Author(s): Zhang L; Muchall HM; Peslherbe GH;

The ground-state equilibrium geometries, electronic structures and vertical excitation energies of methyl- and methoxyl-substituted phenol radical cations and phenoxyl radicals have been investigated using time-dependent density-functional theory (namely TD-B3LYP) and complete-active-space second-order perturbation theory (CASPT2). The "anomalous" large r ...

Article GUID: 23216064

Author(s): Jahangiri S; Mercer SM; Jessop PG; Peslherbe GH;

The solvation behavior of alkyl diammonium chlorides of varying alkyl chain length and the molecular details of their effect on the salting-out of organic molecules in aqueous phase have been investigated by classical molecular dynamics simulations. More specifically, systems containing water, tetrahydrofuran (THF), and their mixtures with a,?-alkyl diamm ...

Article GUID: 23789929

Author(s): Mak CC; Timerghazin QK; Peslherbe GH;

Photoexcitation of iodide-acetonitrile clusters, I(-)(CH3CN)n, to the charge-transfer-to-solvent (CTTS) state and subsequent cluster relaxation could result in the possible formation of cluster analogues of the bulk solvated electron. In this work, the relaxation process of the CTTS excited iodide-acetonitrile binary complex, [I(-)(CH3CN)]*, is investigat ...

Article GUID: 23819756

Author(s): Mak CC; Peslherbe GH;

Upon photoexcitation of iodide-methanol clusters, I(-)(CH3OH)n, to a charge-transfer-to-solvent (CTTS) excited state, extensive relaxation was found to occur, accompanied by a convoluted modulation of the stability of the excited electron, which ultimately decreases substantially. In order to develop a molecular-level understanding of the relaxation proce ...

Article GUID: 24922343

Author(s): Fürst O; Nichols CG; Lamoureux G; D' Avanzo N;

Cholesterol is the major sterol component of all mammalian plasma membranes. Recent studies have shown that cholesterol inhibits both bacterial (KirBac1.1 and KirBac3.1) and eukaryotic (Kir2.1) inward rectifier K(+) (Kir) channels. Lipid-sterol interactions are not enantioselective, and the enantiomer of cholesterol (ent-cholesterol) does not inhibit Kir ...

Article GUID: 25517146

Author(s): Bilkiss B Issack

While it has long been known that cholesterol reduces the permeability of biological membranes to water, the exact mechanism by which cholesterol influences transmembrane permeation is still unclear. The thermodynamic and kinetic contributions to the transport of water across mixed DPPC/cholesterol bilayers of different composition are thus examined by mo ...

Article GUID: 25679811

Author(s): Jean-François Rhéault

A singular aspect of the 2-on-2 hemoglobin structures of groups I and II is the presence of tunnels linking the protein surface to the distal heme pocket, supporting the storage and the diffusion of small apolar ligands to/from the buried active site. As the solubility of apolar ligands is greater in biological membranes than in solution, the association ...

Article GUID: 25723781

Author(s): Sefer Baday

In human cells, membrane proteins of the rhesus (Rh) family excrete ammonium and play a role in pH regulation. Based on high-resolution structures, Rh proteins are generally understood to act as NH3 channels. Given that cell membranes are permeable to gases like NH3, the role of such proteins remains a paradox. Using molecular and quantum mechanical calcu ...

Article GUID: 26190573

Author(s): Maria S Shadrina

Atomistic molecular dynamics simulations of diffusion of O2 from the hemes to the external solvent in the a- and ß-subunits of the human hemoglobin (HbA) tetramer reveal transient gas tunnels that are not seen in crystal structures. We find here that the tunnel topology, which encompasses the reported experimental Xe binding cavities, is identical in HbA& ...

Article GUID: 26226318

Author(s): Maria S Shadrina

Hemoglobin transports O2 by binding the gas at its four hemes. Hydrogen bonding between the distal histidine (HisE7) and heme-bound O2 significantly increases the affinity of human hemoglobin (HbA) for this ligand. HisE7 is also proposed to regulate the release of O2 to the solvent via a transient E7 channel. To reveal the O2 escape routes controlled by H ...

Article GUID: 26226401

Author(s): Sandrine Moreira

CONCLUSION: Homology modeling and molecular dynamics simulations strongly suggest that DpRNL is an RNA ligase 2. The predicted innovative reshaping of DpRNL's catalytic pocket is worthwhile to be tested experimentally.

Article GUID: 26449279

Author(s): Esam A Orabi

A polarizable model for ammonia is optimized based on the ab initio properties of the NH3 molecule and the NH3-NH3 and NH3-H2O dimers calculated at the MP2 level. For larger (NH3)m, NH3(H2O)n, and H2O(NH3)n clusters (m = 2-7 and n = 1-4), the model yields structural and binding energies in good agreement with ab initio calculations without further adjustm ...

Article GUID: 26583551