Electrochemical studies of intramolecular electron transfer in laccase from Trametes versicolor

This paper describes electrochemical behavior of laccase from the fungus Trametes venicolor. The issues related to discrimination of the redox potentials corresponding to copper centers T1 and T2/T3 in the active site and possible mechanism of intramolecular electron transfer have been discussed. The electron-transfer rate constant for laccase immobilized on carbon electrode is 3.4 s(-1). The bioelectrocatalytic activity of the enzyme was studied in the presence of 1,4-hydroquinone (HQ). The kinetics of HQ oxidation is very fast (K-M 3.8 mu M). However, the catalytic activity of laccase in the presence of high concentration of HQ decreases drastically. It is suggested that the T2/T3 copper center is able to accept electrons from HQ molecules directly via intramolecular channel.