ISFETバイオセンサシステムによるL-グルタミン定量の可能性の検討

概要

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A glutamine sensor was constructed by immobilizing L-glutaminase with glutaraldehyde on ISFET(ion selective field effect transistor) to investigate the possibility of determining L-glutamine. The prin-ciple of this sensor is as follows. The output voltage from ISFET, which depends on a very minutepH elevation due to the ammonium ion formation according to the enzymic reaction, is amplified with adifferential amplifier of our own assembled. The amplified voltage was processed automatically with anon-line personal computer via GP-IB interface on a real-time basis. The calibration line for L-glutamine was linear from 1mM to 40mM and the relation coefficientwas 0.967. The sensitivity of this system to L-glutamine was 0.5mM. The time needed for deter-mining one sample was within 13 min. The substrate specificity of this sensor was strict and L-glutamine was the sole compound responding to this sensor among analogues tested. D-glutamine wascompletely inactive to this sensor. It is suggested that L-glutanrine can be determined with this newly constructed ISFET-biosensorsystem with L-glutaminase.