PURIFICATION AND SOME PROPERTIES OF AN OXIDATIVE INHIBITOR IN RABBIT RETICULOCYTE LYSATES

Protein synthesis in rabbit reticulocyte lysates in the presence of he me is inhibited by 50% by the addition of 4 mM GSSG (oxidized glutathi one). The incubation of the rabbit reticulocyte lysate with 4 mM GSSG at 30 degrees C for 30 min will cause activation of an inhibitor of pr otein synthesis which could be purified from the lysates through a fiv e-step procedure. The inhibitor results in a 70-80% inhibition after a lh incubation. The inhibitor consists of one polypeptide of 23 kDa app arent molecular weight and is 90% pure as judged by sodium dodecyl sul fate/polyacrylamide gel electrophoresis. However, in the presence of c AMP (10 mM) or GEF (guanine nucleotide exchange factor) (0.3 mu g), pr otein synthesis in the inhibited reticulocyte lysate will be already r ecovered.