| 1. |
- Boily, Jean-Francois, et al.
(författare)
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Electrostatic cooperativity of hydroxyl groups at metal oxide surfaces
- 2009
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society Publications. - 1932-7447 .- 1932-7455. ; 113:38, s. 16568-16570
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Tidskriftsartikel (refereegranskat)abstract
- The O−H bond distribution of hydroxyl groups at the {110} goethite (α-FeOOH) surface was investigated by molecular dynamics. This distribution was strongly affected by electrostatic interactions with neighboring oxo and hydroxo groups. The effects of proton surface loading, simulated by emplacing two protons at different distances of separation, were diverse and generated several sets of O−H bond distributions. DFT calculations of a representative molecular cluster were also carried out to demonstrate the impact of these effects on the orientation of oxygen lone pairs in neighboring oxo groups. These effects should have strong repercussions on O−H stretching vibrations of metal oxide surfaces.
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| 2. |
- Jacinto, Agrinaldo, et al.
(författare)
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Hydration, Ionic Valence and Cross-linking Propensities of Cations Determine the Stability of Lipopolysaccharide Membranes
- 2014
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Ingår i: Chemical Communications. - Cambridge : Royal Society of Chemistry. - 1359-7345 .- 1364-548X. ; 50:2, s. 231-233
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Tidskriftsartikel (refereegranskat)abstract
- The supra-molecular structure of LPS aggregates governs outer membrane permeability and activation of the host immune response during Gram-negative bacterial infections. Molecular dynamics simulations unveil at atomic resolution the subtle balance between cation hydration and cross-linking ability in modulating phase transitions of LPS membranes.
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| 3. |
- Santos, Denys E. S., et al.
(författare)
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Polymyxin Binding to the Bacterial Outer Membrane Reveals Cation Displacement and Increasing Membrane Curvature in Susceptible but Not in Resistant Lipopolysaccharide Chemotypes
- 2017
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Ingår i: Journal of Chemical Information and Modeling. - : AMER CHEMICAL SOC. - 1549-9596 .- 1549-960X. ; 57:9, s. 2181-2193
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Tidskriftsartikel (refereegranskat)abstract
- Lipid-A is the causative agent of Gram-negative sepsis and is responsible for an increasingly high mortality rate among hospitalized patients. Compounds that bind Lipid-A can limit this inflammatory process. The cationic antimicrobial peptide polymyxin B (Pmx-B) is one of the simplest molecules capable of selectively binding to Lipid-A and may serve as a model for further development of Lipid-A binding agents. Gram-negative bacteria resistance to Pmx-B relies on the upregulation of a number of regulatory systems, which promote chemical modifications of the lipopolysaccharide (LPS) structure and leads to major changes in the physical chemical properties of the outer membrane. A detailed understanding of how the chemical structure of the LPS modulates macroscopic properties of the outer membrane is paramount for the design and optimization of novel drugs targeting clinically relevant strains. We have performed a systematic investigation of Pmx-B binding to outer membrane models composed of distinct LPS chemotypes experimentally shown to be either resistant or susceptible to the peptide. Molecular dynamics simulations were carried out for Pmx-B bound to the penta- and hexa-acylated forms of Lipid-A (more susceptible) and Lipid-A modified with 4-amino-4-deoxy-L-arabinose (resistant) as well as the penta-acylated form of LPS Re (less susceptible). The present simulations show that upon binding to the bacterial outer membrane surface, Pmx-B promotes cation displacement and structural changes in membrane curvature and integrity as a function of the LPS chemotype susceptibility or resistance to the antimicrobial peptide.
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