Effect of hydroxycobalamin on the inhibition of cytochrome c oxidase by cyanide. II - In isolated cytochrome C oxidase.

The effects of hydroxycobalamin on inhibition of the isolated cytochrome c oxidase (EC 1.9.3.1) by cyanide were studied. No effect of hydroxycobalamin (HCo) and cyanocobalamin (CNCo) was observed on isolated cytochrome c oxidase. When cytochrome c oxidase inhibited by cyanide was treated with HCo the reversal of inhibition could be observed through the spectrum of cytochrome c oxidase without reversal of activity; CNCo had no effect. The treatment of cyano-cytochrome c oxidase with HCo suggests that there is the formation of cobalamin-cytochrome c oxidase complex plus CNCo, and it is possible that complex formation would be between the cobalt of cobalamin and proteic part of cytochrome c oxidase.