Electron transfer mediators for PQQ dependent soluble glucose dehydrogenase catalyzed lactose oxidation reaction

The aim of this work was to investigate the application of artificial electron transfer mediators for the pyrroloquinoline quinone-dependent soluble glucose dehydrogenase (PQQ-sGDH) catalyzed lactose oxidation reaction. 1-(N,N-dimethylamine)4-(4-morpholine)benzene (AMB) and N,N’-dimethyl-4,4’-azopyridinium methyl sulfate (MAZP) were used as mediators. The mediators showed a high reactivity with a reduced form of PQQ-sGDH and were used to determine the PQQ-sGDH catalyzed lactose oxidation parameters at pH 7.0 and pH 8.0. The use of MAZP and AMB for the regeneration of the oxidized form of PQQsGDH was investigated by applying the electrochemical oxidation of the mediator. The maximum electroenzymatic lactose bioconversion yield and the biggest average PQQ-sGDH turnover number were reached when the buffer solution pH was 8.0 and AMB was used as an electron acceptor, which was oxidized on a carbon fiber electrode of a large surface area.