A pyridoxal-phosphate protein. The enzyme, which was characterized from the bacterium?Paracoccus denitrificans?NCIMB 8944, is highly specific for the?L-isomer of?erythro-3-hydroxyaspartate. Different from EC?4.3.1.16,?threo-3-hydroxy-L-aspartate ammonia-lyase and EC?4.3.1.27,?threo-3-hydroxy-D-aspartate ammonia-lyase. Requires a divalent cation such as Mn2+, Mg2+, or Ca2+.