title: Observation of the Global Dynamic Collectivity of a Hydration Shell around Apomyoglobin.
abstract: Protein surface hydration is critical to the protein's structural properties and biological activities. However, it is still unknown whether the hydration shell is intrinsically connected and how its fluctuations dynamically interact with protein motion. Here, by selecting five site-specific locations with distinctly different environments around the surface of apomyoglobin, we used a tryptophan scan with femtosecond fluorescence spectroscopy and simultaneously detected hydration water dynamics and tryptophan side-chain relaxations with temperature dependence. We observed two types of relaxations for both interfacial hydration water and the tryptophan side chain. The former is always faster than the latter, and both motions show direct linear correlations with temperature changes, indicating one origin of their motions and hydration water driving of side-chain fluctuations. Significantly, we found the relaxation energy barriers are uniform across the entire protein surface, all less than 20 kJ/mol, strongly suggesting highly extended cooperative water networks and the nature of global dynamic collectivity of the entire hydration shell.
authors.affiliation: Department of Physics, Department of Chemistry and Biochemistry, and Programs of Biophysics, Chemical Physics, and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States.
authors.forename: Yangzhong
authors.initials: Y
authors.lastname: Qin
authors.affiliation: Department of Physics, Department of Chemistry and Biochemistry, and Programs of Biophysics, Chemical Physics, and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States.
authors.forename: Luyuan
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Physics, Department of Chemistry and Biochemistry, and Programs of Biophysics, Chemical Physics, and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States.
authors.forename: Lijuan
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Physics, Department of Chemistry and Biochemistry, and Programs of Biophysics, Chemical Physics, and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States.
authors.forename: Dongping
authors.identifier: http://orcid.org/0000-0001-9381-8992
authors.initials: D
authors.lastname: Zhong