Properties of Stable Hydrogenase from the Purple Sulfur Bacterium Lamprobacter modestohalophilus

O. A. Zadvorny^1*, N. A. Zorin¹, I. N. Gogotov¹, and V. M. Gorlenko²

¹Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino 142290, Moscow Region, Russia; fax: (0967) 33-0532; E-mail: olegz@issp.serpukhov.su

²Institute of Microbiology, Russian Academy of Sciences, pr. 60-letiya Oktyabrya 7/2, Moscow 117811, Russia; fax: (7-095) 135-6530; E-mail: vgorlenko@mail.ru

^* To whom correspondence should be addressed.

Received February 16, 2003; Revision received April 1, 2003

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Some properties of a hydrogenase from the recently isolated phototrophic sulfur bacterium Lamprobacter modestohalophilus strain Syvash and its resistance to a number of inactivating factors have been investigated. The enzyme consists of two subunits, 64 and 30 kD; pI = 4.5. The optimal pH was 8.5-9.5 for hydrogen uptake and 4.0 for H₂ evolution. Hydrogenase preparations were resistant to the effects of O₂, CO, and temperature, revealing high stability under storage. A considerable inactivation of the enzyme was observed at temperatures above 80°C; the temperature optimum of methyl viologen reduction by H₂ was 85°C. Inhibitory effects of Ni²⁺, Cd²⁺, and Mg²⁺ on the hydrogenase activity were shown to be reversible and competitive with respect to methyl viologen in the hydrogen oxidation reaction.

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KEY WORDS: hydrogenase, inhibition, CO, metal ions, purple sulfur bacteria

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