Studies on the conversion of indole acetic acid and oxindole acetic acid by Hygrophorous conicus

The fungus, Hygrophorous conicus, produces the enzyme, indole acetic acid oxidase, when grown in the presence of indole acetic acid (IAA) or tryptamine. The IAA acts both as an inducer and a substrate for this intracellular enzyme. The product of the oxidation catalyzed by the IAA oxidase is oxindole acetic acid (OIAA). Since the IAA and OIAA absorb maximally at two different wavelengths the use of spectrophotometric analysis was possible for assaying for the IAA oxidase activity. Paper chromatography was used for qualitative identification of the IAA and OIAA. The rate of growth and the rate of formation of the enzyme by H. Conicus were studied. The rate of growth was found to be similar to that of other fungi. The formation of the enzyme, however, proved to be somewhat different from that of other inducible enzyme systems. The OIAA formed by the oxidation if IAA was also found to induce the formation of an enzyme in H. conicus. This enzyme catalyzed the destruction of OIAA --Abstract, page ii