Antibodies to dpApT sequence: purification & studies on their specificity & affinity to different ligands.
Antibodies specific to the dinucleotide, dpApT, were elicited in rabbits using a thyroglobulin (Tg) conjugate of dpApT(Tg-dpApT) as the immunogen. The dpApT antibodies were isolated from anti-Tg-dpApT \gamma-globulins by adsorption to an AH-Sepharose-dpApT affinity column and elution with 0.1N HOAc and were further purified using an AH-Sepharose-dpC column. The specificity and affinity of purified dpApT antibodies were analyzed by the inhibition of the binding of [3H]dpApT as well as denatured [32P]DNA to the antibodies with various nonradioactive nucleotides and their derivs. The antibodies were sequence-specific. Their binding to denatured DNA was poorly inhibited by deoxynucleoside 5'-monophosphates as compared to dpApT whereas DNAs from varying sources were inhibitory to different extents. The affinity consts. for the binding of [3H]dpApT to the antibodies as detd. by equil. dialysis were $9.6_x$ 106M-1 at $14^o$ and $2.3_x$106M-1 at $32.5^o$; \Delta$H^o$ and \Delta$S^o$ for the binding were -13.4 kcal/mol and -14.8 cal/deg/mol, resp.