Limited proteolysis as a powerful tool for probing flexible oligopeptide portions among different classes of glutathione transferases

We have probed possible flexible regions of different GSTs by limited prote olysis experiments. The results indicate that each isoenzyme is inactivated by trypsin and protected against this proteolytic attack by glutathione (G SH). Unlike the results previously obtained with glutathione transferases ( GST) GST P1-1, the region most susceptible to the cleavage and responsible for the loss of enzymatic activity in GST Al-l is located at C-terminus (he lix 9) whilst GST M2-2 does not show any primary cleavage site. These findi ngs indicate that helix 2 of GST P1-1 and helix 9 of GST AI-I may perform a class-specific role. (C) 2001 Elsevier Science Ireland Ltd. All rights res erved.