Use of a competitive protein-binding assay for adenosine 3':5'-phosphate for the study of bovine corpus luteum adenylate cyclase.

The use of a competitive protein-binding assay for cyclic AMP, utilizing the binding protein purified from bovine adrenal cortex, for the study of adenylate cyclase activity of the washed 600 g sediment of bovine corpus luteum is validated. A specific assay for cyclic AMP could only be achieved by removal of the degradation products of ATP on a precipitate of nascent BaSO4. Simple dilution of the sample before assay was not sufficient to eliminate interference from degradation products of ATP. An observed variability in optimal ATP substrate and tissue concentrations is though to reflect variability in the enzymic profile of the cyclic corpus luteum. Optima with respect to F-, Mg2+ and pH are more clearly defined and are similar to those reported for adenylate cyclase systems for other tissues.