Chain shuffling to modify properties of recombinant immunoglobulins.

Combinatorial libraries and selection of variants from such libraries have proven to be a successful approach for identifying molecules with novel or improved properties. The importance of antibody (Ab) molecules in basic and applied research, as well as the extensive knowledge of how they interact with their antigen (Ag) targets, have made them favorite targets for modification by this approach. The binding site of Abs can be described as a set of modules that together make up the Ag-binding site. These modules may be defined either as the heavy-chain (HC) and light-chain (LC) variable domains (VH and VL respectively) or as the six individual complementarity-determining regions (CDRs) or hypervariable loops, which act together to form this structure. The variable CDRs reside in a relatively fixed framework region (FR) that makes up the basic structure and fold of the protein.