KINETIC-STUDIES OF ELECTRON-TRANSFER ON PHOTOINDUCED HYDROGEN EVOLUTION WITH HYDROGENASE

The kinetic properties of the elementary processes of electron transfe r on photoinduced hydrogen evolution with hydrogenase, using cytochrom e c(3) and methyl viologen as electron carriers, were studied. The ele ctron transfer from reduced methyl viologen to cytochrome c(3) was mon ophasic and proceeded with a rate constant of 1.5 x 10(7) mol(-1) dm(3 ) s(-1). The rate constants for hydrogenase reduction with reduced cyt ochrome c(3) were determined to be k(2) = 154 s(-1) and K-m = 5.4 x 10 (-7) mol dm(-3), and were more efficient than that of reduced methyl v iologen. These results indicate that cytochrome c(3) reduction with re duced methyl viologen occurs, followed by rapid electron transfer from reduced cytochrome c(3) to hydrogenase.