The RNA binding subset of adenosine antibodies

Hapten specific antibodies were elicited against adenosine-BSA conjugate (Ado-BSA) in rats. By radiohapten assay, two major populations of hapten specific antibodies were identified. They were directed against either adenosine trialcohol (Aox-red) or morpholino-adenosine (Morph-Ade). The association constant (Ka) for the 3H-Aox-red binding population was determined to be 1.02 X 10(7) M-1. Majority of the Aox-red specific antibodies were cross-reactive with Morph-Ade, but they did not cross-react at all with adenosine(A) or deoxyadenosine (dA). 3H-A binding subsets were actually Morph-Ade specific and constitute less than 10% of the hapten specific antibodies. The Ka value for the 3H-A binding was determined to be 4.5 X 10(6) M-1. A very minor and highly cross-reactive subset of Morph-Ade specific antibodies participate in RNA binding. Though a larger proportion of Morph-Ade specific antibodies interact with 3H-A, only a fraction of them bind to RNA. The extreme cross-reactivity and hence, the highly adaptive nature of the binding sites of the antibodies interacting with RNA, might be a stringent requirement for recognising adenine residues of nucleic acids in solution.