Malate Dehydrogenase from the Thermophilic Bacterium Vulcanithermus medioatlanticus

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A. T. Eprintsev^*, M. I. Falaleeva, and N. V. Parfyonova

Voronezh State University, Universitetskaya pl. 1, 394006 Voronezh, Russia; fax: (0732) 208-755; E-mail: bsbc366@main.vsu.ru

^* To whom correspondence should be addressed.

Received July 16, 2004; Revision received September 20, 2004

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Thermostable dimeric malate dehydrogenase (MDH) was isolated from the microorganism of hydrothermal vents Vulcanithermus medioatlanticus. The enzyme was electrophoretically homogeneous and possessed the specific activity of 6.9 U/mg. The large molecular weight of the subunits (55 kD) is likely to provide the rigidity of the enzyme structure (the activation energy of the enzymatic reaction is 32.6 kJ/mol). The thermophilic MDH differs little from the mesophilic enzyme in terms of kinetic and regulatory characteristics.

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KEY WORDS: malate dehydrogenase, purification, Vulcanithermus medioatlanticus, oligomeric structure, catalytic properties, thermostability

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