Malatdehydrogenase

Electrophoretically homogeneous preparations of MDH (CF 1.1.1.37) from bacteria of the genus Sphaerotilus were obtained through multistep purification. A dimeric form of the enzyme (73 kDa) functions during organotrophic growth in S. natans D-380. The molecular weight of the MDH subunits was 35 kDa. Michaelis constants for oxaloacetate, malate, NAD+, NADH were determined. The effect of metal ions on the activity of malate dehydrogenase was also studied, and the temperature optimums for the forward and reverse reactions were obtained. The spatial structure of MDH molecules was studied by atomic force microscopy.