ON THE MECHANISM OF INDOLEACETIC ACID OXIDATION BY WHEAT LEAF ENZYMES

Abstract

Partially purified enzyme preparations of wheat leaves oxidize indoleacetic acid completely in the presence of manganese and a monohydroxyphenol or resorcinol. A characteristic feature of the oxygen uptake is an induction period followed by a rapid oxygen uptake which ceases when 1 mole of oxygen is consumed per mole indoleacetic acid added. One mole of carbon dioxide is evolved per mole indoleacetic acid. There is no lag in carbon dioxide evolution, but it is not given off anaerobically. Oxygen, blue light, and acetaldehyde overcome the induction period. Hydrogen peroxide formed in a final aerobic dehydrogenase step is utilized to provide a source of manganic ions which act as an electron acceptor in an initial oxidative step.