Concurrent Observation of Bulk and Protein Hydration Water by Spin-Label ESR under Nanoconfinement
| Autor: | Yu-Ru Tseng, Yun-Wei Chiang, Yun-Hsuan Kuo |
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| Rok vydání: | 2013 |
| Předmět: |
Models
Molecular Protein Conformation Surface Properties Peptide Activation energy Mice Electrochemistry Animals Nanotechnology General Materials Science Spin label Spectroscopy bcl-2-Associated X Protein chemistry.chemical_classification Chemistry Electron Spin Resonance Spectroscopy Temperature Water Surface hydration Surfaces and Interfaces Condensed Matter Physics Crystallography Dipole Chemical physics Peptides Surface protein BAX Protein |
| Zdroj: | Langmuir. 29:13865-13872 |
| ISSN: | 1520-5827 0743-7463 |
| DOI: | 10.1021/la403002t |
| Popis: | Under nanoconfinement the formation of crystalline ice is suppressed, allowing the study of water dynamics at subfreezing temperatures. Here we report a temperature-dependent investigation (170-260 K) of the behavior of hydration water under nanoconfinement by ESR techniques. A 26-mer-long peptide and the Bax protein are studied. This study provides site-specific information about the different local hydrations concurrently present in the protein/peptide solution, enabling a decent comparison of the hydration molecules-those that are buried inside, in contact with, and detached from the protein surface. Such a comparison is not possible without employing ESR under nanoconfinement. Though the confined bulk and surface hydrations behave differently, they both possess a transition similar to the reported fragile-to-strong crossover transition around 220 K. On the contrary, this transition is absent for the hydration near the buried sites of the protein. The activation energy determined under nanoconfinement is found to be lower in surface hydration than in bulk hydration. The protein structural flexibility, derived from the interspin distance distributions P(r) at different temperatures, is obtained by dipolar ESR spectroscopy. The P(r) result demonstrates that the structural flexibility is strongly correlated with the transition in the surface water, corroborating the origin of the protein dynamical transition at subfreezing temperatures. |
| Databáze: | OpenAIRE |
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