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1.
Hydroxy FAs, one of the gut microbial metabolites of PUFAs, have attracted much attention because of their various bioactivities. The purpose of this study was to identify lactic acid bacteria with the ability to convert linoleic acid (LA) to hydroxy FAs. A screening process revealed that a gut bacterium, Lactobacillus acidophilus NTV001, converts LA mainly into 13-hydroxy-cis-9-octadecenoic acid and resulted in the identification of the hydratase responsible, fatty acid hydratase 1 (FA-HY1). Recombinant FA-HY1 was purified, and its enzymatic characteristics were investigated. FA-HY1 could convert not only C18 PUFAs but also C20 and C22 PUFAs. C18 PUFAs with a cis carbon-carbon double bond at the Δ12 position were converted into the corresponding 13-hydroxy FAs. Arachidonic acid and DHA were converted into the corresponding 15-hydroxy FA and 14-hydroxy FA, respectively. To the best of our knowledge, this is the first report of a bacterial FA hydratase that can convert C20 and C22 PUFAs into the corresponding hydroxy FAs. These novel hydroxy FAs produced by using FA-HY1 should contribute to elucidating the bioactivities of hydroxy FAs.  相似文献   

2.
(Methyl 2-acetamidoacrylate)tricarbonyliron(0) (3) reacts with 2 equivalents of methyllithium to give methyl N-acetylalaninate (4) and 2-acetamido-4-oxopentanoate (5) when the reaction is quenched with trifluoroacetic acid. Production of methyl N-acetylalaninate is dependent only on the presence of trifluoroacetic acid, and the ratio of 4 to 5 generated in these reactions is related to the quantity of trifluoroacetic acid used to quench them. Addition of two equivalents of methyllithium followed by tertiary haloalkanes gives protected β,β,β-trialkyl α-amino acids which may be hydrolysed to give tert-leucine (13) and the new α-amino acids 2-amino-3,3-dimethylpentanoic acid (14) and 2-amino-3,3-dimethylhexanoic acid (15).  相似文献   

3.
2-Hydroxy acids were believed to be absent in algae until this study, in which the analysis of microalgae belonging to Chlorophyta (Chlamydomonas reinhardtii and Chlorella pyrenoidosa), Rhodophyta (Cyanidium caldarium M-8 and Cyanidium caldarium RK-1) and Cyanophyta (Anbaena variabilis, Anacystis nidulans, Oscillatoria species and Phormidium foveolarum) is reported. 2-Hydroxy adds with carbon chain lengths of C16-C26, were found in all the algal samples studied, ranging in concentrations from 4.0 to 320μg/g dry alga. The dominant constituents are 2-hydroxyhexadecanoic, 2-hydroxynonadecanoic, 2-hydroxyhexacosanoic and a branched 2-hydroxy-C19 acid. The distribution patterns of the acids differed significantly among the algal samples. Hence 2-hydroxy acids may be useful for the classification of algal species as well as being an important source of 2-hydroxy acids in the natural environment.  相似文献   

4.
《Anaerobe》1999,5(5):533-537
The ability of Clostridium butyricum cultures in synthetic medium to hydrolyse the tripeptide Leu-Val-Leu was demonstrated using gas chromatography coupled with mass spectrometry. Electrospray mass spectrometry was used to confirm this unknown activity for this C -heterotrophic species listed saccharolytic, non-proteolytic clostridia. The oligopeptide hydrolysis activity is characterised by the detection of the released amino acids and the products of their bioconversion, the corresponding 2-hydroxyacids. This observation opens new aspects in the study of C. butyricum and raised questions about the peptide metabolism by this species. The enzymes implied in the oligopepitide hydrolysis can be regarded as potential virulence factors and being an element in the comprehension of certain pathologies.  相似文献   

5.
Various proline analogs and iron chelators were tested for their effect on collagen formation which occurs in the uterus of the immature rat following the administration of estradiol-17β. dl-3,4-Dehydroproline, l-α-azetidine-2-carboxylic acid and l-pyroglutamic acid reduced the estradiol-17β stimulated formation of hydroxyproline which occurs in the uterus following administration of the hormone while l-thiazolidine-4-carboxylic acid was without effect on this response. The activity of the d- and l-isomers of 3,4-dehydroproline was compared with the racemic mixture; the l-isomer was twice as active as the latter, while the d-isomer was only half as active. l-3,4-Dehydroproline was approximately four times as potent as l-α-azetidine-2-carboxylic acid, the second most active analog of those tested. dl-3,4-Dehydroproline inhibited the incorporation of l-[14C]proline into the proline and hydroxyproline of uterine collagen; it also inhibited the incorporation of [14C]glycine into collagen while having less effect on the incorporation of these amino acids into noncollagen protein. These results indicate dl-3,4-dehydroproline is a fairly specific and potent inhibitor of collagen formation in vivo.These observations indicate that dl-3,4-dehydroproline reduces the hydroxylation of prolyl residues in collagen. Presumably, this occurs in part due to the incorporation of the analog into the collagen molecule in place of proline. It is probably also related to a reduction of prolyl hydroxylase activity which can be demonstrated in the tissues of animals treated with 3,4-dehydroproline. A significant reduction of prolyl hydroxylase activity was shown to persist in the uterus, lung, and heart for approximately 24 h following a single intraperitoneal dose of dl-3,4-dehydroproline (200 mg/kg).  相似文献   

6.
A new β-hydroxy amino acid isolated from the fruiting bodies of Lyophyllum ulmarium was identified as Ds,-erythro-2-amino-4-ethoxy-3-hydroxybutanoic acid by chemical degradation and spectroscopic analyses.  相似文献   

7.
In addition to the previously reported isolation of L-2-amino-4-methylhex-5-enoic acid, eleven known amino acids, mannitol, ergosterol, and two new steroids were isolated from an allegedly hallucinogenic Boletus. A modification of the GC-MS method used for the identification of neutral α-amino acids is also reported.  相似文献   

8.
Intraperitoneal administration to rats of D- or DL-α-hydrazunoimidazolylpropionic acid was found to produce a substantial inactivation of hepatic histidine ammonia-lysase (EC 4.3.1.3) in vivo. Proportional to this loss in enzyme activity was an impairment of the ability of treated rats to oxidize l-[ring-2-14C] histidine to 14CO2. Rats in which hepatic histadine ammonia-lyase activity was either depressed by dl-hydrazunoimidazolylproprionic acid injection or elevated by feeding a high protein diet displayed proportionately altered rates of 3H2O release into plasma water following l-[3-H]histidine administration. Plasma l-histidine clearance following loading with this amino acid was similarly affected by these treatments. Administration of dl-α-hydrazinoimisazolyl-proprionic acid to rats was also found to inactivate non-specifically pyridoxal 5-phosphate enzymes in vivo; pyridoxine injection was found to reverse the dl-α-hydrazinoimidazolylproprionic acid-induced inactivation of hepatic aspartate aminotransferase (EC 2.6.1.1) in vivo, but not that of hepatic histidine ammonia-lyase. These findings demonstrate that histidine ammonia-lyase is the rate-limiting factor in l-histidine degradation in the rat. The potential usefulness of dl-hydrazinoimidazolylproprionic acid in the production of an animal model for histidinemia (hereditary histidine ammonia-lyase deficiency) is discussed.  相似文献   

9.
Murein peptide ligase (Mpl) is an enzyme found in Gram-negative bacteria. It catalyses the addition of tripeptide l-Ala-γ-d-Glu-meso-diaminopimelate to nucleotide precursor UDP-N-acetylmuramic acid during the recycling of peptidoglycan. Although not essential, this enzyme represents an interesting target for antibacterial compounds through the synthesis of alternate substrates whose incorporation into peptidoglycan might be deleterious for the bacterial cell. Therefore, we have synthesised 10 tripeptides l-Ala-γ-d-Glu-Xaa in which Xaa represents amino acids different from diaminopimelic acid. Tripeptide with Xaa = ε-d-Lys proved to be an excellent substrate of Escherichia coli Mpl in vitro. Tripeptides with Xaa = p-amino- or p-nitro-l-phenylalanine were poor substrates, while tripeptides with Xaa = d- or l-2-aminopimelate, dl-2-aminoheptanoic acid, l-Glu, l-norleucine, l-norvaline, l-2-aminobutyric acid or l-Ala were not substrates at all. Although a good Mpl substrate, the d-Lys-containing tripeptide was devoid of antibacterial activity against E. coli, presumably owing to poor uptake.  相似文献   

10.
A Lyophilized preparation of L-2-halo acid dehalogenase was not only stable but also catalytically active in anhydrous dimethyl sulfoxide, toluene, and other organic solvents. 2-Halo acids with long alkyl (C(5)-C(16)) or aromatic (phenyl and benzyl) side chains were inert in water but dehalogenated effectively in anhydrous dimethyl sulfoxide by the lyophilized enzyme. Long chain 2-haloalkanoic acids such as 2-bromohexadecanoic acids were better as substrate than short-chain halo acids (e.g., 2-chloropropanoic acid). The dehalogenation proceed with inversion of C(2) configuration to produce the corresponding (2R)-2-hydroxy acids in anhydrous dimethyl sulfoxide in the same way as found in water.  相似文献   

11.
Thirty-three bacterial strains were isolated from soil, utilizing optically asymmetric degradation of dl-2-hydroxy-4-methylpentanoic acid (dl-HMPA) as the screening probe. Those strains were distributed in the following group and genera: Coryneform and Bacillus, Pseudomonas, and Streptomyces. Among them, the most potent strains, Bacillus freudenreichii NRS-137KH20B and Brevibacterium albidum NRS-130KH20B, could perform the resolution of more than 30 g of dl-HMPA per liter within 4 to 5 days of fermentation. Optically pure l- and d-HMPA enantiomers were obtained in more than 80% theoretical yield, whereas the transformed enantiomer was almost quantitatively recovered as 2-oxo-4-methyl-pentanoic acid in the culture broth. The enantiospecific dehydrogenation responsible for this resolution reaction had a rather wide substrate specificity on straight or branched aliphatic C(4) to C(16) 2-hydroxy acids, exhibiting the optima at chain lengths of either C(7) or C(5), although the enantiospecificity was not changed by chain length. The process was thus successfully extended to the preparation of optically pure C(5) to C(9) 2-hydroxy acids.  相似文献   

12.
2(R)-amino-3-butenoic acid (vinylglycine), the simplest β,γ-unsaturated α-amino acid, has been isolated from the mushroom Rhodophyllus nidorosus (Fr.) Quél. The amino acid occurs as partly racemized d-form. The structure has been confirmed by comparison with synthetic material.  相似文献   

13.
Three fatty acids were synthesized from commercially available alpha-linolenic, stearidonic and eicosapentaenoic acids by C2-elongation using a four step preparative technique. The parent fatty acid methyl esters were reduced to alcohols with LiAlH(4), converted to bromides by treatment with triphenylphosphine dibromide, coupled with a lithiated C2-elongation block--2,4,4-trimethyl-2-oxazoline--to form the corresponding 2,2-dimethyloxazolines of C2-elongated fatty acids, and finally, converted to the target polyunsaturated fatty acids by acidic alcoholysis. Yields of more than 60% were achieved on a gram scale. The resulting 11Z,14Z,17Z-eicosatrienoic, 8Z,11Z,14Z,17Z-eicosatetraenoic and 7Z,10Z,13Z,16Z,19Z-docosapentaenoic acids were obtained as colorless oils with >98% purity and could be used for biochemical investigations without additional purification. The elongated fatty acids were free of byproducts that could result from Z-E isomerization or migration of double bonds.  相似文献   

14.
Structure modification of the β-alanine region (fragment C) of the potent antimitotic agent cryptophycin was investigated. This includes: (1) introduction of substituents at the previously unsubstituted C7 position of the macrolide ring and (2) replacement of the (2R)-3-amino-2-methyl-propanoic acid (β-alanine) with various (1)-amino acids to give the corresponding 15-membered unnatural cryptophycin analogs.  相似文献   

15.
2-Hydroxyoctadecanoic acid was resolved into D and L isomers as salts of 1-phenylethylamine enantiomers The diastereomers of phenylethylamides of 2-hydroxy fatty acids and the corresponding derivatives with protected hydroxy group (acetyl, methyl, trifluoro-acetyl, trimethylsilyl) are well separated by thin-layer or gas-liquid chromatography. This allows a simple microanalysis of configuration and optical purity of 2-hydroxy fatty acids. With this method 2-hydroxy fatty acids from sphingomyelin of the honey-bee were shown to belong exclusively to the D series.  相似文献   

16.
N-Tolylsulfonyl- and N-butyloxycarbonyl-protected β-amino nitriles were prepared to study the effect of the N-protecting group on the biotransformation of the β-amino nitriles to the corresponding β-amino amides and acids. The bioconversions were carried out by using whole cells of Rhodococcus sp. R312 and Rhodococcus erythropolis NCIMB 11540. The bioconversion products of five-membered carbocyclic nitriles were mainly the respective acids whereas the carbocyclic six-membered nitriles were accumulated at the stage of the amide. Benefits of the enzymatic compared with the chemical hydrolysis of β-amino nitriles are the mild reaction conditions for the transformation of the nitrile group in the presence of acid or base labile N-protecting groups. In the present work we concentrated on this chemoselectivity of the biotransformation rather than its potential enantioselectivity, which will be subject of future investigations. Thus, some new compounds were prepared: (±)-(2-cyano-cyclohexyl) carbamic acid tert-butyl ester (4a), (±)-(2-carbamoyl-cyclopentyl) carbamic acid tert-butyl ester (3b) and (±)-(2-carbamoyl-cyclohexyl) carbamic acid tert-butyl ester (4b).  相似文献   

17.
A series of novel polyacetylene substituted 2-hydroxy acids and derivatives were prepared and characterized. Alkylation of butane-2,3-diacetal (BDA) protected glycolic acid with iodoalkyl substituted polyacetylene compounds gave the corresponding diacetal protected polyacetylene substituted 2-hydroxy acids. Diacetal deprotection through acid mediated hydrolysis, transesterification or aminolysis afforded the 2-hydroxy-polyacetylenic acid, ester or amide derivatives. Twenty one of these novel compounds were tested against 10 microbes of clinical importance and several of them showed good antimicrobial activity, in particular against Pseudomonas aeruginosa.  相似文献   

18.
The fungus Aspergillus japonicus MF275 produces himeic acid A (1), containing a 4-pyrone ring, along with its congeners, himeic acids B (2) and C (3). During culture, 1 was gradually converted to 3, the corresponding 4-pyridone derivative. A study of the relationship between the culture pH and the fungal metabolites showed that a decrease from pH 6.5 to pH 2 is essential for production of 1, while a subsequent increase to pH 5 is necessary for production of 3. In addition, we revealed that 1 was non-enzymatically converted to 3 by the incorporation of an ammonium nitrogen atom in a pH 5 buffer, and that 1 was converted to 2 at a conversion ratio of 50% during incubation in MeOH for five days.  相似文献   

19.
Subtulene A, a new cyclic lipopeptide, was isolated from the culture broth of Bacillus subtilis SSE4. This antibiotic compound contained the seven common α-amino acids, l-Asn-1, d-Tyr-2, d-Asn-3, l-Gln-4, l-Pro-5, d-Asn-6, l-Ser-7 and the unique β-amino acid-8 present in the iturin family. 1D and 2D NMR, as well as MS analyses, identified the β-amino acid as 3-amino-13-methyltetradec-8-enoic acid, an Iso C15 long chain β-amino acid. B. subtilis SSE4 was also found to produce iturin A. B. subtilis SSE4 culture filtrate exhibited both antifungal and antibacterial activities.  相似文献   

20.
2(S),3′(S)-N-(3-Amino-3-carboxypropyl)azetidine-2-carboxylic acid and 2(S),3′(S),3″(S)-N-[N-(3-amino-3-carboxypropyl)-3-amino-3-carboxypropyl]azetidine-2-carboxylic acid have been isolated from seeds of Fagus silvatica L. (beechnuts). The structures have been established by PMR- and 13C-NMR-spectroscopy and by synthesis from l-azetidine-2-carboxylic acid. The second of the new amino acids is identical with nicotianamine. previously isolated from Nicotiana tabacum but assigned a different formula. The ring opening reactions of azetidine-2-carboxylic acid in neutral solution have been studied and the chemical and possibly biochemical precursor role of this amino acid for various amino acids including the two new ones described here, nicotianine [N-(3-amino-3-carboxypropyl)nicotinic acid] and methionine is discussed.  相似文献   

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