Local environment effects on charged mutations for developing aggregation-resistant monoclonal antibodies.

Area of Science:

• Biochemistry and Biophysics
• Protein Engineering
• Computational Biology

Background:

• Protein aggregation is a critical challenge for monoclonal antibody therapeutics.
• Charged mutations are a strategy to enhance antibody aggregation resistance.
• The location-dependent effects of charged mutations remain poorly understood.

Purpose of the Study:

• To investigate the mechanism behind location-dependent solubilizing activity of charged mutations in antibodies.
• To analyze the contribution of local and global net charge to solvation free energy changes upon mutation.

Main Methods:

• Performing molecular dynamics simulations on antibody mutants.
• Conducting residue-wise decomposition of solvation free energy.
• Analyzing solvation free energy changes in relation to mutation site and local/global net charge.

Main Results:

• Solvation free energy changes are influenced by both the protein's total net charge and the local net charge within a 15 Å radius of the mutation site.
• A local environment with more positive and fewer negative charges enhances the benefits of a positive charged mutation.
• This local charge effect explains the observed location dependence of charged mutations.

Conclusions:

• A local design principle, in addition to the global net charge, is crucial for optimizing charged mutations in antibodies.
• This principle can guide the rational design of aggregation-resistant antibodies.
• Understanding local solvation effects is key to improving biotherapeutic protein stability.