Radioprotection by mixtures of Mn²⁺, orthophosphate, nucleosides and bases.

(A) BamHI activity. BamHI was irradiated in the indicated mixtures and then assayed for residual activity as in Figure 1B. Abbreviations: PiB, potassium phosphate buffer, pH 7.4; A, adenosine; U, uridine; Ns/Nb, nucleosides and bases (1 mM; see Table S1 for the Ns/Nb added). Irradiations were under aerobic conditions unless stated otherwise (gel 2). (B) Nucleosides prevent protein oxidation. Proteins purified from E. coli were mixed with adenosine (A) or uridine (U), phosphate buffer (PiB), pH 7.4 and Mn²⁺, and irradiated to the indicated doses (kGy). The irradiated proteins were separated by polyacrylamide gel electrophoresis and visualized by Coomassie staining as in Figure 1A. Note, the ability of the DR-ultrafiltrate to prevent in vitro ionizing radiation-induced protein carbonylation corresponds to the preservation of stainable (Coomassie) banding.