NAD kinase interaction with the activator--glutamate dehydrogenase

An electrophoretically homogeneous preparation of the NAD kinase activating factor was isolated from rabbit liver and its physico-chemical properties were investigated. The similarity of molecular weights of the activator subunit and hexamer, pI values, the number of SH-groups to the corresponding parameters for glutamate dehydrogenase and the glutamate dehydrogenase activity demonstrated by this factor allowed for the identification of the NAD kinase activating factor as glutamate dehydrogenase. Using three independent methods, the formation of the NAD kinase--glutamate dehydrogenase complex was shown. Both the oligomeric and monomeric (subunit) forms of NAD kinase were found to be able to form complexes with glutamate dehydrogenase.