Radioprotection of Acholeplasma Laidlawii B by Cysteine

Summary

The radioprotective activity of cysteine is progressively destroyed by ionizing radiation greater than 28·8 krads. Acholeplasma laidlawii B cells are protected after brief pre-irradiation exposure to cysteine, and this response may be membrane-mediated. As the equilibrium concentration of cysteine in the pleuropneumonia-like organism is increased, the rate of cell inactivation decreases monotonically in N₂ and biphasically in air over the concentration ranges examined; in N₂ the decrease is proportional to the logarithm of the cysteine concentration incorporated metabolically into the cell membrane.