Nguyen L T, Nguyen K T, Kopecký J, Nová P, Novotná J, Bĕhal V
Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague.
Biochim Biophys Acta. 1995 Sep 6;1251(2):186-90. doi: 10.1016/0167-4838(95)00095-c.
The first valine dehydrogenase of S. aureofaciens had been described (Vancurová, I., Vancura, A., Volc, J., Neuzil, J., Flieger, M., Basarová, G. and Bĕhal, V. (1988) J. Bacteriol. 170, 5192-5196). In the present work, a second valine dehydrogenase was detected and purified by hydrophobic and fast protein liquid chromatographies. The enzyme has a relative molecular mass (M(r)) of 240,000 and is composed of 6 identical subunits, each of M(r) 41,000. In the presence of NAD, the enzyme catalyzes the reversible deamination of several branched- and straight-chain amino acids. The enzyme activities with L-2-aminobutyrate and deamino-NAD+ are markedly higher than those with L-valine and NAD+, respectively. The enzyme synthesis is significantly induced by L-valine but severely repressed by ammonia. Molecular and catalytic properties of the enzyme distinguish it from the other described valine dehydrogenases. The results directly demonstrate the presence of two valine dehydrogenases in a single Streptomyces species.
金色链霉菌的首个缬氨酸脱氢酶已被报道（万库罗娃，I.，万库拉，A.，沃尔克，J.，诺伊齐尔，J.，弗利格，M.，巴萨罗娃，G.和贝哈尔，V.（1988年）《细菌学杂志》170，5192 - 5196）。在本研究中，通过疏水色谱法和快速蛋白质液相色谱法检测并纯化了第二种缬氨酸脱氢酶。该酶的相对分子质量（M(r)）为240,000，由6个相同的亚基组成，每个亚基的M(r)为41,000。在NAD存在的情况下，该酶催化几种支链和直链氨基酸的可逆脱氨反应。该酶对L - 2 -氨基丁酸和脱氨基NAD⁺的酶活性分别明显高于对L -缬氨酸和NAD⁺的酶活性。该酶的合成受到L -缬氨酸的显著诱导，但受到氨的强烈抑制。该酶的分子和催化特性使其与其他已报道的缬氨酸脱氢酶有所不同。结果直接证明了在单个链霉菌物种中存在两种缬氨酸脱氢酶。
