Mechanisms of the radioprotective effect of cysteamine in Escherichia coli.
The values of the oxygen effect (m) and the maximal protective effect of cysteamine (DMF*) were estimated for four Escherichia coli strains: AB1157 (wild type), AB1886 (uvrA), AB2463 (recA), and p3478 (polA). A correlation made between DMF* and m as well as the kinetics of the increase of DMF with oxygen depletion showed that the protective effect of cysteamine is realized by three mechanisms: (i) anoxia achieved by oxygen reduction, with the DMF varying from 2.2 to 4.2 for different E. coli strains (this protection is the major contribution to the entire mechanism); (ii) lowering of the indirect radiation effect; i.e., for 50 mM cysteamine DMF does not exceed 1.1; and (iii) increase of the efficiency of enzymatic repair. The latter effect of cysteamine is registered only with the wild-type E. coli, the DMF being not less than 1.4.
Korystov YuN
Institute of Biological Physics, Acad. Sci. USSR, Pushchino, Moscow Region.
Vexler
F B
FB
D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D003543:Cysteamine / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects / Q000528:radiation effects*; D011837:Radiation-Protective Agents / Q000494:pharmacology*
D011837:Radiation-Protective Agents; D003543:Cysteamine