Electrochemical study of the redox properties of [2Fe‐2S] ferredoxins Evidence for superreduction of the Rieske [2Fe‐2S] cluster

FEBS Letters

Link, Thomas A¹  Hagen, Wilfred R²  Verhagen, Marc F.J.M² 

[1] Universitätsklinikum Frankfurt, Zentrum für Biologische Chemie, Therapeutische Biochemie, Frankfurt am Main, Germany;Department of Biochemistry, Wageningen Agricultural University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands

关键词: Rieske;    Iron-sulfur cluster;    Spinach ferredoxin;    Cyclic voltammetry;    Superreduction;    SHE;    Standard Hydrogen Electrode;    SCE;    Saturated Calomel Electrode;   

DOI  :  10.1016/0014-5793(95)00152-Y

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Direct, unmediated electrochemistry has been used to compare the redox properties of [2Fe-2S] clusters in spinach ferredoxin, Spirulina platensis ferredoxin and the water soluble fragment of the Rieske protein. The use of electrochemistry enabled, for the first time, the observation of the second reduction step, [Fe(III),Fe(II)] to [Fe(II),Fe(II)], in a biological [2Fe-2S] system. A water-soluble fragment of the Rieske protein from bovine heart bc ₁ complex exhibits two subsequent quasi-reversible responses in cyclic voltammetry on activated glassy carbon. In contrast the ferredoxins from spinach and Spirulina platensis only show one single reduction potential. These results support a seniority scheme for biological iron-sulfur clusters relating cluster size to electron transfer versatility. Electrochemical reduction of spinach ferredoxin in the presence of NADP⁺ and ferredoxin: NADP⁺ oxidoreductase results in the generation of NADPH. The second order rate constant for the reaction between the ferredoxin and the reductase was estimated from cyclic voltammetry experiments to be >3 · 10⁵ M⁻¹ · s⁻¹.

【 授权许可】

Unknown