Effects of nitroaromatic compounds on spectra of D-amino acid oxidase.

D-amino acid oxidase ( D-amino acid oxygen oxidoreductase E.C. 1.4.3.3. ) was found to bind various nitroaromatics with characteristic spectral changes similar in form to those caused by benzoate and its analogues. Nitrobenzene and o-nitroaniline were found to be competitive inhibitors of the enzyme. Dissociation constants of nitroaromatics tested were larger than those of the carboxylates except in the case of o-nitroaniline. Dinitrophenol was also found to bind to the enzyme with almost the same value of dissociation constant as nitrobenzene; on the other hand, dicarboxylates had no complex ability ( 3 ).