Catalyzes the dehydration of D-arabinonate to 2-keto-3-deoxy-D-arabinonate. Participates in a pentose oxidation pathway that converts D-arabinonate to 2-oxoglutarate. D-arabinonate = 2-dehydro-3-deoxy-D-arabinonate + H2O Inhibited by substrate levels above 8 mM. Optimum pH is 6.7. Optimum temperature is 85 degrees Celsius. Homooctamer. Expression is strongly increased by growth on D-arabinose, both at the mRNA and at the protein level. Belongs to the mandelate racemase/muconate lactonizing enzyme family.