Valine Dehydrogenase from Streptomyces hygroscopicus CH-7: Purification and Properties
Valine dehydrogenase (VDH) from Streptomyces hygroscopicus CH-7 was purified 327-fold with 21% yield, using ion exchange and hydrophobic chromatography. The enzyme had an Mr 31000 in denaturing conditions and an Mr 63000 in gel filtration chromatography, indicating that it is homo-dimer. The most pr...
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Published in | Actinomycetologica Vol. 13; no. 2; pp. 76 - 81 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
The Society for Actinomycetes Japan
1999
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Online Access | Get full text |
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Summary: | Valine dehydrogenase (VDH) from Streptomyces hygroscopicus CH-7 was purified 327-fold with 21% yield, using ion exchange and hydrophobic chromatography. The enzyme had an Mr 31000 in denaturing conditions and an Mr 63000 in gel filtration chromatography, indicating that it is homo-dimer. The most preferable substrates are L-valine in deamination reaction and 2-ketoisovalerate in amination reaction. The enzyme requires NAD+ as a cofactor. The VDH from S. hygroscopicus CH-7 shows maximum activity at approximately pH 10.7 and 9.7 for deamination and amination reactions, respectively. The enzyme was significantly inhibited by p-chloromercuri-benzoate, Hg2+ and other metal ions, which suggests that the presence of SH- groups are necessary for the catalytic reaction. The apparent Michaelis constants for L-valine, NAD+ 2-ketoisovalerate, NADH and NH4+ were: 1.26 mM, 0.164 mM, 0.41 mM, 0.026 mM and 50.1 mM. |
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ISSN: | 0914-5818 1881-6371 |
DOI: | 10.3209/saj.13_76 |