Purification and properties of a novel enzyme,N-acylamino acid racemase,from Streptomyces atratus Y-53 |
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Authors: | Shinji Tokuyama Hiroyuki Miya Kazunori Hatano Takeshi Takahashi |
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Institution: | (1) Technology Development Laboratories, Takeda Chemical Industries, Ltd., 17-85, Juso-honmachi 2-chome, 532 Yodogawa-ku, Osaka, Japan;(2) Present address: Hikari Department, Technology Development Laboratories, Takeda Chemical Industries, Ltd., Hikari, 743 Yamaguchi, Japan |
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Abstract: | A novel enzyme, N-acylamino acid racemase, was purified to homogeneity from Streptomyces atratus Y-53 and characterized. This enzyme catalyzes the interconversion of optically active N-acylamino acids. The relative molecular mass (Mr) of the enzyme was estimated to be about 41 000 and 244 000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration, respectively, indicating that the enzyme is composed of six subunits with an equal Mr. The enzyme showed a broad substrate specificity toward N-acylamino acids, such as N-acetylmethionine, N-chloroacetylphenylalanine and N-chloroacetylvaline. The apparent Michaelis constant (Km) values for N-acetyl-l-methionine and N-acetyl-d-methionine were calculated to be 15.2 and 5.6 mm, respectively. Enzyme activity was markedly enhanced by divalent metal ions, such as Co2+, Mg2+ and Mn2+, and was inhibited by metal-chelating reagent, indicating that the enzyme is a metalloenzyme. We propose to name the enzyme N-acylamino acid racemase (acylamino acid racemase).
Correspondence to: S. Tokuyama |
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