Kinetic analysis of engineered antibody-antigen interactions.

Molecular engineering of antibodies has made it possible to produce specific domains of the antibody molecule and combine them with other protein domains to achieve new properties. Using site directed mutagenesis, amino acid residues can be exchanged within the binding site; and, by analysis of crystal structures, the positions of these amino acids can be determined in three dimensions at atomic resolution. In addition, gene libraries and phage selection technology can be used to generate new antibody fragments directly from a gene pool. Both mutagenesis and selection from libraries offer opportunities to identify antibody-derived molecules with altered and useful antigen recognition properties. The detailed analysis of both kinetic and equilibrium binding affinity are therefore essential to understand the activity of the molecules resulting from antibody engineering and to guide the progress of their further design. This paper reviews recently evolving techniques for the binding analysis of antibodies, their functional domains and antibody chimerae.