Influence of Metal Ions on Hydrogenase from the Purple Sulfur Bacterium Thiocapsa roseopersicina

O. A. Zadvorny^*, N. A. Zorin, and I. N. Gogotov

Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russia; fax: (0967) 79-0532; E-mail: olegz@issp.serpukhov.su

^* To whom correspondence should be addressed.

Received December 22, 1999; Revision received August 7, 2000

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The effects of some metal ions on the activity and activation of Thiocapsa roseopersicina hydrogenase have been studied. Inhibitory effects of Ni²⁺ and Cd²⁺ on the catalytic activity of the enzyme were reversible and competitive with respect to methyl viologen (MV) in the reaction of hydrogen oxidation. The affinity of these metal ions to the enzyme increased significantly with increasing pH, suggesting that their interactions are determined by electrostatic forces. Cu²⁺ and Hg²⁺ irreversibly inhibited the hydrogenase activity. A decrease in absorption of hydrogenase at 400 nm in the presence of these metal ions is indicative of the destruction of the FeS cluster in the enzyme.

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KEY WORDS: hydrogenase, metal ions, hydrogen, inhibition, activation, FeS cluster

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