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PubMed1982

beta-Hydroxy fatty acid production by ischemic rabbit heart.

beta-Hydroxymyristate, -palmitate, and -stearate were produced by and accumulated in isolated rabbit heart when perfused ischemically for 2-10 min by the nonrecirculating langendorff technique with 0.75 mM palmitate and 0.16 mM albumin. Tissue fractionation into mitochondria and cytosol showed that by 2 min of ischemia 44% of beta-hydroxypalmitate and 38% beta-hydroxystearate was located in the cytosol; this percentage increased to greater than 50% by 5 min of ischemia. Lipid fractionation studies showed that by 10 min these two beta-hydroxy fatty acids were distributed approximately as 60% acylcarnitine, 20% acyl-coenzyme A (CoA), and 20% free fatty acids. All three chemical forms of beta-hydroxypalmitate were found in both the mitochondria and the cytosol. After 10 min of ischemia beta-hydroxypalmitoyl-CoA and beta-hydroxystearoyl-CoA constituted at least 16% of the incremental long-chain acyl-CoA, whereas beta-hydroxypalmitoylcarnitine and b-hydroxystearoylcarnitine constituted 8% of the incremental long-chain acylcarnitine. These data suggests that myocardial beta-hydroxyacyl-CoA oxidation is limited during ischemia. Substrate accumulates and is transferred to the cytosol where it accumulates primarily as beta-hydroxyacylcarnitine.

Animals↗

PubMed1998

Antitumor properties of boron complexes with hydroxy biguanide and salicyl hydroxamic acid against Ehrlich ascites carcinoma.

A new derivative of hydroxamic acid, hydroxy biguanido hydrochloride monohydrate and its boron derivative, dihydroxy-oxybiguanido boron (III) hydrochloride monohydrate were synthesized. Another boron compound, hydroxo-salicyl-hydroxamato boron (III) was synthesized from known salicyl hydroxamic acid. Antitumor properties of all the compounds evaluated against Ehrlich ascites carcinoma in mice show enhanced survival time when boron is incorporated in the compounds. Hematological parameters, alkaline phosphatase in serum of the treated animals show minimum toxic effects after boron is coupled with their respective hydroxamic acids.

Animals↗

PubMed1984

Vanillic acid, a metabolite of 4-hydroxy-3-methoxyphenylglycol and 4-hydroxy-3-methoxymandelic acid in man.

4-Hydroxy-3-methoxyphenylglycol (HMPG) labelled with 14C was used to study the metabolic fate of HMPG in six healthy volunteers. Besides conjugation and oxidation to 4-hydroxy-3-methoxymandelic acid (HMMA, VMA) a minor portion, 8.4 +/- 1.1% (mean +/- SEM) was excreted as 14C-labelled vanillic acid (VA). To study if VA was formed from HMPG or HMMA (VMA), deuterium-labelled HMPG [( 2H3]HMPG) and HMMA [( 2H6]HMMA) were simultaneously injected intravenously to seven healthy volunteers. The recovery of [2H3]VA from [2H3]HMPG was 8.3 +/- 2.1% and the recovery of [2H6]VA from [2H6]HMMA was 9.0 +/- 2.1%. The 2H-labelled VAs were probably formed by a decarboxylation reaction, in the case of HMPG after previous oxidation to HMMA.

Carbon Radioisotopes↗

PubMed1991

[Synthesis of small peptides containing hydroxy-amino-acid, and its effects on progesterone production].

Eleven peptides containing hydroxy-amino-acid have been synthesized manually by stepwise solid-phase method. Three of them were started on BHA-resin, the others on Merrifield-resin. TFMSA/TFA/p-cresol were used as cleaving reagent in all peptide-resin (1-11) cleavage. Furthermore, HF cleaving procedure was also used parallelly to five of those peptide-resins for contrast. No conspicuous difference in yield was found between TFMSA and HF. The purity of all products was checked by the profiles of analytical reversed phase HPLC (C-18) and the data of amino acid analysis. All synthetic peptides were tested for the effect on progesterone production by rat corpus luteum in vitro. Among them, three peptides, GlyTyr-NH2, LysTyr-NH2 and GlySer Lys-OH, showed significant effect (p less than 0.01) on inhibiting hCG-induced progesterone production.

Amino Acids↗

PubMed1995

Monitoring of lipoprotein oxidation by gas chromatographic analysis of hydroxy fatty acids.

We describe a method developed for the quantitative analysis of hydroxy fatty acids derived from fatty acid monohydroperoxides formed during lipoprotein oxidation. The procedure starts with catalytic hydrogenation of the lipid extract, whereby hydroperoxyl groups are converted to hydroxyl groups and double bonds are eliminated, and the risk for lipid oxidation during the rest of the procedure is eliminated. The fatty acids are converted to methyl esters, which are fractionated by gas chromatography on a nonpolar column. The major differences to existing methods are that a mass spectrometer is not required and that the specificity thus lost is replaced by gas chromatography before and after acetylation of the hydroxyl groups. This changes the retention times of the hydroxyacids with respect to the unsubstituted fatty acids moving them to positions usually occupied by trace components only. The method allows quantification of monohydroxy fatty acids derived from 18-, 20- and 22-carbon polyunsaturated fatty acids. Positional isomers are separated from each other to some extent. The method has been mainly used for analysis of hydroperoxides in human low density lipoprotein preparations and for following lipoprotein oxidation in vitro.

Acetylation↗

PubMed2003

Synthesis of erythro-alpha-amino beta-hydroxy carboxylic acid esters by diastereoselective photocycloaddition of 5-methoxyoxazoles with aldehydes.

A new photoaldol route to alpha-amino-beta-hydroxy carboxylic acid esters is initiated by the photocycloaddition of aromatic or aliphatic aldehydes to 5-methoxyoxazoles. The 4-unsubstituted 5-methyloxazole 1 gave the cycloadducts 8a-f in high yields and excellent exo-diastereoselectivities. Hydrolysis of 8a-f gives the N-acetyl alpha-amino-beta-hydroxy esters 9a-f, which could be subsequently converted into the corresponding Z-didehydro alpha-amino acids 10a-f. Quartenary alpha-amino-beta-hydroxy esters 12, 14, 16, 18, and 20, which are stable against dehydration, were obtained from the 4-alkylated 5-methoxyoxazoles 2-6, in most cases highly erythro-selective due to the high degree of stereocontrol (exo) at the photocycloaddition (to give 11, 13, 15, 17, and 19) level. The relative configurations of the N-acetyl alpha-amino-beta-hydroxy esters were determined by NMR spectroscopy and comparison with chiral pool-derived compounds as well as by X-ray structure determination of the ester 23, formed by hydrolysis of the cycloadduct 22, derived from photocycloaddition of propionaldehyde to the isoleucine-derived oxazole 21.

Aldehydes↗

PubMed1998

Enzyme analyses demonstrate that beta-methylbutyric acid is converted to beta-hydroxy-beta-methylbutyric acid via the leucine catabolic pathway by galactomyces reessii

Galactomyces reessii accomplishes the enzymatic transformation of beta-methylbutyric acid (isovaleric acid) to beta-hydroxy-beta-methylbutyric acid. The enzymatic basis for this bioconversion was evaluated by analyzing cell-free extracts of G. reessii for enzyme activities commonly associated with leucine catabolism. G. reessii extracts contained activities for acyl-CoA synthetase, acyl-CoA dehydrogenase, and enoyl-CoA hydratase, whereas beta-methylbutyric acid hydroxylase, alpha-ketoisocaproate oxygenase, and acyl-CoA oxidase (with isovaleryl-CoA as substrate) were not observed. Furthermore, beta-methylbutyric acid is initially activated to isovaleryl-CoA by acyl-CoA synthetase, dehydrogenated to methylcrotonyl-CoA by acyl-CoA dehydrogenase, hydrated to beta-hydroxy-beta-methylbutyric acid-CoA by enoyl-CoA hydratase, and hydrolyzed to beta-hydroxy-beta-methylbutyric acid in G. reessii extracts. Cell-free extracts converted both isovaleryl-CoA and methylcrotonyl-CoA into beta-hydroxy-beta-methylbutyric acid, thus demonstrating that beta-methylbutyric acid is part of the leucine catabolic pathway. The rate of beta-methylbutyric acid conversion to beta-hydroxy-beta-methylbutyric acid with cell-free extract was 0. 013 &mgr;mol beta-hydroxy-beta-methylbutyric acid (mg protein)-1 h-1, while the conversion rate of leucine was fivefold lower. With whole cells, the highest production rate [0.042 &mgr;mol beta-hydroxy-beta-methylbutyric acid (g cells)-1 h-1] was also observed with beta-methylbutyric acid. The results indicate that beta-methylbutyric acid is transformed to beta-hydroxy-beta-methylbutyric acid through the leucine catabolic pathway.

Journal Article↗

PubMedDate not supplied

Depsipeptide analogues of elastin repeating sequences: conformational analysis.

In this work the effect of elimination of a specific hydrogen bond on the conformation of the repeating peptides of elastin was studied. These repeating sequences are the pentapeptide Val-Pro-Gly-Val-Gly and the hexapeptide Val-Ala-Pro-Gly-Val-Gly. These sequences have been proposed to occur in a beta-turn conformation with a hydrogen bond involving the amide NH of the internal valine residue and the carbonyl oxygen of the residue preceding proline. In the depsipeptide analogues studied in this work, this 4-1 beta-turn hydrogen bond cannot occur. We studied the depsipeptide sequences Val-Pro-Gly-Hiv-Gly and Val-Ala-Pro-Gly-Hiv-Gly (Hiv denotes S-alpha-hydroxyisovaleric acid, the hydroxy acid analogue of valine), as well as the peptide sequences Val-Pro-Gly-Val-Gly and Val-Ala-Pro-Gly-Val-Gly. Compounds studied included sequences with the Boc and benzyl ester protecting groups, derivatives with the acetyl and N-methylamide end groups and polymers of the above sequences. Our conclusions are based on a comparison of depsipeptides with analogous peptides. Conformational analysis was carried out by nmr, CD, and ir spectroscopy. We propose that in the repeating sequences of elastin an equilibrium exists between a gamma-turn structure and a beta-turn structure in the Pro-Gly segment resulting in a structure that combines flexibility with strong conformational preferences. The C7 involves the amide NH of the internal glycine and the carbonyl oxygen of the residue preceding proline. In the N-methylamide derivatives a similar equilibrium exists in the Gly-Val-Gly segment. In the depsipeptides the beta-turn cannot occur and only the gamma-turn is seen. In the polydepsipeptides the major conformational feature is a type I beta-turn involving Gly5 NH and Pro CO.

Amino Acid Sequence↗

PubMed2005

Efficient and versatile stereoselective synthesis of cryptophycins.

The cryptophycins are a family of cyclic depsipeptides with four retrosynthetic units A to D which correspond to the respective amino acids and hydroxy acids. A new synthetic route to unit A allows the selective generation of all four stereogenic centres by introducing two of them in a catalytic asymmetric dihydroxylation, followed by substrate-controlled diastereoselective reactions. The diol also serves as the epoxide precursor. This approach provides selective access to stereoisomers of unit A (enantiomers, epimers) for structure-activity relationship studies. The unit A derivatives were incorporated into cryptophycin-1, cryptophycin-52 and a novel epimer of cryptophycin-52.

Bacterial Proteins↗

PubMed2006

Phosphorylation and glycosylation interplay: protein modifications at hydroxy amino acids and prediction of signaling functions of the human beta3 integrin family.

Protein functions are determined by their three-dimensional structures and the folded 3-D structure is in turn governed by the primary structure and post-translational modifications the protein undergoes during synthesis and transport. Defining protein functions in vivo in the cellular and extracellular environments is made very difficult in the presence of other molecules. However, the modifications taking place during and after protein folding are determined by the modification potential of amino acids and not by the primary structure or sequence. These post-translational modifications, like phosphorylation and O-linked N-acetylglucosamine (O-GlcNAc) modifications, are dynamic and result in temporary conformational changes that regulate many functions of the protein. Computer-assisted studies can help determining protein functions by assessing the modification potentials of a given protein. Integrins are important membrane receptors involved in bi-directional (outside-in and inside-out) signaling events. The beta3 integrin family, including, alpha(IIb)beta3 and alpha(v)beta3, has been studied for its role in platelet aggregation during clot formation and clot retraction based on hydroxyl group modification by phosphate and GlcNAc on Ser, Thr, or Tyr and their interplay on Ser and Thr in the cytoplasmic domain of the beta3 subunit. An antagonistic role of phosphate and GlcNAc interplay at Thr758 for controlling both inside-out and outside-in signaling events is proposed. Additionally, interplay of GlcNAc and phosphate at Ser752 has been proposed to control activation and inactivation of integrin-associated Src kinases. This study describes the multifunctional behavior of integrins based on their modification potential at hydroxyl groups of amino acids as a source of interplay.

Amino Acid Sequence↗

PubMed1991

Identification of an immunoreactive non-proteinaleous component in Borrelia burgdorferi.

Investigations of immunoblots using Borrelia burgdorferi antigen demonstrated that a band, migrating faster than the bromophenol blue front in sodium dodecyl sulfate-gel electrophoresis, reacted strongly with sera containing anti-Borrelia burgdorferi antibodies preferentially of the IgG class. Extraction of this antigenic component and chemical analyses showed that the substance was composed mainly of fatty acids and carbohydrates. Typical structures of classical lipooolysaccharides such as 3-deoxy-D-manno-2-octulosonic acid, hydroxy fatty acids or lipid A could not be detected.

Antibodies, Bacterial↗

PubMed1992

Comet Halley as an aggregate of interstellar dust and further evidence for the photochemical formation of organics in the interstellar medium.

Photolysis of mixtures of CO:NH3:H2O at 12 K results in the formation of an organic residue which is not volatile in high vacuum at room temperature. Analysis of this fraction by GC-MS resulted in the detection of C2-C3 hydroxy acids and hydroxy amides, glycerol, urea, glycine, hexamethylene tetramine, formamidine and ethanolamine. Use of isotopically labeled gases made it possible to establish that the observed products were not contaminants. The reaction pathways for the formation of these products were determined from the position of the isotopic labels in the mass spectral fragments. The significance of these findings to the composition of comets and the origins of life is discussed.

Dust↗

PubMed2006

Enantiomeric enrichment on the prebiotic Earth.

Evaporation of an aqueous solution of a chiral, nonracemic (partially resolved) amino acid or hydroxy acid from a clay or silica surface is shown to produce crystals in six cases that possess increased concentrations of the more abundant enantiomer. The increases range from a factor of 1.2 as the low to a high greater than 6-fold above the near 8% enantiomeric excess starting levels. This newly discovered enantiomeric enrichment process is presented in the context of it having been a possible instrument in the attainment of levels of configurational homogeneity sufficient for the emergence of life on Earth.

Aluminum Silicates↗

PubMed1988

New preparation method for 9-anthryldiazomethane (ADAM) as a fluorescent labeling reagent for fatty acids and derivatives.

A preparation method for 9-anthryldiazomethane (ADAM) as a fluorescent labeling reagent for carboxylic acids is described. 9-Anthraldehyde hydrazone is oxidized with an organic oxidant, N-chlorosuccinimide, in an organic solvent such as ethyl acetate to give ADAM, and then the reaction mixture is directly used as the reagent solution for the derivatization of carboxylic acids. Both the oxidation and the derivatization reaction are carried out at room temperature, and an aliquot of the derivatization mixture is directly injected into a chromatograph. 9-Anthrylmethyl ester derivatives formed from ADAM and various carboxylic acids are sufficiently separated on a reversed-phase column and are sensitively detected fluorometrically. The present method was applied to the high-performance liquid chromatographic determination of long and short chain fatty acids, keto acids, and hydroxy acids.

Anthracenes↗

PubMed1984

Effect of orally administered eicosapentaenoic acid (EPA) on the formation of leukotriene B4 and leukotriene B5 by rat leukocytes.

Eicosapentaenoic acid (EPA) is a poor substrate for the fatty acid cyclo-oxygenase but is a good substrate for lipoxygenase enzymes which catalyse the biosynthesis of hydroperoxy-acids, hydroxy-acids and leukotrienes. Recently, we reported that leukotriene B5 (LTB5) was at least 30 times less potent than LTB4 in causing aggregation, chemokinesis and degranulation of polymorphonuclear leukocytes in vitro. In this paper, the effect of oral administration of EPA on LTB4 and LTB5 production by rat leukocytes stimulated with the calcium ionophore, A23187, was assessed. The concentration of LTB was determined by radioimmunoassay and also by reverse-phase high pressure liquid chromatography using PGB3 as internal standard. Supplementation of a normal rat diet with EPA (240 mg/kg per day) for 4 weeks caused a significant increase in the formation of LTB5 and a decrease in the synthesis of LTB4 by stimulated leukocytes. The EPA-rich diet significantly increased the EPA content of leukocyte phospholipids without altering the content of arachidonic acid (AA) or linoleic acid. The ratio of EPA/AA in leukocytes correlated (r = 0.795, P less than 0.001) with the LTB5/LTB4 ratio produced after stimulation of leukocytes. If LTB4 has a chemotactic role during inflammation, the present data suggest that an EPA rich diet could decrease the accumulation of leukocytes at sites of inflammation.

Administration, Oral↗

PubMedDate not supplied

Effects of polyunsaturated fatty acids and of their oxidation products on cell survival.

The stimulatory, cytostatic and cytotoxic effects of polyunsaturated fatty acids, prostaglandins, thromboxanes, hydroperoxy fatty acids, hydroxy fatty acids and leukotrienes on normal and tumor cells are described. Their effects are related to the ability of the cells to undergo lipid peroxidation. The significance of controlled peroxidation of selected polyunsaturated fatty acids in the control of tumor development is examined. It is suggested that selected polyunsaturated fatty acids if used at appropriate concentrations may have a protective role against cancer development by inducing and/or mediating cytotoxic reactions in malignant cells directly or indirectly through the intermediacy of immune cells.

Animals↗

PubMed1993

Aldehydes in hydrothermal solution: standard partial molal thermodynamic properties and relative stabilities at high temperatures and pressures.

Aldehydes are common in a variety of geologic environments and are derived from a number of sources, both natural and anthropogenic. Experimental data for aqueous aldehydes were taken from the literature and used, along with parameters for the revised Helgeson-Kirkham-Flowers (HKF) equations of state, to estimate standard partial molal thermodynamic data for aqueous straight-chain alkyl aldehydes at high temperatures and pressures. Examples of calculations involving aldehydes in geological environments are given, and the stability of aldehydes relative to carboxylic acids is evaluated. These calculations indicate that aldehydes may be intermediates in the formation of carboxylic acids from hydrocarbons in sedimentary basin brines and hydrothermal systems like they are in the atmosphere. The data and parameters summarized here allow evaluation of the role of aldehydes in the formation of prebiotic precursors, such as amino acids and hydroxy acids on the early Earth and in carbonaceous chondrite parent bodies.

Aldehydes↗

PubMed1991

CH4/NH3/H2O spark tholin: chemical analysis and interaction with Jovian aqueous clouds.

The organic solid (tholin) produced by spark discharge in a CH4 + NH3 + H2O atmosphere is investigated, along with the separable components of its water-soluble fraction. The chemistry of this material serves as a provisional model for the interaction of Jovian organic heteropolymers with the deep aqueous clouds of Jupiter. Intact (unhydrolyzed) tholin is resolved into four chemically distinct fractions by high-pressure liquid chromatography (HPLC). Gel filtration chromatography reveals abundant components at molecular weights approximately or equal to 600-700 and 200-300 Da. Gas chromatography/mass spectrometry of derivatized hydrolysis products of unfractionated tholin shows about 10% by mass protein and nonprotein amino acids, chiefly glycine, alanine, aspartic acid, beta-alanine, and beta-aminobutyric acid, and 12% by mass other organic acids and hydroxy acids. The stereospecificity of alanine is investigated and shown to be racemic. The four principal HPLC fractions yield distinctly different proportions of amino acids. Chemical tests show that small peptides or organic molecules containing multiple amino acid precursors are a possibility in the intact tholins, but substantial quantities of large peptides are not indicated. Candidate 700-Da molecules have a central unsaturated, hydrocarbon- and nitrile-rich core, linked by acid-labile (ester or amide) bonds to amino acid and carboxylic acid side groups. The core is probably not HCN "polymer." The concentration of amino acids from tholin hydrolysis in the lower aqueous clouds of Jupiter, about 0.1 micromole, is enough to maintain small populations of terrestrial microorganisms even if the amino acids must serve as the sole carbon source.

Amino Acids↗