Involved in the ornithine fermentation pathway. Catalyzes the oxidative deamination of (2R,4S)-2,4-diaminopentanoate ((2R,4S)-DAP) to yield 2-amino-4-ketopentanoate (AKP). Although Ord is more efficient with (2R,4S)-DAP, the diastereoisomer (2R,4R)-DAP can also be metabolized. Ord is specific for NAD as hydrogen acceptor. (2R,4S)-2,4-diaminopentanoate + H2O + NAD(+) = (2R)-2-amino-4-oxopentanoate + H(+) + NADH + NH4(+) Allosterically activated by (2R,4S)-DAP. Negatively regulated by AKP, and by both acetyl-CoA and D-alanine. kcat is 34 sec(-1) with NAD as hydrogen acceptor. kcat is 5 sec(-1) with NADP as hydrogen acceptor. Homodimer. Belongs to the DapB family.