Weakened Hydrogen Bonds in Water Confined between Lipid Bilayers: The Existence of a Long-Range Attractive Hydration Force

ChemPhysChem ◽  
2009 ◽  
Vol 10 (9-10) ◽  
pp. 1438-1441 ◽  
Author(s):  
Zoran Arsov ◽  
Michael Rappolt ◽  
Joze Grdadolnik
Keyword(s):  
Hydrogen Bonds ◽  
Lipid Bilayers ◽  
Long Range ◽  
Hydration Force

Study of a model for the main phase transition of lipid bilayers using the Kikuchi cluster method

1984 ◽  
Vol 62 (9) ◽  
pp. 935-942 ◽  
Author(s):  
Alzira M. Stein-Barana ◽  
G. G. Cabrera ◽  
M. J. Zuckermann
Keyword(s):  
Phase Transition ◽  
Lipid Bilayers ◽  
Long Range ◽  
Effective Field ◽  
Order Parameters ◽  
Range Order ◽  
Cluster Method ◽  
Variation Method ◽  
Long Range Order ◽  
Approximate Counting

The statistical mechanics of Doniach's two-state lattice model for the main gel – liquid crystal phase transition of phospholipid bilayers is treated in a similar manner to order–disorder transformations in binary alloys and magnetic systems, using the cluster variation method developed by Kikuchi. Indeed, the analogy holds better for the latter system, since the entropy difference between the two states gives rise to an effective temperature-dependent field. This effective field vanishes at the first-order phase transition, whose latent heat is associated with the discontinuity in the order parameter.We use Kikuchi's approximation with the inclusion of triangle bond correlations, and pair and site probabilities in the expression for free energy. We assume that the lipid chains only interact through nearest neighbour pair potentials and that triangle correlations are important for approximate counting of allowed states. Two long-range order parameters and a short-range order parameter are introduced in the formulation of the theory. Both long-range order parameters are discontinuous at the transition temperature. Numerical results for the physical quantities are presented and discussed with respect to earlier work.

Promoting helicity in carbohydrate-containing foldamers through long-range hydrogen bonds

2007 ◽  
pp. 831-833 ◽  
Author(s):  
David Rodríguez-Lucena ◽  
Juan M. Benito ◽  
Carmen Ortiz Mellet ◽  
José M. García Fernández
Keyword(s):  
Hydrogen Bonds ◽  
Long Range

scholarly journals An Uneven Chain-like Ferromagnetic Copper(II) Coordination Polymer Displaying Metamagnetic Behavior and Long-Range Magnetic Ordering

2021 ◽  
Vol 8 (1) ◽  
pp. 2
Author(s):  
Cai-Ming Liu ◽  
You Song
Keyword(s):  
Molecular Structure ◽  
Coordination Polymer ◽  
Hydrogen Bonds ◽  
Long Range ◽  
Three Dimensional ◽  
Magnetic Ordering ◽  
Antiferromagnetic Interaction ◽  
Ferromagnetic Coupling ◽  
One Dimensional ◽  
1D Chain

Ferromagnetic coupling exists in an uneven chain-like copper(II) complex with both end-on azido and syn-syn carboxylato bridges, (Cu3(L)2(N3)4(H2O)3)n (1, HL = 6-hydroxynicotinic acid). It is the first example of one-dimensional (1D) chain-like copper(II) coordination polymer showing both metamagnetic behavior and long-range magnetic ordering (Tc = 6.7 K), thanks to the interchain hydrogen bonds, which make a three-dimensional (3D) supramolecular array of the entire molecular structure and mediate the interchain antiferromagnetic interaction.

scholarly journals Electrostatic Interactions with Choline and Phosphate Groups Regulate Cisplatin Permeation through a Dioleoylphosphocholine Bilayer

2020 ◽  
Author(s):  
Lorena Ruano ◽  
Gustavo Cárdenas ◽  
Juan Jose Nogueira
Keyword(s):  
Free Energy ◽  
Lipid Bilayers ◽  
Long Range ◽  
Electrostatic Interactions ◽  
Umbrella Sampling ◽  
Energy Minimum ◽  
Free Energy Minimum ◽  
Dynamics Simulations ◽  
First Moment ◽  
Phosphate Groups

The investigation of the intermolecular interactions between platinum-based anticancer drugs and lipid bilayers is of special relevance to unveil the mechanisms involved in different steps of the mode of action of these drugs. We have simulated the permeation of cisplatin through a model membrane composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine lipids by means of umbrella sampling classical molecular dynamics simulations. The initial physisorption of cisplatin in the polar region of the membrane is controlled, in a first moment, by long-range electrostatic interactions with the choline groups, which trap the drug in a shallow free-energy minimum. Then, cisplatin is driven to a deeper free-energy minimum by long-range electrostatic interactions with the phosphate groups. From this minimum to the middle of the bilayer the electrostatic repulsion between cisplatin and the choline groups partially cancels out the electrostatic attraction between cisplatin and the phosphate groups, inducing a general drop of the total interaction with the polar heads. In addition, the attractive interactions with the non-polar tails, which are dominated by van der Waals contributions, gain significance. The large energy barrier found when going from the global minimum to the middle of the membrane indicates that the non-electrostatic interactions between the drug and the non-polar tails are badly reproduced by the fixed point-charge force field used here, and that the introduction of polarization effects are likely necessary.

scholarly journals Tryptophan, an Amino-Acid Endowed with Unique Properties and Its Many Roles in Membrane Proteins

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1032
Author(s):  
Sonia Khemaissa ◽  
Sandrine Sagan ◽  
Astrid Walrant
Keyword(s):  
Amino Acid ◽  
Membrane Proteins ◽  
Hydrogen Bonds ◽  
Membrane Protein ◽  
Lipid Bilayers ◽  
Noncovalent Interactions ◽  
Chemical Properties ◽  
Protein Stabilization ◽  
Physico Chemical

Tryptophan is an aromatic amino acid with unique physico-chemical properties. It is often encountered in membrane proteins, especially at the level of the water/bilayer interface. It plays a role in membrane protein stabilization, anchoring and orientation in lipid bilayers. It has a hydrophobic character but can also engage in many types of interactions, such as π–cation or hydrogen bonds. In this review, we give an overview of the role of tryptophan in membrane proteins and a more detailed description of the underlying noncovalent interactions it can engage in with membrane partners.

Photoluminescence Changes Induced by Self-Organisation in Bridged Silsesquioxanes

2006 ◽  
Vol 514-516 ◽  
pp. 118-122 ◽  
Author(s):  
Luís D. Carlos ◽  
Rute A. Sá Ferreira ◽  
Sonia S. Nobre ◽  
Michel Wong Chi Man ◽  
Joël J. E. Moreau ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Long Range ◽  
Local Structure ◽  
The Self ◽  
Time Resolved ◽  
Emission Properties ◽  
Self Assembling ◽  
Molecular Precursor ◽  
Long Range Ordering ◽  
Bridged Silsesquioxanes

Two organo-bridged silsequioxanes derived from the same molecular precursor were synthesized with completely different local structure, namely long-range ordering. The photoluminescence features (emission, excitation, and time-resolved modes) were studied in the temperature range 13-300 K and compared with those of the molecular precursor. The effects of the self-assembling of the nanobuild blocks on these emission properties were discussed in terms of the magnitude of the hydrogen bonds between adjacent organic groups.

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