title: A new procedure for haptenizing adenosine leading to a more specific radioimmunoassay method.
abstract: Adenosine was coupled to human serum albumin by two different procedures that preserved the purine and ribose rings. The conjugates were evaluated for antigenicity in rabbits and guinea pigs. A conjugate containing 2'(3')-O-succinoyladenosine failed to elicit antibodies, whereas one containing laevulinic acid (O2', 3'-adenosine-acetal) elicited antibodies in all animals injected. The affinity and specificity of binding of adenosine to three selected antisera were evaluated. Dissociation constants of 31-187 nM were observed. Displacement of adenosine binding to all antisera by adenine 5'-nucleotides, adenine, inosine and hypoxanthine required more than 1000-fold higher concentrations than of adenosine itself. Similar affinities for adenosine and 2'-deoxyadenosine were observed. By exploiting the high specificity of the antisera, a radioimmunoassay method was established that was capable of detecting down to 1 pmol of adenosine (20 nM) in unfractionated heart perfusates and cell extracts. The acetal-mediated coupling procedure is applicable to other biologically important cis-diols.
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives / Q000032:analysis* / Q000276:immunology; D000818:Animals; D000918:Antibody Specificity; D006241:Haptens / Q000276:immunology*; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D009206:Myocardium / Q000032:analysis; D009504:Neutrophils / Q000032:analysis; D011817:Rabbits; D011863:Radioimmunoassay / Q000379:methods; D051381:Rats; D012709:Serum Albumin / Q000276:immunology
chemical_list: D006241:Haptens; D007106:Immune Sera; D012709:Serum Albumin; D000241:Adenosine