Catalyzes the dehydrogenation of D-proline. Can also use other D-amino acids, but with lower efficiency. A + D-proline = 1-pyrroline-2-carboxylate + AH2 Optimum pH is 7.5. Half of activity at pH 6.5 and 8.5. Optimum temperature is above 70 degrees Celsius. Homotetramer. Belongs to the DadA oxidoreductase family.