On the hydration of the phosphocholine headgroup in aqueous solution

Foglia, Fabrizia; Lawrence, M. Jayne; Lorenz, Christian D.; McLain, Sylvia E.

doi:10.1063/1.3488998

Cited by 80 publications

(118 citation statements)

References 66 publications

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“…1) adjacent to the onium group and the surrounding water solvent. 11,12,41 This hydrogen bonding from water to this portion of the PC molecule is present in the current solutions, as the g HLOw (r) in Figure 5 (a) in both MD and EPSR fits to the diffraction data show a first peak at around 2.1Å with a coordination number of ∼0.6 hydrogen bonds (Table IV). This value is comparable to that observed in DMSO, where the coordination number was 0.5 for the EPSR simulation, 11 but still exhibits lower coordination of water compared to the 1 bond seen for pure water simulations.…”

Section: Figs 4 (D) and (E)mentioning

confidence: 94%

“…[8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Neutron diffraction experiments have been used to study an aqueous solution of 30 mol% PG, containing 200 mM of 1,2-dipropionyl-sn-glycero-3-phosphocholine (C 3 -PC). The neutron diffraction experiments were performed on the SAN-DALS diffractometer at the ISIS neutron facility, UK.…”

Section: A Neutron Diffractionmentioning

confidence: 99%

“…Empirical Potential Structure Refinement (EPSR) modeling 7 can be used to create a model which 'fits' the measured diffraction data and has been used for a variety of systems to gain a better understanding of the structure of molecules in solution. [11][12][13][14][19][20][21][22] EPSR is Monte Carlo-based simulation which begins with a set of established potentials and then refines these potentials iteratively until a good fit between the measured data and the model is achieved. The EPSR simulation box here contained 10 C 3 -PC lipids, 750 PG molecules (375 R-and 375 S-) and 1750 water molecules (Fig.…”

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confidence: 99%

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On the solvation of the phosphocholine headgroup in an aqueous propylene glycol solution

Rhys

al-Badri

Ziolek

et al. 2018

The Journal of Chemical Physics

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The atomic-scale structure of the phosphocholine (PC) headgroup in 30 mol% propylene glycol (PG) in aqueous solution has been investigated using a combination of neutron diffraction with isotopic substitution experiments and computer simulation techniques -Molecular Dynamics and Empirical Potential Structure Refinement. Here, the hydration of the PC headgroup remains largely intact compared with the hydration of this group in a bilayer and in a bulk water solution, with the PG molecules showing limited interactions with the headgroup. When direct PG interactions with PC do occur, they are most likely to coordinate to the N(CH 3 ) + 3 motifs. Further, PG does not affect the bulk water structure and the addition of PC does not perturb the PG-solvent interactions. This suggests that the reason why PG is able to penetrate into membranes easily is that it does not form stronghydrogen bonding or electrostatic interactions with the headgroup allowing it to easily move across the membrane barrier.

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Section: Figs 4 (D) and (E)mentioning

confidence: 94%

Section: A Neutron Diffractionmentioning

confidence: 99%

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confidence: 99%

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On the solvation of the phosphocholine headgroup in an aqueous propylene glycol solution

Rhys

al-Badri

Ziolek

et al. 2018

The Journal of Chemical Physics

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“…Ab initio molecular dynamics (AIMD) within LDA simulations are performed with a time step Δt = 0.1 fs, which is about one hundredth of the shortest vibration time (inverse vibrational frequency) in the system. Nosémass, which controls the coupling of the thermal bath to the system, is set to 100.0 Ry fs 2 . In these simulations the forces acting on the atoms are calculated from the charge density obtained from the DFT.…”

Section: ■ Computational Detailsmentioning

confidence: 99%

Enhanced Autoionization of Water at Phospholipid Interfaces

et al. 2012

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ABSTRACT:The structure and autoionization of water at the water−phospholipid interface are investigated by ab initio molecular dynamics and ab initio Monte Carlo simulations using local density approximation (LDA) and generalized gradient approximation (GGA) for the exchange−correlation energy functional. Depending on the lipid headgroup, strongly enhanced ionization is observed, leading to the dissociation of several water molecules into H + and OH − per lipid. The results can shed light on the phenomena of the high proton conductivity along membranes that has been reported experimentally. ■ INTRODUCTIONPhospholipids are amphiphilic molecules that, in an aqueous environment, self-assemble into bilayers and form the major structural constituents of biomembranes. Although the affinity of the lipid's headgroup to interfacial water has been widely addressed in the literature, 1,2 the exact chemical nature of this coupling is not fully understood and its strength remains to be quantified. In particular, it is not clear how this coupling affects the structure and dynamics of the interfacial water layer and the proton transport. Enhanced proton conduction along phospholipid−water interfaces was first observed in the mid 1980s.3,4 Recent studies by means of scanning tunneling microscopy (STM) confirm a significant lateral conductivity. This conductivity is believed to be of functional importance because lateral proton diffusion along membrane surfaces represents the most efficient pathway for H + transport between protein pumps. 6 The molecular mechanism underlying the high lateral proton conductivity has not yet been resolved. 7−11In this paper we report ab initio molecular dynamics (AIMD) and ab initio Monte Carlo (AIMC) simulations of interfacial water covering the headgroup of zwitterionic dipalmitoyl−phosphatidylcholine (DPPC) molecule. We perform calculations within the local density approximation and generalized gradient approximation for the exchange−correlation energy functional, with Ceperley−Alder 12 and Perdew− Burke−Ernzerhof 13 parametrizations, respectively. We show that the interfacial water exhibits a strongly enhanced autoionization that is caused by the presence of strong local electric field as well as strong hydrogen bonding. ■ COMPUTATIONAL DETAILSGround State Calculations. To calculate the ground state structure of the DPPC molecule, we first build the molecule by putting atoms together with coordinations according to the bonding rules from chemistry. To relax this structure, density functional theory (DFT) is applied as implemented in the SIESTA code.14 To this end, the DPPC molecule is placed in a unit cell with dimensions much larger than the size of the molecule. The spatial extension of the pure DPPC structure is ≈4 × 29 × 8 Å. We choose a box of 20 × 40 × 20 Å dimensions. As a consequence, because we are dealing with a molecule (a cluster), no periodic boundary conditions are adopted and only the Γ point in the reciprocal space is needed for the energy integration. The mesh cutoff is set to...

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“…Strongly altered hydrogen-bond dynamics in the lipid hydration shells have been observed in the experiments addressing water translational mobility, reorientation, and hydrogen-bond strength. [10][11][12][13][14][15] Interestingly, such studies indicate coupling between the dynamics of water and biological objects which may imply a strong interaction between the solute and the hydration shell. 16,17 It is well known that structure, dynamics and even macroscopic properties of water are determined by the strong intermolecular interactions between the hydrogen-bonded water molecules.…”

Section: Introductionmentioning

confidence: 99%