Electrochemical definitions of O-2 sensitivity and oxidative inactivation in hydrogenases

TY - JOUR

T1 - Electrochemical definitions of O-2 sensitivity and oxidative inactivation in hydrogenases

AU - Vincent, K A

AU - Parkin, A

AU - Lenz, O

AU - Albracht, S P J

AU - Fontecilla-Camps, J C

AU - Cammack, R

AU - Friedrich, B

AU - Armstrong, F A

PY - 2005/12/28

Y1 - 2005/12/28

N2 - A new strategy is described for comparing, quantitatively, the ability of hydrogenases to tolerate exposure to O-2 and anoxic oxidizing conditions. Using protein film voltammetry, the inherent sensitivities to these challenges (thermodynamic potentials and rates of reactions) have been measured for enzymes from a range of mesophilic microorganisms. In the absence Of O-2, all the hydrogenases undergo reversible inactivation at various potentials above that of the H+/H-2 redox couple, and H-2 oxidation activities are thus limited to characteristic "potential windows". Reactions with O-2 vary greatly; the [FeFe]-hydrogenase from Desulfovibrio desulfuricans ATCC 7757, an anaerobe, is irreversibly damaged by O-2, surviving only if exposed to O-2 in the anaerobically oxidized state (which therefore affords protection). In contrast, the membrane-bound [NiFe]-hydrogenase from the aerobe, Ralstonia eutropha, reacts reversibly with O-2 even during turnover and continues to catalyze H-2 oxidation in the presence Of O-2

AB - A new strategy is described for comparing, quantitatively, the ability of hydrogenases to tolerate exposure to O-2 and anoxic oxidizing conditions. Using protein film voltammetry, the inherent sensitivities to these challenges (thermodynamic potentials and rates of reactions) have been measured for enzymes from a range of mesophilic microorganisms. In the absence Of O-2, all the hydrogenases undergo reversible inactivation at various potentials above that of the H+/H-2 redox couple, and H-2 oxidation activities are thus limited to characteristic "potential windows". Reactions with O-2 vary greatly; the [FeFe]-hydrogenase from Desulfovibrio desulfuricans ATCC 7757, an anaerobe, is irreversibly damaged by O-2, surviving only if exposed to O-2 in the anaerobically oxidized state (which therefore affords protection). In contrast, the membrane-bound [NiFe]-hydrogenase from the aerobe, Ralstonia eutropha, reacts reversibly with O-2 even during turnover and continues to catalyze H-2 oxidation in the presence Of O-2

U2 - 10.1021/ja055160v

DO - 10.1021/ja055160v

M3 - Article

SN - 1520-5126

SN - 1520-5126

VL - 127

SP - 18179

EP - 18189

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

IS - 51

ER -