KINETICS OF CO BINDING TO H-MOTIVE OXIDASES OF THE CAA3-TYPE FROM BACILLUS FTU AND OF THE O-TYPE FROM ESCHERICHIA-COLI()

The kinetics of CO rebinding with isolated Bacillus FTU caa3-type oxid ase and with solubilized Escherichia coli membranes (GO103 strain) con taining the o-type oxidase as the main O2-reducing enzyme were studied under reducing conditions by laser flash photolysis of the CO-oxidase complexes. The spectra of the optical absorbance changes upon photoly sis were characteristic of CO-caa3- and CO-o-oxidase complexes in Bac. FTU and E coli, respectively. Small quantities of d-type oxidase in E coli GO103 membranes were detected. The kinetics of CO reassociation with reduced caa3- and o-type oxidases were monophasic with tau 25 30 ms in both cases.