In order to obtain information about the reactivity of enzymes in sterol synthesis of yeast, the effects of some detergents were investigated. Among the detergents used, Triton X-100 was found to exert a unique action, and its effect on the incorporation of 14C-labeled acetate, mevalonate, farnesyl pyrophosphate, or S-adenosyl-L-methionine into squalene, 2,3-oxidosqualene, and sterols in a cell-free system was examined. Triton X-100 showed virtually no effect on the enzyme activities in the reactions from acetyl CoA to farnesyl pyrophosphate, but it had a marked effect on reactions from farnesyl pyrophosphate to ergosterol. Evidence was obtained suggesting that Triton X-100 apparently activated squalene synthetase (EC 2.5.1.21) but inhibited squalene epoxidase (EC 1.14.99.7) and delta 24-sterol methyltransferase (EC 2.1.1.41). The activity of epoxidase was protected from the inhibition by increasing the concentration of cell-free extracts or by the prior addition of lecithin liposomes to the reaction mixture. The inhibition of methyltransferase was partially reversed by treatment with Bio-heads SM-2, but that of epoxidase was not reversed by the treatment.

• PMID: 6752317
• PubMed
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Reference Type

Journal Article | Research Support, Non-U.S. Gov't

Authors

Hata S, Nishino T, Ariga N, Katsuki H

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