Electrochemical study of the effect of ADP and AMP on the kinetics of glutamate dehydrogenase

A chronoamperometric method based on the 'diffusion' layer concept of the c onvective system was used to assay the glutamate dehydrogenase (GLDH) activ ity. Once the reaction was initiated by adding the enzyme GLDH into a well- stirred nicotinamide adenine dinucleotide (NADH, coenzyme) solution, the st eady-state oxidation limiting current of NADH would decrease linearly in a short time. The major advantage of this method is that it directly indicate s the continuous in-situ change of the coenzyme concentration, thus, the re al initial reaction rate of enzyme-catalyzed reaction, V-0, can be determin ed. Using this method, the effect of adenosine-5'-monophosphate (AMP) and a denosine-5'-diphosphate (ADP) on the GLDH activity has been monitored. The results showed that ADP and AMP could increase the activity of GLDH. This a ctivation mechanism was proposed by the voltammetric study. (C) 2000 Elsevi er Science S.A. All rights reserved.