Fryberg M, Avruch L, Oehlschlager A C, Unrau A M
Can J Biochem. 1975 Aug;53(8):881-9. doi: 10.1139/o75-120.
The role of 4,4-dimethylzymosterol (3), 4,4-dimethylfecosterol (4) and 31-norlanosterol (5) in the biosynthesis of ergosterol in Saccharomyces cerevisiae has been investigated. The synthesis of 4 and 5 coupled with the availability of 3 facilitated a search for these sterols in commercial yeast sterol concentrates, fresh laboratory grown yeast and fresh brewery grown yeast. Sterol 4 was not detected in any of these mixtures whereas 5 was found in the first and last and 3 was present in all three sources investigated. Investigation of incorporation of [2-3H]lanosterol into 3, 4 and 5 revealed significant incorporation into 3 but neither 4 nor 5. This observation suggests the principle pathway for ergosterol biosynthesis initially involved 1 leads to 3 leads to 7. Incubation of a mixture of [2,4-3H]zymosterol and [26,27-14C]lanosterol with S. cerevisiae revealed that during the initial phases of aerobic growth the major route from 7 to ergosterol involves zymosterol (11) but as 11 accumulates 4 alpha-methyl-24-methylenezymosterol (8) assumes equal importance.
对酿酒酵母中4,4-二甲基酵母甾醇（3）、4,4-二甲基粪甾醇（4）和31-去甲羊毛甾醇（5）在麦角甾醇生物合成中的作用进行了研究。4和5的合成以及3的可得性促使人们在商业酵母甾醇浓缩物、实验室新鲜培养的酵母和啤酒厂新鲜培养的酵母中寻找这些甾醇。在这些混合物中均未检测到甾醇4，而在第一种和最后一种混合物中发现了5，在所研究的所有三种来源中均存在3。对[2-³H]羊毛甾醇掺入3、4和5的研究表明，其可大量掺入3，但不能掺入4和5。这一观察结果表明，麦角甾醇生物合成的主要途径最初涉及1→3→7。将[2,4-³H]酵母甾醇和[26,27-¹⁴C]羊毛甾醇的混合物与酿酒酵母一起孵育，结果显示，在有氧生长的初始阶段，从7到麦角甾醇的主要途径涉及酵母甾醇（11），但随着11的积累，4α-甲基-24-亚甲基酵母甾醇（8）变得同样重要。
