Fc-fused IdeS enzyme enables rapid, contamination-free generation of F(ab')2 fragments from human IgG

The generation of F(ab')2 fragments from intact immunoglobulin G (IgG) is crucial for many research and therapeutic applications, particularly when Fc-mediated effector functions are undesirable. Fc regions can trigger immune responses, interfere with assays, or cause non-specific binding. Traditional methods for Fc removal often involve enzymatic digestion (e.g., pepsin) followed by purification steps, which can be time-consuming, inefficient, and risk contamination with the degrading enzyme. There's a need for a streamlined, efficient method to produce pure F(ab')2 fragments or Fc-free proteins.

Researchers developed a three-step protocol for generating F(ab')2 fragments from human IgG or Fc-fusion proteins using an IdeS-Fc enzyme. First, target IgG or Fc-fusion proteins were incubated with IdeS-Fc. Second, the resulting Fc fragments, along with the IdeS-Fc enzyme itself (due to its Fc fusion), were retained using protein G agarose beads. This step leverages protein G's affinity for Fc regions. Third, the desired F(ab')2 fragments or Fc-free proteins were collected by centrifugation, effectively separating them from the retained Fc fragments and the IdeS-Fc enzyme in the original buffer.

The developed method successfully achieved the rapid and efficient generation of F(ab')2 fragments from human IgG and Fc-fusion proteins. A key advantage of this approach is the complete removal of the IgG-degrading enzyme, IdeS-Fc, from the final product. This eliminates potential contamination issues often associated with traditional enzymatic digestion methods, ensuring the purity of the F(ab')2 fragments. The use of protein G agarose beads proved effective in simultaneously capturing both the cleaved Fc fragments and the IdeS-Fc enzyme itself, simplifying the purification process. The method yielded Fc-free proteins that were collected by centrifugation in their original buffer, indicating minimal processing and potential for maintaining protein integrity. This streamlined process offers a significant improvement in efficiency and purity for generating antibody fragments.

The method ensures the F(ab')2 fragments or Fc-free proteins are collected in the original buffer without IdeS contamination, a critical benefit for downstream applications.