Increasing the developability of lambda chain antibodies: engineering to confer protein L binding activity and its...

Antibody engineering is essential to the development of commercially viable biotechnological tools. Within this context, Protein L (PpL) is commonly used to purify antibodies due to its ability to bind to the variable light chain. However, one limitation is that protein L does not bind to lambda chain antibodies, which negatively influences their developability. Therefore, the objective of this study was to utilize the lambda antibody mAb3 (an anti-Acanthamoeba IgG) as a template to construct recombinants fragments with protein L binding ability and associated benefits. We were able to produce four functional mAb3-derived scFvs, two of them capable of binding PpL, as demonstrated by PpL-affinity purification, ELISA and western blotting. In addition, it was possible to optimise the thermal stability of one of the PpL-binding scFvs by up to 8.7 °C compared to the original sequence, reaching a melting temperature of 67.2 °C, while maintaining high production yields. The scFvs also conserved the same reactivity profile against Acanthamoeba antigens as the parental molecule. Based on the PpL-binding scFvs, minibody and scFv-Fc fragments were also expressed, all of which retained the PpL-binding and antigen recognition profiles. In conclusion, this study demonstrates that with a few mutations, lambda chain antibodies can be optimized to increase their developability as potential therapeutic or diagnostic molecules.