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. 1975 Jul;56(1):60–66. doi: 10.1104/pp.56.1.60

Metabolism of Tritiated Gibberellins in d-5 Dward Maize

II. [3H]Gibberellin A1, [3H]Gibberellin A3, and Related Compounds 1

Lindsay J Davies a,2, Lawrence Rappaport a
PMCID: PMC541298  PMID: 16659258

Abstract

After 30 minutes of incubation of young leaf sections of d-5 maize (Zea mays L.) in [3H]gibberellin A1 ([3H]GA1), the metabolite [3H]GA8 was present in significant amounts, with a second metabolite, [3H]GA8-glucose ([3H]GA8-glu), appearing soon after. A third [3H]GA1 metabolite, the polar uncharacterized conjugate [3H]GA1-X, took more than 1 hour to appear. The protein synthesis inhibitor cycloheximide inhibited the production of all [3H]GA1 metabolites, indicating a possible protein synthesis requirement for [3H]GA1 metabolism.

By preincubating leaf sections in unlabeled GA1 before exposure to [3H]GA1 or by reducing the specific radioactivity of the [3H]GA1 supplied, it was possible to reduce greatly the conversion of radioactive GA1 to [3H]GA8-glu, without affecting conversion to [3H]GA1-X. Increasing the molar concentration of the [3H]GA1 fed greatly increased the molar yield of [3H]GA1-X, whereas the molar yields of [3H]GA8 and [3H]GA8-glu were much less affected.

The principal metabolite of [3H]GA3 was a very polar compound having chromatographic properties similar to those of the conjugate [3H]GA1-X produced from [3H]GA1. The naturally occurring GAs [3H]GA1, [3H]GA3, and [3H]tetrahydroGA3 were metabolized to a much greater extent than were the artifical derivatives [3H]ketoGA1, [3H]GA1-methyl ester, and [3H]pseudoGA1. Only [3H]GA1 and [3H]GA3, with their identical D ring structures, were converted to [3H]GA1-X type compounds; [3H]-ketoGA1 and [3H]tetrahydroGA3, with modified D rings, were not converted to this type of conjugate.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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