title: Role of glutamic acid 216 in cytochrome P450 2D6 substrate binding and catalysis.
abstract: Human cytochrome P450 (P450) 2D6 is an important enzyme involved in the metabolism of drugs, many of which are amines or contain other basic nitrogen atoms. Asp301 has generally been considered to be involved in electrostatic docking with the basic substrates, on the basis of previous modeling studies and site-directed mutagenesis. Substitution of Glu216 with a residue other than Asp strongly attenuated the binding of quinidine, bufuralol, and several other P450 2D6 ligands. Catalytic activity with the substrates bufuralol and 4-methoxyphenethylamine was strongly inhibited by neutral or basic mutations at Glu216 (>95%), to the same extent as the substitution of Asn at Asp301. Unlike the Asp301 mutants, the Gln216 mutant (E216Q) retained 40% enzyme efficiency with the substrate spirosulfonamide, devoid of basic nitrogen, suggesting that the substitutions at Glu216 affect binding of amine substrates more than other catalytic steps. Attempts to induce catalytic specificity toward new substrates by substitutions at Asp301 and Glu216 were unsuccessful. Collectively, the results provide evidence for electrostatic interaction of amine substrates with Glu216, and we propose that both of these acidic residues plus at least another residue(s) is (are) involved in binding the repertoire of P450 2D6 ligands.
authors.affiliation: Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA. guengerich@toxicology.mx.vanderbilt.edu
authors.forename: F Peter
authors.initials: FP
authors.lastname: Guengerich
authors.forename: Imad H
authors.initials: IH
authors.lastname: Hanna
authors.forename: Martha V
authors.initials: MV
authors.lastname: Martin
authors.forename: Elizabeth M J
authors.initials: EM
authors.lastname: Gillam
mesh_terms: D000588:Amines / Q000737:chemistry; D019943:Amino Acid Substitution / Q000235:genetics; D001665:Binding Sites / Q000235:genetics; D002384:Catalysis; D019389:Cytochrome P-450 CYP2D6 / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics; D004983:Ethanolamines / Q000737:chemistry; D018698:Glutamic Acid / Q000737:chemistry* / Q000235:genetics; D005973:Glutamine / Q000235:genetics; D006801:Humans; D006900:Hydroxylation; D008745:Methylation; D016297:Mutagenesis, Site-Directed; D010084:Oxidation-Reduction; D011485:Protein Binding / Q000235:genetics; D011802:Quinidine / Q000737:chemistry; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D013141:Spiro Compounds / Q000737:chemistry; D055672:Static Electricity; D013379:Substrate Specificity / Q000235:genetics; D013449:Sulfonamides / Q000737:chemistry; D014439:Tyramine / Q000031:analogs & derivatives* / Q000737:chemistry; D000096926:Benzenesulfonamides
chemical_list: D000588:Amines; D019389:Cytochrome P-450 CYP2D6; D004983:Ethanolamines; D018698:Glutamic Acid; D005973:Glutamine; D011802:Quinidine; D011994:Recombinant Proteins; D013141:Spiro Compounds; D013449:Sulfonamides; D014439:Tyramine; C465867:spirosulfonamide; D000096926:Benzenesulfonamides; C010831:bufuralol; C008510:O-methyltyramine