Kinetic studies of electron transfer on photoinduced hydrogen evolution with hydrogenase

Abstract

The kinetic properties of the elementary processes of electron transfer on photoinduced hydrogen evolution with hydrogenase, using cytochrome c 3 and methyl viologen as electron carriers, were studied. The electron transfer from reduced methyl viologen to cytochrome c 3 was monophasic and proceeded with a rate constant of 1.5 × 10 7 mol −1 dm 3 s −1. The rate constants for hydrogenase reduction with reduced cytochrome c 3 were determined to be k 2 = 154 s −1 and K m = 5.4 × 10 −7 mol dm −3, and were more efficient than that of reduced methyl viologen. These results indicate that cytochrome c 3 reduction with reduced methyl viologen occurs, followed by rapid electron transfer from reduced cytochrome c 3 to hydrogenase.