Catalyzes the oxidative deamination of D-amino acids. Has broad substrate specificity; is mostly active on D-alanine, and to a lesser extent, on several other D-amino acids such as D-methionine, D-serine and D-proline, but not on L-alanine. Participates in the utilization of L-alanine and D-alanine as the sole source of carbon, nitrogen and energy for growth. Is also able to oxidize D-amino acid analogs such as 3,4-dehydro-D-proline, D-2-aminobutyrate, D-norvaline, D-norleucine, cis-4-hydroxy-D-proline, and DL-ethionine. A + a D-alpha-amino acid + H2O = a 2-oxocarboxylate + AH2 + NH4(+) Is activated by the HinT protein. Is inhibited by D-cycloserine. Optimum pH is about 8.9 with D-alanine as substrate and about 9 with 3,4-dehydro-D-proline as substrate. Amino-acid degradation; D-alanine degradation; NH(3) and pyruvate from D-alanine: step 1/1. By D-alanine. Is regulated by catabolite repression. Loss of the ability to utilize both D- and L-stereoisomers of alanine as sole sources of carbon, nitrogen and energy for growth (PubMed:13292). A double dtd-dadA deletion mutant has a pronounced growth defect in the presence of D-tyrosine (PubMed:10383414). Belongs to the DadA oxidoreductase family. Was originally thought to be a heterodimer based on the purification of the enzyme first reported from E.coli B, but results of enzyme assays in PubMed:21378189 have indicated that DadA is solely responsible for the observed dehydrogenase activity.