The aggregation of proteins in solution occurs when the balance of hydrogen bonding, electrostatic, hydrophobic, and van der Waals forces becomes sufficiently favorable. Aggregation can proceed from either the folded or denatured state, but is usually quite sensitive to temperature and the solution pH. Additionally, buffer ions and added salts can play a key role, but have been traditionally poorly understood. In this presentation, we will discuss the role that both positively and negatively charged ions play in the salting-in and salting-out of proteins. A combination of thermodynamic data on aggregation (light scattering) will be correlated with NMR, infrared, and sum frequency generation measurements, which reveal the molecular level details for specific ion binding sites with protein backbones and side chains. Such binding at the protein/aqueous interface may be correlated to either salting-in or salting-out behavior depending on whether the system follows a direct or reverse Hofmeister series.

Revealing the role of site-specific ion binding for protein aggregation

246th National Meeting (2013)

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