A mechanism for NADPH inhibition of catalase compound II formation

FEBS Letters

Hillar, A.¹  Nicholls, P.¹ 

[1] Department of Biological Sciences, Brock University, St. Catharines, Ontario, L2S 3A1, Canada

关键词: NADPH;    Catalase;    Compound II;    Peroxide;    Radical;    Ferrocyanide;    Compound I;    catalase peroxide compound I;    Compound II;    catalase peroxide compound II;    NADP;    nicotinamide adenine dinucleotide phosphate;   

DOI  :  10.1016/0014-5793(92)80969-N

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Catalase-bound NADPH both prevents and reverses the accumulation of inactive bovine liver catalase peroxide compound II generated by ‘endogenous’ donors under conditions of steady H₂O₂ formation without reacting rapidly with either compound I or compound II. It thus differs both from classical 2-electron donors of the ethanol type, and from 1-electron donors of the ferrocyanide/phenol type. NADPH also inhibits compound II formation induced by the exogenous one-electron donor ferrocyanide. A catalase reaction scheme is proposed in which the initial formation of compound II from compound I involves production of a neighbouring radical species. NADPH blocks the final formation of stable compound II by reacting as a 2-electron donor to compound II and to this free radical. The proposed behaviour resembles that of labile free radicals formed in cytochrome c peroxidase and myoglobin. Such radical migration patterns within haem enzymes are increasingly common motifs.

【 授权许可】

Unknown