Inhibition of D-amino acid oxidase by aromatic acids.

Benzoate competes with n-amino acids for n-amino acid oxidase and thus inhibits the activity of the oxidase (l-3). Monosubstituted benzoates, depending upon the substituent, have higher and lower affinities for the oxidase than has benzoate (2). Kojic acid, a Y-pyrone, likewise competitively inhibits the oxidase (4). The present report describes the inhibition of n-amino acid oxidase by certain acids, particularly heterocyclic acids having aromatic properties; e.g., acid derivatives of furan, pyrrole, and pyrones. Like the benzoic acids (l-3), kojic acid (4), and 4-7-carbon, straight chain, fatty acids (5), the substances compete with n-amino acids for the oxidase and are in contrast to the aromatic nitrogen compounds that compete with the flavin component of the oxidase (3). The findings suggest some analogies between the inhibitors and the amino acids that bear upon the interaction of these substances with the oxidase.