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1.
Biosci Biotechnol Biochem ; 73(3): 729-32, 2009 Mar 23.
Article in English | MEDLINE | ID: mdl-19270409

ABSTRACT

Replacement of glycine by serine at positions 123 and 124 of phenylalanine dehydrogenases from Bacillus badius and Bacillus sphaericus respectively strikingly decreased enzyme activity toward aromatic amino acids and resulted in an elevation of relative activity toward aliphatic amino acids. The mutant from B. badius preferentially dehydrogenated branched-chain amino acids, while that from B. sphaericus acted on amino acids with straight-chain amino acids.


Subject(s)
Alcohol Oxidoreductases/genetics , Alcohol Oxidoreductases/metabolism , Amino Acid Substitution , Amino Acids/chemistry , Amino Acids/metabolism , Bacillus/enzymology , Kinetics , Mutation , Substrate Specificity
2.
J Biosci Bioeng ; 100(6): 662-6, 2005 Dec.
Article in English | MEDLINE | ID: mdl-16473777

ABSTRACT

Efficient selective synthesis of the secondary amide surfactant N-methyl lauroylethanolamide from methyl laurate and N-methylethanol amine by carrier-fixed Chirazyme L-2 (Candida antarctica) using a kinetic strategy has been demonstrated. When different solvents were screened for product yields using Chirazyme L-2, acetonitrile was found to be optimal. The rate of the reaction increased sharply by increasing the molar ratio of the reactants and the reaction temperature. When the reaction was performed at 50 degrees C for 36 h with 50 mmol ester and 100 mmol amine, the product was obtained in a 97.1% yield. With 50 mmol ester and 150 mmol amine, the highest yield (97.3%) was obtained after 16 h of incubation at 50 degrees C. It took only 5 h to get a yield of 95.8% at 60 degrees C using 50 mmol ester and 200 mmol amine. The enzyme activity in the amidation reaction mixture did not decrease notably even after six uses.


Subject(s)
Ethanolamines/chemistry , Laurates/chemistry , Laurates/chemical synthesis , Lipase/chemistry , Surface-Active Agents/chemical synthesis , Enzyme Activation , Fungal Proteins , Substrate Specificity
3.
J Antibiot (Tokyo) ; 57(11): 739-47, 2004 Nov.
Article in English | MEDLINE | ID: mdl-15712669

ABSTRACT

We have previously shown that gene clusters for biosyntheses of terpentecin and BE-40644, a diterpene antibiotic and a sesquiterpene antibiotic, respectively, were located in the adjacent mevalonate pathway gene clusters. In this study, a mevalonate pathway gene cluster was cloned from Streptomyces sp. strain KO-3988, which was known to produce furaquinocin A, employing a hybridization experiment using a 3-hydroxy-3-methyl glutaryl CoA (HMG-CoA) reductase gene, which had been previously cloned from the strain KO-3988, as a probe. By sequencing flanking regions, we found four open reading frames that could encode a putative cytochrome P450 (ORF1), an isoprenoid cyclase (ORF2), an unknown protein (ORF3), and a polyprenyl diphosphate synthase gene (ORF4) in the upstream region of the mevalonate pathway gene cluster, though we did not find any genes related to furaquinocin A biosynthesis. The two ORFs (ORF2 and 4) were expressed as recombinant enzymes in E. coli and used for studies to investigate functions of these products. The ORF4 product was confirmed to be a geranylgeranyl diphosphate (GGDP, C20) synthase. The ORF2 product proved to catalyze a conversion of GGDP into copalyl diphosphate, the first example of an enzyme with this function of prokaryotic origin. These results again showed that actinomycetes possessing the mevalonate pathway usually produce an isoprenoid and that its biosynthetic gene cluster exists in adjacent the mevalonate pathway gene cluster.


Subject(s)
Alkyl and Aryl Transferases/genetics , Mevalonic Acid/metabolism , Plant Proteins/genetics , Streptomyces/enzymology , Streptomyces/genetics , Anti-Bacterial Agents/biosynthesis , Chromatography, High Pressure Liquid , Cloning, Molecular , DNA, Bacterial/genetics , Deoxyribonuclease BamHI/biosynthesis , Deoxyribonuclease BamHI/genetics , Escherichia coli/metabolism , Molecular Sequence Data , Multigene Family/genetics , Reverse Transcriptase Polymerase Chain Reaction
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