A Generic Rate Equation for modeling Enzymatic Reactions under Living Conditions

Based on our experience in kinetic modelling of coupled multiple metabolic pathways, we propose a generic rate equation for the dynamical modelling of metabolic kinetics. It is symmetric for forward and backward reactions. It’s Michaelis-Menten-King-Altman form makes the kinetic parameters (or functions) easy to relate to experimental values in database and to use in computation. In addition, such uniform form is ready to arbitrary number of substrates and products with different stiochiometry. We explicitly show how to obtain such rate equation rigorously for three well-known binding mechanisms. Hence the proposed rate equation is formally exact under the quasi-steady state condition. Various features of this generic rate equation are discussed. In particular, for irreversible reactions, the product inhibition which directly arise from enzymatic reaction is eliminated in a natural way. We also discuss how to include the effects of modifiers and cooperativity.