Role of Domain-Domain Interactions on the Self-Association and Physical Stability of Monoclonal Antibodies: Effect of pH and Salt.
Amy Y Xu, Marco A Blanco, Maria Monica Castellanos, Curtis W Meuse, Kevin Mattison, Ioannis Karageorgos, Harold W Hatch, Vincent K Shen, Joseph E Curtis
Author Information
Amy Y Xu: Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States. ORCID
Marco A Blanco: Discovery Pharmaceutical Sciences, Merck Research Laboratories, Merck & Co., Inc, West Point, Pennsylvania 19486, United States.
Maria Monica Castellanos: Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, Maryland 20850, United States. ORCID
Curtis W Meuse: Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, Maryland 20850, United States. ORCID
Kevin Mattison: Malvern Panalytical, Westborough, Massachusetts 01581, United States.
Ioannis Karageorgos: Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, Maryland 20850, United States.
Harold W Hatch: Chemical Sciences Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States. ORCID
Vincent K Shen: Chemical Sciences Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States.
Joseph E Curtis: NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States. ORCID
Monoclonal antibodies (mAbs) make up a major class of biotherapeutics with a wide range of clinical applications. Their physical stability can be affected by various environmental factors. For instance, an acidic pH can be encountered during different stages of the mAb manufacturing process, including purification and storage. Therefore, understanding the behavior of flexible mAb molecules in acidic solution environments will benefit the development of stable mAb products. This study used small-angle X-ray scattering (SAXS) and complementary biophysical characterization techniques to investigate the conformational flexibility and protein-protein interactions (PPI) of a model mAb molecule under near-neutral and acidic conditions. The study also characterized the interactions between Fab and Fc fragments under the same buffer conditions to identify domain-domain interactions. The results suggest that solution pH significantly influences mAb flexibility and thus could help mAbs remain physically stable by maximizing local electrostatic repulsions when mAbs become crowded in solution. Under acidic buffer conditions, both Fab and Fc contribute to the repulsive PPI observed among the full mAb at a low ionic strength. However, as ionic strength increases, hydrophobic interactions lead to the self-association of Fc fragments and, subsequently, could affect the aggregation state of the mAb.
