Single-chain variable fragments lack the constant [[Fc region]] found in complete antibody molecules, and, thus, the common binding sites (e.g., [[Proteinprotein G]]) cannot be used to purify antibodies. These fragments can often be purified or immobilized using [[Proteinprotein L]], since Proteinprotein L interacts with the variable region of kappa light chains. More commonly, scientists incorporate a six histidine tag on the c-terminus of the scFv molecule and purify them using immobilized metal affinity chromatography (IMAC). For unknown reasons, some scFv can also be captured by [[Proteinprotein A]].
