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

McMahon, Colm P. and Rocchitta, Gaia Giovanna Maria and Serra, Pier Andrea and Kirwan, Sarah M. and Lowry, John P. and O'Neill, Robert D. (2006) The Efficiency of immobilised glutamate oxidase decreases with surface enzyme loading: an electrostatic effect, and reversal by a polycation significantly enhances biosensor sensitivity. Analyst, Vol. 131 (1), p. 68-72. eISSN 1364-5528. Article.

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DOI: 10.1039/B511643K

Abstract

The apparent Michaelis constant, KM, 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 µM−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.

Item Type:Article
ID Code:4938
Status:Published
Refereed:Yes
Uncontrolled Keywords:Glutamate oxidase, Michaelis constant, polyethyleneimine, glucose biosensors
Subjects:Area 05 - Scienze biologiche > BIO/14 Farmacologia
Divisions:001 Università di Sassari > 01 Dipartimenti > Neuroscienze, scienze materno infantili
Publisher:Royal Society of Chemistry
eISSN:1364-5528
Deposited On:23 Nov 2010 10:24

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