Peroxide interaction with pulsed cytochrome oxidase. Optical and EPR studies.

EPR and optical analysis of the 420 nm form of cytochrome oxidase (Kumar, C., Naqui, A., and Chance, B. (1984) J. Biol. Chem. 259, 2073-2076) shows that 1) the 420 nm form possesses a 605 nm band, g = 5 EPR signals, and a slightly blue shifted 655 nm band; 2) the reaction of H2O2 with the 420 nm form generates the peroxide complex (Soret band at 427 nm) with the formation of a 580 nm band and abolition of both the 655 nm band and the g = 5 EPR signal. Comparison of our results with past data shows that various forms of oxidase formed from the resting oxidase through different protocols may be identified to be either the 420 nm or the 427 nm form and leads to identification of a peroxy intermediate during oxidase turnover.