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1.
We describe a series of conformationally-restricted cinnamic acid peptidomimetics as well as several cinnamic acid isosteres, including 3-phenylpropionic acids, 2-amino-3-phenylpropionic acids, phenoxyacetic acids and 2-phenylcyclopropylcarboxylic acids. Several analogues demonstrated low to sub-nanomolar potencies against alpha(v)beta(3) and greater than 200-fold selectivity against the other beta(3) integrin alpha(IIb)beta(3). In whole 293 cells, many of these analogues also showed modest selectivity against other alpha(v) integrins such as alpha(v)beta(1) and alpha(v)beta(5). These compounds were synthesized from readily available starting materials using either Heck or Mitsunobu coupling conditions.  相似文献   

2.
(R)-3-Amino-3-phenylpropionic acid ((R)-beta-Phe) and (S)-3-amino-3-phenylpropionic acid ((S)-beta-Phe) are key compounds on account of their use as intermediates in synthesizing pharmaceuticals. Enantiomerically pure non-natural amino acids are generally prepared by enzymatic resolution of the racemic N-acetyl form, but despite the intense efforts this method could not be used for preparing enantiomerically pure beta-Phe, because the effective enzyme had not been found. Therefore, screening for microorganisms capable of amidohydrolyzing (R,S)-N-acetyl-3-amino-3-phenylpropionic acid ((R,S)-N-Ac-beta-Phe) in an enantiomer-specific manner was performed. A microorganism having (R)-enantiomer-specific amidohydrolyzing activity and another having both (R)-enantiomer- and (S)-enantiomer-specific amidohydrolyzing activities were obtained from soil samples. Using 16S rDNA analysis, the former organism was identified as Variovorax sp., and the latter as Burkholderia sp. Using these organisms, enantiomerically pure (R)-beta-Phe (>99.5% ee) and (S)-beta-Phe (>99.5% ee) with a high molar conversion yield (67%-96%) were obtained from the racemic substrate.  相似文献   

3.
A novel beta-transaminase gene was cloned from Mesorhizobium sp. strain LUK. By using N-terminal sequence and an internal protein sequence, a digoxigenin-labeled probe was made for nonradioactive hybridization, and a 2.5-kb gene fragment was obtained by colony hybridization of a cosmid library. Through Southern blotting and sequence analysis of the selected cosmid clone, the structural gene of the enzyme (1,335 bp) was identified, which encodes a protein of 47,244 Da with a theoretical pI of 6.2. The deduced amino acid sequence of the beta-transaminase showed the highest sequence similarity with glutamate-1-semialdehyde aminomutase of transaminase subgroup II. The beta-transaminase showed higher activities toward d-beta-aminocarboxylic acids such as 3-aminobutyric acid, 3-amino-5-methylhexanoic acid, and 3-amino-3-phenylpropionic acid. The beta-transaminase has an unusually broad specificity for amino acceptors such as pyruvate and alpha-ketoglutarate/oxaloacetate. The enantioselectivity of the enzyme suggested that the recognition mode of beta-aminocarboxylic acids in the active site is reversed relative to that of alpha-amino acids. After comparison of its primary structure with transaminase subgroup II enzymes, it was proposed that R43 interacts with the carboxylate group of the beta-aminocarboxylic acids and the carboxylate group on the side chain of dicarboxylic alpha-keto acids such as alpha-ketoglutarate and oxaloacetate. R404 is another conserved residue, which interacts with the alpha-carboxylate group of the alpha-amino acids and alpha-keto acids. The beta-transaminase was used for the asymmetric synthesis of enantiomerically pure beta-aminocarboxylic acids. (3S)-Amino-3-phenylpropionic acid was produced from the ketocarboxylic acid ester substrate by coupled reaction with a lipase using 3-aminobutyric acid as amino donor.  相似文献   

4.
Excretion of 2-ketoisovaleric acid (KIV) was demonstrated in Streptomyces cinnamonensis mutants resistant to valine analogues 2-amino-3-chlorobutyrate, 2-aminobutyrate and norleucine, respectively. The highest KIV concentrations of 170–230 mg l−1 were found in cultivation liquids of norleucine-resistant strains. Biochemical analyses of the acetohydroxyacid synthase (AHAS), valine dehydrogenase (VDH) and branched chain amino acid aminotransferase activities revealed the deregulation of the valine-synthesizing pathway, resulting in KIV excretion. In the 2-amino-3-chlorobutyrate-resistant strain, the activity of AHAS increased 23- to 31-fold compared with the parental strain. The norleucine-resistant mutants combined both a 10- to 23-fold increase in AHAS activity and lack of efficient feedback regulation by valine. In the double 2-amino-3-chlorobutyrate plus norleucine-resistant mutant, the AHAS activity was only four to eight-fold higher, but release of feedbackregulation was conserved. Similarly, feedback regulation was inefficient in 2-aminobutyrate-resistant strains, however the AHAS activity was lower than in the parental strain. A strong induction of VDH was observed in all regulatory mutants.  相似文献   

5.
Derivatives of the available plant triterpenes glycyrrhetic acid and betulin (betulin succinates and amides of betulonic and 18beta-glycyrrhetic acids containing fragments of long-chain amino acids and a peptide) were synthesized. The inhibitory action of these compounds on the growth of MT-4, MOLT-4, CEM. and Hep G2 tumor cells and their effect on the apoptosis of these cells were studied. It was shown that betulonic acid amides are more effective inhibitors of the tumor cell growth than the corresponding amides of glycyrrhetic acid. It was also found that betulonic acid amides containing fragments of caprylic, pelargonic, and undecanoic acids are more effective inhibitors of tumor cell growth than betulinic acid. The 17-dipeptide derivative of betulonic acid N-{N-[3-oxo-20(29)-lupen-28-oyl]-9-aminononanoyl}-3-amino-3-phenylpropionic acid exhibited the maximum inhibitory activity toward the tumor cells studied. Data on the induction of apoptosis in tumor cells by betulin derivatives at a concentration of 10 microg/ml were obtained by flow cytometry. The amides of betulonic acid proved to be the most effective inducers of apoptosis.  相似文献   

6.
A bacterial strain that grew on 4-amino-3-hydroxybenzoic acid was isolated from farm soil. The isolate, strain 10d, was identified as a species of Bordetella. Cell extracts of Bordetella sp. strain 10d grown on 4-amino-3-hydroxybenzoic acid contained an enzyme that cleaved this substrate. The enzyme was purified to homogeneity with a 110-fold increase in specific activity. The purified enzyme was characterized as a meta-cleavage dioxygenase that catalyzed the ring fission between C2 and C3 of 4-amino-3-hydroxybenzoic acid, with the consumption of 1 mol of O2 per mol of substrate. The enzyme was therefore designated as 4-amino-3-hydroxybenzoate 2,3-dioxygenase. The molecular mass of the native enzyme was 40 kDa based on gel filtration; the enzyme is composed of two identical 21-kDa subunits according to SDS/PAGE. The enzyme showed a high dioxygenase activity only for 4-amino-3-hydroxybenzoic acid. The Km and Vmax values for this substrate were 35 micro m and 12 micro mol.min-1.(mg protein)-1, respectively. Of the 2-aminophenols tested, only 4-aminoresorcinol and 6-amino-m-cresol inhibited the enzyme. The enzyme reported here differs from previously reported extradiol dioxygenases, including 2-aminophenol 1,6-dioxygenase, in molecular mass, subunit structure and catalytic properties.  相似文献   

7.
Amino acids such as DL-2-amino-n-butyric acid, DL-alanine, L-lysine monohydrochloride, DL-valine and L-proline enhanced total xylanase production from Staphylococcus sp. SG-13 up to 5.5-fold. The present study showed that xylanase production has mainly been governed by the chemical structure of amino acids and their analogues.  相似文献   

8.
A number of laboratory strains and clinical isolates of Escherichia coli utilized several aromatic acids as sole sources of carbon for growth. E. coli K-12 used separate reactions to convert 3-phenylpropionic and 3-(3-hydroxyphenyl)propionic acids into 3-(2,3-dihydroxyphenyl)propionic acid which, after meta-fission of the benzene nucleus, gave succinate, pyruvate, and acetaldehyde as products. Enzyme assays and respirometry showed that all enzymes of this branched pathway were inducible and that syntheses of enzymes required to convert the two initial growth substrates into 3-(2,3-dihydroxyphenyl)propionate are under separate control. E. coli K-12 also grew with 3-hydroxycinnamic acid as sole source of carbon; the ability of cells to oxidize cinnamic and 3-phenylpropionic acids, and hydroxylated derivatives, was investigated. The lactone of 4-hydroxy-2-ketovaleric acid was isolated from enzymatic reaction mixtures and its properties, including optical activity, were recorded.  相似文献   

9.
Derivatives of the available plant triterpenes glycyrrhetic acid and betulin (betulin succinates and amides of betulonic and 18β-glycyrrhetic acids containing fragments of long-chain amino acids and a peptide) were synthesized. The inhibitory action of these compounds on the growth of MT-4, MOLT-4, CEM, and Hep G2 tumor cells and their effect on the apoptosis of these cells were studied. It was shown that betulonic acid amides are more effective inhibitors of the tumor cell growth than the corresponding amides of glycyrrhetic acid. It was also found that betulonic acid amides containing fragments of caprylic, pelargonic, and undecanoic acids are more effective inhibitors of tumor cell growth than betulinic acid. The 17-dipeptide derivative of betulonic acid N-{N-[3-oxo-20(29)-lupen-28-oyl]-9-aminononanoyl}-3-amino-3-phenylpropionic acid exhibited the maximum inhibitory activity toward the tumor cells studied. Data on the induction of apoptosis in tumor cells by betulin derivatives at a concentration of 10 μg/ml were obtained by flow cytometry. The amides of betulonic acid proved to be the most effective inducers of apoptosis.  相似文献   

10.
The conversion by a methanogenic consortium of phenol into phenylalanine, with benzoic and phenylpropionic acid as intermediates, was investigated. When (sup14)C-labelled phenol was fed to the consortium, the radioactivity was mostly transferred into methane and CO(inf2), but 4% of the radioactivity was found in the water fraction after extraction of the culture medium with an organic solvent. Utilization of labelled compounds and analysis by gas chromatography coupled with mass spectrometry revealed that a fraction of the benzoic acid produced was transformed into 3-phenylpropionic acid. When fully (sup13)C-labelled acetic acid was fed to the consortium, the labels were incorporated at the 1 and 2 positions of 3-phenylpropionic acid. When deuterium-labelled 3-phenylpropionic acid was fed to the consortium, part of the phenylalanine of the biomass was labelled. These metabolic transformations are reversible, since deuterium-labelled phenylalanine generated labelled 3-phenylpropionic acid. Cinnamic acid was also transformed into 3-phenylpropionic acid.  相似文献   

11.
The enzyme L-alanine:4,5-dioxovalerate aminotransferase (EC 2.6.1.43), which catalyzes the synthesis of 5-aminolevulinic acid, was purified 161-fold from Chlorella regularis. The enzyme also showed L-alanine:glyoxylate aminotransferase activity (EC 2.6.1.44). The activity of glyoxylate aminotransferase was 56-fold greater than that of 4,5-dioxovalerate aminotransferase. The ratio of the two activities remained nearly constant during purification, and when the enzyme was subjected to a variety of treatments. 4,5-Dioxovalerate aminotransferase activity was competitively inhibited by glyoxylate, with a Ki value of 0.5 mM. Double-reciprocal plots of velocity versus 4,5-dioxovalerate with varying L-alanine concentrations indicate a ping-pong reaction mechanism. The apparent Km values for 4,5-dioxovalerate and L-alanine were 0.12 and 3.5 mM, respectively. The enzyme is an acidic protein having an isoelectric point of 4.8. The molecular weight of the enzyme was estimated to be 126,000, with two identical subunits. These results suggest that, in Chlorella, as in bovine liver mitochondria and Euglena, both 4,5-dioxovalerate and glyoxylate aminotransferase activities are associated with the same protein. From the activity ratio of transamination and catalytic properties, it is concluded that this enzyme does not function primarily as a part of the 5-carbon pathway to 5-aminolevulinic acid synthesis.  相似文献   

12.
A two-step enzymatic synthesis process of 4-hydroxyisoleucine is suggested. In the first step, the aldol condensation of acetaldehyde and alpha-ketobutyrate catalyzed by specific aldolase results in the formation of 4-hydroxy-3-methyl-2-keto-pentanoate (HMKP). In the second step, amination of HMKP by the branched-chain amino acid aminotransferase leads to synthesis of 4-hydroxyisoleucine. An enzyme possessing HMKP aldolase activity (asHPAL) was purified 2500-fold from a crude extract of Arthrobacter simplex strain AKU 626. Sequencing of the asHPAL structural gene showed that the purified enzyme belongs to the HpcH/HpaI aldolase family. The 4-hydroxyisoleucine was synthesized in vitro from acetaldehyde, alpha-ketobutyrate and l-glutamate using a coupled aldolase/branched-chain amino acid aminotransferase bienzymatic reaction.  相似文献   

13.
The aminotransferase that catalyzes the formation of δ-aminolevulinic acid from glutamate-1-semialdehyde or from glutamate in a reconstituted enzyme system was isolated and partially purified from Chlorella vulgaris. The apparent molecular weight of the aminotransferase was determined by Sephadex G-100 and Ultrogel AcA 54 gel filtration to be 60,000 ± 5,000. Catalytic activity of the aminotransferase required pyrixodal phosphate (PALP). The cofactor could not be removed by gel filtration after exposure of the enzyme to PALP. Aminotransferase was inhibited by gabaculine (3-amino-2,3-dihydrobenzoic acid). The concentration of gabaculine required for half maximal inhibition was about 0.05 micromolar. Aminotransferase activity could be regained upon the removal of gabaculine by gel filtration and supplementing the assay medium with PALP. Neither the inhibitory action of gabaculine nor its reversibility was affected by preincubation of the enzyme with the keto acids levulinate and δ-aminolevulinic acid.  相似文献   

14.
A mutant derivative of a novel pseudomonad isolated from the soil accumulated acetophenone when supplied with cinnamic acid. The microorganism has been identified as an unclassified Pseudomonas sp., similar to Pseudomonas acidovorans. Mass spectrum analysis of the product acetophenone derived from catabolism of cinnamic acid in the presence of O(2) or H(2)O supported the conclusion that cinnamic acid degradation is initiated by addition of water to the double bond of the side chain, followed by dehydrogenation to generate 3-keto-3-phenylpropionic acid. The intermediate 3-keto-3-phenylpropionic acid is accumulated in cultures of the mutant during active cinnamic acid catabolism. However, this intermediate is unstable so a portion of it spontaneously decarboxylates to form acetophenone. Neither 3-keto-3-phenylpropionic acid nor acetophenone is a precedented intermediate in cinnamic acid degradation. Isolation of the novel strain and mutant provide the rudiments for a process to produce natural acetophenone by biotransformation of natural cinnamic acid.  相似文献   

15.
M J Ernest 《Biochemistry》1982,21(26):6761-6767
Tyrosine aminotransferase messenger ribonucleic acid (mRNA) activity in rat liver was rapidly increased 3-6-fold following in vivo administration of hydrocortisone acetate, dibutyryladenosine cyclic 3',5'-phosphate, or the protein synthesis inhibitor cycloheximide. Treatment with the steroid hormone or cyclic nucleotide in combination with cycloheximide resulted in levels of tyrosine aminotransferase mRNA 10-20-fold greater than control values. These changes in mRNA activity were not accompanied by changes in albumin mRNA or total liver template activity. The rapid decline in tyrosine aminotransferase mRNA activity following cordycepin inhibition of de novo RNA synthesis was prevented by cycloheximide treatment. This protection was not observed when pactamycin was substituted for cycloheximide, demonstrating that the inhibition of protein synthesis per se was not responsible for the stabilization of tyrosine aminotransferase mRNA. Based upon the effects of cycloheximide and pactamycin on rat liver polysome structure, it is concluded that the cycloheximide-mediated increase in tyrosine aminotransferase mRNA activity is the result of stabilization of the mRNA molecule which renders the message less susceptible to inactivation and degradation in the cytoplasm. The action of cycloheximide is very specific for tyrosine aminotransferase, phosphoenolpyruvate carboxykinase, and probably several other mRNAs that code for minor liver proteins that turn over rapidly in response to hormonal or metabolic stimuli.  相似文献   

16.
Evidence for an enamine mechanism of inactivation of pig brain gamma-aminobutyric acid (GABA) aminotransferase by (S,E)-4-amino-5-fluoropent-2-enoic acid is presented. apo-GABA aminotransferase reconstituted with [3H]pyridoxal 5'-phosphate is inactivated by (S,E)-4-amino-5-fluoropent-2-enoic acid and the pH is raised to 12. All of the radioactivity is released from the enzyme as an adduct of the cofactor; no [3H]pyridoxamine 5'-phosphate is generated.  相似文献   

17.
The involvement of glutamine aminotransferase activity in glutamine catabolism by Saccharomyces cerevisiae under microaerophilic conditions was studied. We were able to show that there are at least two different glutamine aminotransferase activities that are differentiated genetically, by their substrate specificity (pyruvate and glyoxylate dependence), and their different modes of regulation. The pyruvate-dependent glutamine aminotransferase activity plays a major role in glutamine catabolism under microaerophilic conditions since the wild-type strain S288C showed a 10-fold higher activity in static cultures than in agitated ones. The same strain also had 3-fold higher glutaminase B activity in agitated cultures than in static ones. Pyruvate-dependent glutamine aminotransferase activity is not regulated directly by O2 itself since a rho- strain showed a high activity regardless of the extent of aeration of cultures. Finally, we were able to isolate a mutant, strain CN20, derived from the rho- strain and unable to utilize glutamine as the sole nitrogen source, which was severely affected in pyruvate-dependent but not in glyoxylate-dependent aminotransferase activity.  相似文献   

18.
Haloferax sp. D1227, isolated from soil contaminated with highly saline oil brine, is the first halophilic archaeon to demonstrate the utilization of aromatic compounds (i.e., benzoic acid, cinnamic acid, and 3-phenylpropionic acid) as sole carbon and energy sources for growth. The degradation of 3-phenylpropionic acid in this strain was studied to examine the strategies utilized by Archaea to metabolize aromatic compounds. Based on our findings of (1) the extracellular accumulation of cinnamic acid, benzoic acid, 3-hydroxybenzoic acid, and gentisic acid in cultures of Haloferax D1227 grown on 3-phenylpropionic acid, (2) the presence of an 3-phenylpropionylCoA dehydrogenase, (3) the ATP, CoA, and NAD-dependent conversion of cinnamic acid to benzoylCoA, and (4) the presence of gentisate 1,2-dioxygenase, we propose that Haloferax D1227 metabolizes 3-phenylpropionic acid by initial 2-carbon shortening of the side chain to benzoylCoA via a mechanism similar to fatty acid β-oxidation, fol-lowed by aromatic degradation using a gentisate pathway. The upper aliphatic pathway from 3-phenylpropionic acid to benzoic acid is regulated separately from the lower gentisate pathway. Received: January 7, 1998 / Accepted: July 22, 1998  相似文献   

19.
Reaction of 7-amino-3-[5'-methyl-1',3',4'-thiadiazol-2'-ylthiomethyl]cephalo-sporanic acid with heterocyclic amines using basic alumina under microwave irradiation (MWI) afforded new cephalosporin analogs in shorter reaction time with improved yield as compared to conventional heating. All the synthesised compounds were tested for their in vitro antibacterial activity, using cefotaxime and cephalothin as reference drugs. All compounds showed significant in vitro antibacterial activity against E. herbicola, P. vulgaries, and Z. mobilis.  相似文献   

20.
A series of novel 2-(5-aminomethylene-4-oxo-2-thioxothiazolidin-3-yl)-3-phenylpropionic acid ethyl esters has been synthesized. Target compounds were evaluated for their trypanocidal activity towards Trypanosoma brucei brucei and Trypanosoma brucei gambiense. Several hit-compounds (8, 10, 12) inhibited growth of the parasites at sub-micromolar concentrations (IC50 0.027–1.936 µM) and showed significant selectivity indices (SI = 108–1396.2) being non-toxic towards the human primary fibroblasts. The screening of anticancer activity in vitro within NCI DTP protocol allowed to identify active 2-(5-{[5-(2,4-dichlorobenzyl)-thiazol-2-ylamino]-methylene}-4-oxo-2-thioxothiazolidin-3-yl)-3-phenylpropionic acid ethyl ester 14 that demonstrated inhibition against all 59 human tumor cell lines with the average GI50 value of 2.57 μM. It was established that the activity type (antitrypanosomal or anticancer) as well as its level depends on the character of enamine fragment in the C5 position of thiazolidinone core.  相似文献   

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