Collaborator: Dr. Ravi Datta

Alumni: Dr. Mohammed Yousef

We are interested in modeling the behavior of concentrated multicomponent protein (crowded) solutions. Crowded protein solutions are found naturally in cells and have tremendous impact on cellular function.

We have modeled the osmotic pressure of both single and binary crowded protein solutions using a novel approach that recognizes that the nonlinear behavior is coupled to hydration and ion binding. This model suggested that the solvent-solute contributions, are substantially more significant in describing osmotic pressure than that assumed by virial expansion models based on McMillan-Mayer theory. When applying the model to single crowded protein solutions in physiological solutions, it was discovered that all of the protein nonideal behavior was coupled to the protein hydration which was directly related to the protein solvent accessible surface area. Interestingly, this significant hydration was always a monolayer of water (see figure). When these factors were taken into account, the solution behaved ideally with respect to the free water (water not interacting with the protein).

Applying the more general form of this model to binary proteins also results in an improved representation of measured osmotic pressure. Our current research investigates the additional contributions of interaction including protein aggregation that can affect osmotic pressure for binary protein systems.