BIOT 17 |
| Current models for electrostatic interactions in the unfolded state operate on simplified representations of proteins instead of an ensemble of three-dimensional structures. Thus, existing models cannot investigate the effects of organization in the unfolded state. We developed a method for modeling these interactions that uses three-dimensional protein structures. Our method was used to calculate electrostatic properties of T62P Staphylococcal nuclease (Snase), a variant known to resemble unfolded wild-type Snase. Proton binding data measured potentiometrically were compared with our calculations. We find that an ensemble of highly disordered structures is consistent with the data, but we cannot rule out the possibility of some organization. Energetically, our calculations indicate that weak, non-specific Coulomb interactions are unavoidable in the unfolded state, and while these contribute minimally to organization, they are not negligible in calculations of protein stability. Therefore, the electrostatic properties of Snase are determined more by a background of fluctuating ions rather than a particular chain conformation. |
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Biophysical and Biomolecular Symposium: Protein Folding & Characterization
8:00 AM-11:10 AM, Sunday, August 19, 2007 BCEC -- 106, Oral
Division of Biochemical Technology |