Dynamics and mechanism of ultrafast water–protein interactions

Protein hydration is essential to its structure, dynamics, and function, but water–protein interactions have not been directly observed in real time at physiological temperature to our awareness. By using a tryptophan scan with femtosecond spectroscopy, we simultaneously measured the hydration water...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2016-07, Vol.113 (30), p.8424-8429
Main Authors: Qin, Yangzhong, Wang, Lijuan, Zhong, Dongping
Format: Article
Language:English
Subjects:
Algorithms
Biological Sciences
Kinetics
Models, Chemical
Molecular Dynamics Simulation
Molecules
Motion
Physical Sciences
Protein Binding
Protein Conformation
Proteins
Proteins - chemistry
Proteins - metabolism
Spectrometry, Fluorescence - methods
Spectrum analysis
Surface Properties
Temperature
Thermodynamics
Time Factors
Tryptophan
Water
Water - chemistry
Water - metabolism
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Summary:Protein hydration is essential to its structure, dynamics, and function, but water–protein interactions have not been directly observed in real time at physiological temperature to our awareness. By using a tryptophan scan with femtosecond spectroscopy, we simultaneously measured the hydration water dynamics and protein side-chain motions with temperature dependence. We observed the heterogeneous hydration dynamics around the global protein surface with two types of coupled motions, collective water/side-chain reorientation in a few picoseconds and cooperative water/side-chain restructuring in tens of picoseconds. The ultrafast dynamics in hundreds of femtoseconds is from the outer-layer, bulk-type mobile water molecules in the hydration shell. We also found that the hydration water dynamics are always faster than protein side-chain relaxations but with the same energy barriers, indicating hydration shell fluctuations driving protein side-chain motions on the picosecond time scales and thus elucidating their ultimate relationship.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1602916113