Analytical Sciences

Abstract − Analytical Sciences, 22(9), 1261 (2006).

Application of the Nanogold-4,4′-bis(methanethiol)biphenyl Modified Gold Electrode to the Determination of Tyrosinase-Catechol Reaction Kinetics in Acetonitrile
Toshio NAKAMURA, Jujie REN, Kai-mei ZHU, Shinshi KAWARA, and Baokang JIN
Department of Chemistry, Faculty of Science, Shinshu University, Asahi, Matsumoto 390-8621, Japan
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 Km of tyrosinase for catechol is 5.5 ± 0.4 mM (n = 5).