Enzymatic Esterification of Indole-3-acetic Acid to myo-Inositol and Glucose

Abstract

Incubation of mature sweet corn kernels of Zea mays in dilute solutions of (14)C-labeled indole-3-acetic acid leads to the formation of (14)C-labeled esters of myo-inositol, glucose, and glucans. Utilizing this knowledge it was found that an enzyme preparation from immature sweet corn kernels of Zea mays catalyzed the CoA- and ATP-dependent esterification of indole-3-acetic acid to myo-inositol and glucose. The esters formed were 2-O-(indole-3-acetyl)-myo-inositol, 1-dl-1-O-(indole-3-acetyl)-myo-inositol, di-O-(indole-3-acetyl)-myo-inositol, tri-O-(indole-3-acetyl)-myo-inositol, 2-O-(indole-3-acetyl)-d-glucopyranose, 4-O-(indole-3-acetyl)-d-glucopyranose and 6-O-(indole-3-acetyl)-d-glycopyranose. An assay system was developed for measuring esterification of (14)C-labeled indole-3-acetic acid by ammonolysis of the esters followed by isolation and counting the radioactive indole-3-acetamide.