Crosslinking and Degradation of Deoxyribonucleic Acid Gels with Varying Water Contents When Irradiated with Electrons

Publisher Website
Google Scholar
Abstract
When water is introduced into a DNA system it profoundly affects the type of radiation response obtained. In the absence of oxygen, direct action produces both degradation and crosslinking, the latter predominating and causing the production of insoluble gels for DNA to water ratios up to 3:1. At greater water contents degradation by indirect action, which produces only breaks in one chain of the twin helix, overwhelms the crosslinking resulting from direct action and insoluble gels are not formed. When oxygen is present crosslinking does not occur because oxygen combines with the active centers (radicals) which lead to crosslinks and the availability of such centers to oxygen diffusion is increased as the DNA gels become swollen with water. Under these conditions the efficiency of scission of the twin helix by indirect and direct action is in the ratio of 1.3:1.