Hydrogel Tethering Enhances Interdomain Stabilization of Single Chain Antibodies

Here, we identify the importance of molecular crowding agents in the functional stabilization of scFv antibodies. Antibodies were tethered through an engineered calmodulin (CaM)-binding peptide into a stimulus-responsive hydrogel composed of poly(ethylene glycol) (PEG)-functionalized CaM. Macromolecular crowding is modulated by transient heating, which decreases effective pore sizes. Using a fluorescent ligand bound to the scFv, frequency-domain fluorescence spectroscopy was used to assess the structural coupling between the VH and the VL domains and relationships with functional stabilization. There is minimal structural coupling between the VH and the VL domains in solution, as is apparent from the substantial rotational mobility for the bound ligand, that is suggestive of an independent mobility for the VH and the VL domains. In comparison, the hydrogel matrix acts to structurally couple the VH and the VL domains, resulting in a reduction in rotational mobility and a retention of ligand binding in the ...