Study of kinetics of Aspergillus niger glucose oxidase reaction with pentacyanoferrates containing nucleophilic ligands

Abstract

Complexes of pentacyanoferrate(III) and nucleophilic ligands were synthesized and reactivity with glucose oxidase (GO) from Aspergillus niger was determined at pH 7.2. As nucleophilic ligands ammonia, imidazole or pyrazole were used. For comparison the reactivity of ferricyanide with GO was measured at the same conditions. Calculated apparent bimolecular constants of reduced enzyme interaction with the complexes variem from 2.4 • 102 to 3.0 • 103 M–1 • s–1. The distance of electron transfer between the enzyme active centre and the complexes was calculated using outer sphere electron transfer theory (Marcus theory). It varied between 8.1–10.2 Å. Keywords: glucose oxidase, pentacyanoferrate, hexacyanoferrate(III), electron transfer