Electrochemical analysis of enzyme reactions for sarcosine oxidases

Abstract

Enzyme reactions for sarcosine oxidases from different origins (SOD: from Arthrobacter sp., and SOX: from Bacillus sp.) were analyzed by cyclic voltammetry based on mediated oxidation of the enzymes. The catalytic limiting current observed was used to estimate the enzyme reaction rate(V). The effective mediators for SOD and SOX were not always the same, indicating that the microscopic structures near the redox center of these enzymes would different from each other. Among the mediators examined, octacyanomolybdate acts as an excellent mediator for both SOD and SOX. For the SOD-Mo(CN)₈^4- system, it was observed that the rate (V) shows a hyperbolic dependece on both the sarcosine (S) and the mediator (M) concentrations, giving the Michaelis-Menten type kinetics as V=V_max/(1+K_m1/[S]+K_m2/[M]). For the SOX-Mo(CN)₈^4- system, on the other hand, sigmoidal curves were obtained in V vs. [S] and V vs. [M] plots with the rate expression of second-order dependence on both the [S] and [M].