IAA-OXIDASE ACTIVITY, DOPA-OXIDATIONS AND INACTIVATION OF DOPA AS IAA-OXIDASIC INHIBITOR IN LENS ROOTS EXTRACTS.
Department of Plant Physiology, Botanical Institute, University of Liège (Belgium).
Department of Plant Physiology, Botanical Institute, University of Liège (Belgium).
Department of Plant Physiology, Botanical Institute, University of Liège (Belgium).
Abstract
Four concentrations of Lens roots extracts have been studied as to their oxidative capacity on IAA and DOPA. The kinetics of oxidations are quite different according to the concentrations of the extracts. IAA destruction increases with enzymatic extract concentration. DOPA oxidation does not run parallelly. Inhibitors of the DOPA reaction are proved to be present in extracts by the inhibition of a purified tyrosinase when Lens extracts are added.
Peroxidases of Lens are able to oxidize DOPA since H202 greatly increases the reaction. DOPA, according to its o-diphenolic structure, acts as an IAA-oxidasic inhibitor. Preincubation of DOPA with enzymic extract or tyrosinase results in a diminution of the IAA-oxidasic inhibition. H202 activates the inhibitor neutralisation by the enzymic extract.
The inactivation of DOPA as IAA-oxidasic inhibitor seems thus simply involve oxidation by a polyphenoloxidase or by a peroxidase.