threo-3-Hydroxy-<small>D</small>-aspartate ammonia-lyase (EC 4.3.1.27, <small>D</small>-threo-3-hydroxyaspartate dehydratase) is an enzyme with systematic name threo-3-hydroxy-<small>D</small>-aspartate ammonia-lyase (oxaloacetate-forming). This enzyme catalyses the following chemical reaction
This enzyme is a pyridoxal-phosphate protein.