title: Relating Protein-Protein Interactions and Aggregation Rates From Low to High Concentrations.
abstract: At low protein concentrations (c2), non-native protein aggregation rates are known to be sensitive to changes in conformational stability and "weak" or "colloidal" protein-protein interactions. Protein-protein interactions are also known to be strong functions of c2. In the present work, protein-protein interactions and rates of aggregation were quantified systematically for a monoclonal antibody (MAb) across a broad range of c2 at pH 5.1 and 6.5, with or without 5 wt/wt % sucrose or 100 mM NaCl present. Aggregation rates were determined from initial-rate analysis with size-exclusion chromatography, and interactions were quantified with static and dynamic laser light scattering. A number of hypotheses were tested regarding whether changes in protein-protein interactions can be predictive of changes in aggregation rates versus c2. Hypotheses were based on (i) changes in thermodynamic activity; (ii) statistical mechanical fluctuation theory; and (iii) surface-contact probabilities. Arguments based on (i) and (ii) were qualitatively inconsistent with experimental rates and scattering. Hypothesis (iii) was reasonably successful and resulted in a semiquantitative correlation between rates and protein-protein interactions across almost 2 orders of magnitude in c2. However, (iii) requires one to assume that the concentration-dependent protein-protein Kirkwood-Buff integral is a reasonable surrogate for contact probabilities.
authors.affiliation: Department of Chemical & Biomolecular Engineering, University of Delaware, Newark, Delaware 19716.
authors.forename: Ranendu
authors.initials: R
authors.lastname: Ghosh
authors.affiliation: Department of Chemical & Biomolecular Engineering, University of Delaware, Newark, Delaware 19716.
authors.forename: Cesar
authors.initials: C
authors.lastname: Calero-Rubio
authors.affiliation: Department of Drug Product Science and Technology, Bristol-Myers Squibb, New Brunswick, New Jersey 08901.
authors.forename: Atul
authors.initials: A
authors.lastname: Saluja
authors.affiliation: Department of Chemical & Biomolecular Engineering, University of Delaware, Newark, Delaware 19716. Electronic address: cjr@udel.edu.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Roberts
mesh_terms: D000911:Antibodies, Monoclonal / Q000737:chemistry; D002850:Chromatography, Gel / Q000379:methods; D000067493:Dynamic Light Scattering / Q000379:methods; D006863:Hydrogen-Ion Concentration; D008027:Light; D066329:Protein Aggregates; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D011506:Proteins / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D000911:Antibodies, Monoclonal; D066329:Protein Aggregates; D011506:Proteins
keywords: biophysical models; biotechnology; light scattering (dynamic); protein aggregation; protein formulation