Mechanism of the second methylation in sitosterol side-chain biosynthesis in higher plants: metabolic fate of 28-hydrogens of 24-methylenecholesterol in Morus alba cell cultures
✍ Scribed by Tatsuya Okuzumi; Yuko Kaji; Hiroki Hamada; Yoshinori Fujimoto
- Book ID
- 104210234
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- French
- Weight
- 123 KB
- Volume
- 41
- Category
- Article
- ISSN
- 0040-4039
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✦ Synopsis
Biosynthesis of the side-chain of sitosterol in higher plants involves two methylation steps by attack of Sadenosylmethionine. The stereochemical features of the second methylation, namely, of the conversion from 24methylenecholesterol to isofucosterol in higher plants has been investigated. Feeding studies of synthesized [28E-2 H]-and [28Z-2 H]-24-methylenecholesterols to cultured cells of Morus alba followed by 2 H NMR analysis of the resulting isofucosterol established that the second methylation proceeded in such a manner that addition of the methyl group and proton loss occur on opposite faces of the original ∆ 24(28) -double bond.