Kinetics of CO binding to putative Na(+)-motive oxidases of the o-type from Bacillus FTU and of the d-type from Escherichia coli.

ABSTRACT

The kinetics of CO reassociation with isolated Bacillus FTU o-type oxidase and with solubilized membranes of Escherichia coli (GO102 strain) containing the d-type oxidase only, upon laser flash photolysis under reducing conditions, were studied. In both cases, kinetics are shown to be composed of three phases (tau 35-70 microseconds, 0.25-0.5 ms and 2-5 ms). The spectra of the flash-induced absorbance changes of the first kinetic components proved to be characteristic of CO-o- and CO-b595 d-cytochrome complexes in Bac. FTU and E. coli, respectively. The spectra of the second and the third components appeared to be nearly the same in Bac. FTU and E. coli with peaks for the former at 436-437 and 590 nm and troughs at 419-420 and 569 nm; and for the latter with peaks at 436-437 and 558-560 nm and troughs at 419-420 and 575-578 nm. The similarity between the putative Na(+)-pumping Bac. FTU o- and E. coli d-type oxidases and their difference from the H(+)-motive Bac. FTU caa3- and E. coli o-type oxidases are discussed.