Directly and indirectly determinable rate constants in Michaelian enzyme-catalyzed reactions

Abstract

Backed by kinetic schemes, attempts had been made to derive equations for the calculation of all zero-order first-order rate constants (ZOFORC) for the activation of the enzyme-substrate (ES) complex and its deactivation, k+2 and k -2, respectively. The values of ZOFORC, including the kind for the dissociation of the enzyme-product complex (EP) to free enzyme (E) and product (P), are hardly reported. The methods of research were primarily Bernfeld and Lineweaver methods. The goal of the research was to determine ways for the utilization of experimental data for the determination of verifiable and quantifiable rate constants, with the following objectives: 1) To derive equations for the first order rate constants, k+2 and k-2, for the activation of ES and its deactivation, respectively; 2) to quantify by calculation the first order rate constant for product release; 3) ultimately quantify the rate constants, k-2 and k+2; and 4) to advise the reactor, process, chemical engineers, etc. in different industrial concerns on the usefulness of k-2 and k+2. The value of ZOFORC for the dissociation of EP to free E and P is 3.155 exp. (+5)/min; the values of k+2 and k-2 are 3.513 exp. (+4) and 2.377 exp. (+8)/min, respectively. Ultimately, it is imperative for all stakeholder groups to devise means of controlling the enzymatic rate of catalysis by manipulating the magnitudes of k+2 and k-2 in particular. The derived equations can be fitted to the experimentally generated and calculated data. A future research project should entail conducting the assay under optimum conditions so as to verify possible variations in the ZOFORC values when compared with values generated outside optimum conditions.