Purification, and some molecular and enzymatic features of a novel ccb-type cytochrome c oxidase from a microaerobic denitrifier, Magnetospirillum magnetotacticum.

A novel ccb-type cytochrome c oxidase was purified from the magnetic bacterium, Magnetospirillum magnetotacticum MS-1. The enzyme was composed of three subunits with M(r)'s of 43,000, 34,000 and 28,000, respectively, and contained 0.91 mol of protoheme, 2.0 mol of heme c and 0.70 g atom of copper per mol of minimal structural unit. One mol of enzyme oxidized 187 mol of horse heart ferrocytochrome c and 34.4 mol of M. magnetotacticum ferrocytochrome c550/s. The cytochrome c oxidase activity of the enzyme was 50% inhibited by 12 microM KCN. The enzyme seems to function as the terminal oxidase in microaerobic respiration.