Photoaffinity labeling of oxidosqualene cyclase and squalene cyclase by a benzophenone-containing inhibitor
Photoaffinity labeling of oxidosqualene cyclase and squalene cyclase by a benzophenone-containing inhibitor
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DOI：
10.1021/bi980366c
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发表时间：
1998-04-28
期刊：
影响因子：
2.9
通讯作者：
Prestwich, GD
中科院分区：
文献类型：
--
作者：
Abe, I;Zheng, YF;Prestwich, GD
一种新的口服活性氧化角鲨烯：羊毛甾醇环化酶（OSLC）抑制剂（Ro 48 -8071; Morand，O. H.等人（1997）J. Lipid Res.38，373-390）显示了对来自酸热脂环酸芽孢杆菌（Alicyclobacillus acidocaldarius）（IC 50 = 9.0 nM，K-I = 6.6 nM）和OSLC（对于均质大鼠肝OSLC，IC 50 = 40 nM，K-I = 22 nM）的细菌角鲨烯：hopene环化酶（SHC）的有效非竞争性抑制。氚标记的同位素异构体（18.8 Ci/mmol）的这种非萜类化合物抑制剂，它具有二苯甲酮（BP）的载体，化学合成的光亲和标记。在360 nm处的UV照射后，观察到OSLC和SHC酶的特异性、有效的共价修饰。通过与1000倍摩尔过量的18-硫杂-2，3-氧化角鲨烯或非萜类抑制剂BIBX 79共孵育，[H-3] Ro 48 -8071对OSLC和SHC的标记被竞争性取代。还用自杀底物（3S）-29-亚甲基-2，3-氧化角鲨烯实现了OSLC标记的置换。因此，这些酶的非底物Ro 48 -8071和萜类和非萜类抑制剂似乎共享一个共同的结合位点。
A new orally active oxidosqualene:lanosterol cyclase (OSLC) inhibitor (Ro48-8071; Morand, O. H. et al. (1997) J. Lipid Res. 38, 373-390) showed potent noncompetitive inhibition of bacterial squalene:hopene cyclase (SHC) from Alicyclobacillus acidocaldarius (IC50 = 9.0 nM, K-I = 6.6 nM) and OSLC (IC50 = 40 nM, K-I = 22 nM for homogeneous rat liver OSLC). A tritium-labeled isotopomer (18.8 Ci/mmol) of this nonterpenoid inhibitor, which possesses a benzophenone (BP) photophore, was chemically synthesized as a photoaffinity label. Specific, efficient covalent modification of both OSLC and SHC enzymes was observed after UV irradiation at 360 nm. Labelling of both OSLC and SHC by [H-3]Ro48-8071 was competitively displaced by coincubation with a 1000-fold molar excess of 18-thia-2,3-oxidosqualene or the nonterpenoid inhibitor BIBX79. Displacement of labelling of OSLC was also achieved with the suicide substrate (3S)-29-methylidene-2,3-oxidosqualene. Thus, the nonsubstrate Ro48-8071 and both terpenoid and nonterpenoid inhibitors of these enzymes appear to share a common binding site.