Catalyzes the reversible reductive amination of pyruvate to L-alanine. May play a role in cell wall synthesis as L-alanine is an important constituent of the peptidoglycan layer (By similarity). H2O + L-alanine + NAD(+) = H(+) + NADH + NH4(+) + pyruvate Amino-acid degradation; L-alanine degradation via dehydrogenase pathway; NH(3) and pyruvate from L-alanine: step 1/1. Homohexamer. Trimer of dimer (By similarity). Belongs to the AlaDH/PNT family.