David Nes W, Nichols Shawn D
Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409-1061, USA.
Phytochemistry. 2006 Aug;67(16):1716-21. doi: 10.1016/j.phytochem.2006.02.023. Epub 2006 May 2.
The Zygomycetes fungus Mortierella alpina was cultured to growth arrest to assess the phytosterol biosynthesis pathway in a less-advanced fungus. The mycelium was found to produce 13 sterols, but no ergosterol. The sterol fractions were purified to homogeneity by HPLC and their identifies determined by a combination of GC-MS and 1H NMR spectroscopy. The principal sterol of the mycelium was cholesta-5, 24-dienol (desmosterol) (83%), with lesser amounts of 24beta-methyl-cholesta-5,25(27)-dienol (codisterol) (2%), 24-methyldesmosterol (6%), 24(28)-methylene cholesterol (3%) and lanosterol (3%) and several other minor compounds (3%). The total sterol accounted for approximately 0.07% of the mycelial dry wt. Mycelium fed methionine-methyl-2H3 for 6 days, generated 3 2H-24-methyl(ene) sterols, [C28-2H2]24(28)-methylenecholesterol, [C28-2H3]24-methylcholesta-5,24-dienol and [C28-2H3]24beta-methyl-cholesta-5,25(27)-dienol. The formation of the 24-methyl sterols seems to be catalyzed by the direct methylation of a common Delta24-acceptor sterol thereby bypassing the intermediacy of an isomerization step for rearrangement of the Delta24(28)-bond to Delta25(25)-position as operates in Ascomycetes fungi and all plants.
培养高山被孢霉（一种接合菌纲真菌）使其生长停滞，以评估一种进化程度较低的真菌中的植物甾醇生物合成途径。发现该菌丝体能产生13种甾醇，但没有麦角甾醇。通过高效液相色谱法（HPLC）将甾醇馏分纯化至同质，并通过气相色谱 - 质谱联用（GC - MS）和核磁共振氢谱（1H NMR）光谱相结合的方法确定其结构。菌丝体的主要甾醇是胆甾 - 5,24 - 二烯醇（desmosterol）（83%），还有少量的24β - 甲基 - 胆甾 - 5,25(27) - 二烯醇（codisterol）（2%）、24 - 甲基去氢胆甾醇（6%）、24(28) - 亚甲基胆固醇（3%）和羊毛甾醇（3%）以及其他几种次要化合物（3%）。总甾醇约占菌丝体干重的0.07%。用甲基 - 2H3标记的甲硫氨酸喂养菌丝体6天，产生了3种含2H的24 - 甲基（亚甲基）甾醇，即[C28 - 2H2]24(28) - 亚甲基胆固醇、[C28 - 2H3]24 - 甲基胆甾 - 5,24 - 二烯醇和[C28 - 2H3]24β - 甲基 - 胆甾 - 5,25(27) - 二烯醇。24 - 甲基甾醇的形成似乎是由一种常见的Δ24 - 受体甾醇直接甲基化催化的，从而绕过了在子囊菌纲真菌和所有植物中发生的将Δ24(28) - 键重排为Δ25(25) - 位置的异构化步骤。
