title: In-vitro and in-vivo effects of the CYP2C9*11 polymorphism on warfarin metabolism and dose.
abstract: OBJECTIVE
  To determine the in-vitro and in-vivo effects of the CYP2C9*11 polymorphism on (S)-warfarin metabolism.
  
  
  RESULTS
  The *11 allele that results in mutation of Arg335-->Trp occurred with a frequency of approximately 1% in Caucasian and African-American populations. Four subjects carrying the *1/*11 genotype were identified in a clinical cohort of 192 warfarin patients. Compared to control subjects with the *1/*11 genotype (n=127), the *1/*11 group exhibited a 33% reduction in warfarin maintenance dose, that was independent of study population age or INR. In-vitro studies directed towards understanding the mechanism of reduced in-vivo activity revealed very low levels of holo-CYP2C9.11 expression in insect cells and decreased solubility in the presence of detergent. Membrane preparations of CYP2C9.11 contained inactive P420 and exhibited a shorter half-life for thermally induced conversion of P450 to P420 than CYP2C9.1. Metabolic studies demonstrated that functional CYP2C9.11 possessed similar (S)-warfarin hydroxylation regioselectivity and modestly reduced catalytic efficiency relative to the wild-type enzyme.
  
  
  CONCLUSIONS
  In-vivo reduction in CYP2C9 (S)-warfarin activity due to the CYP2C9*11 polymorphism may largely be a consequence of decreased enzyme stability resulting in compromised expression of holo-enzyme. Increased enzyme lability of CYP2C9.11 may be related to improper folding due to the disruption of conserved salt-bridge and hydrogen bonding contacts in the loop region between the J and J' helices of the protein.
authors.affiliation: Department of Medicinal Chemistry, University of Washington, Seattle, WA 98195, USA.
authors.forename: Guoying
authors.initials: G
authors.lastname: Tai
authors.forename: Frederico
authors.initials: F
authors.lastname: Farin
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Rieder
authors.forename: Albert W
authors.initials: AW
authors.lastname: Dreisbach
authors.forename: David L
authors.initials: DL
authors.lastname: Veenstra
authors.forename: Christophe L M J
authors.initials: CL
authors.lastname: Verlinde
authors.forename: Allan E
authors.initials: AE
authors.lastname: Rettie
mesh_terms: D000925:Anticoagulants / Q000378:metabolism*; D001189:Aryl Hydrocarbon Hydroxylases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D065729:Cytochrome P-450 CYP2C9; D004305:Dose-Response Relationship, Drug; D005260:Female; D005838:Genotype; D006801:Humans; D006900:Hydroxylation; D066298:In Vitro Techniques; D007564:Japan; D015810:Linkage Disequilibrium; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D016297:Mutagenesis, Site-Directed; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D013696:Temperature; D014859:Warfarin / Q000378:metabolism*; D044465:White People / Q000235:genetics*
chemical_list: D000925:Anticoagulants; D014859:Warfarin; C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9; D001189:Aryl Hydrocarbon Hydroxylases; D009251:NADPH-Ferrihemoprotein Reductase