Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 34
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Biosci Biotechnol Biochem ; 85(2): 464-466, 2021 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-33604621

RESUMO

Here, we report a novel industrial aspartame production route, involving the enzymatic production of α-l-aspartyl-l-phenylalanine ß-methylester from l-aspartic acid dimethylester and l-phenylalanine by α-amino acid ester acyl transferase. The route also involves the chemical transformation of α-l-aspartyl-l-phenylalanine ß-methylester to α-l-aspartyl-l-phenylalanine methylester hydrochloride (aspartame hydrochloride) in an aqueous solution with methanol and HCl, followed by HCl removal to form aspartame.


Assuntos
Aciltransferases/metabolismo , Aspartame/química , Aspartame/síntese química , Indústrias , Técnicas de Química Sintética , Metanol/química , Água/química
2.
Bioorg Med Chem ; 26(7): 1327-1332, 2018 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-28698052

RESUMO

A panel of microorganisms was screened for selective reduction ability towards a racemic mixture of prochiral 2-amino-3-methyl-4-ketopentanoate (rac-AMKP). Several of the microorganisms tested produced greater than 0.5mM 4-hydroxyisoleucine (HIL) from rac-AMKP, and the stereoselectivity of HIL formation was found to depend on the taxonomic category to which the microorganism belonged. The enzymes responsible for the AMKP-reducing activity, ApAR and FsAR, were identified from two of these microorganisms, Aureobasidium pullulans NBRC 4466 and Fusarium solani TG-2, respectively. Three AMKP reducing enzymes, ApAR, FsAR, and the previously reported BtHILDH, were reacted with rac-AMKP, and each enzyme selectively produced a specific composition of HIL stereoisomers. The enzymes appeared to have different characteristics in recognition of the stereostructure of the substrate AMKP and in control of the 4-hydroxyl group configuration in the HIL product.


Assuntos
Oxirredutases do Álcool/metabolismo , Ascomicetos/enzimologia , Fusarium/enzimologia , Isoleucina/análogos & derivados , Sequência de Aminoácidos , Biocatálise , Isoleucina/biossíntese , Isoleucina/química , Alinhamento de Sequência
3.
Biosci Biotechnol Biochem ; 80(11): 2132-2137, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27352072

RESUMO

The establishment of renewable biofuel and chemical production is desirable because of global warming and the exhaustion of petroleum reserves. Sebacic acid (decanedioic acid), the material of 6,10-nylon, is produced from ricinoleic acid, a carbon-neutral material, but the process is not eco-friendly because of its energy requirements. Laccase-catalyzing oxidative cleavage of fatty acid was applied to the production of dicarboxylic acids using hydroxy and oxo fatty acids involved in the saturation metabolism of unsaturated fatty acids in Lactobacillus plantarum as substrates. Hydroxy or oxo fatty acids with a functional group near the carbon-carbon double bond were cleaved at the carbon-carbon double bond, hydroxy group, or carbonyl group by laccase and transformed into dicarboxylic acids. After 8 h, 0.58 mM of sebacic acid was produced from 1.6 mM of 10-oxo-cis-12,cis-15-octadecadienoic acid (αKetoA) with a conversion rate of 35% (mol/mol). This laccase-catalyzed enzymatic process is a promising method to produce dicarboxylic acids from biomass-derived fatty acids.

4.
Proc Natl Acad Sci U S A ; 110(44): 17808-13, 2013 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-24127592

RESUMO

In the representative gut bacterium Lactobacillus plantarum, we identified genes encoding the enzymes involved in a saturation metabolism of polyunsaturated fatty acids and revealed in detail the metabolic pathway that generates hydroxy fatty acids, oxo fatty acids, conjugated fatty acids, and partially saturated trans-fatty acids as intermediates. Furthermore, we observed these intermediates, especially hydroxy fatty acids, in host organs. Levels of hydroxy fatty acids were much higher in specific pathogen-free mice than in germ-free mice, indicating that these fatty acids are generated through polyunsaturated fatty acids metabolism of gastrointestinal microorganisms. These findings suggested that lipid metabolism by gastrointestinal microbes affects the health of the host by modifying fatty acid composition.


Assuntos
Ácidos Graxos Insaturados/metabolismo , Trato Gastrointestinal/microbiologia , Lactobacillus plantarum/enzimologia , Metabolismo dos Lipídeos/fisiologia , Redes e Vias Metabólicas/fisiologia , Sequência de Aminoácidos , Animais , Sequência de Bases , Cromatografia Líquida , Clonagem Molecular , Primers do DNA/genética , Trato Gastrointestinal/metabolismo , Lactobacillus plantarum/metabolismo , Redes e Vias Metabólicas/genética , Camundongos , Dados de Sequência Molecular , Família Multigênica/genética , Oxirredução , Oxirredutases/genética , Oxirredutases/metabolismo , Análise de Sequência de DNA , Homologia de Sequência , Organismos Livres de Patógenos Específicos , Espectrometria de Massas em Tandem
5.
Biosci Biotechnol Biochem ; 77(8): 1650-4, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23924711

RESUMO

A succinimide-assimilating bacterium, Pseudomonas putida s52, was found to be a potent producer of pyruvate from fumarate. Using washed cells from P. putida s52 as catalyst, 400 mM pyruvate was produced from 500 mM fumarate in a 36-h reaction. Bromopyruvate, a malic enzyme inhibitor, was used for the selection of mutants with higher pyruvate productivity. A bromopyruvate-resistant mutant, P. putida 15160, was found to be an effective catalyst for pyruvate production. Moreover, under batch bioreactor conditions, 767 mM of pyruvate was successfully produced from 1,000 mM fumarate in a 72-h reaction with washed cells from P. putida 15160 as catalyst.


Assuntos
Fermentação/genética , Oxirredução , Pseudomonas putida/enzimologia , Ácido Pirúvico/química , Reatores Biológicos , Cruzamento , Imidas/química , Imidas/metabolismo , Cinética , Ácido Pirúvico/isolamento & purificação
6.
Microbiologyopen ; 2(3): 471-81, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23554367

RESUMO

A unique operon structure has been identified in the genomes of several plant- and insect-associated bacteria. The distinguishing feature of this operon is the presence of tandem hilA and hilB genes encoding dioxygenases belonging to the PF13640 and PF10014 (BsmA) Pfam families, respectively. The genes encoding HilA and HilB from Pantoea ananatis AJ13355 were cloned and expressed in Escherichia coli. The culturing of E. coli cells expressing hilA (E. coli-HilA) or both hilA and hilB (E. coli-HilAB) in the presence of l-isoleucine resulted in the conversion of l-isoleucine into two novel biogenic compounds: l-4'-isoleucine and l-4,4'-dihydroxyisoleucine, respectively. In parallel, two novel enzymatic activities were detected in the crude cell lysates of the E. coli-HilA and E. coli-HilAB strains: l-isoleucine, 2-oxoglutarate: oxygen oxidoreductase (4'-hydroxylating) (HilA) and l-4'-hydroxyisoleucine, 2-oxoglutarate: oxygen oxidoreductase (4-hydroxylating) (HilB), respectively. Two hypotheses regarding the physiological significance of C-4(4')-hydroxylation of l-isoleucine in bacteria are also discussed. According to first hypothesis, the l-isoleucine dihydroxylation cascade is involved in synthesis of dipeptide antibiotic in P. ananatis. Another unifying hypothesis is that the C-4(4')-hydroxylation of l-isoleucine in bacteria could result in the synthesis of signal molecules belonging to two classes: 2(5H)-furanones and analogs of N-acyl homoserine lactone.


Assuntos
Dioxigenases/genética , Dioxigenases/metabolismo , Isoleucina/metabolismo , Redes e Vias Metabólicas/genética , Pantoea/enzimologia , Pantoea/metabolismo , Biotransformação , Clonagem Molecular , Escherichia coli/genética , Expressão Gênica
7.
Biosci Biotechnol Biochem ; 77(3): 618-23, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23470770

RESUMO

An enzymatic production method for synthesizing L-alanyl-L-glutamine (Ala-Gln) from L-alanine methyl ester hydrochloride (AlaOMe) and L-glutamine (Gln) was developed in this study. The cultivation conditions for an Escherichia coli strain overexpressing α-amino acid ester acyltransferase from Sphingobacterium siyangensis AJ 2458 (SAET) and reaction conditions for Ala-Gln production were optimized. A high cell density culture broth prepared by fed-batch cultivation showed 440 units/mL of Ala-Gln-producing activity. In addition, an Ala-Gln-producing reaction using intact E. coli cells overexpressing SAET under optimum conditions was conducted. A total Ala-Gln yield of 69.7 g/L was produced in 40 min. The molar yield was 67% against both AlaOMe and Gln.


Assuntos
DNA Recombinante/genética , Dipeptídeos/biossíntese , Escherichia coli/genética , Escherichia coli/metabolismo , Sphingobacterium/enzimologia , Sphingobacterium/genética , Aminoácido N-Acetiltransferase , Técnicas de Cultura , Escherichia coli/crescimento & desenvolvimento , Indústrias
8.
Appl Microbiol Biotechnol ; 97(6): 2467-72, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22584432

RESUMO

L-Leucine 5-hydroxylase (LdoA) previously found in Nostoc punctiforme PCC 73102 is a novel type of Fe(II)/α-ketoglutarate-dependent dioxygenase. LdoA catalyzed regio- and stereoselective hydroxylation of L-leucine and L-norleucine into (2S,4S)-5-hydroxyleucine and (2S)-5-hydroxynorleucine, respectively. Moreover, LdoA catalyzed sulfoxidation of L-methionine and L-ethionine in the same manner as previously described L-isoleucine 4-hydroxylase. Therefore LdoA should be a promising biocatalyst for effective production of industrially useful amino acids.


Assuntos
Dioxigenases/isolamento & purificação , Dioxigenases/metabolismo , Ferro/metabolismo , Ácidos Cetoglutáricos/metabolismo , Leucina/análogos & derivados , Leucina/metabolismo , Nostoc/enzimologia , Etionina/metabolismo , Metionina/metabolismo , Norleucina/metabolismo , Safrol/análogos & derivados , Safrol/metabolismo
9.
FEMS Microbiol Lett ; 331(2): 97-104, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22448874

RESUMO

L-isoleucine-4-hydroxylase (IDO) is a recently discovered member of the Pfam family PF10014 (the former DUF 2257 family) of uncharacterized conserved bacterial proteins. To uncover the range of biochemical activities carried out by PF10014 members, eight in silico-selected IDO homologues belonging to the PF10014 were cloned and expressed in Escherichia coli. L-methionine, L-leucine, L-isoleucine and L-threonine were found to be catalysed by the investigated enzymes, producing L-methionine sulfoxide, 4-hydroxyleucine, 4-hydroxyisoleucine and 4-hydroxythreonine, respectively. An investigation of enzyme kinetics suggested the existence of a novel subfamily of bacterial dioxygenases within the PF10014 family for which free L-amino acids could be accepted as in vivo substrates. A hypothesis regarding the physiological significance of hydroxylated l-amino acids is also discussed.


Assuntos
Aminoácidos/metabolismo , Bactérias/enzimologia , Dioxigenases/metabolismo , Escherichia coli/enzimologia , Bactérias/classificação , Bactérias/genética , Clonagem Molecular , Dioxigenases/classificação , Dioxigenases/genética , Escherichia coli/genética , Hidroxilação , Isoleucina/metabolismo , Cinética , Leucina/metabolismo , Metionina/metabolismo , Especificidade por Substrato , Treonina/metabolismo
10.
Biosci Biotechnol Biochem ; 75(11): 2087-92, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22056425

RESUMO

The gene encoding α-amino acid ester acyl transferase (AET), the enzyme that catalyzes the peptide-forming reaction from amino acid methyl esters and amino acids, was cloned from Empedobacter brevis ATCC14234 and Sphingobacterium siyangensis AJ2458 and expressed in Escherichia coli. This is the first report on the aet gene. It encodes a polypeptide composed of 616 (ATCC14234) and 619 (AJ2458) amino acids residues. The V(max) values of these recombinant enzymes during the catalysis of L-alanyl-L-glutamine formation from L-alanine methylester and L-glutamine were 1,010 U/mg (ATCC14234) and 1,154 U/mg (AJ2458). An amino acid sequence similarity search revealed 35% (ATCC14234) and 36% (AJ2458) identity with an α-amino acid ester hydrolase from Acetobacter pasteurianus, which contains an active-site serine in the consensus serine enzyme motif, GxSYxG. In the deduced amino acid sequences of AET from both bacteria, the GxSYxG motif was conserved, suggesting that AET is a serine enzyme.


Assuntos
Aciltransferases/genética , Alanina/metabolismo , Flavobacterium/enzimologia , Glutamina/metabolismo , Sphingobacterium/enzimologia , Aciltransferases/metabolismo , Alanina/genética , Sequência de Aminoácidos , Sequência de Bases , Clonagem Molecular , Flavobacterium/genética , Glutamina/genética , Dados de Sequência Molecular , Homologia de Sequência de Aminoácidos , Sphingobacterium/genética
11.
Biochem Biophys Res Commun ; 416(1-2): 188-93, 2011 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-22093837

RESUMO

Linoleic acid isomerase was identified as a multi-component enzyme system that consists of three enzymes that exist in both the membrane and soluble fractions of Lactobacillus plantarum. One enzyme (CLA-HY) is present in the membrane fraction, while two enzymes (CLA-DH and CLA-DC) exist in the soluble fraction. Three Escherichia coli transformants expressing CLA-HY, CLA-DH, and CLA-DC were constructed. Conjugated linoleic acid (CLA) and 10-hydroxy-12-octadecenoic acid were generated from linoleic acid only when all these three E. coli transformants were used as catalysts simultaneously. CLA-HY catalyzed the hydration reaction, a part of linoleic acid isomerization, to produce 10-hydroxy-12-octadecenoic acid. This multi-component enzyme system required oxidoreduction cofactors such as NADH and FAD. This is the first report to reveal enzymes genes and the elaborate machinery that synthesizes CLA, especially an important isomer of cis-9, trans-11-CLA, in lactic acid bacteria.


Assuntos
Proteínas de Bactérias/química , Enzimas/química , Lactobacillus plantarum/enzimologia , Ácidos Linoleicos Conjugados/biossíntese , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Catálise , Clonagem Molecular , Enzimas/genética , Enzimas/isolamento & purificação , Lactobacillus plantarum/genética
12.
Appl Environ Microbiol ; 77(19): 6926-30, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21821743

RESUMO

We determined the enzymatic characteristics of an industrially important biocatalyst, α-ketoglutarate-dependent l-isoleucine dioxygenase (IDO), which was found to be the enzyme responsible for the generation of (2S,3R,4S)-4-hydroxyisoleucine in Bacillus thuringiensis 2e2. Depending on the amino acid used as the substrate, IDO catalyzed three different types of oxidation reactions: hydroxylation, dehydrogenation, and sulfoxidation. IDO stereoselectively hydroxylated several hydrophobic aliphatic l-amino acids, as well as l-isoleucine, and produced (S)-3-hydroxy-l-allo-isoleucine, 4-hydroxy-l-leucine, (S)-4-hydroxy-l-norvaline, 4-hydroxy-l-norleucine, and 5-hydroxy-l-norleucine. The IDO reaction product of l-isoleucine, (2S,3R,4S)-4-hydroxyisoleucine, was again reacted with IDO and dehydrogenated into (2S,3R)-2-amino-3-methyl-4-ketopentanoate, which is also a metabolite found in B. thuringiensis 2e2. Interestingly, IDO catalyzed the sulfoxidation of some sulfur-containing l-amino acids and generated l-methionine sulfoxide and l-ethionine sulfoxide. Consequently, the effective production of various modified amino acids would be possible using IDO as the biocatalyst.


Assuntos
Aminoácidos/metabolismo , Bacillus thuringiensis/enzimologia , Bacillus thuringiensis/metabolismo , Dioxigenases/metabolismo , Hidroxilação , Ácidos Cetoglutáricos/metabolismo , Especificidade por Substrato
13.
Biosci Biotechnol Biochem ; 75(2): 318-22, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21307591

RESUMO

Linoleic acid isomerase in Lactobacillus plantarum was found to be a novel multi-component enzyme system widespread in membrane and soluble fractions. The isomerization reaction involved a hydration step, 10-hydroxy-12-octadecenoic acid production from linoleic acid, as part of the reaction, and the hydration reaction was catalyzed by the membrane fraction. Both membrane and soluble fractions were required for the whole isomerization reaction, i.e., conjugated linoleic acid (CLA) production from linoleic acid, and for CLA production from 10-hydroxy-12-octadecenoic acid, a reaction intermediate. The multi-component enzyme system was inhibited by o-phenanthroline, and divalent metal ions such as Ni(2+) and Co(2+) restored activity. Metal oxides such as VO(4)(3+), MoO(4)(2+), and MnO(4)(2+) enhanced activity. The multi-component enzyme systems required oxidoreduction cofactors such as NADH together with FAD or NADPH for total activity.


Assuntos
Coenzimas/metabolismo , Isomerases/metabolismo , Lactobacillus plantarum/enzimologia , Ácido Linoleico/metabolismo , Sistema Livre de Células/efeitos dos fármacos , Sistema Livre de Células/metabolismo , Quelantes/farmacologia , Isomerases/química , Isomerases/isolamento & purificação , Ácidos Linoleicos Conjugados/biossíntese , Metais/farmacologia , Oxirredução
14.
Appl Microbiol Biotechnol ; 89(6): 1929-38, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21069315

RESUMO

4-Hydroxyisoleucine (HIL) found in fenugreek seeds has insulinotropic and anti-obesity effects and is expected to be a novel orally active drug for insulin-independent diabetes. Here, we show that the newly isolated strain Bacillus thuringiensis 2e2 and the closely related strain B. thuringiensis ATCC 35646 operate a novel metabolic pathway for L-isoleucine (L-Ile) via HIL and 2-amino-3-methyl-4-ketopentanoic acid (AMKP). The HIL synthesis was catalyzed stereoselectively by an α-ketoglutaric acid-dependent dioxygenase and to be useful for efficient production of a naturally occurring HIL isomer, (2S,3R,4S)-HIL. The (2S,3R,4S)-HIL was oxidized to (2S,3R)-AMKP by a NAD(+)-dependent dehydrogenase. The metabolic pathway functions as an effective bypass pathway that compensates for the incomplete tricarboxylic acid (TCA) cycle in Bacillus species and also explains how AMKP, a vitamin B(12) antimetabolite with antibiotic activity, is synthesized. These novel findings pave a new way for the commercial production of HIL and also for AMKP.


Assuntos
Bacillus thuringiensis/metabolismo , Vias Biossintéticas/genética , Isoleucina/análogos & derivados , Isoleucina/biossíntese , Bacillus thuringiensis/genética , Coenzimas/metabolismo , Dioxigenases/genética , Dioxigenases/metabolismo , Cetoácidos/metabolismo , NAD/metabolismo , Oxirredução , Oxirredutases/metabolismo , Ácidos Pentanoicos/metabolismo
15.
N Biotechnol ; 27(4): 317-23, 2010 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-20188874

RESUMO

Three extracellular ligninolytic oxidoreductases that are produced by a commercial laccase-producing Trametes sp. Ha1 were purified and characterized. This fungus showed strong ligninolytic oxidoreductase activity with and without hydrogen peroxide present in the reaction mixture. The oxidoreductase activity was found to be derived from two laccases and a peroxidase. One of the two laccases represents a main component of the commercial laccase preparation from Trametes sp. Ha1. This enzyme had a high thermostability, which makes it attractive for practical applications. The second laccase was induced by the addition of p-xylidine into the culture medium and showed unique characteristics with respect to pI value and substrate specificity. The peroxidase showed wide oxidation activity against aromatic compounds.


Assuntos
Lacase/metabolismo , Peroxidases/metabolismo , Trametes/enzimologia , Meios de Cultura/farmacologia , Eletroforese em Gel de Poliacrilamida , Indução Enzimática/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Estabilidade Enzimática/efeitos dos fármacos , Espaço Extracelular/efeitos dos fármacos , Espaço Extracelular/enzimologia , Isoenzimas/antagonistas & inibidores , Isoenzimas/biossíntese , Lacase/antagonistas & inibidores , Lacase/biossíntese , Especificidade por Substrato/efeitos dos fármacos , Trametes/efeitos dos fármacos , Xilenos/farmacologia
16.
Biochem Biophys Res Commun ; 390(3): 506-10, 2009 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-19850012

RESUMO

The unique function of 4-hydroxyisoleucine (4-HIL) is to stimulate glucose-induced insulin secretion in a glucose-dependent manner. 4-HIL is distributed only in certain kinds of plants and mushrooms, but the biosynthetic mechanism of 4-HIL has not been elucidated. Moreover, 4-HIL-producing microorganisms have not been reported. l-isoleucine (l-Ile) hydroxylating activity producing 4-HIL was detected in a cell lysate of Bacillus thuringiensis strain 2e2 AKU 0251 obtained from the mid-late exponential phase of growth. Properties of the purified hydroxylase demonstrated that it is a alpha-ketoglutaric acid (alpha-KG) dependent l-Ile dioxygenase (IDO) and requires alpha-KG, ferric ion, and ascorbic acid for its maximum activity. IDO showed high stereoselectivity in l-Ile hydroxylation producing only (2S,3R,4S)-4-HIL. The N-terminal 22 amino acids sequence revealed high homology to a hypothetical protein (GenBank ID: RBTH_06809) in B. thuringiensis serovar israelensis ATCC 35646. The histidine motif, which is conserved in alpha-KG dependent dioxygenases, is found in RBTH_06809.


Assuntos
Bacillus thuringiensis/enzimologia , Dioxigenases/metabolismo , Isoleucina/análogos & derivados , Sequência de Aminoácidos , Dioxigenases/química , Dioxigenases/genética , Hidroxilação , Isoleucina/biossíntese , Isoleucina/química , Dados de Sequência Molecular
17.
J Biosci Bioeng ; 108(3): 190-3, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19664550

RESUMO

Screening was carried out for microorganisms able to produce N-(l-alpha-l-aspartyl)-l-phenylalanine methyl ester [APM] from l-isoasparagine and l-phenylalanine methyl ester hydrochloride. Of the 422 strains examined, 44 strains belonging to the family Enterobacteriaceae were found to produce APM. The enzyme catalyzing APM production was purified and identified as dipeptidase E.


Assuntos
Asparagina/química , Dipeptidases/isolamento & purificação , Fenilalanina/análogos & derivados , Biotecnologia/métodos , Catálise , Citrobacter/enzimologia , Dipeptidases/análise , Dipeptidases/química , Eletroforese em Gel de Poliacrilamida , Enterobacteriaceae/enzimologia , Escherichia coli/enzimologia , Concentração de Íons de Hidrogênio , Modelos Químicos , Fenilalanina/química , Proteínas Recombinantes/química , Salmonella typhimurium/enzimologia , Shigella flexneri/enzimologia
18.
Biosci Biotechnol Biochem ; 73(5): 1221-3, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19420686

RESUMO

In the last few decades, enzymatic production of 3,4-dihydroxyphenyl-L-alanine (L-dopa) using tyrosine phenol-lyase (Tpl) has been industrialized. This method has an intrinsic problem of tyrosine contamination because Tpl is synthesized under tyrosine-induced conditions. Herein, we constructed a hyper-L-dopa-producing strain by exploiting a mutant TyrR, an activator of tpl. The highest productivity was obtained for the strain grown under non-induced conditions. It was 30-fold higher than that obtained for tyrosine-induced wild-type cells.


Assuntos
Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Erwinia/citologia , Erwinia/metabolismo , Levodopa/biossíntese , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Mutação
19.
Appl Microbiol Biotechnol ; 84(1): 87-97, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19319523

RESUMO

Lactobacillus plantarum AKU 1009a effectively transforms linoleic acid to conjugated linoleic acids of cis-9,trans-11-octadecadienoic acid (18:2) and trans-9,trans-11-18:2. The transformation of various polyunsaturated fatty acids by washed cells of L. plantarum AKU 1009a was investigated. Besides linoleic acid, alpha-linolenic acid [cis-9,cis-12,cis-15-octadecatrienoic acid (18:3)], gamma-linolenic acid (cis-6,cis-9,cis-12-18:3), columbinic acid (trans-5,cis-9,cis-12-18:3), and stearidonic acid [cis-6,cis-9,cis-12,cis-15-octadecatetraenoic acid (18:4)] were found to be transformed. The fatty acids transformed by the strain had the common structure of a C18 fatty acid with the cis-9,cis-12 diene system. Three major fatty acids were produced from alpha-linolenic acid, which were identified as cis-9,trans-11,cis-15-18:3, trans-9,trans-11,cis-15-18:3, and trans-10,cis-15-18:2. Four major fatty acids were produced from gamma-linolenic acid, which were identified as cis-6,cis-9,trans-11-18:3, cis-6,trans-9,trans-11-18:3, cis-6,trans-10-18:2, and trans-10-octadecenoic acid. The strain transformed the cis-9,cis-12 diene system of C18 fatty acids into conjugated diene systems of cis-9,trans-11 and trans-9,trans-11. These conjugated dienes were further saturated into the trans-10 monoene system by the strain. The results provide valuable information for understanding the pathway of biohydrogenation by anaerobic bacteria and for establishing microbial processes for the practical production of conjugated fatty acids, especially those produced from alpha-linolenic acid and gamma-linolenic acid.


Assuntos
Ácidos Graxos Insaturados/metabolismo , Ácidos Graxos/metabolismo , Lactobacillus plantarum/metabolismo , Ácidos Linoleicos Conjugados/metabolismo , Biotransformação , Ácidos Graxos/química , Ácidos Graxos Insaturados/química , Hidrogenação , Lactobacillus plantarum/química , Ácidos Linoleicos Conjugados/química , Ácido alfa-Linoleico/química , Ácido alfa-Linoleico/metabolismo
20.
Biosci Biotechnol Biochem ; 72(11): 3002-5, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18997407

RESUMO

Genes encoding alpha-methylserine hydroxymethyltransferase from Aminobacter sp. AJ110403 and Ensifer sp. AJ110404 were cloned and expressed in Escherichia coli. The purified enzymes were homodimers with a 46-kDa subunit and contained 1 mol/mol-subunit of pyridoxal 5'-phosphate. The V(max) of these enzymes catalyzing the conversion of alpha-methyl-L-serine to D-alanine via tetrahydrofolate was 22.1 U/mg (AJ110403) and 15.4 U/mg (AJ110404).


Assuntos
Alphaproteobacteria/enzimologia , Alphaproteobacteria/genética , Glicina Hidroximetiltransferase/genética , Proteínas Recombinantes/genética , Sinorhizobium/enzimologia , Sinorhizobium/genética , Sequência de Aminoácidos , Precipitação Química , Clonagem Molecular , Glicina Hidroximetiltransferase/química , Glicina Hidroximetiltransferase/isolamento & purificação , Glicina Hidroximetiltransferase/metabolismo , Dados de Sequência Molecular , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...