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Dynamics at the protein-water interface from 17O spin relaxation in deeply supercooled solutions

Mattea, Carlos LU ; Qvist, Johan LU and Halle, Bertil LU (2008) In Biophysical Journal 95(6). p.2951-2963
Abstract
Most of the decisive molecular events in biology take place at the protein-water interface. The dynamical properties of the hydration layer are therefore of fundamental importance. To characterize the dynamical heterogeneity and rotational activation energy in the hydration layer, we measured the 17O spin relaxation rate in dilute solutions of three proteins in a wide temperature range extending down to 238 K. We find that the rotational correlation time can be described by a power-law distribution with exponent 2.1 – 2.3. Except for a small fraction of secluded hydration sites, the dynamic perturbation in the hydration layer is the same for all proteins and does not differ in any essential way from the hydration shell of small organic... (More)
Most of the decisive molecular events in biology take place at the protein-water interface. The dynamical properties of the hydration layer are therefore of fundamental importance. To characterize the dynamical heterogeneity and rotational activation energy in the hydration layer, we measured the 17O spin relaxation rate in dilute solutions of three proteins in a wide temperature range extending down to 238 K. We find that the rotational correlation time can be described by a power-law distribution with exponent 2.1 – 2.3. Except for a small fraction of secluded hydration sites, the dynamic perturbation in the hydration layer is the same for all proteins and does not differ in any essential way from the hydration shell of small organic solutes. In both cases, the dynamic perturbation factor is less than 2 at room temperature and exhibits a maximum near 260 K. This maximum implies that, at low temperatures, the rate of water molecule rotation has a weaker temperature dependence in the hydration layer than in bulk water. We attribute this difference to the temperature-independent constraints that the protein surface imposes on the water H-bond network. The free hydration layer studied here differs qualitatively from confined water in solid protein powder samples. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biophysical Journal
volume
95
issue
6
pages
2951 - 2963
publisher
Cell Press
external identifiers
  • wos:000258826900031
  • scopus:55549086517
ISSN
1542-0086
DOI
10.1529/biophysj.108.135194
language
English
LU publication?
yes
id
7ed2e5e4-d2a2-4747-8ed9-c7d64b174be8 (old id 1227833)
alternative location
http://dx.doi.org/10.1529/biophysj.108.135194
date added to LUP
2008-09-05 11:25:55
date last changed
2017-09-17 05:02:12
@article{7ed2e5e4-d2a2-4747-8ed9-c7d64b174be8,
  abstract     = {Most of the decisive molecular events in biology take place at the protein-water interface. The dynamical properties of the hydration layer are therefore of fundamental importance. To characterize the dynamical heterogeneity and rotational activation energy in the hydration layer, we measured the 17O spin relaxation rate in dilute solutions of three proteins in a wide temperature range extending down to 238 K. We find that the rotational correlation time can be described by a power-law distribution with exponent 2.1 – 2.3. Except for a small fraction of secluded hydration sites, the dynamic perturbation in the hydration layer is the same for all proteins and does not differ in any essential way from the hydration shell of small organic solutes. In both cases, the dynamic perturbation factor is less than 2 at room temperature and exhibits a maximum near 260 K. This maximum implies that, at low temperatures, the rate of water molecule rotation has a weaker temperature dependence in the hydration layer than in bulk water. We attribute this difference to the temperature-independent constraints that the protein surface imposes on the water H-bond network. The free hydration layer studied here differs qualitatively from confined water in solid protein powder samples.},
  author       = {Mattea, Carlos and Qvist, Johan and Halle, Bertil},
  issn         = {1542-0086},
  language     = {eng},
  number       = {6},
  pages        = {2951--2963},
  publisher    = {Cell Press},
  series       = {Biophysical Journal},
  title        = {Dynamics at the protein-water interface from 17O spin relaxation in deeply supercooled solutions},
  url          = {http://dx.doi.org/10.1529/biophysj.108.135194},
  volume       = {95},
  year         = {2008},
}