Application of the Nanogold-4,4′-bis(methanethiol)biphenyl Modified Gold Electrode to the Determination of Tyrosinase-Catechol Reaction Kinetics in Acetonitrile

Abstract

The reactivity of tyrosinase adsorbed on nanogold bound with 4,4′-bis(methanethiol)biphenyl monolayer self-assembled on a gold disk with catechol in a dipolar aprotic solvent, acetonitrile (AN), was studied by cyclic voltammetric and amperometric methods. Tyrosinase exhibited characteristics of a Michaelis-Menten kinetic mechanism. The tyrosinase attached to the nanogold continued to react with substrates in AN even when the water content was lower than 0.01 w/w%. The apparent Michaelis-Menten constant K_m of tyrosinase for catechol is 5.5 ± 0.4 mM (n = 5).