The Dissociation of d-Fructose 1,6-Diphosphatase by Adenosine 5'-Phosphate

Abstract

Abstract Adenosine 5'-monophosphate, an inhibitor of the d-fructose 1,6-diphosphatase isolated from Candida utilis, induces a specific dissociation of this enzyme at pH 9.2. On the basis of sucrose density gradient centrifugation and gel filtration on Sephadex G-100, it may be concluded that the molecule has dissociated into subunits having one-half the molecular weight of the native enzyme. The dissociation occurs only at alkaline pH and in the cold. It is prevented by low concentrations of fructose 1,6-diphosphate (0.01 mm). d-Fructose 1,6-diphosphatase which has been desensitized to the inhibitory action of 5'-AMP is not dissociated. The results suggest that the dissociation induced by 5'-AMP may be an extreme manifestation of more subtle alterations in the quaternary structure of the enzyme which occur in the presence of substrate at physiological pH.