Enhancement of Enzymatic Synthesis of Citrate in vitro by Indole‐3‐Acetic Acid

Indoleacetic acid in physiological concentrations was shown to enhance the synthesis of citiate by purified citrate condensing enzyme from castor beans and pig heart. Michaelis constants reveal that with indoleacetic acid in the reaction mixture a higher concentration of acetyl‐CoA was necessary to give maximal velocity. V values with indoleacetic acid in the reaction (physiological concentrations) exceeded V without indoleacetic acid in reaction. Citric acid synthesized from 14 C acetyl CoA was highly radioactive when indoleacetie acid was present in the reaction, indicating that indoleacetic acid did in fact enhance the synthesis. The data were discussed from the point of view that these studies may provide the basis for studies directed at ultimate understanding of the mechanism of action of indoleacetic acid.