Progress curve analysis of enzyme reactions by flow microcalorimetry: Use of a pseudo-first order approximation

Abstract

We describe a method for determining the pseudo-first order rate constant of a chemical reaction by flow microcalorimetry operating in the flow-through mode. The impulse response of the instrument was described by a Gamma distribution and the equation of the thermogram was computed analytically. The resulting equation was fitted to the data by simulated annealing. The method was applied to an enzyme reaction following Michaelis–Menten kinetics by means of a new empirical equation relating the apparent rate constant to the kinetic parameters V_max and K_m. The method was exemplified by a kinetic study of horse serum butyrylcholinesterase.