Stabilization of a monoclonal antibody during purification and formulation by addition of basic amino acid excipients

Background: Protein stability of therapeutic monoclonal antibodies during processing and final storage is imperative for the commercial success of the product. Amino acid addition is one of the options for stabilization of proteins that can be employed during the manufacturing process and storage. Results: Use of arginine in the elution buffer during Protein A purification and subsequent neutralization doubled the yield of antibody compared with the original glycine-based elution buffer. The role of amino acids in stabilizing monoclonal antibody liquid formulations was then studied using differential scanning calorimetry. Increase in the unfolding transition temperatures (T) of immunoglobulin G (IgG) was measured after supplementing a glycine buffer with a range of amino acids. The basic amino acids histidine, lysine, and arginine stabilized all three domains of IgG. The neutral amino acids serine and alanine provided less stabilization; glutamine, proline, and the acidic amino acids provided negligible stabilization. Conclusion: The positive charge on the side-chain of histidine, lysine, and arginine appears to be the most important factor affecting the IgG stabilization. It is probable that the mechanism for IgG stabilisation is the same for all of the basic amino acids and that it binds transiently to IgG side chains, altering water populations in the solvation shell, making unfolding and aggregation less energetically favourable