Formal kinetic treatment of the possible role of proteins in DNA radiation tolerance, protection and sensitization

The formal-kinetic calculations have been made of the postirradiation behaviour of a "protein-DNA" water system with marked variations in protein and DNA concentrations. Protein is a strong competitive acceptor of active products of radiolysis of water and free radicals of DNA. The radioresistance of DNA in such a system and the influence of mercaptoethylamine, sensitizers and oxygen on DNA injury are discussed. The results of the calculations are compared with the data on the composition of cell nuclei and the data on the comparative radioresistance of cells, cell cycle, protective effects, and sensitization. In most cases, the results of the calculations do not contradict the experimental data. It is assumed that the protein protection may be the major factor in considering the endogenous radioresistance.