work suggests as more methyl groups are attached on the aromatic ring, SOA products from these aromatic hydrocarbons become less oxidized per mass/carbon.

Aromatic Structure in Simulates Titan Aerosol

NASA Technical Reports Server (NTRS)

Trainer, Melissa G.; Loeffler, M. J.; Anderson, C. M.; Hudson, R. L.; Samuelson, R. E.; Moore, M. A.

2011-01-01

demonstrated in the aerosol mass spectra shown in Figure 2. The aromatic aerosol also demonstrates strong chemical reactivity when exposed to laboratory air, indicating substantial stored chemical potential. Oxidatoin and solubility studies wil be presented and implicatoins for prebiotic chemistry o nTitan will be discussed.

S-acylation of SOD1, CCS, and a stable SOD1-CCS heterodimer in human spinal cords from ALS and non-ALS subjects.

PubMed

Antinone, Sarah E; Ghadge, Ghanashyam D; Ostrow, Lyle W; Roos, Raymond P; Green, William N

2017-01-25

Previously, we found that human Cu, Zn-superoxide dismutase (SOD1) is S-acylated (palmitoylated) in vitro and in amyotrophic lateral sclerosis (ALS) mouse models, and that S-acylation increased for ALS-causing SOD1 mutants relative to wild type. Here, we use the acyl resin-assisted capture (acyl-RAC) assay to demonstrate S-acylation of SOD1 in human post-mortem spinal cord homogenates from ALS and non-ALS subjects. Acyl-RAC further revealed that endogenous copper chaperone for SOD1 (CCS) is S-acylated in both human and mouse spinal cords, and in vitro in HEK293 cells. SOD1 and CCS formed a highly stable heterodimer in human spinal cord homogenates that was resistant to dissociation by boiling, denaturants, or reducing agents and was not observed in vitro unless both SOD1 and CCS were overexpressed. Cysteine mutations that attenuate SOD1 maturation prevented the SOD1-CCS heterodimer formation. The degree of S-acylation was highest for SOD1-CCS heterodimers, intermediate for CCS monomers, and lowest for SOD1 monomers. Given that S-acylation facilitates anchoring of soluble proteins to cell membranes, our findings suggest that S-acylation and membrane localization may play an important role in CCS-mediated SOD1 maturation. Furthermore, the highly stable S-acylated SOD1-CCS heterodimer may serve as a long-lived maturation intermediate in human spinal cord.

S-acylation of SOD1, CCS, and a stable SOD1-CCS heterodimer in human spinal cords from ALS and non-ALS subjects

PubMed Central

Antinone, Sarah E.; Ghadge, Ghanashyam D.; Ostrow, Lyle W.; Roos, Raymond P.; Green, William N.

2017-01-01

Previously, we found that human Cu, Zn-superoxide dismutase (SOD1) is S-acylated (palmitoylated) in vitro and in amyotrophic lateral sclerosis (ALS) mouse models, and that S-acylation increased for ALS-causing SOD1 mutants relative to wild type. Here, we use the acyl resin-assisted capture (acyl-RAC) assay to demonstrate S-acylation of SOD1 in human post-mortem spinal cord homogenates from ALS and non-ALS subjects. Acyl-RAC further revealed that endogenous copper chaperone for SOD1 (CCS) is S-acylated in both human and mouse spinal cords, and in vitro in HEK293 cells. SOD1 and CCS formed a highly stable heterodimer in human spinal cord homogenates that was resistant to dissociation by boiling, denaturants, or reducing agents and was not observed in vitro unless both SOD1 and CCS were overexpressed. Cysteine mutations that attenuate SOD1 maturation prevented the SOD1-CCS heterodimer formation. The degree of S-acylation was highest for SOD1-CCS heterodimers, intermediate for CCS monomers, and lowest for SOD1 monomers. Given that S-acylation facilitates anchoring of soluble proteins to cell membranes, our findings suggest that S-acylation and membrane localization may play an important role in CCS-mediated SOD1 maturation. Furthermore, the highly stable S-acylated SOD1-CCS heterodimer may serve as a long-lived maturation intermediate in human spinal cord. PMID:28120938

Engineering Aromatic-Aromatic Interactions To Nucleate Folding in Intrinsically Disordered Regions of Proteins.

PubMed

Balakrishnan, Swati; Sarma, Siddhartha P

2017-08-22

Aromatic interactions are an important force in protein folding as they combine the stability of a hydrophobic interaction with the selectivity of a hydrogen bond. Much of our understanding of aromatic interactions comes from "bioinformatics" based analyses of protein structures and from the contribution of these interactions to stabilizing secondary structure motifs in model peptides. In this study, the structural consequences of aromatic interactions on protein folding have been explored in engineered mutants of the molten globule protein apo-cytochrome b 5 . Structural changes from disorder to order due to aromatic interactions in two variants of the protein, viz., WF-cytb5 and FF-cytb5, result in significant long-range secondary and tertiary structure. The results show that 54 and 52% of the residues in WF-cytb5 and FF-cytb5, respectively, occupy ordered regions versus 26% in apo-cytochrome b 5 . The interactions between the aromatic groups are offset-stacked and edge-to-face for the Trp-Phe and Phe-Phe mutants, respectively. Urea denaturation studies indicate that both mutants have a C m higher than that of apo-cytochrome b 5 and are more stable to chaotropic agents than apo-cytochrome b 5 . The introduction of these aromatic residues also results in "trimer" interactions with existing aromatic groups, reaffirming the selectivity of the aromatic interactions. These studies provide insights into the aromatic interactions that drive disorder-to-order transitions in intrinsically disordered regions of proteins and will aid in de novo protein design beyond small peptide scaffolds.

Thermochemistry and gas-phase ion energetics of 2-hydroxy-4-methoxy-benzophenone (oxybenzone).

PubMed

Lago, A F; Jimenez, P; Herrero, R; Dávalos, J Z; Abboud, J-L M

2008-04-10

We have investigated the thermochemistry and ion energetics of the oxybenzone (2-hydroxy-4-methoxy-benzophenone, C14H12O3, 1H) molecule. The following parameters have been determined for this species: gas-phase enthalpy for the of neutral molecule at 298.15K, (Delta(f)H0(m)(g) = -303.5 +/- 5.1 kJ x mol-1), the intrinsic (gas-phase) acidity (GA(1H) = 1402.1 +/- 8.4 kJ x mol-1), enthalpy of formation for the oxybenzone anion (Delta(f)H0(m)(1-,g) = -402.3 +/- 9.8 kJ x mol-1). We also have obtained the enthalpy of formation of, 4-hydroxy-4'-methoxybenzophenone (Delta(f)H0(m)(g) = -275.4 +/- 10 kJ x mol-1) and 3-methoxyphenol anion (Delta(f)H0(m)(C7H7O2-,g) = -317.7 +/- 8.7 kJ x mol-1). A reliable experimental estimation of enthalpy related to intramolecular hydrogen bonding in oxybenzone has also been obtained (30.1 +/- 6.3 kJ x mol-1) and compared with our theoretical calculations at the B3LYP/6-311++G** level of theory, by means of an isodesmic reaction scheme. In addition, heat capacities, temperature, and enthalpy of fusion have been determined for this molecule by differential scanning calorimetry.

Cr6+-containing phases in the system CaO-Al2O3-CrO42--H2O at 23 °C

NASA Astrophysics Data System (ADS)

Pöllmann, Herbert; Auer, Stephan

2012-01-01

Synthesis and investigation of lamellar calcium aluminium hydroxy salts was performed to study the incorporation of chromate ions in the interlayer of lamellar calcium aluminium hydroxy salts. Different AFm-phases (calcium aluminate hydrate with alumina, ferric oxide, mono-anion phase) containing chromate were synthesized. These AFm-phases belong to the group of layered double hydroxides (LDHs). 3CaO·Al2O3·CaCrO4·nH2O and C3A·1/2Ca(OH)2·1/2CaCrO4·12H2O were obtained as pure phases and their different distinct interlayer water contents and properties determined. Solid solution of chromate-containing phases and tetracalcium-aluminate-hydrate (TCAH) were studied. The uptake of chromate into TCAH from solutions was proven. Chromate contents in solution decrease to <0.2 mg/l.

4-[(E)-(2,4-Difluoro­phen­yl)(hydroxy­imino)meth­yl]piperidinium picrate

PubMed Central

Jasinski, Jerry P.; Butcher, Ray J.; Yathirajan, H. S.; Mallesha, L.; Mohana, K. N.

2009-01-01

The title compound, C12H15F2N2O+·C6H2N3O7 −, a picrate salt of 4-[(E)-(2,4-difluoro­phen­yl)(hydroxy­imino)meth­yl]piper­idine, crystallizes with two independent mol­ecules in a cation–anion pair in the asymmetric unit. In the cation, a methyl group is tris­ubstituted by hydroxy­imino, piperidin-4-yl and 2,4-difluoro­phenyl groups, the latter of which contains an F atom disordered over two positions in the ring [occupancy ratio 0.631 (4):0.369 (4)]. The mean plane of the hydr­oxy group is in a synclinical conformation nearly orthogonal [N—C—C—C = 72.44 (19)°] to the mean plane of the piperidine ring, which adopts a slightly distorted chair conformation. The dihedral angle between the mean plane of the 2,4-difluoro­phenyl and piperidin-4-yl groups is 60.2 (3)°. In the picrate anion, the mean planes of the two o-NO2 and single p-NO2 groups adopt twist angles of 5.7 (2), 25.3 (7) and 8.3 (6)°, respectively, with the attached planar benzene ring. The dihedral angle between the mean planes of the benzene ring in the picrate anion and those in the hydroxy­imino, piperidin-4-yl and 2,4-difluoro­phenyl groups in the cation are 84.9 (7), 78.9 (4) and 65.1 (1)°, respectively. Extensive hydrogen-bond inter­actions occur between the cation–anion pair, which help to establish the crystal packing in the unit cell. This includes dual three-center hydrogen bonds with the piperidin-4-yl group, the phenolate and o-NO2 O atoms of the picrate anion at different positions in the unit cell, which form separate N—H⋯(O,O) bifurcated inter­molecular hydrogen-bond inter­actions. Also, the hydr­oxy group forms a separate hydrogen bond with a nearby piperidin-4-yl N atom, thus providing two groups of hydrogen bonds, which form an infinite two-dimensional network along (011). PMID:21577832

Solvatochromicity of 3-hydroxy-4-(1-(2,4-dihydroxyphenyl)-2-hydroxy-2,2-diphenylethylidene)cyclohexa-2,5-dienone for screening of solvents

NASA Astrophysics Data System (ADS)

Babu, D. Suresh; Singh, W. Marjit; Kalita, Dipjyoti; Baruah, Jubaraj B.

2010-01-01

The quinonic compound 3-hydroxy-4-(1-(2,4-dihydroxyphenyl)-2-hydroxy-2,2-diphenylethylidene)cyclohexa-2,5-dienone ( I) is synthesised by the reaction of benzil with 1,3-dihydroxybenzene in basic medium. Solution of this compound shows visibly distinct colour differences in different solvents. From the different absorption maxima of the compound in visible spectra it can be used as an excellent analytical reagent to screen different solvents.

40 CFR 721.10055 - 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts.

Code of Federal Regulations, 2014 CFR

2014-07-01

...-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts. 721.10055 Section 721.10055 Protection of...-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts. (a) Chemical substance and...-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts (PMN P-03-46; CAS No. 136504-87-5) is subject to...

40 CFR 721.10055 - 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts.

Code of Federal Regulations, 2013 CFR

2013-07-01

...-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts. 721.10055 Section 721.10055 Protection of...-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts. (a) Chemical substance and...-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts (PMN P-03-46; CAS No. 136504-87-5) is subject to...

40 CFR 721.10055 - 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts.

Code of Federal Regulations, 2012 CFR

2012-07-01

...-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts. 721.10055 Section 721.10055 Protection of...-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts. (a) Chemical substance and...-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts (PMN P-03-46; CAS No. 136504-87-5) is subject to...

Plant acyl-CoA:lysophosphatidylcholine acyltransferases (LPCATs) have different specificities in their forward and reverse reactions

USDA-ARS?s Scientific Manuscript database

Acyl-CoA:lysophosphatidylcholine acyltransferase (LPCAT) enzymes have central roles inacyl editing of phosphatidylcholine (PC). Plant LPCAT genes were expressed in yeast and characterized biochemically in microsomal preparations of the cells. Specificities for different acyl-CoAs were similar for se...

Magnetic graphene oxide as adsorbent for the determination of polycyclic aromatic hydrocarbon metabolites in human urine.

PubMed

Zhu, Linli; Xu, Hui

2014-09-01

Detection of monohydroxy polycyclic aromatic hydrocarbons metabolites in urine is an advisable and valid method to assess human environmental exposure to polycyclic aromatic hydrocarbons. In this work, novel Fe3O4/graphene oxide composites were prepared and their application in the magnetic solid-phase extraction of monohydroxy polycyclic aromatic hydrocarbons in urine was investigated by coupling with liquid chromatography and mass spectrometry. In the hybrid material, superparamagnetic Fe3O4 nanoparticles provide fast separation to simplify the analytical process and graphene oxide provides a large functional surface for the adsorption. The prepared magnetic nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and vibrating sample magnetometry. The experimental conditions were optimized systematically. Under the optimal conditions, the recoveries of these compounds were in the range of 98.3-125.2%, the relative standard deviations ranged between 6.8 and 15.5%, and the limits of detection were in the range of 0.01-0.15 ng/mL. The simple, quick, and affordable method was successfully used in the analysis of human urinary monohydroxy polycyclic aromatic hydrocarbons in two different cities. The results indicated that the monohydroxy polycyclic aromatic hydrocarbons level in human urine can provide useful information for environmental exposure to polycyclic aromatic hydrocarbons. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis, structure and research on quasi-aromaticity of a new organically templated aluminoborate: [NH0.5C4H4NH0.5][AlB12O14(OH)12

NASA Astrophysics Data System (ADS)

Hu, HengBin; Chen, XiangYi; Deng, Song; Cai, Feng; Sun, YanQiong; Chen, YiPing

2012-02-01

By employing hydrothermal method, we identify a new organically templated aluminoborate [NH0.5C4H4NH0.5][AlB12O14(OH)12] which is structurally determined by single crystal X-ray diffraction and characterized by simulated and experimental IR, 2D IR COS (two-dimensional infrared correlation spectroscopy), NICS (nucleus-independent chemical shifts) and Mulliken charges calculations. Although the cluster anions [AlB12O14(OH)12]- is identical to the counterpart of compound reported by Lin et al. at 2008, we firstly bring up its quasi-aromaticity, discuss and confirm it by NICS, Mulliken charges calculations and magnetic-induced 2D IR COS, and conclude that three isolated and non-coplanar four-center six-electron π bonds of cluster could cooperate and interact with each other to form a closed conjugated large π orbital system, endowing the cluster anions with quasi-aromaticity. Thus, a one-dimensional chain is constructed by π-π stacked interaction between quasi-aromatic clusters and aromatic pyrazine along [1 0¯ 1] direction. The title compound crystallizes in monoclinic space group C2/c with a = 18.397(4), b = 12.0670(16), c = 11.075(2) Å, α = 90.00, β = 116.483(11), γ = 90.00°, Z = 4, V = 2200.6(7) Å, R = 0.0442 and wR = 0.1128 for 2689 observed reflections.

Structure-Activity Relationships for Rates of Aromatic Amine Oxidation by Manganese Dioxide.

PubMed

Salter-Blanc, Alexandra J; Bylaska, Eric J; Lyon, Molly A; Ness, Stuart C; Tratnyek, Paul G

2016-05-17

New energetic compounds are designed to minimize their potential environmental impacts, which includes their transformation and the fate and effects of their transformation products. The nitro groups of energetic compounds are readily reduced to amines, and the resulting aromatic amines are subject to oxidation and coupling reactions. Manganese dioxide (MnO2) is a common environmental oxidant and model system for kinetic studies of aromatic amine oxidation. In this study, a training set of new and previously reported kinetic data for the oxidation of model and energetic-derived aromatic amines was assembled and subjected to correlation analysis against descriptor variables that ranged from general purpose [Hammett σ constants (σ(-)), pKas of the amines, and energies of the highest occupied molecular orbital (EHOMO)] to specific for the likely rate-limiting step [one-electron oxidation potentials (Eox)]. The selection of calculated descriptors (pKa, EHOMO, and Eox) was based on validation with experimental data. All of the correlations gave satisfactory quantitative structure-activity relationships (QSARs), but they improved with the specificity of the descriptor. The scope of correlation analysis was extended beyond MnO2 to include literature data on aromatic amine oxidation by other environmentally relevant oxidants (ozone, chlorine dioxide, and phosphate and carbonate radicals) by correlating relative rate constants (normalized to 4-chloroaniline) to EHOMO (calculated with a modest level of theory).

N-2-Hydroxy-4-methoxyacetophenone- N'-4-nitrobenzoyl hydrazine: Synthesis and structural characterization

NASA Astrophysics Data System (ADS)

Bessy Raj, B. N.; Kurup, M. R. Prathapachandra

2007-04-01

A new aroyl hydrazone, N-2-hydroxy-4-methoxyacetophenone- N'-4-nitrobenzoyl hydrazine was prepared by the condensation reaction of 2-hydroxy-4-methoxyacetophenone and 4-nitrobenzoyl hydrazine. Characterization of the compound was done by elemental analysis and electronic, infrared and NMR spectral analyses. The complete structural assignment of the compound was done by NMR studies by using COSY homonuclear and HSQC heteronuclear techniques. The crystal and molecular structure was determined by single crystal X-ray diffraction studies: crystallized in the monoclinic system, space group P2 1/ n, Z = 4, a = 7.3343(9) Å, b = 20.3517(9) Å, c = 10.1375(5) Å, α = 90.00°, β = 95.735(7)° and γ = 90.00°. From the crystal structure, it is concluded that the compound exists as the keto isomer in the solid state. There is a completely extended conformation in the central part of the molecule C5 sbnd C8 dbnd N1 sbnd N2 sbnd C10 dbnd O2 with an E configuration at the double bond of the hydrazinic bridge.

Synthesis of 7-hydroxy-4'-methoxyflavanone and 7-hydroxy-4'-methoxyflavone as a candidate anticancer against cervical (HeLa) cancer cell and colon (WiDr) cancer cell by in vitro

NASA Astrophysics Data System (ADS)

Matsjeh, Sabirin; Anwar, Chairil; Solikhah, Eti Nurwening; Farah, Harra Ismi; Nurfitria, Kurnia

2017-03-01

The compound 7-hydroxy-4'-methoxyflavanone and 7-hydroxy-4'-methoxyflavone have been synthesized through cyclization reaction of 2 ', 4'-dihydroxy-4-methoxychalcone (1,3-diphenyl-2-propene-1-one). The 2 ', 4'-dihydroxy-4-methoxychalcone were synthesized through Claisen-Schmidt condensation from 2,4-dihydroxyacetophenone and 4-methoxybenzaldehyde (anisaldehyde) in aqueous KOH as a catalyst in ethanol. The 7-hydroxy-4'-methoxyflavanone has been synthesized through cyclization reaction of 2 ', 4'-dihydroxy-4-methoxychalcone by Oxa-Michael addition reaction with sulfuric acid as a catalyst in ethanol. The 7-hydroxy-4'-methoxyflavone has been synthesized through oxidative cyclization reaction of 2 ', 4'-dihydroxy-4-methoxychalcone using I2 in DMSO as a catalyst with a mole ratio (1: 1) mol. All these producets were characterized by FT-IR, GC-MS, and 1H-NMR and 13C-NMR spectrometer. Both of these compounds were tested citotoxycity activity as an anticancer against cervical and colon cancer cells (HeLa and WiDr cell lines) using MTT assay in vitro. Dose series given test solution concentration on HeLa and WiDr cells starting from 0,78; 1,56; 3,12; 6,25; 12,50; 25; 50 and 100 µg/mL with a long incubation treatment for 24 hours. The results study showed that the 7-hydroxy-4'-methoxyflavanone as bright yellow crystals with a melting point 172-174 ° C and a yield of 56.67% and the 7-hydroxy-4'-methoxyflavone as bright yellow crystals with a yield of 88, 31%, and a melting point of 263-265 ° C. The test results cytotoxic 7-hydroxy-4-methoxyflavone showed active against HeLa cells with IC50 value of 25.73 µg/mL and was quite active in the WiDr cells with IC50 value of 83.75 µg/mL. The result of the activity of 7-hydroxy-4-methoxyflavanone show active cytotoxic activity against HeLa and WiDr cell growth with IC50 value of 40.13 µg/mL and 37.85 µg/mL. IC50 value indicated that 7-hydroxy-4'-methoxyflavone and 7-hydroxy-4'-methoxyflavanone potential as inhibitors in HeLa and

The Toluene o-Xylene Monooxygenase Enzymatic Activity for the Biosynthesis of Aromatic Antioxidants

PubMed Central

Pizzo, Elio; Notomista, Eugenio; Pezzella, Alessandro; Di Cristo, Carlo; De Lise, Federica; Di Donato, Alberto; Izzo, Viviana

2015-01-01

Monocyclic phenols and catechols are important antioxidant compounds for the food and pharmaceutic industries; their production through biotransformation of low-added value starting compounds is of major biotechnological interest. The toluene o-xylene monooxygenase (ToMO) from Pseudomonas sp. OX1 is a bacterial multicomponent monooxygenase (BMM) that is able to hydroxylate a wide array of aromatic compounds and has already proven to be a versatile biochemical tool to produce mono- and dihydroxylated derivatives of aromatic compounds. The molecular determinants of its regioselectivity and substrate specificity have been thoroughly investigated, and a computational strategy has been developed which allows designing mutants able to hydroxylate non-natural substrates of this enzyme to obtain high-added value compounds of commercial interest. In this work, we have investigated the use of recombinant ToMO, expressed in cells of Escherichia coli strain JM109, for the biotransformation of non-natural substrates of this enzyme such as 2-phenoxyethanol, phthalan and 2-indanol to produce six hydroxylated derivatives. The hydroxylated products obtained were identified, isolated and their antioxidant potential was assessed both in vitro, using the DPPH assay, and on the rat cardiomyoblast cell line H9c2. Incubation of H9c2 cells with the hydroxylated compounds obtained from ToMO-catalyzed biotransformation induced a differential protective effect towards a mild oxidative stress induced by the presence of sodium arsenite. The results obtained confirm once again the versatility of the ToMO system for oxyfunctionalization reactions of biotechnological importance. Moreover, the hydroxylated derivatives obtained possess an interesting antioxidant potential that encourages the use of the enzyme for further functionalization reactions and their possible use as scaffolds to design novel bioactive molecules. PMID:25915063

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

New series of aromatic/ five-membered heteroaromatic butanesulfonyl hydrazones as potent biological agents: Synthesis, physicochemical and electronic properties

NASA Astrophysics Data System (ADS)

Hamurcu, Fatma; Mamaş, Serhat; Ozdemir, Ummuhan Ozmen; Gündüzalp, Ayla Balaban; Senturk, Ozan Sanlı

2016-08-01

The aromatic/five-membered heteroaromatic butanesulfonylhydrazone derivatives; 5-bromosalicylaldehydebutanesulfonylhydrazone(1), 2-hydroxy-1-naphthaldehydebutane sulfonylhydrazone(2), indole-3-carboxaldehydebutanesulfonylhydrazone (3), 2-acetylfuran- carboxyaldehydebutanesulfonylhydrazone(4), 2-acetylthiophenecarboxyaldehydebutane- sulfonylhydrazone(5) and 2-acetyl-5-chlorothiophenecarboxyaldehydebutanesulfonyl hydrazone (6) were synthesized by the reaction of butane sulfonic acid hydrazide with aldehydes/ketones and characterized by using elemental analysis, 1H NMR, 13C NMR and FT-IR technique. Their geometric parameters and electronic properties consist of global reactivity descriptors were also determined by theoretical methods. The electrochemical behavior of the butanesulfonylhydrazones were investigated by using cyclic voltammetry (CV), controlled potential electrolysis and chronoamperometry (CA) techniques. The number of electrons transferred (n), diffusion coefficient (D) and standard heterogeneous rate constants (ks) were determined by electrochemical methods.

Paradoxical post-exercise responses of acylated ghrelin and leptin during a simulated night shift.

PubMed

Morris, Christopher J; Fullick, Sarah; Gregson, Warren; Clarke, Neil; Doran, Dominic; MacLaren, Don; Atkinson, Greg

2010-05-01

Approximately 10% of employees undertake night work, which is a significant predictor of weight gain, possibly because responses to activity and eating are altered at night. It is known that the appetite-related hormone, acylated ghrelin, is suppressed after an acute bout of exercise during the day, but no researcher has explored whether evening exercise alters acylated ghrelin and other appetite-related outcomes during a subsequent night shift. Six healthy men (mean +/- SD: age 30 +/- 8 yrs, body mass index 23.1 +/- 1.1 kg/m(2)) completed two crossover trials (control and exercise) in random order. Participants fasted from 10:00 h, consumed a test meal at 18:00 h, and then cycled at 50% peak oxygen uptake or rested between 19:00-20:00 h. Participants then completed light activities during a simulated night shift which ended at 05:00 h. Two small isocaloric meals were consumed at 22:00 and 02:00 h. Venous blood samples were drawn via cannulation at 1 h intervals between 19:00-05:00 h for the determination of acylated ghrelin, leptin, insulin, glucose, triglyceride, and non-esterified fatty acids concentrations. Perceived hunger and wrist actimetry were also recorded. During the simulated night shift, mean +/- SD acylated ghrelin concentration was 86.5 +/- 40.8 pg/ml following exercise compared with 71.7 +/- 37.7 pg/ml without prior exercise (p = 0.015). Throughout the night shift, leptin concentration was 263 +/- 242 pg/ml following exercise compared with 187 +/- 221 pg/ml without prior exercise (p = 0.017). Mean levels of insulin, triglyceride, non-esterified fatty acids, and wrist actimetry level were also higher during the night shift that followed exercise (p < 0.05). These data indicate that prior exercise increases acylated ghrelin and leptin concentrations during a subsequent simulated night shift. These findings differ from the known effects of exercise on acylated ghrelin and leptin during the day, and therefore have implications for energy balance during

Paradoxical post-exercise responses of acylated ghrelin and leptin during a simulated night-shift

PubMed Central

Morris, Chris; Fullick, Sarah; Gregson, Warren; Clarke, Neil; Doran, Dominic; MacLaren, Don; Atkinson, Greg

2009-01-01

Approximately 10% of employees undertake night-work which is a significant predictor of weight-gain, possibly because responses to activity and eating are altered at night. It is known that the appetite-related hormone, acylated ghrelin is suppressed after an acute bout of exercise during the day, but no researcher has explored whether evening exercise alters acylated ghrelin and other appetite-related outcomes during a subsequent night-shift. Six healthy men (mean±SD: age 30±8 yrs, body mass index 23.1±1.1 kg/m2) completed two crossover trials (control and exercise) in a random order. Participants fasted from 10:00 h, consumed a test meal at 18:00 h and then cycled at 50% peak oxygen uptake or rested between 19:00-20:00 h. Participants then completed light activities during a simulated night-shift which ended at 05:00 h. Two small isocaloric meals were consumed at 22:00 and 02:00 h. Venous blood samples were drawn via cannulation at 1-h intervals between 19:00-05:00 h for the determination of acylated ghrelin, leptin, insulin, glucose, triglyceride and non-esterified fatty acids concentrations. Perceived hunger and wrist actimetry were also recorded. During the night-shift, mean±SD acylated ghrelin concentration was 86.5±40.8 pg/ml following exercise compared with 71.7±37.7 pg/ml without prior exercise (P=0.015). Throughout the night-shift, leptin concentration was 263±242 pg/ml following exercise compared with 187±221 pg/ml without prior exercise (P=0.017). Mean levels of insulin, triglyceride, non-esterified fatty acids and wrist actimetry were also higher during the night-shift that followed exercise (P<0.05). These data indicate that prior exercise increases acylated ghrelin and leptin concentrations during a subsequent simulated night-shift. These findings differ from the known effects of exercise on acylated ghrelin and leptin during the day, and therefore have implications for energy balance during night-work. PMID:20524803

Impact of fatty acyl composition and quantity of triglycerides on bioaccessibility of dietary carotenoids.

PubMed

Huo, Tianyao; Ferruzzi, Mario G; Schwartz, Steven J; Failla, Mark L

2007-10-31

A carotenoid-rich salad meal with varying amounts and types of triglycerides (TG) was digested using simulated gastric and small intestinal conditions. Xanthophylls (lutein and zeaxanthin) and carotenes (alpha-carotene, beta-carotene, and lycopene) in chyme and micelle fraction were quantified to determine digestive stability and efficiency of micellarization (bioaccessibility). Micellarization of lutein (+zeaxanthin) exceeded that of alpha- and beta-carotenes, which was greater than that of lycopene for all test conditions. Micellarization of carotenes, but not lutein (+zeaxanthin), was enhanced (P < 0.05) by addition of TG (2.5% v/w) to the meal and was dependent on fatty acyl chain length in structured TG (c18:1 > c8:0 > c4:0). The degree of unsaturation of c18 fatty acyl chains in TG added to the salad purée did not significantly alter the efficiency of micellarization of carotenoids. Relatively low amounts of triolein and canola oil (0.5-1%) were required for maximum micellarization of carotenes, but more oil (approximately 2.5%) was required when TG with medium chain saturated fatty acyl groups (e.g., trioctanoin and coconut oil) was added to the salad. Uptake of lutein and beta-carotene by Caco-2 cells also was examined by exposing cells to micelles generated during the simulated digestion of salad purée with either triolein or trioctanoin. Cell accumulation of beta-carotene was independent of fatty acyl composition of micelles, whereas lutein uptake was slightly, but significantly, increased from samples with digested triolein compared to trioctanoin. The results show that the in vitro transfer of alpha-carotene, beta-carotene, and lycopene from chyme to mixed micelles during digestion requires minimal (0.5-1%) lipid content in the meal and is affected by the length of fatty acyl chains but not the degree of unsaturation in TG. In contrast, fatty acyl chain length has limited if any impact on carotenoid uptake by small intestinal epithelial cells. These

Biodegradation of high-molecular-weight polycyclic aromatic hydrocarbons under anaerobic conditions: Overview of studies, proposed pathways and future perspectives.

PubMed

Nzila, Alexis

2018-05-07

The biodegradation of low- and high-molecular-weight polycyclic aromatic hydrocarbons (PAHs) (LWM-PAHs and HMW-PAHs, respectively) has been studied extensively under aerobic conditions. Molecular O 2 plays 2 critical roles in this biodegradation process. O 2 activates the aromatic rings through hydroxylation prior to ring opening and serves as a terminal electron acceptor (TEA). However, several microorganisms have devised ways of activating aromatic rings, leading to ring opening (and thus biodegradation) when TEAs other than O 2 are used (under anoxic conditions). These microorganisms belong to the sulfate-, nitrate-, and metal-ion-reducing bacteria and the methanogens. Although the anaerobic biodegradation of monocyclic aromatic hydrocarbons and LWM-PAH naphthalene have been studied, little information is available about the biodegradation of HMW-PAHs. This manuscript reviews studies of the anaerobic biodegradation of HMW-PAHs and identifies gaps that limit both our understanding and the efficiency of this biodegradation process. Strategies that can be employed to overcome these limitations are also discussed. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

MedlinePlus

... Orphanet: Short chain acyl-CoA dehydrogenase deficiency Screening, Technology and Research in Genetics Patient Support and Advocacy Resources (5 links) Children Living with Inherited Metabolic Disease (CLIMB) Children's Mitochondrial ...

40 CFR 721.10193 - 1-Butanaminium, N-(3-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts.

Code of Federal Regulations, 2011 CFR

2011-07-01

...-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts. 721.10193 Section 721.10193 Protection of...-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts. (a) Chemical substance and...-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts (PMN P-06-263, Chemical B; CAS No...

40 CFR 721.10174 - 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts.

Code of Federal Regulations, 2011 CFR

2011-07-01

...-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. 721.10174 Section 721.10174 Protection of...-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. (a) Chemical substance...-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts (PMN P-04-139...

Detection of 1-O-malylglucose: pelargonidin 3-O-glucose-6''-O-malyltransferase activity in carnation (Dianthus caryophyllus).

PubMed

Abe, Yutaka; Tera, Masayuki; Sasaki, Nobuhiro; Okamura, Masachika; Umemoto, Naoyuki; Momose, Masaki; Kawahara, Nobuo; Kamakura, Hiroyuki; Goda, Yukihiro; Nagasawa, Kazuo; Ozeki, Yoshihiro

2008-09-05

Carnations have anthocyanins acylated with malate. Although anthocyanin acyltransferases have been reported in several plant species, anthocyanin malyltransferase (AMalT) activity in carnation has not been identified. Here, an acyl donor substance of AMalT, 1-O-beta-D-malylglucose, was extracted and partially purified from the petals of carnation. This was synthesized chemically to analyze AMalT activity in a crude extract from carnation. Changes in the AMalT activity showed close correlation to the accumulation of pelargonidin 3-malylglucoside (Pel 3-malGlc) during the development of red petals of carnation, but neither AMalT activity nor Pel 3-malGlc accumulation was detectable in roots, stems and leaves.

Novel endogenous N-acyl amides activate TRPV1-4 receptors, BV-2 microglia, and are regulated in brain in an acute model of inflammation

PubMed Central

Raboune, Siham; Stuart, Jordyn M.; Leishman, Emma; Takacs, Sara M.; Rhodes, Brandon; Basnet, Arjun; Jameyfield, Evan; McHugh, Douglas; Widlanski, Theodore; Bradshaw, Heather B.

2014-01-01

A family of endogenous lipids, structurally analogous to the endogenous cannabinoid, N-arachidonoyl ethanolamine (Anandamide), and called N-acyl amides have emerged as a family of biologically active compounds at TRP receptors. N-acyl amides are constructed from an acyl group and an amine via an amide bond. This same structure can be modified by changing either the fatty acid or the amide to form potentially hundreds of lipids. More than 70 N-acyl amides have been identified in nature. We have ongoing studies aimed at isolating and characterizing additional members of the family of N-acyl amides in both central and peripheral tissues in mammalian systems. Here, using a unique in-house library of over 70 N-acyl amides we tested the following three hypotheses: (1) Additional N-acyl amides will have activity at TRPV1-4, (2) Acute peripheral injury will drive changes in CNS levels of N-acyl amides, and (3) N-acyl amides will regulate calcium in CNS-derived microglia. Through these studies, we have identified 20 novel N-acyl amides that collectively activate (stimulating or inhibiting) TRPV1-4. Using lipid extraction and HPLC coupled to tandem mass spectrometry we showed that levels of at least 10 of these N-acyl amides that activate TRPVs are regulated in brain after intraplantar carrageenan injection. We then screened the BV2 microglial cell line for activity with this N-acyl amide library and found overlap with TRPV receptor activity as well as additional activators of calcium mobilization from these lipids. Together these data provide new insight into the family of N-acyl amides and their roles as signaling molecules at ion channels, in microglia, and in the brain in the context of inflammation. PMID:25136293

C-H carbonylation: In situ acyl triflates ace it

NASA Astrophysics Data System (ADS)

Lee, Yong Ho; Morandi, Bill

2018-02-01

A simple palladium catalyst has mediated the facile formation of aroyl triflates -- an extremely reactive class of electrophiles. These intermediates, generated in situ, enable the Friedel-Crafts acylation of traditionally unreactive arenes, addressing a significant gap in C-H carbonylation methodology.

The orexigenic hormone acyl-ghrelin increases adult hippocampal neurogenesis and enhances pattern separation

PubMed Central

Kent, Brianne A.; Beynon, Amy L.; Hornsby, Amanda K.E.; Bekinschtein, Pedro; Bussey, Timothy J.; Davies, Jeffrey S.; Saksida, Lisa M.

2015-01-01

Summary An important link exists between intact metabolic processes and normal cognitive functioning; however, the underlying mechanisms remain unknown. There is accumulating evidence that the gut hormone ghrelin, an orexigenic peptide that is elevated during calorie restriction (CR) and known primarily for stimulating growth hormone release, has important extra-hypothalamic functions, such as enhancing synaptic plasticity and hippocampal neurogenesis. The present study was designed to evaluate the long-term effects of elevating acyl-ghrelin levels, albeit within the physiological range, on the number of new adult born neurons in the dentate gyrus (DG) and performance on the Spontaneous Location Recognition (SLR) task, previously shown to be DG-dependent and sensitive to manipulations of plasticity mechanisms and cell proliferation. The results revealed that peripheral treatment of rats with acyl-ghrelin enhanced both adult hippocampal neurogenesis and performance on SLR when measured 8–10 days after the end of acyl-ghrelin treatment. Our data show that systemic administration of physiological levels of acyl-ghrelin can produce long-lasting improvements in spatial memory that persist following the end of treatment. As ghrelin is potentially involved in regulating the relationship between metabolic and cognitive dysfunction in ageing and neurodegenerative disease, elucidating the underlying mechanisms holds promise for identifying novel therapeutic targets and modifiable lifestyle factors that may have beneficial effects on the brain. PMID:25462915

Effect of chitosan, O-carboxymethyl chitosan, and N-[(2-hydroxy-3-N,N-dimethylhexadecyl ammonium)propyl] chitosan chloride on overweight and insulin resistance in a murine diet-induced obesity.

PubMed

Liu, Xiaofei; Zhi, Xiaona; Liu, Yunfei; Wu, Bo; Sun, Zhong; Shen, Jun

2012-04-04

Two water-soluble chitosan derivatives, O-carboxymethyl chitosan (O-CM-chitosan) and N-[(2-hydroxy-3-N,N-dimethylhexadecyl ammonium)propyl] chitosan chloride (N-CQ-chitosan), were prepared, and the therapeutic effects of chitosan, O-CM-chitosan, and N-CQ-chitosan on insulin resistance were simultaneously evaluated by rats fed on a high-fat diet. The parameters of high-fat diet-induced rats indicated that chitosan and its two derivatives not only have low cytotoxicity but can control overnutrition by fat and achieve insulin resistance therapy. However, the results in experiment in vivo showed that the therapeutic degree varied by the molecular weight and surface charge of chitosan, O-CM-chitosan, and N-CQ-chitosan. N-CQ-chitosan with a MW of 5 × 10(4) decreased body weight, the ratio of fat to body weight, triglyceride, fasting plasma glucose, fasting plasma insulin, free fatty acid, and leptin by 11, 17, 44, 46, 44, 87, and 64% and increased fecal lipid by 95%, respectively.

Carbon-carbon bond cleavage of 1,2-hydroxy ethers b7 vanadium(V) dipicolinate complexes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanson, Susan K; Gordon, John C; Thorn, David L

2009-01-01

The development of alternatives to current petroleum-based fuels and chemicals is becoming increasingly important due to concerns over climate change, growing world energy demand, and energy security issues. Using non-food derived biomass to produce renewable feedstocks for chemicals and fuels is a particularly attractive possibility. However, the majority of biomass is in the form of lignocellulose, which is often not fully utilized due to difficulties associated with breaking down both lignin and cellulose. Recently, a number of methods have been reported to transform cellulose directly into more valuable materials such as glucose, sorbitol, 5-(chloromethyl)furfural, and ethylene glycol. Less progress hasmore » been made with selective transformations of lignin, which is typically treated in paper and forest industries by kraft pulping (sodium hydroxide/sodium sulfide) or incineration. Our group has begun investigating aerobic oxidative C-C bond cleavage catalyzed by dipicolinate vanadium complexes, with the idea that a selective C-C cleavage reaction of this type could be used to produce valuable chemicals or intermediates from cellulose or lignin. Lignin is a randomized polymer containing methoxylated phenoxy propanol units. A number of different linkages occur naturally; one of the most prevalent is the {beta}-O-4 linkage shown in Figure 1, containing a C-C bond with 1,2-hydroxy ether substituents. While the oxidative C-C bond cleavage of 1,2-diols has been reported for a number of metals, including vanadium, iron, manganese, ruthenium, and polyoxometalate complexes, C-C bond cleavage of 1,2-hydroxy ethers is much less common. We report herein vanadium-mediated cleavage of C-C bonds between alcohol and ether functionalities in several lignin model complexes. In order to explore the scope and potential of vanadium complexes to effect oxidative C-C bond cleavage in 1,2-hydroxy ethers, we examined the reactivity of the lignin model complexes pinacol monomethyl

Structural and Functional Studies of Fatty Acyl Adenylate Ligases from E. coli and L. pneumophila

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Z.; Swaminathan, S.; Zhou, R.

2011-02-18

Fatty acyl-AMP ligase (FAAL) is a new member of a family of adenylate-forming enzymes that were recently discovered in Mycobacterium tuberculosis. They are similar in sequence to fatty acyl-coenzyme A (CoA) ligases (FACLs). However, while FACLs perform a two-step catalytic reaction, AMP ligation followed by CoA ligation using ATP and CoA as cofactors, FAALs produce only the acyl adenylate and are unable to perform the second step. We report X-ray crystal structures of full-length FAAL from Escherichia coli (EcFAAL) and FAAL from Legionella pneumophila (LpFAAL) bound to acyl adenylate, determined at resolution limits of 3.0 and 1.85 {angstrom}, respectively. Themore » structures share a larger N-terminal domain and a smaller C-terminal domain, which together resemble the previously determined structures of FAAL and FACL proteins. Our two structures occur in quite different conformations. EcFAAL adopts the adenylate-forming conformation typical of FACLs, whereas LpFAAL exhibits a unique intermediate conformation. Both EcFAAL and LpFAAL have insertion motifs that distinguish them from the FACLs. Structures of EcFAAL and LpFAAL reveal detailed interactions between this insertion motif and the interdomain hinge region and with the C-terminal domain. We suggest that the insertion motifs support sufficient interdomain motions to allow substrate binding and product release during acyl adenylate formation, but they preclude CoA binding, thereby preventing CoA ligation.« less

Structural and Functional Studies of Fatty Acyl Adenylate Ligases from E. coli and L. pneumophila

DOE Office of Scientific and Technical Information (OSTI.GOV)

Z Zhang; R Zhou; J Sauder

2011-12-31

Fatty acyl-AMP ligase (FAAL) is a new member of a family of adenylate-forming enzymes that were recently discovered in Mycobacterium tuberculosis. They are similar in sequence to fatty acyl-coenzyme A (CoA) ligases (FACLs). However, while FACLs perform a two-step catalytic reaction, AMP ligation followed by CoA ligation using ATP and CoA as cofactors, FAALs produce only the acyl adenylate and are unable to perform the second step. We report X-ray crystal structures of full-length FAAL from Escherichia coli (EcFAAL) and FAAL from Legionella pneumophila (LpFAAL) bound to acyl adenylate, determined at resolution limits of 3.0 and 1.85 {angstrom}, respectively. Themore » structures share a larger N-terminal domain and a smaller C-terminal domain, which together resemble the previously determined structures of FAAL and FACL proteins. Our two structures occur in quite different conformations. EcFAAL adopts the adenylate-forming conformation typical of FACLs, whereas LpFAAL exhibits a unique intermediate conformation. Both EcFAAL and LpFAAL have insertion motifs that distinguish them from the FACLs. Structures of EcFAAL and LpFAAL reveal detailed interactions between this insertion motif and the interdomain hinge region and with the C-terminal domain. We suggest that the insertion motifs support sufficient interdomain motions to allow substrate binding and product release during acyl adenylate formation, but they preclude CoA binding, thereby preventing CoA ligation.« less

Expression of Cyanobacterial Acyl-ACP Reductase Elevates the Triacylglycerol Level in the Red Alga Cyanidioschyzon merolae.

PubMed

Sumiya, Nobuko; Kawase, Yasuko; Hayakawa, Jumpei; Matsuda, Mami; Nakamura, Mami; Era, Atsuko; Tanaka, Kan; Kondo, Akihiko; Hasunuma, Tomohisa; Imamura, Sousuke; Miyagishima, Shin-ya

2015-10-01

Nitrogen starvation is known to induce the accumulation of triacylglycerol (TAG) in many microalgae, and potential use of microalgae as a source of biofuel has been explored. However, nitrogen starvation also stops cellular growth. The expression of cyanobacterial acyl-acyl carrier protein (ACP) reductase in the unicellular red alga Cyanidioschyzon merolae chloroplasts resulted in an accumulation of TAG, which led to an increase in the number and size of lipid droplets while maintaining cellular growth. Transcriptome and metabolome analyses showed that the expression of acyl-ACP reductase altered the activities of several metabolic pathways. The activities of enzymes involved in fatty acid synthesis in chloroplasts, such as acetyl-CoA carboxylase and pyruvate dehydrogenase, were up-regulated, while pyruvate decarboxylation in mitochondria and the subsequent consumption of acetyl-CoA by the tricarboxylic acid (TCA) cycle were down-regulated. Aldehyde dehydrogenase, which oxidizes fatty aldehydes to fatty acids, was also up-regulated in the acyl-ACP reductase expresser. This activation was required for the lipid droplet accumulation and metabolic changes observed in the acyl-ACP reductase expresser. Nitrogen starvation also resulted in lipid droplet accumulation in C. merolae, while cell growth ceased as in the case of other algal species. The metabolic changes that occur upon the expression of acyl-ACP reductase are quite different from those caused by nitrogen starvation. Therefore, there should be a method for further increasing the storage lipid level while still maintaining cell growth that is different from the metabolic response to nitrogen starvation. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Solid state synthesis, structural, physicochemical and optical properties of an inter-molecular compound: 2-hydroxy-1, 2-diphenylethanone-4-nitro-o-phenylenediamine system

NASA Astrophysics Data System (ADS)

Rai, U. S.; Singh, Manjeet; Rai, R. N.

2017-09-01

The phase diagram of 2-hydroxy-1, 2-diphenylethanone (HDPE)-4-nitro-o-phenylenediamine (NOPDA) system, determined by the thaw-melt method, gives two eutectics E1 (m p = 66.0 °C) and E2 (m p = 155.0 °C) with 0.30 and 0.55 mol fractions of NOPDA, respectively, and an 1:1 inter-molecular compound (IMC) (m p 162.0 °C). This IMC was synthesized by adopting the green synthetic method of solid state reaction. While its formation and structure were confirmed by the X-ray diffraction and spectroscopic methods, the ORTEP view gives mode of crystal packing, C‒H…O, C‒H…N, π-π stacking and the inter-molecular hydrogen bonding in the compound. The single crystal of the IMC shows 53% transmission and emits significantly higher dual fluorescence, and the band gap was computed to be 3.04 eV. The values of solubility of the IMC, measured in the temperature range 304-322 K, satisfy the mole fraction (X) and temperature equation: Xeq= 5.1324 × 10-7 e 0.01356T.

Knockout of the regulatory site of 3-ketoacyl-ACP synthase III enhances short- and medium-chain acyl-ACP synthesis.

PubMed

Abbadi, A; Brummel, M; Spener, F

2000-10-01

3-ketoacyl-acyl carrier protein synthase (KAS) III catalyses the first condensing step of the fatty acid synthase (FAS) type II reaction in plants and bacteria, using acetyl CoA and malonyl-acyl carrier protein (ACP) as substrates. Enzymatic characterization of recombinant KAS III from Cuphea wrightii embryo shows that this enzyme is strongly inhibited by medium-chain acyl-ACP end products of the FAS reaction, i.e. inhibition by lauroyl-ACP was uncompetitive towards acetyl CoA and non-competitive with regard to malonyl-ACP. This indicated a distinct attachment site for regulatory acyl-ACPs. Based on alignment of primary structures of various KAS IIIs and 3-ketoacyl CoA synthases, we suspected the motif G290NTSAAS296 to be responsible for binding of regulatory acyl-ACPs. Deletion of the tetrapeptide G290NTS293 led to a change of secondary structure and complete loss of KAS III condensing activity. Exchange of asparagine291 to aspartate, alanine294 to serine and alanine295 to proline, however, produced mutant enzymes with slightly reduced condensing activity, yet with insensitivity towards acyl-ACPs. To assess the potential of unregulated KAS III as tool in oil production, we designed in vitro experiments employing FAS preparations from medium-chain fatty acid-producing Cuphea lanceolata seeds and long-chain fatty acid-producing rape seeds, each supplemented with a fivefold excess of the N291D KAS III mutant. High amounts of short-chain acyl-ACPs in the case of C. lanceolata, and of medium-chain acyl-ACPs in the case of rape seed preparations, were obtained. This approach targets regulation and offers new possibilities to derive transgenic or non-transgenic plants for production of seed oils with new qualities.

Acyl Coenzyme A Thioesterase 7 Regulates Neuronal Fatty Acid Metabolism To Prevent Neurotoxicity

PubMed Central

Ellis, Jessica M.; Wong, G. William

2013-01-01

Numerous neurological diseases are associated with dysregulated lipid metabolism; however, the basic metabolic control of fatty acid metabolism in neurons remains enigmatic. Here we have shown that neurons have abundant expression and activity of the long-chain cytoplasmic acyl coenzyme A (acyl-CoA) thioesterase 7 (ACOT7) to regulate lipid retention and metabolism. Unbiased and targeted metabolomic analysis of fasted mice with a conditional knockout of ACOT7 in the nervous system, Acot7N−/−, revealed increased fatty acid flux into multiple long-chain acyl-CoA-dependent pathways. The alterations in brain fatty acid metabolism were concomitant with a loss of lean mass, hypermetabolism, hepatic steatosis, dyslipidemia, and behavioral hyperexcitability in Acot7N−/− mice. These failures in adaptive energy metabolism are common in neurodegenerative diseases. In agreement, Acot7N−/− mice exhibit neurological dysfunction and neurodegeneration. These data show that ACOT7 counterregulates fatty acid metabolism in neurons and protects against neurotoxicity. PMID:23459938

Acyl coenzyme A thioesterase 7 regulates neuronal fatty acid metabolism to prevent neurotoxicity.

PubMed

Ellis, Jessica M; Wong, G William; Wolfgang, Michael J

2013-05-01

Numerous neurological diseases are associated with dysregulated lipid metabolism; however, the basic metabolic control of fatty acid metabolism in neurons remains enigmatic. Here we have shown that neurons have abundant expression and activity of the long-chain cytoplasmic acyl coenzyme A (acyl-CoA) thioesterase 7 (ACOT7) to regulate lipid retention and metabolism. Unbiased and targeted metabolomic analysis of fasted mice with a conditional knockout of ACOT7 in the nervous system, Acot7(N-/-), revealed increased fatty acid flux into multiple long-chain acyl-CoA-dependent pathways. The alterations in brain fatty acid metabolism were concomitant with a loss of lean mass, hypermetabolism, hepatic steatosis, dyslipidemia, and behavioral hyperexcitability in Acot7(N-/-) mice. These failures in adaptive energy metabolism are common in neurodegenerative diseases. In agreement, Acot7(N-/-) mice exhibit neurological dysfunction and neurodegeneration. These data show that ACOT7 counterregulates fatty acid metabolism in neurons and protects against neurotoxicity.

Effect of lanthanides on the aromatic system of benzoic acid

NASA Astrophysics Data System (ADS)

Lewandowski, Włlodzimierz

1983-08-01

The stucture of lanthanide complexes with benzoic acid was investigated by IR and UV absorption spectra. To determine the effect of metal coordination on the aromatic system of benzoic acid, IR spectra of Ln(OBz) 3 (Ln is a lanthanide except promethium; BzO is benzoic acid radical) were compared with ligand and sodium benzoate spectra. Also, changes in frequency and relative intensity of the ? bands in the 1600-1400 cm -1 region, were analyzed in terms of the atomic number of lanthanides. It is shown that lanthanides disturb the aromatic system of the benzoate ligand less than sodium. This effect is discussed in terms of the bonds formed.

Solubilization and partial purification of constituents of acyl-CoA elongase from Lunaria annua.

PubMed

Fehling, E; Lessire, R; Cassagne, C; Mukherjee, K D

1992-06-05

All the constituent enzymes of acyl-CoA elongase, i.e., beta-ketoacyl-CoA synthase, beta-ketoacyl-CoA reductase, beta-hydroxyacyl-CoA dehydrase and trans-2-enoyl-CoA reductase, have been solubilized from a 15,000 x g particulate fraction from developing seeds of honesty (Lunaria annua) using Triton X-100. All these activities were retained upon subsequent precipitation of the solubilized protein with polyethylene glycol and resuspension of the precipitate followed by ion exchange chromatography of the resulting protein on DEAE-cellulose. A 4.2-fold enrichment of the acyl-CoA elongase was thus obtained. Further chromatography of the DEAE fraction containing all the constituents of acyl-CoA elongase on Ultrogel yielded a major protein fraction exhibiting the activities of beta-ketoacyl-CoA synthase and beta-ketoacyl-CoA reductase only. Almost 30-fold purification of the beta-ketoacyl-CoA synthase was thus achieved. The beta-ketoacyl-CoA synthase was inhibited only at high concentrations of cerulenin, but at very low concentrations of iodoacetamide. Inhibition could be reduced by preincubation with thioesters, indicating that an enzyme thioester intermediate is involved in the condensation reaction of the acyl-CoA elongation.

Polyimidazoles via aromatic nucleophilic displacement

NASA Technical Reports Server (NTRS)

Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor)

1992-01-01

Polyimidazoles (PI) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl) imidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The reactions are carried out in polar aprotic solvents such as N,N-dimethyl acetamide, sulfolane, N-methylpyrrolidinone, dimethylsulfoxide, or diphenylsulfone using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. The di(hydroxyphenyl) imidazole monomers are prepared by reacting an aromatic aldehyde with a dimethoxybenzil or by reacting an aromatic dialdehyde with a methoxybenzil in the presence of ammonium acetate. The di(methoxyphenyl) imidazole is subsequently treated with aqueous hydrobromic acid to give the di(hydroxphenyl) imidazole monomer. This synthetic route has provided high molecular weight PI of new chemical structure, is economically and synthetically more favorable than other routes, and allows for facile chemical structure variation due to the availability of a large variety of activated aromatic dihalides and dinitro compounds.

Polyimidazoles via aromatic nucleophilic displacement

NASA Technical Reports Server (NTRS)

Hergenrother, Paul M. (Inventor); Connell, John W. (Inventor)

1991-01-01

Polyimidazoles (Pl) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl)imidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The reactions are carried out in polar aprotic solvents such as N,N-dimethylacetamide, sulfolane, N-methylpyrroldinone, dimethylsulfoxide, or diphenylsulfone using alkali metal bases such as potassium carbonate at elevated temperature under nitrogen. The di(hydroxyphenyl)imidazole monomers are prepared by reacting an aromatic aldehyde with a dimethoxybenzil or by reacting an aromatic dialdehyde with a methoxybenzil in the presence of ammonium acetate. The di(methoxyphenyl)imidazole is subsequently treated with aqueous hydrobromic acid to give the di(hydroxyphenyl)imidazole monomer. This synthetic route has provided high molecular weight Pl of new chemical structure, is economically and synthetically more favorable than other routes, and allows for facile chemical structure variation due to the availability of a large variety of activated aromatic dihalides and dinitro compounds.

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

S-Acylation of the cellulose synthase complex is essential for its plasma membrane localization.

PubMed

Kumar, Manoj; Wightman, Raymond; Atanassov, Ivan; Gupta, Anjali; Hurst, Charlotte H; Hemsley, Piers A; Turner, Simon

2016-07-08

Plant cellulose microfibrils are synthesized by a process that propels the cellulose synthase complex (CSC) through the plane of the plasma membrane. How interactions between membranes and the CSC are regulated is currently unknown. Here, we demonstrate that all catalytic subunits of the CSC, known as cellulose synthase A (CESA) proteins, are S-acylated. Analysis of Arabidopsis CESA7 reveals four cysteines in variable region 2 (VR2) and two cysteines at the carboxy terminus (CT) as S-acylation sites. Mutating both the VR2 and CT cysteines permits CSC assembly and trafficking to the Golgi but prevents localization to the plasma membrane. Estimates suggest that a single CSC contains more than 100 S-acyl groups, which greatly increase the hydrophobic nature of the CSC and likely influence its immediate membrane environment. Copyright © 2016, American Association for the Advancement of Science.

Role of methyl group number on SOA formation from monocyclic aromatic hydrocarbons photooxidation under low-NOx conditions

NASA Astrophysics Data System (ADS)

Li, L.; Tang, P.; Nakao, S.; Chen, C.-L.; Cocker, D. R., III

2016-02-01

Substitution of methyl groups onto the aromatic ring determines the secondary organic aerosol (SOA) formation from the monocyclic aromatic hydrocarbon precursor (SOA yield and chemical composition). This study links the number of methyl groups on the aromatic ring to SOA formation from monocyclic aromatic hydrocarbons photooxidation under low-NOx conditions (HC/NO > 10 ppbC : ppb). Monocyclic aromatic hydrocarbons with increasing numbers of methyl groups are systematically studied. SOA formation from pentamethylbenzene and hexamethylbenzene are reported for the first time. A decreasing SOA yield with increasing number of methyl groups is observed. Linear trends are found in both f44 vs. f43 and O / C vs. H / C for SOA from monocyclic aromatic hydrocarbons with zero to six methyl groups. An SOA oxidation state predictive method based on benzene is used to examine the effect of added methyl groups on aromatic oxidation under low-NOx conditions. Further, the impact of methyl group number on density and volatility of SOA from monocyclic aromatic hydrocarbons is explored. Finally, a mechanism for methyl group impact on SOA formation is suggested. Overall, this work suggests that, as more methyl groups are attached on the aromatic ring, SOA products from these monocyclic aromatic hydrocarbons become less oxidized per mass/carbon on the basis of SOA yield or chemical composition.

Structure-Activity Relationships for Rates of Aromatic Amine Oxidation by Manganese Dioxide

DOE PAGES

Salter-Blanc, Alexandra J.; Bylaska, Eric J.; Lyon, Molly A.; ...

2016-04-13

New energetic compounds are designed to minimize their potential environmental impacts, which includes their transformation and the fate and effects of their transformation products. The nitro groups of energetic compounds are readily reduced to amines, and the resulting aromatic amines are subject to oxidation and coupling reactions. Manganese dioxide (MnO 2) is a common environmental oxidant and model system for kinetic studies of aromatic amine oxidation. Here in this study, a training set of new and previously reported kinetic data for the oxidation of model and energetic-derived aromatic amines was assembled and subjected to correlation analysis against descriptor variables that ranged from general purpose [Hammettmore » $$\\sigma$$ constants ($$\\sigma^-$$), pK as of the amines, and energies of the highest occupied molecular orbital (E HOMO)] to specific for the likely rate-limiting step [one-electron oxidation potentials (E ox)]. The selection of calculated descriptors (pK a), E HOMO, and E ox) was based on validation with experimental data. All of the correlations gave satisfactory quantitative structure-activity relationships (QSARs), but they improved with the specificity of the descriptor. The scope of correlation analysis was extended beyond MnO 2 to include literature data on aromatic amine oxidation by other environmentally relevant oxidants (ozone, chlorine dioxide, and phosphate and carbonate radicals) by correlating relative rate constants (normalized to 4-chloroaniline) to E HOMO (calculated with a modest level of theory).« less

Structure-Activity Relationships for Rates of Aromatic Amine Oxidation by Manganese Dioxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salter-Blanc, Alexandra J.; Bylaska, Eric J.; Lyon, Molly A.

New energetic compounds are designed to minimize their potential environmental impacts, which includes their transformation and the fate and effects of their transformation products. The nitro groups of energetic compounds are readily reduced to amines, and the resulting aromatic amines are subject to oxidation and coupling reactions. Manganese dioxide (MnO 2) is a common environmental oxidant and model system for kinetic studies of aromatic amine oxidation. Here in this study, a training set of new and previously reported kinetic data for the oxidation of model and energetic-derived aromatic amines was assembled and subjected to correlation analysis against descriptor variables that ranged from general purpose [Hammettmore » $$\\sigma$$ constants ($$\\sigma^-$$), pK as of the amines, and energies of the highest occupied molecular orbital (E HOMO)] to specific for the likely rate-limiting step [one-electron oxidation potentials (E ox)]. The selection of calculated descriptors (pK a), E HOMO, and E ox) was based on validation with experimental data. All of the correlations gave satisfactory quantitative structure-activity relationships (QSARs), but they improved with the specificity of the descriptor. The scope of correlation analysis was extended beyond MnO 2 to include literature data on aromatic amine oxidation by other environmentally relevant oxidants (ozone, chlorine dioxide, and phosphate and carbonate radicals) by correlating relative rate constants (normalized to 4-chloroaniline) to E HOMO (calculated with a modest level of theory).« less

Aromatic as well as aliphatic hydrocarbon solvent axonopathy.

PubMed

Spencer, Peter S; Kim, Min Sun; Sabri, Mohammad I

2002-03-01

Superfund sites that contain mixtures of aromatic and aliphatic solvents represent an undefined health hazard. After prolonged exposure to relatively high levels of certain aliphatic solvents (e.g. n-hexane, 2-hexanone), humans and animals develop a dose-dependent neurodegeneration that occurs clinically as a symmetrical peripheral neuropathy. This is triggered by the action of 2,5-hexanedione (1,2-diacetylethane), a 1,4-diketone (gamma-diketone) metabolite that targets proteins required for the maintenance of neuronal (and testicular Sertoli cell) integrity. Certain aromatic solvents (1,2-diethylbenzene, 1,2,4-triethylbenzene) cause electrophysiological changes consistent with sensorimotor neuropathy in rodents, but the underlying mechanisms and pathogenesis are unclear. Our recent studies show that the o-diacetyl derivative and likely metabolite of 1,2-diethylbenzene, 1,2-diacetylbenzene, behaves as a neurotoxic (aromatic) gamma-diketone of high neurotoxic potency. Rats treated with 1,2-diacetylbenzene develop limb weakness associated with proximal, neurofilament-filled giant axonal swellings comparable to those seen in animals treated with the potent 3,4-dimethyl derivative of 2,5-hexanedione. The blue chromogen induced by treatment with 1,2-diacetylbenzene is under study as a possible urinary biomarker of exposure to aromatic solvents (e.g. 1,2-diethylbenzene, tetralin) with neurotoxic potential. Development and validation of sensitive new biomarkers, especially for non-cancer endpoints, will aid in assessing the health risk associated with exposure to hazardous substances at Superfund sites.

Plasma fatty acyl-carnitines during 8 weeks of overfeeding: relation to diet energy expenditure and body composition: the PROOF study.

PubMed

Bray, George A; Redman, Leanne M; de Jonge, Lilian; Rood, Jennifer; Sutton, Elizabeth F; Smith, Steven R

2018-06-01

Overfeeding is a strategy for evaluating the effects of excess energy intake. In this secondary analysis we tested the possibility that different levels of dietary protein might differentially modify the response of fatty acyl-carnitines to overfeeding. Twenty-three healthy adult men and women were overfed by 40% for 8 weeks while in-patients with diets containing 5% (LPD), 15% (NPD) or 25% (HPD) protein. Plasma fatty acyl-carnitines were measured by gas chromatography/mass spectrometry (GC/MS) at baseline and after 8 weeks of overfeeding. Measurements included: body composition by DXA, energy expenditure by ventilated hood and doubly-labeled water, fat cell size from subcutaneous fat biopsies, and fat distribution by CT scan. Analysis was done on 5 groups of fatty acyl-carnitines identified by principal components analysis and 6 individual short-chain fatty acyl carnitines. Higher protein intake was associated with significantly lower 8 week levels of medium chain fatty acids and C2, C4-OH and C 6:1, but higher values of C3 and C5:1 acyl-carnitines derived from essential amino acids. In contrast energy and fat intake were only weakly related to changes in fatty acyl-carnitines. A decease or smaller rise in 8 week medium chain acyl-carnitines was associated with an increase in sleeping energy expenditure (P = 0.0004), and fat free mass (P < 0.0001) and a decrease in free fatty acid concentrations (FFA) (P = 0.0067). In contrast changes in short-chain fatty acyl-carnitines were related to changes in resting energy expenditure (P = 0.0026), and fat free mass (P = 0.0007), and C4-OH was positively related to FFA (P = 0006). Protein intake was the major factor influencing changes in fatty acyl carnitines during overfeeding with higher values of most acyl-fatty acids on the low protein diet. The association of dietary protein and fat intake may explain the changes in energy expenditure and metabolic variables resulting in the observed

Amide-transforming activity of Streptomyces: possible application to the formation of hydroxy amides and aminoalcohols.

PubMed

Yamada, Shinya; Miyagawa, Taka-Aki; Yamada, Ren; Shiratori-Takano, Hatsumi; Sayo, Noboru; Saito, Takao; Takano, Hideaki; Beppu, Teruhiko; Ueda, Kenji