Catalyzes the deamination of D-threo-3-hydroxyaspartate (D-THA). Also exhibits dehydratase activity towards L-threo-3-hydroxyaspartate (L-THA), L-erythro-3-hydroxyaspartate (L-EHA) and D-serine. (3R)-3-hydroxy-D-aspartate = NH4(+) + oxaloacetate Divalent metal ions, such as manganese, cobalt and nickel. Strongly inhibited by hydroxylamine. Modestly inhibited by EDTA. kcat is 10.93 sec(-1) for D-THA. kcat is 3.03 sec(-1) for L-THA. kcat is 8.68 sec(-1) for L-EHA. kcat is 0.89 sec(-1) for D-serine. Optimum pH is 8.5. Optimum temperature is 50 degrees Celsius. Monomer. Belongs to the DSD1 family.