Human cytochrome P450 8B1 (CYP8B1) is involved in conversion of cholesterol to bile acids. It hydroxylates the steroid ring at C12 to ultimately produce the bile acid cholic acid. Studies implicated this enzyme as a good drug target for nonalcoholic fatty liver disease and type 2 diabetes, but there are no selective inhibitors known for this enzyme and no structures to guide inhibitor development. Herein, the human CYP8B1 protein was generated and used to identify and characterize interactions with a series of azole inhibitors, which tend to be poorly selective P450 inhibitors. Structurally related miconazole, econazole, and tioconazole bound with submicromolar dissociation constants and were effective inhibitors of the native reaction. CYP8B was cocrystallized with S-tioconazole to yield the first X-ray structure. This inhibitor bound in the active site with its azole nitrogen coordinating the heme iron, consistent with inhibitor binding and inhibition assay data. Additionally, the CYP8B1 active site was compared with similar P450 enzymes to identify features that may facilitate the design of more selective inhibitors. Selective inhibitors should promote a better understanding of the role of CYP8B1 inhibition in normal physiology and disease states and provide a possible treatment for nonalcoholic fatty liver disease and type 2 diabetes.

人细胞色素 P450 8B1 (CYP8B1) 参与胆固醇向胆汁酸的转化。它使 C12 处的类固醇环羟基化，最终产生胆汁酸胆酸。研究表明这种酶是治疗非酒精性脂肪肝和 2 型糖尿病的良好药物靶点，但没有已知的这种酶的选择性抑制剂，也没有指导抑制剂开发的结构。在此，人类 CYP8B1 蛋白被生成并用于识别和表征与一系列唑类抑制剂的相互作用，这些唑类抑制剂往往是选择性较差的 P450 抑制剂。结构相关的咪康唑、益康唑和噻康唑与亚微摩尔解离常数结合，是天然反应的有效抑制剂。CYP8B 与S共结晶-噻康唑产生第一个 X 射线结构。这种抑制剂结合在活性位点，其唑氮与血红素铁协调，与抑制剂结合和抑制测定数据一致。此外，将 CYP8B1 活性位点与类似的 P450 酶进行比较，以确定可能有助于设计更具选择性的抑制剂的特征。选择性抑制剂应有助于更好地了解 CYP8B1 抑制在正常生理和疾病状态中的作用，并为非酒精性脂肪肝和 2 型糖尿病提供可能的治疗方法。