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

The interaction between hydrogenases from either Desulfovibrio desulfuricans or Clostridium 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 Cl. pasteurianum. With methyl viologen apparent Km and Vm values were 0.5 mM and 0.62 μmol H2/min per milligram protein for the Cl. pasteurianum and 0.7 and 6.2 μmol H2/min per milligram 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 Cl. pasteurianum. Maximal rate of hydrogen production was less with the polymeric than with methyl viologen. The results suggest that 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 Cl. pasteurianum.