Involved in the regulation of sugars and amino acids metabolisms during the night period. (S)-malate + NAD(+) = CO2 + NADH + pyruvate Divalent metal cations. Prefers magnesium or manganese. Activated by 2-ketoglutarate, phosphoenolpyruvate (PEP), fructose 1,6-biphosphate (FBP) and coenzyme A (acetyl-CoA and CoA) as homodimer and by oxaloacetate (OAA), 2-ketoglutarate, succinate, fumarate and CoA as heterodimer NAD-MEH. Repressed by succinate and fumarate as homodimer, in the presence of NAD(+) and competitively toward the substrate L-malate. kcat is 44.1 sec(-1) for the homodimer and 39 sec(-1) for the NAD-MEH heterodimer with NAD as substrate. In the presence of coenzyme A (CoA), kcat is 69.1 sec(-1) for the homodimer and 40.6 sec(-1) for the NAD-MEH heterodimer with NAD as substrate. Optimum pH is 6.6 for homodimer and 6.5 for NAD-MEH heterodimer. In the presence of coenzyme A (CoA), optimum pH is 6.8 for both homodimer and NAD-MEH heterodimer. Homodimer. Heterodimer of two related subunits in NAD-MEH complex. Interacts with NAD-ME1. Expressed in leaves, stems, flowers, and roots (at protein level). Present in pollen. In flowers, mostly present in anthers, stigmatic papillae, gynoecium (apical part) and filaments, and, barely in sepals (at protein level). In developing siliques, localized in the apical part and the abscission zone. In seedlings, expressed in cotyledons, hypocotyls, and root tip. Accumulates slowly in leaves as they mature, in the mesophyll and the cells that surround the vascular bundles. Accumulates during the night period (at protein level). When associated with NAD-ME1 disruption, loss of NAD-dependent malic enzyme activity associated with an altered steady-state levels of sugars and amino acids at the end of the light period. Belongs to the malic enzymes family. Truncated N-terminus. Truncated N-terminus.