Type

Journal Article

Authors

Jens Erik Nielsen
Kaare Teilum
Lawrence P. McIntosh
Zigmantas Toleikis
Damien Farrell
Kristine Steen Jensen
Predrag Kukić
Bertrand García-Moreno E

Subjects

Physics

Topics
protein dielectric constant protein conformation electric fields models molecular coulomb s law nuclear magnetic resonance biomolecular humans protein protein interface static electricity protein structure proteins animals chemistry protein function cattle finite difference nmr buckingham s equation protein electrostatics poisson boltzmann equation thermodynamic parameters

Protein Dielectric Constants Determined from NMR Chemical Shift Perturbations (2013)

Abstract Understanding the connection between protein structure and function requires a quantitative under-standing of electrostatic effects. Structure-based electrostatics calculations are essential for this purpose, but their use has been limited by a long-standing discussion on which value to use for the dielectric constants (εeff and εp) required in Coulombic models and Poisson-Boltzmann models. The currently used values for εeff and εp are essentially empirical parameters calibrated against thermodynamic properties that are indirect measurements of protein electric fields. Wedetermine optimal values for εeff and εp by measuring protein electric fields in solution using direct detection of NMR chemical shift perturbations (CSPs). We measured CSPs in fourteen proteins to get a broad and general characterization of electric fields. Coulomb’s law reproduces the measured CSPs optimally with a protein dielectric constant (εeff) 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 (εp) rangedsfrom 2-5 with an optimum of 3. It is striking how similar this value is to the dielectric constant of 2-4 measured for protein powders, and how different it is from the εp of 6-20 used in models based on the Poisson-Boltzmann equation when calculating thermodynamic parameters. Because the value of εp = 3 is obtained by analysis of NMR chemical shift perturbations instead of thermodynamic parameters such as pKa values, it is likely to describe only the electric field and thus represent a more general, intrinsic, and transferable εp common to most folded proteins.
Collections Ireland -> University College Dublin -> Biomolecular and Biomedical Science Research Collection
Ireland -> University College Dublin -> College of Science
Ireland -> University College Dublin -> School of Biomolecular & Biomedical Science

Full list of authors on original publication

Jens Erik Nielsen, Kaare Teilum, Lawrence P. McIntosh, Zigmantas Toleikis, Damien Farrell, Kristine Steen Jensen, Predrag Kukić, Bertrand García-Moreno E

Experts in our system

1
Jens Erik Nielsen
University College Dublin
Total Publications: 27
 
2
Damien Farrell
University College Dublin
Total Publications: 16