Electrochemical determination of gamma-glutamyl transpeptidase activity and its application to a miniaturized analysis system.
A novel method to determine the activity of gamma-glutamyl transpeptidase (gamma-GTP) was developed. gamma-l-glutamyl-l-glutamate and glycyl-glycine were used as the substrates for gamma-GTP. l-glutamate produced by the enzymatic reaction was measured with an amperometric l-glutamate sensor. Following the mixing of the substrate solution and a sample solution, the current generated on the l-glutamate sensor continued to increase at a constant rate. The method was used to construct a miniaturized analysis system for the determination of gamma-GTP activity. The system consisted of the l-glutamate sensor formed on a glass substrate and a polydimethylsiloxane (PDMS) flow channel. Since the l-glutamate concentration in the solution increased as the solution was mobilized through the flow channel, a constant current increase was observed. The relation between the slope of the response curve and the activity of gamma-GTP was linear between 35 U l(-1) and 659 U l(-1). The rate analysis in the micro flow channel minimized the influence of interferents. The reproducibility of the output of the micro system was found to be good with a relative standard deviation (R.S.D.) of 5.6% at 659 U l(-1). The activities of gamma-GTP in human serum samples were also determined and compared with values obtained with a conventional spectroscopic method. The values obtained by the two methods were consistent with a correlation coefficient of 0.953.
Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan.
Sanjay
S
Upadhyay
Naoto
N
Ohgami
Hitoshi
H
Kusakabe
Hiroaki
H
Suzuki
D015415:Biomarkers / Q000097:blood; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D001774:Blood Chemical Analysis / Q000295:instrumentation / Q000379:methods; D004151:Dipeptides / Q000737:chemistry*; D004563:Electrochemistry / Q000295:instrumentation* / Q000379:methods; D004789:Enzyme Activation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005971:Glutamates / Q000737:chemistry*; D006033:Glycylglycine / Q000737:chemistry*; D006801:Humans; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods; D008904:Miniaturization; D005723:gamma-Glutamyltransferase / Q000097:blood* / Q000737:chemistry*
D015415:Biomarkers; D004151:Dipeptides; D005971:Glutamates; D006033:Glycylglycine; C082810:gamma-glutamylglutamate; D005723:gamma-Glutamyltransferase