The cytochrome c binding site on cytochrome c oxidase.

Cytochrome c oxidase (EC 1.9.3.1) is the terminal enzyme of the mitochondria respiratory chain catalysing electron transfer from cytochrome c to molecular oxygen [ 1,2]. The molecular mechanism of this process is still not understood. At present, little is known about such important structural features as the position of the prosthetic groups or the location and characteristics of the cytochrome c binding sites in the cytochrome c oxidase complex 131. The aim of this paper is to provide information about this latter problem as part of a more general effort of our laboratories to elucidate the relationship between structure and functions of cytochrome c oxidase. as in [S]. Cytochrome c oxidase was isolated from beef heart as in [7], the final dialysis step was omitted. The activity, measured polarographically in 0.5% Tween 80, 50 mM phosphate buffer (pH_7i4) ranged_fym 130170 mol cytochrome c. s . molaa3 . The covalent enzyme-substrate complex was