HETEROGENEITY OF ANTIBODIES TO ADENOSINE 5'-MONOPHOSPHATE

Antibodies to 5''-AMP were produced in rabbits by injecting a conjugate of the nucleotide (oxidized with periodate) with bovine serum albumin. AMP-specific antibodies were isolated by affinity chromatography. The antiserum was first applied on oligoadenylic acids-agarose column and then the unbound proteins on a morpholine derivative of AMP-agarose column. The antibodies purified on these 2 columns interact differently with AMP derivatives as shown by immunodiffusion. These results are confirmed by the values of the binding constants of the complexes Fab fragments, AMP and AMP derivatives. The study of Fab fragment.sbd.C(8)-substituted AMP derivative complexes suggest a a syn conformation for the bound bound nucleotide. Thermodynamic parameters for the Fab fragment-AMP complexes were determined (.DELTA.H.degree. [standard free enthalpy change] = -13 kcal/mol and .DELTA.S.degree. [standard free entropy change] = -15 cal .cntdot. degree-1 .cntdot. mol-1).