Effects of high energy irradiation on respiratory enzyme systems

Abstract

The irradiation sensitivity of the cytochrome system was investigated, using as examples baker's yeast andE. coli. A method is described with which the proportion of reduced cytochrome in cell suspensions could be measured spectrometrically. In contrast to isolated cytochrome, which is easily oxydized by Roentgen rays, the cytochrome of living cells is very stable to Roentgen rays. The electrone transport is not influenced by high energy rays. It is probable that the hydrogen transport is also undisturbed. Only if the cell is so damaged by high doses of rays that every exchange of substances is impossible, i.e. if the cell is dead, is the ferrocytochrome oxydized and perhaps also destroyed. The oxydation is thus a secondary process resulting from death of the cell by rays. It is supposed that the changes in energy metabolism described in the literature, especially the disturbances of oxydative phosphorylation, are also secondary processes.