Purification and Physicochemical Properties of Malate Dehydrogenase from Bacteria of the Genus Beggiatoa

A. T. Eprintsev^*, M. I. Falaleeva, I. Yu. Stepanova, and N. V. Parfenova

Department of Plant Biochemistry and Physiology, Voronezh State University, Universitetskaya pl. 1, Voronezh, 394693 Russia; fax: (0732) 78-9755; E-mail: bsbc366@main.vsu.ru

^* To whom correspondence should be addressed.

Received December 19, 2001; Revision received April 2, 2002

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Homogeneous malate dehydrogenase (MDH) with a specific activity of 20-24 units per mg protein was purified from the sulfur bacterium Beggiatoa leptomitiformis strain D-402 grown organotrophically and lithotrophically and from the organotrophic bacterium Beggiatoa alba. MDHs from the B. leptomitiformis strain D-402 grown under organotrophic conditions and from B. alba are homodimers with the subunit molecular weight of 40 kD. Tetrameric MDH is formed in B. leptomitiformis strain D-402 grown under lithotrophic conditions. The dimeric and tetrameric forms of MDH from B. leptomitiformis D-402display some differences in kinetic properties.

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KEY WORDS: malate dehydrogenase, Beggiatoa leptomitiformis strain D-402, lithotrophy, purification, subunit structure, catalytic properties

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