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. 1985 Oct 15;231(2):369–374. doi: 10.1042/bj2310369

Involvement of 3-dehydroecdysone in the 3-epimerization of ecdysone.

N P Milner, H H Rees
PMCID: PMC1152755  PMID: 3840685

Abstract

The epimerization of ecdysone to 3-epiecdysone has been investigated in a dialysed cytosolic enzyme preparation from midgut of sixth instar Spodoptera littoralis larvae, with particular emphasis on establishing the intermediacy of 3-dehydroecdysone. Incubation of ecdysone with the dialysed cytosolic preparation furnished 3-dehydroecdysone as the only detectable product, the reaction being oxygen-dependent. The enzyme preparation catalysed reduction of 3-dehydroecdysone to 3-epiecdysone and ecdysone in the presence of NADH or NADPH. Whereas formation of 3-epiecdysone greatly predominated over that of ecdysone in the presence of NADPH, the converse applied when the cofactor was NADH. 3-Epiecdysone incubated with the enzyme preparation in the presence of various cofactors was not metabolized, indicating the irreversibility of the reduction of 3-dehydroecdysone to 3-epiecdysone and, hence, of the 3-epimerization process. The foregoing results, together with comparison of the metabolism of 3-dehydro[3H]ecdysone and [3H]ecdysone by the enzyme preparation in the presence of unlabelled ecdysone and NADPH, support the intermediacy of 3-dehydroecdysone in the 3-epimerization of ecdysone.

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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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