title: Both Reversible Self-Association and Structural Changes Underpin Molecular Viscoelasticity of mAb Solutions.
abstract: The role of antibody structure (conformation) in solution rheology is probed. It is demonstrated here that pH-dependent changes in the tertiary structure of 2 mAb solutions lead to viscoelasticity and not merely a shear viscosity (η) increase. Steady shear flow curves on mAb solutions are reported over broad pH (3.0 ≤ pH ≤ 8.7) and concentration (2 mg/mL ≤ c ≤ 120 mg/mL) ranges to comprehensively characterize their rheology. Results are interpreted using size exclusion chromatography, differential scanning calorimetry, analytical ultracentrifugation, near-UV circular dichroism, and dynamic light scattering. Changes in tertiary structure with concentration lead to elastic yield stress and increased solution viscosity in solution of "mAb1." These findings are supported by dynamic light scattering and differential scanning calorimetry, which show increased hydrodynamic radius of mAb1 at low pH and a reduced melting temperature Tm, respectively. Conversely, another molecule at 120 mg/mL solution concentration is a strong viscoelastic gel due to perturbed tertiary structure (seen in circular dichroism) at pH 3.0, but the same molecule responds as a viscous liquid due to reversible self-association at pH 7.4 (verified by analytical ultracentrifugation). Both protein-protein interactions and structural perturbations govern pH-dependent viscoelasticity of mAb solutions.
authors: Formulation Sciences Department, MedImmune, One MedImmune Way, Gaithersburg, Maryland 20878.
authors: Prasad S
authors: PS
authors: Sarangapani
authors: Process and Purification Sciences Department, MedImmune, One MedImmune Way, Gaithersburg, Maryland 20878.
authors: Justin
authors: J
authors: Weaver
authors: Analytical Biotechnology Department, MedImmune, One MedImmune Way, Gaithersburg, Maryland 20878.
authors: Arun
authors: A
authors: Parupudi
authors: National Center for Macromolecular Hydrodynamics, University of Nottingham, School of Biosciences, College Road, Sutton Bonnington Campus, Sutton Bonnington, LE12 5RD, UK.
authors: Tabot M D
authors: TMD
authors: Besong
authors: National Center for Macromolecular Hydrodynamics, University of Nottingham, School of Biosciences, College Road, Sutton Bonnington Campus, Sutton Bonnington, LE12 5RD, UK.
authors: Gary G
authors: GG
authors: Adams
authors: National Center for Macromolecular Hydrodynamics, University of Nottingham, School of Biosciences, College Road, Sutton Bonnington Campus, Sutton Bonnington, LE12 5RD, UK.
authors: Stephen E
authors: SE
authors: Harding
authors: Formulation Sciences Department, MedImmune, One MedImmune Way, Gaithersburg, Maryland 20878.
authors: Prakash
authors: P
authors: Manikwar
authors: Materials Science and Engineering Department, Penn State University, University Park, Pennsylvania 16802.
authors: Maria M
authors: MM
authors: Castellanos
authors: Formulation Sciences Department, MedImmune, One MedImmune Way, Gaithersburg, Maryland 20878.
authors: Steven M
authors: SM
authors: Bishop
authors: Formulation Sciences Department, MedImmune, One MedImmune Way, Gaithersburg, Maryland 20878. Electronic address: jai.pathak@nih.gov.
authors: Jai A
authors: JA
authors: Pathak
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000032:analysis* / Q000737:chemistry*; D016466:CHO Cells; D002152:Calorimetry, Differential Scanning / Q000379:methods; D002850:Chromatography, Gel / Q000379:methods; D006224:Cricetinae; D003412:Cricetulus; D004548:Elasticity; D019999:Pharmaceutical Solutions / Q000032:analysis / Q000737:chemistry; D054730:Protein Interaction Domains and Motifs; D012212:Rheology / Q000379:methods; D014783:Viscosity
chemical_list: D000911:Antibodies, Monoclonal; D019999:Pharmaceutical Solutions
keywords: analytical ultra-centrifugation; calorimetry (DSC); diffusion; light scattering (dynamic); mAb; protein aggregation; protein formulation; protein structure; rheology; viscosity