Trzaskos J M, Fischer R T, Ko S S, Magolda R L, Stam S, Johnson P, Gaylor J L
Du Pont Merck Pharmaceutical Company, Wilmington, Delaware 19880-0400, USA.
Biochemistry. 1995 Aug 1;34(30):9677-81. doi: 10.1021/bi00030a004.
Selected 15-, 32-, and 15,32-substituted lanosterol analogs are shown here to display time-dependent inactivation and lanosterol 14 alpha-methyl demethylase. These molecules are competitive with respect to substrate and require NADPH and O2 in order to display time dependence, thus supporting the premise that they are mechanism-based inactivators. Structural features required for lanosterol demethylation by the lanosterol demethylase such as nuclear double bond location and availability of an abstractable 15 alpha-proton are also essential elements for time-dependent inactivation. 32-(S)-Vinyllanost-8-en-3 beta,32-diol is a potent time-dependent inactivator (Kinact/Ki = 0.36 min-1 microM-1), while the 32-(R)-vinyllanost-8-en-3 beta,32-diol functions solely as a competitive demethylase inhibitor. These results support the premise that stereoselective oxidation occurs during lanosterol demethylation and that the 32-pro-S proton is abstracted during the demethylation reaction.
本文展示了选定的15位、32位以及15,32位取代的羊毛甾醇类似物具有时间依赖性失活作用，并作用于羊毛甾醇14α-甲基脱甲基酶。这些分子在底物方面具有竞争性，且需要NADPH和O2才能表现出时间依赖性，因此支持了它们是基于机制的失活剂这一前提。羊毛甾醇脱甲基酶进行羊毛甾醇脱甲基化所需的结构特征，如核双键位置和可被提取的15α-质子的可用性，也是时间依赖性失活的关键要素。32-(S)-乙烯基羊毛甾-8-烯-3β,32-二醇是一种有效的时间依赖性失活剂（Kinact/Ki = 0.36 min-1 microM-1），而32-(R)-乙烯基羊毛甾-8-烯-3β,32-二醇仅作为竞争性脱甲基酶抑制剂起作用。这些结果支持了以下前提：在羊毛甾醇脱甲基化过程中发生立体选择性氧化，并且在脱甲基反应过程中32位前手性S质子被提取。
