Two-dimensional resonance Raman spectroscopy of oxygen- and water-ligated myoglobins
| Autor: | Thomas P. Cheshire, Andrew M. Moran, Zhenkun Guo, Brian P. Molesky |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Resonance Raman spectroscopy
Analytical chemistry General Physics and Astronomy Protoporphyrins Molecular Dynamics Simulation 010402 general chemistry Spectrum Analysis Raman 01 natural sciences symbols.namesake Molecular dynamics 0103 physical sciences Animals Coherent anti-Stokes Raman spectroscopy Horses Physical and Theoretical Chemistry Spectroscopy Muscle Skeletal Quantitative Biology::Biomolecules 010304 chemical physics Molecular Structure Chemistry Myoglobin Anharmonicity Temperature Resonance Water 0104 chemical sciences Oxygen Chemical physics Molecular vibration symbols Raman spectroscopy Hydrophobic and Hydrophilic Interactions Algorithms |
| Zdroj: | The Journal of chemical physics. 145(3) |
| ISSN: | 1089-7690 |
| Popis: | Two-dimensional resonance Raman (2DRR) spectroscopy has recently been developed as a tool for studies of structural heterogeneity and photochemical dynamics in condensed phases. In this paper, 2DRR spectroscopy is used to investigate line broadening mechanisms of both oxygen- and water-ligated myoglobins. General signatures of anharmonicity and inhomogeneous line broadening are first established with model calculations to facilitate signal interpretation. It is shown that the present quasi-degenerate version of 2DRR spectroscopy is insensitive to anharmonicity, because signal generation is allowed for harmonic modes. Rather, the key information to be gained from 2DRR spectroscopy pertains to the line broadening mechanisms, which are fairly obvious by inspection of the data. 2DRR signals acquired for both heme protein systems reveal significant heterogeneity in the vibrational modes local to the heme’s propionic acid side chains. These side chains are known to interact with solvent, because they protrude from the hydrophobic pocket that encloses the heme. Molecular dynamics simulations suggest that the heterogeneity detected in our 2DRR experiments reflects fluctuations in the geometries of the side chains. Knowledge of such thermal motions will be useful for understanding protein function (e.g., ligand binding) because the side chains are an effective “gateway” for the exchange of thermal energy between the heme and solvent. |
| Databáze: | OpenAIRE |
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