Effect of gamma irradiation on dye-DNH binding.

This paper attempts to analyse the effect of (a) gamma radiation and (b) the presence of histones in the form of nucleohistones (DNH) on the modes of ligand (Proflavine, Pf) binding to DNH. Effects were investigated by spectrophotometry. A certain dose of radiation which causes appreciable DNA denaturation has much less effect on DNH. There is a 'threshold' dose beyond which DNH denaturation is directly proportional to dose as in the case of DNA. The histones in DNH act as a shield and at higher doses get dissociated to expose the double helix to radiations. Ligand binding has a further stabilizing effect against radiation damage to DNH.