Levich Institute Seminar Announcement, 03/31/2009
Tuesday, 03/31/2009
4:00 PM
Mudd Building, Room #825
500 West 120th Street
Columbia University

Professor Erik Fernandez
University of Virginia
Department of Chemical Engineering

"A Molecular View of Unraveling Proteins"


[This is a CCNY/Columbia NSF-IGERT Soft Materials seminar]

ABSTRACT


During purification, marginally stable proteins can undergo conformational changes that can lead to complex chromatographic behavior and/or aggregation. The multiphase nature of adsorbed and aggregated proteins complicates analysis by commonly used biophysical techniques.

We are investigating protein conformation changes that occur during adsorption to chromatography media with hydrogen-deuterium isotope exchange. Measurements have revealed the effects of surface chemistry, pore structure, and solution environment on protein conformation and chromatographic behavior. Rather counterintuitive effects have been observed for salts, and we have developed a four-state thermodynamic model that can describe them. We are currently investigating whether we can predict which portions of a protein will unfold based on solution phase measurements and/or a statistical mechanical model of the protein conformational ensemble.

We have also applied many of these approaches to the biopharmaceutical interferon- as well as the aggregating A [1-40] peptide relevant to Alzheimer's disease. For interferon- we have been able to identify regions of the protein that are structurally perturbed in aggregates. For A [1-40], we have revealed information about oligomer distributions and elucidated a structural feature distinctive to the most toxic portion of the oligomer population.

These examples demonstrate the potential for these approaches to reveal information about structural, kinetic, and thermodynamic aspects of conformational changes occurring during adsorption and aggregation. Further, these results expose some of the general characteristics of the folding/unfolding transition in partially denaturing environments. Such insights will inform development of more effective theoretical process design tools and proteins themselves for improved structure and function in biotechnological applications.