| Abstract: | The regulatory subunit of type II cAMP-dependent proteinkinase was isolated from cytosol of the rabbit small intestinal mucosa by affinity chromatography. The preparation contained 3 proteolytic enzymes and occurred in two forms differing as regards cAMP affinity. The cAMP-binding capacity of the preparation was equal to 17 nmol cAMP/mg protein. To study the topography of the cAMP-binding center, use was made of cAMP analogs. It was demonstrated that introduction of the substituents into the 8th position of the purine ring and substitution with respect to the N6-exoaminogroup affected insignificantly the analog affinity for the cAMP-binding center. At the same time the substituents introduced into the first position of the adenine base, into the area of the 2'-hydroxyl group of ribose and into the cyclophosphate part of the cAMP molecule considerably decreased the analog affinity for the regulatory center of type II cAMP-dependent proteinkinase. |
