Activity and Kinetic Characterization of Four Human CYP2D6 Polymorphisms using the Substrates Bufuralol and Dextromethorphan

Abstract

Human cytochrome P450 enzymes (CYPs) are a heme‐containing enzyme superfamily that have a major role in the metabolism of drugs along with other endogenous and exogenous chemicals. Human CYP2D6 is responsible for approximately 12% of CYP‐mediated drug metabolism. There are over 100 different allelic variants of CYP2D6 with metabolic profiles ranging from poor to ultra‐rapid. Four CYP2D6 allelic variants, three with a small series of distal mutations (*34, *17‐2, *17‐3) and one possible ultra‐metabolizer (*53), were expressed and purified in E. coli to further characterize their interactions with the substrates bufuralol and dextromethorphan using HPLC with UV detection. Km and vmax values were measured for comparison between variants and the reference *1. Previous molecular dynamics simulations of these allelic variants with and without a ligand bound suggested that varied flexibility and active site accessibility altered interaction with substrates. The current metabolic and kinetic studies are compared to these molecular dynamics models to broaden the understanding of substrate interactions for CYP2D6 variants with local and distal mutations relative to the active site.Support or Funding InformationNIH 1R15‐GM086767‐02