Involved in the ornithine fermentation pathway. Catalyzes the oxidative deamination of (2R,4S)-2,4-diaminopentanoate (DAP) to yield 2-amino-4-ketopentanoate (AKP). (2R,4S)-2,4-diaminopentanoate + H2O + NAD(+) = (2R)-2-amino-4-oxopentanoate + H(+) + NADH + NH4(+) (2R,4S)-2,4-diaminopentanoate + H2O + NADP(+) = (2R)-2-amino-4-oxopentanoate + H(+) + NADPH + NH4(+) Inhibited by p-chloromercuribenzoate, iodoacetate and N-ethylmaleimide. Homodimer. Belongs to the DapB family.