Yes! There are many different additives/excipients/preservatives that can be added to formulation buffers to increase a biologic’s stability. It is important that the additives do not interfere with the function or structure of the biologic, so all functional assays and characterization must be completed in the final formulation buffer that includes any additives. Some examples of additives used to increase stability are amino acids, sugars, salts, or small amounts of surfactants.
Batabyal et al. emphasize the importance of proper buffer formulation and characterization in the article “Shaping IR Spectroscopy into a Powerful Tool for Biopharma Characterization.” In this study, polysorbate 80 (PS 80) was introduced to the formulation buffer for a monoclonal antibody. PS 80 is commonly used in aqueous drug products to increase stability; however, it is important that the introduction of PS 80 does not change the structure or function of the drug product. MMS had no issues with buffer or excipient interference and generated clean protein structural information that showed PS 80does not affect the structure of the monoclonal antibody.
A different example can be seen in the application note titled “Using MMS to Measure Buffer-Induced Structural Changes in an Alpha-helix Rich Enzyme,” where the buffering conditions did impact the structure of lysozyme. Four different buffering conditions were tested, and it was determined that lysozyme has the highest fractional contribution of alpha-helical structure when it’s in tris buffer compared to water, phosphate buffer, and PBS. Lysozyme is the most active when in tris buffer and this may be due to the optimized structure with higher alpha-helical content. Since the active site of lysozyme is sandwiched between regions of alpha-helix, it makes sense that loss in alpha-helical content would result in less activity.
Lysozyme primary and tertiary structure highlighting the active site near the Asp-52 and Glu-35 amino acids. (Gálvez-Iriqui, et al. "Lysozymes: characteristics, mechanism of action and technological applications on the control of pathogenic microorganisms." Revista mexicana de fitopatología 38.3 (2020):360-383.)