Static and dynamic properties of antibody proteins in solution - the effects of crowding and charge-tuning

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The efficient medical dosage of antibodies requires high concentrations in aqueous solutions. These solutions can in addition contain other molecules, denoted crowding agents, which help to increase the maximum protein concentration or circumvent protein aggregation. We propose to study both static and dynamic properties of highly concentrated aqueous antibody solutions using small-angle scattering, neutron spectroscopy, and complementary techniques. In particular, we address the effects of macromolecular crowding and ion-induced charges on the effective protein-protein interactions, phase behavior, and global as well as internal dynamics of antibodies in solution. We also focus on the dynamic, transient, or static cluster phases in this system depending on the employed physical parameters. The systematic investigation will cover both the effect of self-crowding by the antibody proteins themselves as well as by external crowding agents such as other proteins (e.g. BSA), polymers (e.g. PEG), and sugars (e.g. trehalose). With view at the peculiar three-lobed conformation of immunoglobulin antibody proteins, the project will in particular be guided by the role and importance of the protein shape in the determination of the static and dynamic properties of the protein solutions. Whilst addressing questions related to biophysics and biomedicine, we will employ both experimental and theoretical concepts and methods from soft-matter physics. These methods provide a unique access to molecular length scales and to picosecond to nanosecond time scales of molecular motions. Our proposed study addresses important questions regarding applied protein science as well as fundamental mechanisms of crowding in solutions of anisotropic particles.