The bispecific antibody fragment known as Diabody-CH3 is made up of two distinct polypeptide chains, one of which has a heavy chain variable region (VH) and the other a light chain variable region (VL). A short peptide linker, typically consisting of five amino acids, connects the two chains to create a single-chain Fv (scFv) fragment. Through VH-VH interactions, two scFv fragments combine to create a dimer known as a diabody. Due to the coupling of VH and VL from distinct chains, each Diabody molecule contains two antigen-binding sites. This allows Diabody to identify two distinct antigens at once, resulting in bispecificity.