Tyr‐139 in Thermus thermophilus 3‐isopropylmalate dehydrogenase is involved in catalytic function

FEBS Letters

Oshima, Tairo¹  Miyazaki, Kentaro¹ 

[1] Department of Life Science, Tokyo Institute of Technology, Nagatsuta 4259, Yokohama 227, Japan

关键词: Active site;    Catalysis;    3-Isopropylmalate dehydrogenase;    IPMDH;    3-isopropylmalate dehydrogenase;    ICDH;    isocitrate dehydrogenase;   

DOI  :  10.1016/0014-5793(93)80478-D

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The role of Tyr-139, which is thought to be located at the active site of Thermus thermophilus HB8 3-isopropylmalate dehydrogenase, has been investigated by site-specific replacement with phenylalanine. The replacement scarcely affected the Michaelis constant (K _m) for 3-isopropylmalate, but caused a 13-fold decrease of that for NAD. The catalytic constant (k _cat) showed a 14-fold decrease. Accordingly, the catalytic efficiency (k _cat/K _m) decreased for 3-isopropylmalate but not for NAD. The results suggest that Tyr-139 is involved in the catalytic function through interaction with 3-isopropylmalate.

【 授权许可】

Unknown