Formate Dehydrogenase of Clostridium thermoaceticum : Incorporation of Selenium-75, and the Effects of Selenite, Molybdate, and Tungstate on the Enzyme

Abstract

The formation of the nicotinamide adenine dinucleotide phosphate-dependent formate dehydrogenase in Clostridium thermoaceticum is stimulated by the presence of molybdate and selenite in the growth medium. The highest formate dehydrogenase activity was obtained with 2.5 × 10⁻⁴ M Na₂MoO₄ and 5 × 10⁻⁵ Na₂SeO₃. Tungstate but not vanadate could replace molybdate and stimulate the formation of formate dehydrogenase. Tungstate stimulated activity more than molybdate, and in combination with molybdate the stimulation of formation of formate dehydrogenase was additive. Formate dehydrogenase was isolated from cells grown in the presence of Na₂⁷⁵SeO₂, and a correlation was observed between bound ⁷⁵Se and enzyme activity.