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Specialized iNANO Lecture: The Dielectric Constant of Proteins Determined from NMR Chemical Shift Perturbations

Associate professor Kaare Teilum,Department of Biology, Biomolecular Sciences, Copenhagen University, Copenhagen

Info about event

Time

Friday 10 January 2014,  at 11:15 - 12:00

Location

The auditorium of the iNANO House (1593-012), Gustav Wieds Vej 14, 8000 Aarhus C

 

Associate professor Kaare Teilum, Department of Biology, Biomolecular Sciences, Copenhagen University, Copenhagen, Denmark

The Dielectric Constant of Proteins Determined from NMR Chemical Shift Perturbations

NMR chemical shifts of protein amide groups are highly sensitive to the electrostatic environment. Consequently, we measured electric fields in proteins in solution using direct detection of NMR chemical shift perturbations (CSPs) in 14 proteins to get a broad and general characterization of electric fields. The data were used to determine optimal values of the dielectric constant for the interior of proteins in both Coulombic and Poisson-Boltzmann models. Coulomb's law reproduces the measured CSPs optimally with a protein dielectric constant from 3 to 13, with an optimal value across all proteins of 6.5. However, when the water-protein interface is treated with finite difference Poisson-Boltzmann calculations, the optimal protein dielectric constant ranged from 2 to 5 with an optimum of 3. This value is likely to describe only the electric field and thus represent a general, intrinsic, and transferable dielectric constant common to most folded proteins.

 
Host:
Associate Professor Frans Mulder, iNANO & Dept. of Chemistry, Aarhus University