The Effect of β-irradiation on Deoxyribonucleoprotein

Abstract

The infra-red absorption spectrum, 45Ca uptake, and dielectric increment of calf thymus deoxyribonucleoprotein (DNP) was measured after or during irradiation with [beta] - rays from 3H2O. With 600 rads, a shoulder at 6-17 [mu] appeared and the absorption at 7- 09 [mu] increased. Ca3(PO4)2 also shows absorption peaks at these wavelengths. Uptake of 45Ca in DNP increased by 13-27% with 600 rads. The dielectric increment decreased gradually with increasing doses after 300 rads. When Ca++ was added to the DNP solution prior to irradiation, the dielectric increment began to decrease with smaller doses. All these observations can be explained by complex formation between Ca++ and 2 neighboring phosphates of the DNA moiety, which are exposed on dissociation of DNP into DNA and protein due to ionizing radiation.