Thermal stability studies of immunoglobulins using capillary isoelectric focusing and capillary zone electrophoretic methods.

The affinity of an antibody towards its antigen is highly specific to its conformation, in order to have optimal antibody-antigen interaction. The increase of temperature might cause changes in antibody conformations. The change of structure conformations may be reflected in the isoelectric points (pI values), peak shape and absorbance of the antibody. In this study, a monoclonal antibody was heated over a period of time. Capillary isoelectric focusing (cIEF) and capillary zone electrophoresis (CZE) were used to monitor the change in the antibody. The longer the heating period, the lower the pI values were under cIEF conditions. CZE also showed changes in peak shapes and decreases in absorbance of the antibody with heating.