Dynamics of Hydrophobic Core Phenylalanine Residues Probed by Solid-State Deuteron NMR
| العنوان: | Dynamics of Hydrophobic Core Phenylalanine Residues Probed by Solid-State Deuteron NMR |
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| المؤلفون: | Dmitry Ostrovsky, Toni Villafranca, Liliya Vugmeyster, Gina L. Hoatson, Andrew S. Lipton, Wei Xu, Janelle Sharp, Robert L. Vold |
| المصدر: | The Journal of Physical Chemistry B. 119:14892-14904 |
| بيانات النشر: | American Chemical Society (ACS), 2015. |
| سنة النشر: | 2015 |
| مصطلحات موضوعية: | Quantitative Biology::Biomolecules, Magnetic Resonance Spectroscopy, Chemistry, Phenylalanine, Relaxation (NMR), Nuclear magnetic resonance spectroscopy, Atmospheric temperature range, Article, Surfaces, Coatings and Films, Solvent, Crystallography, Deuterium, Materials Chemistry, Side chain, Physical and Theoretical Chemistry, Hydrophobic and Hydrophilic Interactions, Softening, Conformational isomerism |
| الوصف: | We conducted a detailed investigation of the dynamics of two phenylalanine side chains in the hydrophobic core of the villin headpiece subdomain protein (HP36) in the hydrated powder state over the 298–80 K temperature range. Our main tools were static deuteron NMR measurements of longitudinal relaxation and line shapes supplemented with computational modeling. The temperature dependence of the relaxation times reveals the presence of two main mechanisms that can be attributed to the ring-flips, dominating at high temperatures, and small-angle fluctuations, dominating at low temperatures. The relaxation is non-exponential at all temperatures with the extent of non-exponentiality increasing from higher to lower temperatures. This behavior suggests a distribution of conformers with unique values of activation energies. The central values of the activation energies for the ring-flipping motions are among the smallest reported for aromatic residues in peptides and proteins and point to a very mobile hydrophobic core. The analysis of the widths of the distributions, in combination with the earlier results on the dynamics of flanking methyl groups (Vugmeyster et al., J. Phys. Chem. B 2013, 117, 6129–6137), suggests that the hydrophobic core undergoes slow concerted fluctuations. There is a pronounced effect of dehydration on the ring-flipping motions, which shifts the distribution toward more rigid conformers. The cross-over temperature between the regions of dominance of the small-angle fluctuations and ring-flips shifts from 195 K in the hydrated protein to 278 K in the dry one. This result points to the role of solvent in softening the core and highlights aromatic residues as markers of the protein dynamical transitions. |
| تدمد: | 1520-5207 1520-6106 |
| DOI: | 10.1021/acs.jpcb.5b09299 |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::91b7e8d7ea179301991562d74b4cd6d3 https://doi.org/10.1021/acs.jpcb.5b09299 |
| Rights: | OPEN |
| رقم الانضمام: | edsair.doi.dedup.....91b7e8d7ea179301991562d74b4cd6d3 |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 15205207 15206106 |
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| DOI: | 10.1021/acs.jpcb.5b09299 |