Bioelectrocatalytic oxidation of glucose by hexose oxidase directly wired to graphite

TY - JOUR

T1 - Bioelectrocatalytic oxidation of glucose by hexose oxidase directly wired to graphite

AU - Fapyane, Deby

AU - Poulsen, Charlotte H.

AU - Ferapontova, Elena E.

PY - 2016/4

Y1 - 2016/4

N2 - Glucose-oxidizing enzymes are widely used in electrochemical biosensors and biofuel cells; in most applications glucose oxidase, an enzyme with non-covalently bound FAD and low capability of direct electronic communications with electrodes, is used. Here, we show that another glucose-oxidizing enzyme with a covalently bound FAD center, hexose oxidase (HOX), adsorbed on graphite, exhibits a pronounced non-catalytic voltammetric response from its FAD, at - 307 mV vs. Ag/AgCl, pH 7, characterized by the heterogeneous electron transfer (ET) rate constant of 29.2 ± 4.5 s - 1. Direct bioelectrocatalytic oxidation of glucose by HOX proceeded, although, with a 350 mV overpotential relative to FAD signals, which may be connected with a limiting step in biocatalysis under conditions of the replacement of the natural redox partner, O 2, by the electrode; mediated bioelectrocatalysis was consistent with the potentials of a soluble redox mediator used. The results allow development of HOX-based electrochemical biosensors for sugar monitoring and biofuel cells exploiting direct ET of HOX, and, not the least, fundamental studies of ET non-complicated by the loss of FAD from the protein matrix.

AB - Glucose-oxidizing enzymes are widely used in electrochemical biosensors and biofuel cells; in most applications glucose oxidase, an enzyme with non-covalently bound FAD and low capability of direct electronic communications with electrodes, is used. Here, we show that another glucose-oxidizing enzyme with a covalently bound FAD center, hexose oxidase (HOX), adsorbed on graphite, exhibits a pronounced non-catalytic voltammetric response from its FAD, at - 307 mV vs. Ag/AgCl, pH 7, characterized by the heterogeneous electron transfer (ET) rate constant of 29.2 ± 4.5 s - 1. Direct bioelectrocatalytic oxidation of glucose by HOX proceeded, although, with a 350 mV overpotential relative to FAD signals, which may be connected with a limiting step in biocatalysis under conditions of the replacement of the natural redox partner, O 2, by the electrode; mediated bioelectrocatalysis was consistent with the potentials of a soluble redox mediator used. The results allow development of HOX-based electrochemical biosensors for sugar monitoring and biofuel cells exploiting direct ET of HOX, and, not the least, fundamental studies of ET non-complicated by the loss of FAD from the protein matrix.

KW - Hexose oxidase (HOX)

KW - Bioelectrocatalysis

KW - Direct electron transfer

KW - Glucose oxidation

KW - DIRECT ELECTRON-TRANSFER

KW - FLAVIN ADENINE-DINUCLEOTIDE

KW - HORSERADISH-PEROXIDASE

KW - ENZYME ELECTRODES

KW - GOLD ELECTRODE

KW - NADH OXIDATION

KW - GLASSY-CARBON

KW - FUEL-CELLS

KW - ELECTROCATALYSIS

KW - FLAVOHEMOGLOBIN

UR - http://www.scopus.com/inward/record.url?scp=84958162101&partnerID=8YFLogxK

U2 - 10.1016/j.elecom.2016.01.012

DO - 10.1016/j.elecom.2016.01.012

M3 - Journal article

SN - 1388-2481

VL - 65

SP - 1

EP - 4

JO - Electrochemistry Communications

JF - Electrochemistry Communications

ER -