The Radiosensitization ofMicrococcus Sodonensisby N-ethyl Maleimide

SummaryRadiosensitization of the bacterium Micrococcus sodonensis by N-ethyl maleimide (NEM) has been obtained by administering the sensitizer before, during, and after irradiation. It has been shown that there are three different mechanisms of sensitization by NEM:(i) caused by an intracellular reaction, presumably with sulphydryl groups,(ii) caused by the reaction of NEM with a reducing species, probably with the electron, to give a short-lived toxic product, and(iii) caused by interference with the post-irradiation repair processes.The experiments also indicate that NEM is able to penetrate the cell while another sulphydryl poison, iodoacetamide, cannot. This accounts for some of the difference in the mode of action of these two radiosensitizers.