THE FORMATE COMPLEX OF THE CYTOCHROME BO QUINOL OXIDASE OF ESCHERICHIA-COLI EXHIBITS A G = 12 EPR FEATURE ANALOGOUS TO THAT OF SLOW CYTOCHROME-OXIDASE

The cytochrome bo quinol oxidase of Escherichia coli is homologous in sequence and in structure to cytochrome aa3 type cytochrome oxidase in subunit 1, which contains the catalytic core. The cytochrome bo enzyme forms a formate complex which exhibits 'g = 12' and 'g = 2.9' EPR signals at X band; similar signals have previously been observed only in association with the 'slow' and formate-ligated states of cytochrome oxidase. These signals arise from transitions within integral spin multiplets identified with the homologous heme copper binuclear catalytic centers in both enzymes.