title: Nanocomposites of graphene and cytochrome P450 2D6 isozyme for electrochemical-driven tramadol metabolism.
abstract: Cytochrome P450 enzymes (cyt P450s) with an active center of iron protoheme are involved in most clinical drugs metabolism process. Herein, an electrochemical platform for the investigation of drug metabolism in vitro was constructed by immobilizing cytochrome P450 2D6 (CYP2D6) with cyt P450 reductase (CPR) on graphene modified glass carbon electrode. Direct and reversible electron transfer of the immobilized CYP2D6 with the direct electron transfer constant of 0.47 s(-1) and midpoint potential of -0.483 V was obtained. In the presence of substrate tramadol, the electrochemical-driven CYP2D6 mediated catalytic behavior toward the conversion of tramadol to o-demethyl-tramadol was confirmed. The Michaelis-Menten constant (Km(app)) and heterogeneous reaction rate constant during the metabolism of tramadol were calculated to be 23.85 μM and 1.96 cm s(-1), respectively. The inhibition effect of quinidine on CYP2D6 catalyze-cycle was also investigated. Furthermore, this system was applied to studying the metabolism of other drugs.
authors.affiliation: Jiangsu Province Hi-Tech Key Laboratory for Bio-medical Research, School of Chemistry and Chemical Engineering, Southeast University , Jiangning District 211189, Nanjing, Jiangsu Province, People's Republic of China.
authors.forename: Dongmei
authors.initials: D
authors.lastname: Cui
authors.forename: Li
authors.initials: L
authors.lastname: Mi
authors.forename: Xuan
authors.initials: X
authors.lastname: Xu
authors.forename: Jusheng
authors.initials: J
authors.lastname: Lu
authors.forename: Jing
authors.initials: J
authors.lastname: Qian
authors.forename: Songqin
authors.initials: S
authors.lastname: Liu
mesh_terms: D055162:Biocatalysis / Q000187:drug effects; D019389:Cytochrome P-450 CYP2D6 / Q000737:chemistry* / Q000378:metabolism*; D065690:Cytochrome P-450 CYP2D6 Inhibitors / Q000494:pharmacology; D004563:Electrochemistry; D004566:Electrodes; D004579:Electron Transport; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism; D006108:Graphite / Q000737:chemistry*; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D053761:Nanocomposites / Q000737:chemistry*; D011094:Polyethyleneimine / Q000737:chemistry; D011487:Protein Conformation; D011802:Quinidine / Q000494:pharmacology; D014147:Tramadol / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D065690:Cytochrome P-450 CYP2D6 Inhibitors; D004800:Enzymes, Immobilized; D007527:Isoenzymes; D014147:Tramadol; D006108:Graphite; D011094:Polyethyleneimine; D019389:Cytochrome P-450 CYP2D6; D011802:Quinidine