Hexokinase electrode

Derivatization was found necessary for efficient HPLC separation. The quantitive conversion of the unreacted substrate was guaranteed (and tested) by a large excess of hexokinase over initial GO and of ATP over 2-deoxyglucose. The loss of GO activity following acid quenching and neutralization was assayed by an oxygen electrode. 

Less sensitive systems are obtained when enzyme reactions are used, in which ATP is one of the cofactors. For example, the phosphorylation of glucose by hexokinase requires ATP as cosubstrate (Eq. (11.9)). Thus, a glucose electrode was combined with hexokinase and signal reduction was observed when ATP was present [120]. 

Fig. 95. Enzyme sequence electrode for maltose determination containing a hexokinase anti-interference layer for glucose.

ADP/ATP pyruvate kinase + hexokinase membrane with LDH+LMO O2 electrode 220 Wollenberger (1987b)... 

ADP/ATP Hexokinase/pyruvate kinase Oxygen electrode with lactate dehydrogenase/lactate monooxygenase modified carbon-electrode with glucose-6-phosphate dehydrogenase... 

Both the avidin-biotin (88, 89] and antigen-antibody (90, 91] strategies have been taken up for depositing successive monomolecular layers onto electrode surfaces. The former was even used to build a bienzymatic coating associating a redox enzyme, glucose oxidase, to a nonredox enzyme, hexokinase, so as to make the electrode sensitive to the substrate of the nonredox enzyme, ATP (Sch. 7) (87]. 

Anicet, A., Bourdillon, C., Moiroux, J., Savdant, J.-M. Step-by-step avidin-biotin construction of bienzyme electrodes. Kinetic analysis of the coupling between the catalytic activities of immobihzed mono-molecular layers of glucose oxidase and hexokinase. Langmuir 1999,15, 6527-6533. 

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