Antigenicity of poly(dA-dT)center dot poly(dA-dT) photocrosslinked with 8-methoxypsoralen

We report the formation of photocrosslink (diadduct) between duplex poly(dA-dT) and 8-methoxy-psoralen inferred on the basis of UV and fluorescence characteristics, T-m, nuclease S1 digestibility, and hydroxyapatite column chromatography. The photo-crosslink was highly immunogenic inducing high titer antibodies in goat. The affinity constant of antigen-antibody interaction quantitated by precipitin titration was found to be 2.71 x 10(9) M(-1), calculated by Langmuir isotherm plot. These antibodies were highly specific showing recognition of almost exclusively of nucleic acid-furocoumarin photoadducts and could be used as a probe to detect and quantitate DNA modified with furocoumarins in health and disease. Antibodies against poly(dA-dT)-furocoumarin photocrosslink might be a better probe because of repeated A-T sequences on the immunogen. (C) 1996 Academic Press, Inc.