Catalyzes a reversible NAD-dependent dehydrogenase reaction involved in central metabolism and redox homeostasis between organellar compartments. (S)-malate + NAD(+) = H(+) + NADH + oxaloacetate Decreased activity upon treatment with hydrogen peroxide. kcat is 608 sec(-1) with oxaloacetate as substrate (PubMed:29194485). kcat is 677 sec(-1) with NADH as substrate (PubMed:29194485). Forms a homodimer (PubMed:29194485). Forms a disulfide-linked homodimer upon oxidation (PubMed:29194485). Interacts with 14-3-3-like proteins GRF1 GRF3 and GRF8 (PubMed:22104211). Interacts with TRX1, TRX2, TRX3, TRX4 and TRX5 (PubMed:29194485). Expressed in rosette leaves. Belongs to the LDH/MDH superfamily. MDH type 2 family.