A new spectral intermediate in cyanide binding with the oxidized cytochrome c oxidase

FEBS Letters

Berka, Vladimir¹  Musatov, Andrey¹  Konstantmov, Alexander A.³  Vygodina, Tatiana³  Nicholls, P.² 

[1] Laboratory of Biophysics, Institute of Experimental Physics, Slovac Academy of Sciences, Kosice, Czech and Slovak Federal Republic;Department of Biological Sciences, Brock University, St. Catharines, Ont., Canada;A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russian Federation

关键词: Cytochrome c oxidase;    Cyanide;    CuB;    Ligand binding;    Azide;    Respiratory chain;   

DOI  :  10.1016/0014-5793(93)81171-U

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Reaction of cyanide with oxidized cytochrome c oxidase at a low concentration of the ligand and pH > 8 reveals an initial phase, not reported earlier, associated with a small blue shift of the absorption spectrum, which is followed by a conventional red shift of the heme a ₃ ³⁺. The initial blue shift resembles the spectral changes induced under the same conditions by low concentrations of azide and it is not observed in the presence of 0.3 mM azide. It is suggested that, similarly to NO, cyanide and HN₃ cannot only bind to heme a ₃ but to Cu²⁺ _B as well, perturbing the spectrum of a ³⁺ ₃ indirectly. A rapid binding to Cu²⁺ _B could provide the long-sought intermediate in the cyanide reaction with heme a ³⁺ ₃, the existence of which is implied by the Michaelis-Menten type kinetics of the latter process.

【 授权许可】

Unknown