title: Dynamic disorder-driven substrate inhibition and bistability in a simple enzymatic reaction.
abstract: Conformations and catalytic rates of enzymes (biological catalysts) fluctuate over a wide range of time scales. Recent experimental and theoretical investigations demonstrated case studies where the enzymatic catalysis rate follows the Michaelis-Menten (MM) rate law despite molecular fluctuations. In this paper, we investigate deviations from MM law and their effects on the dynamical behavior of the enzymatic network. We consider a simple kinetic scheme for a single substrate enzymatic reaction in which the product release step is treated explicitly. We examine how conformational fluctuations affect the underlying rate law in the quasi-static limit when conformational dynamics is very slow in one of the states. Our numerical results and analytically solvable model indicate that slow conformational fluctuations of the enzyme-substrate complex lead to non-MM behavior, substrate inhibition, and possible bistability of the reaction network.
authors.affiliation: Department of Bioengineering, Rice University, Houston, Texas 77005, USA.
authors.forename: Srabanti
authors.initials: S
authors.lastname: Chaudhury
authors.forename: Oleg A
authors.initials: OA
authors.lastname: Igoshin
mesh_terms: D000494:Allosteric Regulation; D002384:Catalysis; D004798:Enzymes / Q000737:chemistry / Q000378:metabolism; D008433:Mathematics; D008962:Models, Theoretical; D013379:Substrate Specificity; D013816:Thermodynamics
chemical_list: D004798:Enzymes