Structure of human microsomal cytochrome P4502C8 - Evidence for a peripheral fatty acid binding site
Structure of human microsomal cytochrome P4502C8 - Evidence for a peripheral fatty acid binding site
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DOI：
10.1074/jbc.m312516200
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发表时间：
2004-03-05
影响因子：
4.8
通讯作者：
Johnson, EF
中科院分区：
文献类型：
--
作者：
Schoch, GA;Yano, JK;Johnson, EF
用X射线结晶学方法测定了人微粒体细胞色素P450 2C8的2.7埃分子结构。通过在残基28之前用短的亲水序列替换疏水的N末端跨膜结构域来修饰膜蛋白以使其结晶。天然序列的结构从残基28到用于纯化的C-末端组氨酸标签的开始是完整的。CYP2C8是肝脏主要的药物代谢酶之一，可以氧化治疗药物如紫杉醇和西立伐他汀，以及内生菌如维甲酸和花生四烯酸。与其首选底物的相对较大的尺寸一致，活性中心体积是观察到的CYP2C5结构的两倍。延伸的活性部位空腔被Beta1片层和螺旋F‘所限制，这在哺乳动物P450中还没有涉及到底物识别。由螺旋F、F‘、G’和G相互作用形成的对称二聚体是由两个棕榈酸分子结合在二聚体界面上形成的对称二聚体。在溶液中观察到该二聚体，质谱仪证实了棕榈酸与该酶的结合。这一新的发现确定了P450中的一个外围结合部位，该结合部位可能有助于P450代谢中的药物-药物相互作用。
A 2.7-Angstrom molecular structure of human microsomal cytochrome P450 2C8 (CYP2C8) was determined by x-ray crystallography. The membrane protein was modified for crystallization by replacement of the hydrophobic N-terminal transmembrane domain with a short hydrophilic sequence before residue 28. The structure of the native sequence is complete from residue 28 to the beginning of a C-terminal histidine tag used for purification. CYP2C8 is one of the principal hepatic drug-metabolizing enzymes that oxidizes therapeutic drugs such as taxol and cerivastatin and endobiotics such as retinoic acid and arachidonic acid. Consistent with the relatively large size of its preferred substrates, the active site volume is twice that observed for the structure of CYP2C5. The extended active site cavity is bounded by the beta1 sheet and helix F' that have not previously been implicated in substrate recognition by mammalian P450s. CYP2C8 crystallized as a symmetric dimer formed by the interaction of helices F, F', G', and G. Two molecules of palmitic acid are bound in the dimer interface. The dimer is observed in solution, and mass spectrometry confirmed the association of palmitic acid with the enzyme. This novel finding identifies a peripheral binding site in P450s that may contribute to drug-drug interactions in P450 metabolism.