Kumar Suresh
Centre for Bioinformatics Research, Institute of Systems Biology (INBIOSIS), University Kebangsaan Malaysia, 43600, UKM Bangi, Selangor, Malaysia.
BMC Res Notes. 2015 Jan 17;8:9. doi: 10.1186/s13104-015-0976-4.
Cytochrome P450s (CYPs) are important heme-containing proteins, well known for their monooxygenase reaction. The human cytochrome P450 4X1 (CYP4X1) is categorized as "orphan" CYP because of its unknown function. In recent studies it is found that this enzyme is expressed in neurovascular functions of the brain. Also, various studies have found the expression and activity of orphan human cytochrome P450 4X1 in cancer. It is found to be a potential drug target for cancer therapy. However, three-dimensional structure, the active site topology and substrate specificity of CYP4X1 remain unclear.
In the present study, the three-dimensional structure of orphan human cytochrome P450 4X1 was generated by homology modeling using Modeller 9v8. The generated structure was accessed for geometrical errors and energy stability using PROCHECK, VERFIY 3D and PROSA. A molecular docking analysis was carried out against substrates arachidonic acid and anandamide and the docked substrates were predicted for drug-likeness, ADME-Tox parameters and biological spectrum activity.
The three-dimensional model of orphan human cytochrome P450 4X1 was generated and assessed with various structural validation programmes. Docking of orphan human cytochrome P450 4X1 with arachidonic acid revealed that TYR 112, ALA 126, ILE 222, ILE 223, THR 312, LEU 315, ALA 316, ASP 319, THR 320, PHE 491 and ILE 492 residues were actively participating in the interaction, while docking of CYP4X1 with anandamide showed that TYR 112, GLN 114, PRO 118, ALA 126, ILE 222, ILE 223, SER 251, LEU 315, ALA 316 and PHE 491 key residues were involved in strong interaction.
From this study, several key residues were identified to be responsible for the binding of arachidonic acid and anandamide with orphan human cytochrome P450 4X1. Both substrates obeyed Lipinski rule of five in drug-likeness test and biological spectrum prediction showed anticarcinogenic activity. Compared to anandamide, arachidonic acid showed strong interaction with cytochrome P450 4X1 and also less health effect in certain human system in ADME-Tox prediction. These findings provide useful information on the biological role and structure-based drug design of orphan human cytochrome P450 4X1.
细胞色素P450（CYPs）是重要的含血红素蛋白，以其单加氧酶反应而闻名。人类细胞色素P450 4X1（CYP4X1）因其功能未知而被归类为“孤儿”CYP。最近的研究发现该酶在大脑的神经血管功能中表达。此外，多项研究发现孤儿人类细胞色素P450 4X1在癌症中的表达和活性。它被发现是癌症治疗的潜在药物靶点。然而，CYP4X1的三维结构、活性位点拓扑结构和底物特异性仍不清楚。
在本研究中，使用Modeller 9v8通过同源建模生成孤儿人类细胞色素P450 4X1的三维结构。使用PROCHECK、VERFIY 3D和PROSA对生成的结构进行几何误差和能量稳定性评估。针对花生四烯酸和阿南酰胺底物进行分子对接分析，并预测对接底物的类药性、ADME-Tox参数和生物光谱活性。
生成了孤儿人类细胞色素P450 4X1的三维模型，并用各种结构验证程序进行了评估。孤儿人类细胞色素P450 4X1与花生四烯酸的对接显示，酪氨酸112、丙氨酸126、异亮氨酸222、异亮氨酸223、苏氨酸312、亮氨酸315、丙氨酸316、天冬氨酸319、苏氨酸320、苯丙氨酸491和异亮氨酸492残基积极参与相互作用，而CYP4X1与阿南酰胺的对接表明，酪氨酸112、谷氨酰胺114、脯氨酸118、丙氨酸126、异亮氨酸222、异亮氨酸223、丝氨酸251、亮氨酸315、丙氨酸316和苯丙氨酸491关键残基参与了强相互作用。
通过本研究，确定了几个关键残基负责花生四烯酸和阿南酰胺与孤儿人类细胞色素P450 4X1的结合。两种底物在类药性测试中均符合Lipinski五规则，生物光谱预测显示具有抗癌活性。与阿南酰胺相比，花生四烯酸与细胞色素P450 4X1的相互作用更强，并且在ADME-Tox预测中对某些人体系统的健康影响较小。这些发现为孤儿人类细胞色素P450 4X1的生物学作用和基于结构的药物设计提供了有用信息。
