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Influence of Polarization on Carbohydrate Hydration: A Comparative Study Using Additive and Polarizable Force Fields
journal contribution
posted on 2016-06-06, 00:00 authored by Poonam Pandey, Sairam S. MallajosyulaCarbohydrates
are known to closely modulate their surrounding solvent structures
and influence solvation dynamics. Spectroscopic investigations studying
far-IR regions (below 1000 cm–1) have observed spectral
shifts in the libration band (around 600 cm–1) of
water in the presence of monosaccharides and polysaccharides. In this
paper, we use molecular dynamics simulations to gain atomistic insight
into carbohydrate–water interactions and to specifically highlight
the differences between additive (nonpolarizable) and polarizable
simulations. A total of six monosaccharide systems, α and β
anomers of glucose, galactose, and mannose, were studied using additive
and polarizable Chemistry at HARvard Macromolecular Mechanics (CHARMM)
carbohydrate force fields. Solvents were modeled using three additive
water models TIP3P, TIP4P, and TIP5P in additive simulations and polarizable
water model SWM4 in polarizable simulations. The presence of carbohydrate
has a significant effect on the microscopic water structure, with
the effects being pronounced for proximal water molecules. Notably,
disruption of the tetrahedral arrangement of proximal water molecules
was observed due to the formation of strong carbohydrate–water
hydrogen bonds in both additive and polarizable simulations. However,
the inclusion of polarization resulted in significant water-bridge
occupancies, improved ordered water structures (tetrahedral order
parameter), and longer carbohydrate–water H-bond correlations
as compared to those for additive simulations. Additionally, polarizable
simulations also allowed the calculation of power spectra from the
dipole–dipole autocorrelation function, which corresponds to
the IR spectra. From the power spectra, we could identify spectral
signatures differentiating the proximal and bulk water structures,
which could not be captured from additive simulations.
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polarizable water model SWM 4Polarizable Force Fields Carbohydrates5Pcarbohydrate force fieldspower spectrawater moleculesadditive water models TIP 3P TIP 4Ppolarizable simulationsgain atomistic insightinfluence solvation dynamicsHARvard Macromolecular Mechanicsbulk water structuresIRadditive simulationsCHARMM
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