title: A theoretical validation of the substrate depletion approach to determining kinetic parameters.
abstract: The substrate depletion approach is an increasingly popular alternative to the traditional method (observing product formation) of determining the kinetic parameters (KM and Vmax) of an enzyme. Obach and Reed-Hagen (Drug Metab Dispos 30:831-837, 2002) used an empirical relationship between substrate depletion rate constants and initial substrate concentration to determine kinetic parameters for a number of cytochrome P450-catalyzed reactions. We present a proof that this relationship can be derived from the Michaelis-Menten equation and, therefore, that kinetic parameters obtained by the substrate depletion approach are equivalent and comparable to those obtained by the traditional product formation approach. Analysis of a simulated data set produced similar kinetic parameters regardless of which approach was used, confirming the theoretical result.
authors.affiliation: Department of Medicinal Chemistry, Box 357610, University of Washington, Seattle, WA 91895-7610, USA.
authors.forename: Abhinav
authors.initials: A
authors.lastname: Nath
authors.forename: William M
authors.initials: WM
authors.lastname: Atkins
mesh_terms: D003198:Computer Simulation; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D008722:Methods; D008962:Models, Theoretical; D004364:Pharmaceutical Preparations / Q000737:chemistry / Q000378:metabolism; D015203:Reproducibility of Results
chemical_list: D004364:Pharmaceutical Preparations; D003577:Cytochrome P-450 Enzyme System