Water Orientation at Ceramide/Water Interfaces Studied by Heterodyne-Detected Vibrational Sum Frequency Generation Spectroscopy and Molecular Dynamics Simulation
Klauda, Jeffery B.
KAUST DepartmentPhysical Sciences and Engineering (PSE) Division
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AbstractLipid/water interaction is essential for many biological processes. The water structure at the nonionic lipid interface remains little known, and there is no scope of a priori prediction of water orientation at nonionic interfaces, either. Here, we report our study combining advanced nonlinear spectroscopy and molecular dynamics simulation on the water orientation at the ceramide/water interface. We measured χ spectrum in the OH stretch region of ceramide/isotopically diluted water interface using heterodyne-detected vibrational sum-frequency generation spectroscopy and found that the interfacial water prefers an overall hydrogen-up orientation. Molecular dynamics simulation indicates that this preferred hydrogen-up orientation of water is determined by a delicate balance between hydrogen-up and hydrogen-down orientation induced by lipid-water and intralipid hydrogen bonds. This mechanism also suggests that water orientation at neutral lipid interfaces depends highly on the chemical structure of the lipid headgroup, in contrast to the charged lipid interfaces where the net water orientation is determined solely by the charge of the lipid headgroup.
CitationAdhikari A, Re S, Nishima W, Ahmed M, Nihonyanagi S, et al. (2016) Water Orientation at Ceramide/Water Interfaces Studied by Heterodyne-Detected Vibrational Sum Frequency Generation Spectroscopy and Molecular Dynamics Simulation. The Journal of Physical Chemistry C 120: 23692–23697. Available: http://dx.doi.org/10.1021/acs.jpcc.6b08980.
SponsorsThis work was partly supported by JSPS KAKENHI Grant Number JP25104005. A.A. acknowledges JSPS for a postdoctoral fellowship. Y.S. acknowledges financial support from Center of Innovation Program from Japan Science and Technology Agency, JST. J.B.K. acknowledges financial support from the National Science Foundation (NSF) through Grant MCB-1149187.
PublisherAmerican Chemical Society (ACS)