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Structural modification of gibberellins by in-vitro hydroxylating systems
R L Jones1, J L Stoddart, J Macmillan
1Department of Botany, University of California, Berkeley, U.S.A..
Abstract:
The behaviour of gibberellins A4, A5 and A7 (GA4, GA5 and GA7) has been studied in various in vitro hydroxylating systems. Incubation of GA4 and GA7 in peroxidase/dihydroxyfumarate or tyrosinase/ascorbate formulations resulted in the production of additional biologically-active zones on thin-layer chromatograms of the reaction mixtures. The product from GA7/peroxidase incubations was conclusively identified as GA7 norketone by gas/liquid chromatography-mass spectrometry and nuclear magnetic resonance spectrometry. A similar reaction is inferred for GA4 in the same system and for both GA4 and GA7 with tyrosinase/ascorbate. By analogy, the product derived from GA5 in the non-enzymatic ascorbate/ferrous iron system may be GA5 norketone. The reaction kinetics and the biological activity of the products are discussed.
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