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Updated: Aug 14, 2026
Using Enzyme-based Biosensors to Measure Tonic and Phasic Glutamate in Alzheimer's Mouse Models
Published on: May 3, 2017
The efficiency of immobilised glutamate oxidase decreases with surface enzyme loading: an electrostatic effect, and
Colm P McMahon1, Gaia Rocchitta, Pier A Serra
1UCD School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland.
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.
