Substrate Concentration Dependence of Apparent Maximum Reaction Rate and Michaelis Constant Observed in Immobilized Enzyme Reactions

Expressions for apparent kinetic parameters V^app_m ane K^app_m observed in immobilized enzyme reactions with diffusional and electrostatic effects are proposed on the basis of the equation of a tangent to the curve of a S_b/υ versus S_b plot. The validity of these expressions is shown by comparing the expression for K^app_m with two approximate expressions proposed by other workers for the reaction catalyzed by an enzyme immobilized on the external surface of a nonporous support. Calculation showed that the effect of substrate concentration on V^app_m and K^app_m is basically different for systems where an enzyme is immobilized on the external and pore surfaces respectively of supports.