Immunochemical properties of D-amino-acid oxidase

Antiserum against homogeneous hog kidney D-amino-acid oxidase (D-amino-acid: oxygen oxidoreductase (deaminating), EC 1.4.3.3) was elicited in rabbits, and monospecific antibodies were prepared by affinity chromatography. The antibodies inhibited up to 90% of hog D-amino-acid oxidase activity, and 100% of the enzyme could be immunoprecipitated. The antibodies inhibited both holoenzyme and reconstituted apoprotein to a similar degree, indicating that they did not interfere with the FAD-binding site of the protein. The antibodies inhibited D-amino-acid oxidase activity from other mammalian species to a similar degree, while the enzyme activities from birds, amphibians, fishes and yeast were inhibited and immunoprecipitated to lower extents. In immunoblotting experiments, after SDS-polyacrylamide gel electrophoresis, the antibodies recognized a single band of about 40 kDa in all the species analyzed, and the entity of the signal was inversely related to the phylogenetic distance from mammals. The antibodies did not inhibit D-alanine dehydrogenase activity from Escherichia coli, but gave positive bands in immunoblotting.