[Effect of carbonic acid on glutamate dehydrogenase interaction with NADH]

The method of fluorescent titration was used to study the effect of carbonic acid on the process of NADH binding with the purified preparation of glutamate dehydrogenase as well as on fluorescent properties of the above mentioned coenzyme. It is shown that in bicarbonate buffer at the alkaline values of pH there is a decrease in the maximal capacity of the binding sites of the enzyme with low affinity to co-enzyme. The capacity of high-affinity binding sites in this case is unchanged. It is found that pCO2, HCO3- and H+ exert an effect on the dissociation constants of the NADH-glutamate dehydrogenase complex as well as on fluorescent properties of bound NADH. It is supposed that the effects observed are a result of the interaction of dissolved carbon dioxide with free amino groups of protein molecule.