Nonlinear Scaling of Surface Water Diffusion with Bulk Water Viscosity of Crowded Solutions

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• 作者：John M. Franck ; John A. Scott ; Songi Han
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：March 20, 2013
• 年：2013
• 卷：135
• 期：11
• 页码：4175-4178
• 全文大小：211K
• 年卷期：v.135,no.11(March 20, 2013)
• ISSN：1520-5126

文摘

The translational hydration dynamics within 0.5鈥?.5 nm of the surface of a DPPC liposome, a model biomacromolecular surface, is analyzed by the recently developed Overhauser dynamic nuclear polarization (ODNP) technique. We find that dramatic changes to the bulk solvent cause only weak changes in the surface hydration dynamics. Specifically, both a >10-fold increase in bulk viscosity and the restriction of diffusion by confinement on a multiple nm length-scale change the local translational diffusion coefficient of the surface water surrounding the lipid bilayer by <2.5-fold. By contrast, previous ODNP studies have shown that changes to the biomacromolecular surface induced by folding, binding, or aggregation can cause local hydration dynamics to vary by factors of up to 30.(1, 2) We suggest that the surface topology and chemistry at the 鈮?.5 nm scale, rather than the characteristics of the solvent, nearly exclusively determine the macromolecule鈥檚 surface hydration dynamics.