Role of Lys‐110 of human NADH‐cytochrome b 5 reductase in NADH binding as probed by site‐directed mutagenesis

FEBS Letters

Nagai, Takushi¹  Yubisui, Toshitsugu¹  Shirabe, Komei¹  Fujimoto, Yoshio¹  Takeshita, Masazumi¹ 

[1] Department of Biochemistry, Oita Medical University, Hasama-machi, Oita 879-55, Japan

关键词: NADH-cytochrome b 5 reductase;    NADH binding;    Site-directed mutagenesis;    b 5R;    NADH-cytochrome b 5 reductase;    FNR;    ferredoxin-NADP+ reductase;    K110A;    the mutant enzyme with a Lys residue at position 110 (Lys-110) replaced by Ala;    K110M;    the mutant with Lys-110 replaced by Met;    K110R;    the mutant with Lys-110 replaced by Arg;   

DOI  :  10.1016/0014-5793(93)81104-8

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Lys-110 of human NADH-cytochrome b ₅ reductase was replaced by Ala, Met, or Arg by site-directed mutagenesis to evaluate the role of the residue. K _m values of purified Lys-110 → Ala and Lys-110 → Met mutants for NADH were approximately 200-fold and 1,100-fold higher than that of the wild-type, respectively, while the value of the Arg mutant was almost the same as that of the wild-type. These results indicate that the positive charge at position 110 is important for NADH binding. The k _cat value of Lys-110 → Ala was not affected, indicating that the residue only participates in the binding process in the reaction by forming an ionic interaction with phosphoryl group of NADH.

【 授权许可】

Unknown