title: On the human CYP2C9*13 variant activity reduction: a molecular dynamics simulation and docking study.
abstract: Cytochrome P450 2C9 (CYP2C9) plays a key role in the metabolism of clinical drugs. CYP2C9 is a genetically polymorphic enzyme and some of its allelic variants have less activity compared to the wild-type form. Drugs with a narrow therapeutic index may cause serious toxicity to the individuals who carry such allele. CYP2C9*13, firstly identified by some of the present authors in a Chinese poor metabolizer of lornoxicam, is characterized by mutation encoding Leu90Pro substitution. Kinetic experiments show that CYP2C9*13 has less catalytic activity in elimination of diclofenac and lornoxicam in vitro. In order to explore the structure-activity relationship of CYP2C9*13, the three-dimensional structure models of the substrate-free CYP2C9*1 and its variant CYP2C9*13 are constructed on the basis of the X-ray crystal structure of human CYP2C9*1 (PDB code 1R9O) by molecular dynamics simulations. The structure change caused by Leu90Pro replacement is revealed and used to explain the dramatic decrease of the enzymatic activity in clearance of the two CYP2C9 substrates: diclofenac and lornoxicam. The trans configuration of the bond between Pro90 and Asp89 in CYP2C9*13 is firstly identified. The backbone of residues 106-108 in CYP2C9*13 turns over and their side chains block the entrance for substrates accessing so that the entrance of *13 shrinks greatly than that in the wild-type, which is believed to be the dominant mechanism of the catalytic activity reduction. Consequent docking study which is consistent with the results of the kinetic experiments by Guo et al. identifies the most important residues for enzyme-substrate complexes.
authors.affiliation: State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China.
authors.forename: Y-H
authors.initials: YH
authors.lastname: Zhou
authors.forename: Q-C
authors.initials: QC
authors.lastname: Zheng
authors.forename: Z-S
authors.initials: ZS
authors.lastname: Li
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: M
authors.initials: M
authors.lastname: Sun
authors.forename: C-C
authors.initials: CC
authors.lastname: Sun
authors.forename: D
authors.initials: D
authors.lastname: Si
authors.forename: L
authors.initials: L
authors.lastname: Cai
authors.forename: Y
authors.initials: Y
authors.lastname: Guo
authors.forename: H
authors.initials: H
authors.lastname: Zhou
mesh_terms: D019943:Amino Acid Substitution; D001189:Aryl Hydrocarbon Hydroxylases / Q000737:chemistry* / Q000235:genetics; D001665:Binding Sites / Q000187:drug effects; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D065729:Cytochrome P-450 CYP2C9; D004008:Diclofenac / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010894:Piroxicam / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D010894:Piroxicam; D004008:Diclofenac; C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9; D001189:Aryl Hydrocarbon Hydroxylases; C059451:lornoxicam