Purity ≥ 95% by RP-HPLC, FPLC, or reducing/non-reducing SDS-PAGE Silver Stain. Chromatographically purified. Malate Dehydrogenase is an enzyme that catalyzes the conversion of (S)-malate and NAD+ to oxaloacetate and NADH. The DNA encoding MDH was cloned from cDNA library of chicken heart. Unit Definition: One unit is defined as 1umol of NAD+ production per minute under the assay conditions (25°C, pH 7.5).