1-Anilinonaphthalene-8-sulphonate, a fluorescent conformational probe for glutamate dehydrogenase

The interaction of 1-anilinonaphthalene-8-sulphonate with ox liver glutamate dehydrogenase was examined. 2. The fluorescence of the dye is enhanced 100-fold on binding. 3. A further enhancement is observed when NADH and GTP are added to the enzyme. 4. By using this property of the dye to measure conformational equilibria in the enzyme the effects of coenzyme, inhibitors, enzyme concentration, ionic strength and pH on the allosteric transitions were studied. 5. GTP and NADH interact with the enzyme in a heterotropic manner. 6. The rate of the structural transition brought about by GTP and NADH is biphasic with half-lives of 34 and 200msec. 7. The relation of these observations to regulatory mechanisms is discussed.