Characteristic differences in the mode of quinone reduction and stability between energy‐coupled and ‐uncoupled NADH‐quinone reductases from bacterial respiratory chain

FEBS Letters

Hayashi, Maki¹  Unemoto, Tsutomu¹  Miyoshi, Tohoru¹ 

[1] Laboratory of Membrane Biochemistry, Faculty of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263, Japan

关键词: Respiratory chain;    NADH-quinone reductase;    One-electron transfer;    Two-electron transfer;    Proton pump;    Sodium pump;   

DOI  :  10.1016/0014-5793(92)80835-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Bacterial respiratory chain has two types of NADH-quinone reductase (NQR): one is energy-coupled (type-1) and the other has no energy-transducing capacity, that is, energy-uncoupled (type-2). Each of the NADH-reacting flavoprotein subunits of NQR-1 from Escherichia coli and the marine Vibrio alginolyticus reduced quinone to semiquinone radicals by the one-electron transfer pathway and was very sensitive to preincubation with NADH. On the other hand, the NQR-2 from these bacteria reduced quinone to quinol by the two-electron transfer pathway and was insensitive to preincubation with NADH. Since the NQR-1 from E. coli functions as a proton pump, whereas that from the marine V. alginolyticus functions as a sodium pump, the formation of semiquinone radicals as an intermediate is likely to be a common mechanism to functioning as either proton or sodium pump.

【 授权许可】

Unknown