Probing antibody-antigen interactions

Antibodies bind antigens via noncovalent bonds, such as hydrogen bonds, ionic, hydrophobic, and Van der Waals forces, and their interactions depend strongly on the distance between two interacting molecules. While each individual bond is weak, the collective noncovalent bonds between the antibody and antigen can be strong when all the interacting molecules work together synergistically. Because there are a very large number of these interactions and the antigen and antibody are large, flexible, dynamic molecules, binding between an antibody and antigen is a very complex process. The binding interactions may also be time dependent, because formation of an antibody-antigen complex may involve a sequential series of interactions which induce conformational changes that generate some bonds while breaking others. Because of the dynamic and transient state of antibody-antigen interactions, measurements of the antibody-antigen interactions can be quite complicated and inconsistent, and the results may vary depending on the sample treatment conditions and technique utilized (1).