Acts on oxaloacetate, sulfopyruvate but not on pyruvate. Has a higher selectivity for the coenzyme NADH than for NADPH. (S)-malate + NAD(+) = H(+) + NADH + oxaloacetate (S)-malate + NADP(+) = H(+) + NADPH + oxaloacetate (2S)-3-sulfolactate + NAD(+) = 3-sulfopyruvate + H(+) + NADH Homodimer. Belongs to the LDH2/MDH2 oxidoreductase family.