Beef liver 3-hydroxyanthranilic acid oxidase.

The oxidation of 3-hydroxyanthranilic acid, an intermediate in the conversion of tryptophan to niacin (l-3), is catalyzed by a liver oxidase (4). The first recognized product, termed Compound I (5), yields quinolinic acid spontaneously or picolinic acid under the influence of a liver carboxylase (6). The intermediate is detectable by its absorption maximum at 360 rnp (4). Wiss and Bettendorf (7) have identified the compound as I-amino-4-formyl-l , 3-butadiene-l , 2-dicarboxylic acid on the basis of infrared and ultraviolet spectra of several derivatives. Other studies in this laboratory (8) are directed towards obtaining further information concerning the structure of Compound I. In the kinetic studies to be reported the rate of appearance of Compound I has been used as a measure of oxidase activity. Activation of dialyzed, aged enzyme extracts by ferrous iron and reduced glutathione has been observed and inhibition by sulfhydry1 reagents has been studied.