Catalyzes the alpha,beta-elimination reaction of both L- and D-alpha,beta-diaminopropionate (DAP) to form pyruvate and ammonia. In vitro the D-isomer of serine is degraded to pyruvate, though very poorly; other amino acids (L-serine, D- and L-threonine, D- and L-beta-Cl-alanine) are not substrates. In vivo allows poor growth on L-DAP or a DL-DAP mixture but not on D-DAP alone, this may be due to a poor promoter. DL-DAP is toxic in the absence of this enzyme, it may inhibit enzymes involved in the synthesis of pyruvate and aspartate, as well as amino acids derived from them. (S)-2,3-diaminopropanoate + H(+) + H2O = 2 NH4(+) + pyruvate (R)-2,3-diaminopropanoate + H(+) + H2O = 2 NH4(+) + pyruvate Binds 1 pyridoxal phosphate per subunit. Optimum pH is 8.0. Homodimer. Slightly induced by DL-DAP. No growth on minimal medium plus DL-DAP; growth can be restored by a mix of 8 amino acids (Arg, Asn, Cys, Glu, Ile, Leu, Met and Thr). Belongs to the diaminopropionate ammonia-lyase family.