Description
Malate dehydrogenase is an enzyme in the citric acid cycle that catalyzes the conversion of malate into oxaloacetate (using NAD+) and vice versa (this is a reversible reaction). Malate dehydrogenase is not to be confused with malic enzyme, which catalyzes the conversion of malate to pyruvate producing NADPH. Malate dehydrogenase is also involved in gluconeogenesis, the synthesis of glucose from smaller molecules. Pyruvate in the mitochondria is acted upon by pyruvate carboxylase to form oxaloacetate, a citric acid cycle intermediate. In order to get the oxaloacetate out of the mitochondria, malate dehydrogenase reduces it to malate, and it then traverses the inner mitochondrial membrane. Once in the cytosol, the malate is oxidized back to oxaloacetate by cytosolic malate dehydrogenase. Finally, phosphoenol-pyruvate carboxy kinase (PEPCK) converts oxaloacetate to phosphoenol pyruvate.
Abbr
MDH (Decarboxylating), Native (Thermophillic bacteria)
Source
Thermophillic bacteria
Applications
Diagnostic test and biosensors; NADH recycling; carboxylation and decarboxylation at high temperatures. This enzyme is a potential candidate for biocatalysis, suitable for pharmaceutical development / manufacturing.
Enzyme Commission Number
EC 1.1.1.38
Unit Definition
One unit of enzyme is defined as the amount catalyzing the oxidation of 1μmol NADH (ε= 6.22 mM-1cm-1) per min at 37°C.
Thermal stability
~100% stability after 1 hour at 70°C
Buffer
50 mM Tris-HCl (pH 8.0), 50 mM NaCl
Synonyms
malic dehydrogenase; L-malate dehydrogenase; NAD-L-malate dehydrogenase; malic acid dehydrogenase; NAD-dependent malic dehydrogenase; NAD-malate dehydrogenase; NAD-malic dehydrogenase; malate NAD dehydrogenase; NAD-dependent malate dehydrogenase; NAD-sp; ECific malate dehydrogenase; NAD-linked malate dehydrogenase; MDH; L-malate-NAD+ oxidoreductase; S-malate: NAD+ oxidoreductase; EC 1.1.1.38; Malate Dehydrogenase