Pharmacological analysis of sterol Δ8-Δ7 isomerase proteins with [3H]ifenprodil
Pharmacological analysis of sterol Δ8-Δ7 isomerase proteins with [3H]ifenprodil
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DOI：
10.1124/mol.54.3.591
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发表时间：
1998-09-01
影响因子：
3.6
通讯作者：
Paik, YK
中科院分区：
文献类型：
--
作者：
Moebius, FF;Reiter, RJ;Paik, YK
甾醇Delta 8-Delta 7异构酶(SLS)催化甾醇B环上C8-9到C7-8的双带移动。令人惊讶的是，真菌(ERG2p)和脊椎动物[emopamil结合蛋白(EBP)]的同工酶在结构上完全不相关，而Sigma(1)受体，一种未知功能的哺乳动物蛋白质，与酵母ERG2p有很大的相似性。在这里，我们比较了Sis和相关蛋白与[H-3]ifenprodil作为常见的高亲和力放射性配体(K-d=1.4-19 nM)的药物结合特性，证明了ERG2p、sigma(1)受体和EBP之间的密切药理关系。这使得Sis成为结构多样化的酶的一个显着的例子，具有相似的药理特征和以高亲和力结合来自不同化学基团的药物的倾向。我们确定了多种对人EBP(K-I=0.5-14 nm)具有纳摩尔亲和力的实验药物，如MDL28315、AY9944、曲帕诺和U18666A。这些化合物以及杀菌剂三吗啉和临床上使用的药物他莫昔芬、氯米芬、胺碘酮和阿帕莫尔都能抑制重组人EBP的体外活性(IC_(50)=0.015-54mM)。人EBP对H-3-三苯氧胺(K-d=3+/-2 nM)的高亲和力意味着EBP携带先前描述的微粒体抗雌激素结合位点。EBP与结构不同的亲脂胺的相互作用表明，应对相关结构的新化合物进行反筛选以抑制该酶，以避免干扰甾醇Delta 8-Delta 7异构化。
Sterol Delta 8-Delta 7 isomerases (Sls) catalyze the shift of the double band from C8-9 to C7-8 in the B-ring of sterols. Surprisingly, the isoenzymes in fungi (ERG2p) and vertebrates [emopamil binding protein (EBP)] are structurally completely unrelated, whereas the sigma(1) receptor, a mammalian protein of unknown function, bears significant similarity with the yeast ERG2p. Here, we compare the drug binding properties of Sis and related proteins with [H-3]ifenprodil as a common high affinity radioligand (K-d = 1.4-19 nM), demonstrating an intimate pharmacological relationship among ERG2p, sigma(1) receptor, and EBP. This renders Sis a remarkable example for structurally diverse enzymes with similar pharmacological profiles and the propensity to bind drugs from different chemical groups with high affinity. We identified a variety of experimental drugs with nanomolar affinity for the human EBP (K-i = 0.5-14 nM) such as MDL28315, AY9944, triparanol, and U18666A. These compounds, as well as the fungicide tridemorph and the clinically used drugs tamoxifen, clomiphene, amiodarone, and opipramol, inhibit the in vitro activity of the recombinant human EBP (IC50 = 0.015-54 mu M). The high affinity of the human EBP for H-3-tamoxifen (K-d = 3 +/- 2 nM) implies that the EBP carries the previously described microsomal antiestrogen binding site. Interactions of the EBP with structurally diverse lipophilic amines suggest that novel compounds of related structure should be counterscreened for inhibition of the enzyme to avoid interference with sterol Delta 8-Delta 7 isomerization.