Radioimmunoassay of cytidine 3',5' monophosphate (cCMP). I. Development of the assay.

A method is presented for the production of reagents for a radioimmunoassay for cCMP. cCMP was succinylated at the 2′0 position with 1,4 ¹⁴C] succinic anhydride, and the monosuccinyl cCMP coupled to Keyhole limpet hemocyanin and injected into rabbits. Antibodies to cCMP were produced that showed minimal crossreactivity with other cyclic nucleotides. Monosuccinyl cCMP was coupled to tyrosine methyl ester, then labeled with ¹²⁵I, and used as the radiolabeled ligand in the immunoassay of cCMP. By use of this assay, the concentration of cCMP in various tissues of rat and guinea pig have been determined.