The apparent Michaelis constant, K(M), for glutamate oxidase (GluOx) immobilised on Pt electrodes increased systematically with enzyme loading. The effect was due, at least in part, to electrostatic repulsion between neighbouring oxidase molecules and the anionic substrate, glutamate (Glu). This understanding has allowed us to increase the Glu sensitivity of GluOx-based amperometric biosensors in the linear response region (100+/-11 nA cm(-2)microM(-1) at pH 7.4; SD, n=23) by incorporating a polycation (polyethyleneimine, PEI) to counterbalance the polyanionic protein. Differences in the behaviour of glucose biosensors of a similar configuration highlight a limitation of using glucose oxidase as a model enzyme in biosensor design.

The efficiency of immobilised glutamate oxidase decreases with surface enzyme loading: an electrostatic effect, and reversal by a polycation significantly enhances biosensor sensitivity / Mcmahon, Cp; Rocchitta, Gaia Giovanna Maria; Serra, Pier Andrea; Kirwan, Sm; Lowry, Jp; O'Neill, Rd. - In: ANALYST. - ISSN 0003-2654. - 131:1(2006), pp. 68-72.

The efficiency of immobilised glutamate oxidase decreases with surface enzyme loading: an electrostatic effect, and reversal by a polycation significantly enhances biosensor sensitivity

ROCCHITTA, Gaia Giovanna Maria;SERRA, Pier Andrea;
2006

Abstract

The apparent Michaelis constant, K(M), for glutamate oxidase (GluOx) immobilised on Pt electrodes increased systematically with enzyme loading. The effect was due, at least in part, to electrostatic repulsion between neighbouring oxidase molecules and the anionic substrate, glutamate (Glu). This understanding has allowed us to increase the Glu sensitivity of GluOx-based amperometric biosensors in the linear response region (100+/-11 nA cm(-2)microM(-1) at pH 7.4; SD, n=23) by incorporating a polycation (polyethyleneimine, PEI) to counterbalance the polyanionic protein. Differences in the behaviour of glucose biosensors of a similar configuration highlight a limitation of using glucose oxidase as a model enzyme in biosensor design.
The efficiency of immobilised glutamate oxidase decreases with surface enzyme loading: an electrostatic effect, and reversal by a polycation significantly enhances biosensor sensitivity / Mcmahon, Cp; Rocchitta, Gaia Giovanna Maria; Serra, Pier Andrea; Kirwan, Sm; Lowry, Jp; O'Neill, Rd. - In: ANALYST. - ISSN 0003-2654. - 131:1(2006), pp. 68-72.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11388/50271
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