Effect of monoclonal antibodies in preventing carboxypeptidase A aggregation.

With an increase in temperature, carboxypeptidase A shows a decrease in solubility that is accompanied by loss of enzymic activity and conformational changes leading to its aggregation. In the present study we investigated the suppression of enzyme aggregation via its interaction with two monoclonal antibodies raised against the native protein. The protein aggregation process was monitored by ELISA measurements and determination of residual enzymic activity. As previously found, selected monoclonal antibodies which do not inhibit the biological activity of the antigen and bind with a similar affinity constant to their epitopes on the molecule exhibit a chaperone-like activity in the refolding of their antigen. These antibodies have an inhibitory effect on the aggregation of the enzyme which seems to be related to the location of the antigenic site recognized by each antibody. Identifying the aggregating epitopes' as sequences that are related to the sites where protein aggregation is initiated and preparing monoclonal antibodies against these regions may facilitate the understanding and prevention of protein-aggregation processes.