Application of the nanogold-4,4'-bis(methanethiol)biphenyl modified gold electrode to the determination of tyrosinase-catechol reaction kinetics in acetonitrile.

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).