Abscisic Acid Metabolism by a Cell-free Preparation from Echinocystis lobata Liquid Endoserum
- 1 December 1976
- journal article
- Published by Oxford University Press (OUP) in Plant Physiology
- Vol. 58 (6), 790-795
- https://doi.org/10.1104/pp.58.6.790
Abstract
A cell-free enzyme system capable of metabolizing abscisic acid has been obtained from Eastern Wild Cucumber (Echinocystis lobata Michx.) liquid endosperm. The reaction products were determined to be phaseic acid (PA) and dihydrophaseic acid (DPA) by co-chromatography on thin layer chromatograms as the free acids, methyl esters, and their respective oxidation or reduction products. The crude enzyme preparation was separated by centrifugation into a particulate abscisic acid (ABA)-hydroxylating activity and a soluble PA-reducing activity. The particulate ABA-hydroxylating enzyme showed a requirement for O(2) and NADPH, inhibition by CO, and high substrate specificity for (+)-ABA. Acetylation of short term incubation mixtures gave evidence for the presence of 6'-hydroxymethyl-ABA as an intermediate in PA formation. Determinations of endogenous ABA and DPA concentrations suggest that the ABA-hydroxylating and PA-reducing enzymes are extensively metabolizing ABA in the intact E. lobata seed.Keywords
This publication has 6 references indexed in Scilit:
- Abscisic Acid Metabolism in Water-stressed Bean LeavesPlant Physiology, 1975
- The Metabolism of Hormones during Seed Germination and DormancyPlant Physiology, 1974
- The 4-Hydroxylation of Cinnamic Acid by Sorghum Microsomes and the Requirement for Cytochrome P-450Journal of Biological Chemistry, 1974
- Activity and Metabolism of 14C-(±)-Abscisic Acid DerivativesPlant Physiology, 1972
- Metabolism of 2-14C-(±)-Abscisic Acid in Excised Bean AxesPlant Physiology, 1972
- Asymmetry, Its Importance to the Action and Metabolism of Abscisic AcidScience, 1971