The electrical properties and stability of DNA to UV radiation and aromatic hydrocarbons

Studies of the d. c. conductive behavior of solid gels of DNA under high vacuum have shown that a reproducible energy gap of 2.4 eV and a photoelectric effect may be obtained following extensive evacuation procedures. Admission of air for short periods has a reversible effect on this photoelectirc effect and semiconductive behavior. After prolonged illumination in air the sample becomes permanently affected and will not reproduce the photoelectric effect or give rise to a semiconduction energy gap of 2.4 eV but give rise to a permanently lower energy gap of 1.6 eV. The effect of ultraviolet irradiation on the thermal denaturation of DNA in the presence of six aromatic hydrocarbons has been examined in order to determine the extent to which the presence of the hydrocarbon protects the DNA against ultraviolet damage.