Refolding of Aggregation‐Prone ScFv Antibody Fragments Assisted by Hydrophobically Modified Poly(sodium acrylate) Derivatives

ScFv antibody fragments are a promising alternative to full‐length antibodies for both therapeutic and diagnosis applications. They can be overexpressed in bacteria, which enables easy large scale production. Since scFv are artificial constructs, they are poorly soluble and prone to aggregation, which makes them difficult to manipulate and to refold. Here, stabilization and refolding of scFv fragments from urea‐unfolded solutions are reported based on the use of micromolar amounts of polymers playing the role of artificial chaperons. Using fluorescence correlation spectroscopy, the size and aggregation number of complexes of scFv with unmodified or hydrophobically modified poly(sodium acrylate) are determined. The evolution of the secondary structure along the refolding procedure, in the presence or absence of 0.4 m l‐arginine at scFv:polymer < 1:5 (w/w), is determined by high‐sensitivity synchrotron‐radiation circular dichroism. Measurements reveal that refolding in the presence of polymers yields native‐like secondary structure, though a different folding pathway can be followed compared to refolding in the absence of polymer. This is the first report on the use of macromolecular additives to assist refolding of a multidomain protein of therapeutic interest. Amphiphilic derivatives of poly(acrylicacid) are assessed for their ability to help chemical refolding of aggregation‐prone scFv. Weak noncovalent associations with the polymers impart solubility to scFv and are compatible with recovery of a native‐like conformation.