Malate dehydrogenases (MDH; EC 1.1.1.37) belong to the NAD-dependent dehydrogenases, and catalyze the reversible conversion of malate into oxaloacetate. MDH is a rather ubiquitous enzyme, for which several isoforms have been identified, differing in their subcellular localization and their specifity for the coenzyme NAD or NADP[1]. Malate metabolism plays a key role in mitochondrial respiration and as a mediator of hormone-induced enhancement of mitochondrial respiration. MDH is essential for transamination of glutamate by aspartate aminotransferase. These combined reactions are the mitochondrial part of the malate aspartate shuttle and are of importance in gluconeogenesis and ureogenesis and for the release of insulin by pancreatic islets[2].