A KINETIC-ANALYSIS OF GAMMA-AMINOBUTYRATE AMINOTRANSFERASE IN PRESENCE AND ABSENCE OF INHIBITORS

The kinetics of the reaction catalyzed by gamma-aminobutyric acid tran saminase (GABA-T) is studied both in the absence and in the presence t wo inhibitors: n-dipropylacetate (n-DPA) and 4-amino-2-azide-butyric a cid (GABA azide). A novel kinetic model is proposed, that is based on an experimentally derived rate equation, which describes the kinetics of the transamination process accounting for the competitive inhibitio n of the ketoacid and of the added inhibitor (n-DPA, GABA azide). The consequence of the ketoacid inhibition on the primary and secondary do uble reciprocal plots of the initial velocity against the substrates c oncentration is examined. The kinetic parameters which describe the ra te of the transamination reaction are derived and compared with data r eported in the literature. The higher inhibition power of GABA azide w ith respect to n-DPA is also assessed and discussed.