Schematic representation of intact antibody (IgG) and various genetically engineered [single-chain Fv, scFv; scFv dimers such as (scFv)2 and diabody; and larger fragments such as minibodies and scFv-Fc containing single constant domains and intact Fc regions respectively] and enzymatically derived antibody fragments [Fab and F(ab’)2]. VH and VL represent the heavy and light chain variable regions, CH1, CH2, and CH3 are the heavy chain constant region domains, and CL is the light chain constant region domain.