The interaction of polymeric viologens with hydrogenases from Desulfovibrio desulfuricans and Clostridium pasteurianum

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Abstract
The interaction between hydrogenases from either D. desulfuricans or C. pasteurianum and electron donors methyl viologen or polymeric viologens was examined. Extracts from each organism contained a single gel electrophoretic band of active hydrogenase. The hydrogenase of D. desulfuricans was much more stable than that of G. pasteurianum. With methyl viologen apparent Km and Vm values were 0.5 mM and 0.62 .mu.mol H2/min per mg protein for the C. pasteurianum and 0.7 and 6.2 .mu.mol H2/min per mg protein, respectively for the D. desulfuricans enzyme. The hydrogenases bound the polymeric viologens more tightly than methyl viologen, more so for the enzyme of D. desulfuricans than for C. pasteurianum. Maximal rate of H2 production was less with the polymeric than with methyl viologen. The D. desulfuricans enzyme in conjunction with a polymeric viologen may perform better in a cell-free system aimed at hydrogen production than that from C. pasteurianum.