scholarly journals Interfacial water molecules at biological membranes: Structural features and role for lateral proton diffusion

PLoS ONE ◽  
2018 ◽  
Vol 13 (2) ◽  
pp. e0193454 ◽  
Author(s):  
Trung Hai Nguyen ◽  
Chao Zhang ◽  
Ewald Weichselbaum ◽  
Denis G. Knyazev ◽  
Peter Pohl ◽  
...  
Keyword(s):  
Biological Membranes ◽  
Structural Features ◽  
Water Molecules ◽  
Interfacial Water ◽  
Proton Diffusion

Interfacial water molecules in SH3 interactions: a revised paradigm for polyproline recognition

2012 ◽  
Vol 443 (1) ◽  
pp. 328-328
Author(s):  
J.M. Martin-Garcia ◽  
J. Ruiz-Sanz ◽  
I. Luque
Keyword(s):  
Water Molecules ◽  
Interfacial Water

scholarly journals Bis(3-carbamoylpyridin-1-ium) phosphite monohydrate

2018 ◽  
Vol 74 (9) ◽  
pp. 1295-1298
Author(s):  
Jan Fábry
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Water Molecule ◽  
Secondary Amine ◽  
Symmetry Plane ◽  
Structural Features ◽  
Water Molecules ◽  
Amine Groups

Two of the constituent molecules in the title structure, 2C6H7N2O+·HPO3 2−·H2O, i.e. the phosphite anion and the water molecule, are situated on a symmetry plane. The molecules are held together by moderate N—H...O and O—H...N, and weak O—H...O and C—H...Ocarbonyl hydrogen bonds in which the amide and secondary amine groups, and the water molecules are involved. The structural features are usual, among them the H atom bonded to the P atom avoids hydrogen bonding.

scholarly journals Structural features of high-local-density water molecules: Insights from structure indicators based on the translational order between the first two molecular shells

2019 ◽  
Vol 99 (6) ◽  
Author(s):  
Joan Manuel Montes de Oca ◽  
Sebastián R. Accordino ◽  
Alejandro R. Verde ◽  
Laureano M. Alarcón ◽  
Gustavo A. Appignanesi
Keyword(s):  
Local Density ◽  
Structural Features ◽  
Water Molecules ◽  
Translational Order

Similarities between ATP-dependent and ion-coupled multidrug transporters

2005 ◽  
Vol 33 (5) ◽  
pp. 1008-1011 ◽  
Author(s):  
H. Venter ◽  
S. Shahi ◽  
L. Balakrishnan ◽  
S. Velamakanni ◽  
A. Bapna ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Recent Work ◽  
Lactococcus Lactis ◽  
Biological Membranes ◽  
Structural Features ◽  
Membrane Transporters ◽  
Motive Force ◽  
Atp Binding ◽  
Multidrug Transporter ◽  
Multidrug Transporters

The movement of drugs across biological membranes is mediated by two major classes of membrane transporters. Primary-active, ABC (ATP-binding cassette) multidrug transporters are dependent on ATP-binding/hydrolysis, whereas secondary-active multidrug transporters are coupled to the proton (or sodium)-motive force that exists across the plasma membrane. Recent work on LmrA, an ABC multidrug transporter in Lactococcus lactis, suggests that primary- and secondary-active multidrug transporters share functional and structural features. Some of these similarities and their implications for the mechanism of transport by ABC multidrug transporters will be discussed.

AB Initio Simulation on Grotthuss Mechanism

2005 ◽  
Author(s):  
Jiahua Han ◽  
Hongtan Liu
Keyword(s):  
Ab Initio ◽  
Water Clusters ◽  
Dominant Role ◽  
High Mobility ◽  
Weight Fraction ◽  
Solvation Shell ◽  
Water Molecules ◽  
Proton Diffusion ◽  
Ab Initio Simulations ◽  
Grotthuss Mechanism

Ab initio simulations on Grotthuss mechanism have been carried out. Using the simulation results together with the existing experimental data, all the popular propositions for Grotthuss mechanism, including the one recently proposed by Noam [1], have been checked. Combining with the charge distribution calculation and the movement of the positive charge center inside the protonated water cluster during the proton diffusion process, only one mechanism is shown probable, while all the other proposed mechanisms are excluded. According to this probable mechanism, the high mobility of proton inside water is caused by the high diffusion rate of H5O2+, while the diffusion of H5O2+ is mainly induced by the thermal movement of water molecules at the second solvation shell of H5O2+ cation and the Zundel polarization inside the cation ion. Furthermore, the external field and thermo-dynamic effects play important roles during the transport process by affecting the reorientation of water molecules at the neighborhood of the second solvation shell of H5O2+ to induce the Zundel polarization and by providing the energy for the cleavage of the hydrogen bond between a newly formed water molecule and H5O2+. Because the weight (fraction) of H5O2+ among protonated water clusters decreases as temperature increases, this proposed mechanism is considered to play the dominant role only when temperature is below 572 K, above which, protons transport by other mechanisms become dominant.

scholarly journals Exploring the Landscape of Diazabicyclooctane (DBO) Inhibition: Avibactam Inactivation of PER-2 β-Lactamase

2017 ◽  
Vol 61 (6) ◽  
Author(s):  
Melina Ruggiero ◽  
Krisztina M. Papp-Wallace ◽  
Magdalena A. Taracila ◽  
Maria F. Mojica ◽  
Christopher R. Bethel ◽  
...  
Keyword(s):  
Active Site ◽  
Therapeutic Option ◽  
Structural Features ◽  
Atomic Mass ◽  
Stable Complex ◽  
Water Molecules ◽  
Gram Negative Bacteria ◽  
Biophysical Properties ◽  
Content Type ◽  
Class A

ABSTRACT PER β-lactamases are an emerging family of extended-spectrum β-lactamases (ESBL) found in Gram-negative bacteria. PER β-lactamases are unique among class A enzymes as they possess an inverted omega (Ω) loop and extended B3 β-strand. These singular structural features are hypothesized to contribute to their hydrolytic profile against oxyimino-cephalosporins (e.g., cefotaxime and ceftazidime). Here, we tested the ability of avibactam (AVI), a novel non-β-lactam β-lactamase inhibitor to inactivate PER-2. Interestingly, the PER-2 inhibition constants (i.e., k 2/K = 2 × 103 ± 0.1 × 103 M−1 s−1, where k 2 is the rate constant for acylation (carbamylation) and K is the equilibrium constant) that were obtained when AVI was tested were reminiscent of values observed testing the inhibition by AVI of class C and D β-lactamases (i.e., k 2/K range of ≈103 M−1 s−1) and not class A β-lactamases (i.e., k 2/K range, 104 to 105 M−1 s−1). Once AVI was bound, a stable complex with PER-2 was observed via mass spectrometry (e.g., 31,389 ± 3 atomic mass units [amu] → 31,604 ± 3 amu for 24 h). Molecular modeling of PER-2 with AVI showed that the carbonyl of AVI was located in the oxyanion hole of the β-lactamase and that the sulfate of AVI formed interactions with the β-lactam carboxylate binding site of the PER-2 β-lactamase (R220 and T237). However, hydrophobic patches near the PER-2 active site (by Ser70 and B3-B4 β-strands) were observed and may affect the binding of necessary catalytic water molecules, thus slowing acylation (k 2/K) of AVI onto PER-2. Similar electrostatics and hydrophobicity of the active site were also observed between OXA-48 and PER-2, while CTX-M-15 was more hydrophilic. To demonstrate the ability of AVI to overcome the enhanced cephalosporinase activity of PER-2 β-lactamase, we tested different β-lactam–AVI combinations. By lowering MICs to ≤2 mg/liter, the ceftaroline-AVI combination could represent a favorable therapeutic option against Enterobacteriaceae expressing bla PER-2. Our studies define the inactivation of the PER-2 ESBL by AVI and suggest that the biophysical properties of the active site contribute to determining the efficiency of inactivation.

Spontaneous protein desorption from self-assembled monolayer (SAM)-coated gold nanoparticles

2018 ◽  
Vol 20 (1) ◽  
pp. 68-74 ◽  
Author(s):  
Ranran Tian ◽  
Mengbo Luo ◽  
Jingyuan Li
Keyword(s):  
Gold Nanoparticles ◽  
Lateral Diffusion ◽  
Water Molecules ◽  
Interfacial Water ◽  
Self Assembled Monolayer ◽  
Adsorption Affinity ◽  
Self Assembled

Interfacial water molecules and lateral diffusion of protein reduce the adsorption affinity of protein and promote protein desorption.

Controversy regarding the secondary active water transport hypothesis

2002 ◽  
Vol 80 (5) ◽  
pp. 525-533 ◽  
Author(s):  
Jean-Yves Lapointe ◽  
Marilène P Gagnon ◽  
Dominique G Gagnon ◽  
Pierre Bissonnette
Keyword(s):  
Osmotic Pressure ◽  
Water Transport ◽  
Xenopus Oocyte ◽  
Biological Membranes ◽  
Cell Swelling ◽  
Water Molecules ◽  
Intracellular Diffusion ◽  
Glucose Molecule

Historically, water transport across biological membranes has always been considered a passive process, i.e., the net water transport is proportional to the gradients of hydrostatic and osmotic pressure. More recently, this dogma was challenged by the suggestion that secondary active transporters such as the Na/glucose cotransporter (SGLT1) could perform secondary active water transport with a fixed stoichiometry. In the case of SGLT1, the stoichiometry would consist of one glucose molecule to two Na+ ions to 220–400 water molecules. In the present minireview, we summarize and criticize the evidence supporting and opposing this water cotransport hypothesis. Published and unpublished observations from our own laboratory are also presented in support of the idea that transport-dependent osmotic gradients begin to build up immediately after cotransport commences and are fully responsible for the cell swelling observed.Key words: Xenopus oocyte, intracellular diffusion, water cotransport, SGLT1.

Viscosity and Structure of KDP Aqueous Solution

2017 ◽  
Vol 898 ◽  
pp. 1776-1782
Author(s):  
Yu Lin Wu ◽  
Yi Su ◽  
Yao Liu ◽  
Yong Wang ◽  
Lei Zhang ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Empirical Formula ◽  
Structural Features ◽  
Solution Viscosity ◽  
Water Molecules ◽  
Diffraction Spectrum ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fitting In ◽  
Kdp Crystals

The corresponding relationship among KDP solution viscosity, concentration and temperature was researched respectively, to explore the empirical formula of the viscosity of KDP solution. The experimental results showed that the viscosity increased with the increase of ionic strength and reciprocal of temperature. Viscosity had exponent relation to ionic strength and reciprocal of temperature, fitting in well with the empirical formula: See formula in paper. The X-ray diffraction analysis showed that with the increasing amount of KDP, a new peak emerging in the diffraction spectrum accorded with molecular structure of KDP crystals, and some peaks which accorded with the structural features of water molecules gradually disappeared. It showed that with the increase of the amount of KDP, the internal structure of KDP solution had changed.

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