Radiosensitization of phosphate release from 3'- and 5'-nucleotides: correlations between chemical change and biological inactivation.

SummaryThe effect of nitrobenzene radiosensitizers on the release of inorganic phosphate in aqueous solutions of 3′- and 5′-nucleotides in the absence of oxygen is quite specific. The 5′-purine nucleotides are sensitized, whereas both 3-'purine and-pyrimidine nucleotides are protected. Sensitization and protection increase with increasing nitrobenzene electron affinity and concentration. The 5′-pyrimidine nucleotides can be protected or sensitized, depending on sensitizer electron affinity and concentration. Correlations between enhancement ratios for chemical and biological damage (Chinese-hamster cell killing in hypoxia) are examined with a view to relating radiation chemical change in cellular molecules to biological inactivation.