title: Estimation of kinetic parameters when modifiers are bound in enzyme-catalyzed reactions.
abstract: Modifiers of enzyme-catalyzed reactions can have various types of effects on the velocity, but the most important effect is that they provide multiple pathways to products. The rapid-equilibrium kinetic effects of modifiers are explored for the enzyme-catalyzed reaction A --> products. When a single molecule of modifier X is bound, the mechanism involves three independent equilibrium expressions and two rate constants. But when two molecules of X are bound are bound in two reactions, there are five independent equilibria and three paths to products. The advantages of using a computer to derive rapid-equilibrium rate equations are that more complicated rate equations can be derived and the kinetic parameters can be estimated using the minimum number of velocity measurements. The mechanism with three paths to products is of special interest because the effects of cooperativity can be studied. Thermodynamic cycles can be used to estimate additional kinetic parameters.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Room 6-215, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA. alberty@mit.edu
authors.forename: Robert A
authors.initials: RA
authors.lastname: Alberty
mesh_terms: D055162:Biocatalysis; D004798:Enzymes / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D011485:Protein Binding; D013816:Thermodynamics
chemical_list: D004798:Enzymes