(S)-malate + NAD(+) = H(+) + NADH + oxaloacetate Enzyme activity is enhanced by acetylation. Homodimer. Expressed in flagella of epididymal sperm. Acetylation is enhanced after treatment either with trichostin A (TCA) or with nicotinamide (NAM) with the appearance of tri- and tetraacetylations. Glucose also increases acetylation. Belongs to the LDH/MDH superfamily. MDH type 1 family.