Effect of oxidative stress, produced by cumene hydroperoxide, on the various steps of protein synthesis. Modifications of elongation factor-2.

We have studied the effect of oxidative stress on protein synthesis in rat liver. Cumene hydroperoxide (CH) was used as an oxidant agent. The approach used was to determine the ribosomal state of aggregation and the time for assembly and release of polypeptide chains in the process of protein synthesis in rat liver in vivo. The results suggest that the elongation step is the most sensitive to CH treatment. The measurement of both carbonyl groups content and ADP-ribosylatable elongation factor 2 (EF-2), the main protein involved in the elongation step, indicates that under CH treatment EF-2 is oxidatively modified and a lower amount of active EF-2 is present. These results are corroborated by in vitro oxidation of EF-2 and could explain for the decline in the elongation step.