PEG-NAD* IN AMPEROMETRIC DEHYDROGENASE ELECTRODES WITH COENZYME RECYCLING

Abstract

A new method for the synthesis of PEG-NAD* via activation of PEG with carbonyldiimidazole is described; a very stable non-dialysable and biologically active coenzyme derivative is obtained. In compact amperometric dehydrogenase electrodes this coenzyme derivative, physically entrapped with the dehydrogenase and placed in proximity to a modified graphite electrode surface, leads to enzyme deactivation and extraction of the catalyst. Therefore electrodes with low response and short lifetime result. In addition the response of these electrodes is dominated by the very high diffusion coefficient and the high viscosity of its solution. Possibilities to overcome these problems are discussed.