pK(a) values for the unfolded state under native conditions explain the pH-dependent stability of PGB1

Autor: Carl Diehl, Mikael C. Bauer, Sara Linse, Mikael Akke, Stina Lindman, Mikael Lund, Frans A. A. Mulder
Přispěvatelé: Molecular Dynamics
Jazyk: angličtina
Rok vydání: 2010
Předmět:
STAPHYLOCOCCAL NUCLEASE
Molecular Sequence Data
Population
Biophysics
Thermodynamics
IONIZABLE GROUPS
Molecular Dynamics Simulation
Molecular dynamics
Bacterial Proteins
GAUSSIAN-CHAIN MODEL
Computational chemistry
Amino Acid Sequence
Amino Acids
Physics::Chemical Physics
NUCLEAR-MAGNETIC-RESONANCE
education
Nuclear Magnetic Resonance
Biomolecular
Protein Unfolding
education.field_of_study
Quantitative Biology::Biomolecules
N-TERMINAL DOMAIN
biology
Chemistry
Protein
Quantitative Biology::Molecular Networks
Chemical shift
Titrimetry
Hydrogen-Ion Concentration
Electrostatics
Protein Structure
Tertiary
PK VALUES
CHARGE-CHARGE INTERACTIONS
Unfolded protein response
biology.protein
Mutant Proteins
Protein G
ELECTROSTATIC INTERACTIONS
Protons
Protein pKa calculations
PROTEIN STABILITY
SIDE-CHAIN
Heteronuclear single quantum coherence spectroscopy
Zdroj: Biophysical Journal, 99(10), 3365-3373. CELL PRESS
ISSN: 0006-3495
Popis: Understanding the role of electrostatics in protein stability requires knowledge of these interactions in both the folded and unfolded states. Electrostatic interactions can be probed experimentally by characterizing ionization equilibria of titrating groups, parameterized as pK(a) values. However, pK(a) values of the unfolded state are rarely accessible under native conditions, where the unfolded stale has a very low population. Here, we report pK(a) values under nondenaturing conditions for two unfolded fragments of the protein G B1 domain that mimic the unfolded state of the intact protein. pK(a) values were determined for carboxyl groups by monitoring their pH-dependent C-13 chemical shifts. Monte Carlo simulations using a Gaussian chain model provide corrections for changes in electrostatic interactions that arise from fragmentation of the protein. Most pK(a) values for the unfolded state agree well with model values, but some residues show significant perturbations that can be rationalized by local electrostatic interactions. The pH-dependent stability was calculated from the experimental pK(a) values of the folded and unfolded states and compared to experimental stability data. The use of experimental pK(a) values for the unfolded state results in significantly improved agreement with experimental data, as compared to calculations based on model data alone.
Databáze: OpenAIRE
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