Glutamate oxidase advances in the selective bioanalytical detection of the
neurotoxic amino acid b-ODAP in grass pea:
A decade of progress
G. Moges, N. Wodajo, L. Gorton, Y. Yigzaw, K. Kalcher, A. Belay, G. Akalu, B. M. Nair, and T. Solomon
Department of Chemistry, Addis Ababa, Ethiopia;
Department of Analytical Chemistry, Institute of Chemistry, Karl-Franzens
University, Graz, Austria; Department of Analytical Chemistry, University
of Lund, Sweden; Applied Nutrition and Food Chemistry, University of
Lund, Sweden
Abstract: The search for an enzyme as a reagent for selective
bioanalytical detection of the neurotoxic amino acid, b-N-oxalyl
L-alpha, b-diaminopropionic acid, b-ODAP
(found in grass pea, Lathyrus sativus) led to its redox catalytic reaction
by glutamate oxidase (GluOx). Homogeneous kinetic studies and an immobilized
GluOx reactor-based flow-injection assay were initially made for beta-ODAP
with small immobilized GluOx/catalase glutamate destroying prereactors.
The method was applied to examine the toxin content in processed grass
pea. The kinetics and the equilibrium of the thermal isomerization of
b-ODAP to the nontoxic isomer a-ODAP
established that GluOx is specific to the neurotoxin. The first ever
GluOx-based amperometric biosensor for liquid chromatography (LC) detection
was reported in 1997. This biosensor coupled with a refractive index
detector improved LC performance. The most recent work with GluOx resulted
in MnO2-based screen-printed amperometric biosensor, with
offline elimination of glutamate interference by glutamate decarboxylase.
A single-shot chemiluminescent sensor developed for hydrogen peroxide
is also proposed for b-ODAP with GluOx application.
This decade of progress resulted from studies that included four Ph.D.
(Ethiopia, Sweden, Austria), four M.Sc. (Ethiopia, Sweden) and Licentiate
(Sweden) theses projects, plus one collaborative project in Sweden.
The advances in grass pea research may be regarded as a model north–south
cooperation for research and education.
*Plenary lectures presented at the Inaugural Conference for the Southern and Eastern Africa Network of Analytical Chemists (SEANAC), Gaborone, Botswana, 7-10 July 2003. Other presentations are published in this issue, pp. 697-888.
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