Purification, characterization and developmental expression of indole-3-ethanol oxidase from seeds of Phaseolus vulgaris.

Purification of indole-3-ethanol (IEt) oxidase was carried out from extracts of the seeds of two bean cultivars. The IEt oxidase from the Labrador cultivar was purified more than 1000-fold and had a molecular weight of about 56 kD. The enzyme reaction required oxygen and produced hydrogen peroxide, was not stimulated by either NADP or FAD, and was inhibited by EDTA and iodoacetate. Physiologically-relevant inhibitors included gibberellic acid, indoleacetic acid and indoleacetaldehyde, through at higher than physiological concentrations. IEt oxidase from the Farden Losa cultivar differed in some properties, but an antiserum prepared against this enzyme detected corresponding proteins from the Labrador and Tendergreen cultivars. In developing Tendergreen bean seeds, the IEt oxidase activity was temporally correlated with IEt levels. Parallel immunochemical measurement of IEt was obscured by non-specific reactions.