Effect of L‐Aspartate Concentration on the Response of the Amperometric L‐Glutamate Sensor for the Measurement of L‐Glutamate and Aspartate Aminotransferase Activity in Serum

Abstract

L‐glutamate oxidase was immobilized in a photo‐cross‐linkable polymer membrane on a palladium strip electrode for the amperometric measurement of aspartate aminotransferas eactivity. The sample, serum for example, was injected into a buffered L‐aspartate and α‐ketoglutarate solution. L‐aspartate is the essential substrate and can transfer to L‐glutamate via the aspartate aminotransferase catalyzing reaction. Aspartate aminotransferase activity can be measured by determining the increasing rate of L‐glutamate. Under the optimal condition, the current increasing rate was proportional to the aspartate aminotransferase activity of the sample in the range of 8–200 U/L. The data are in good correlation (R2= 0.998) with data from a commercial aspartate aminotransferase assay kit. Good reproducibility (relative standard deviation=3.03%, n=8) was obtained from a sample with 50 U/L aspartate aminotransferase activity. The sensor is expectable to be applied in a clinical point‐of‐care diagnosis.