scholarly journals α-Synuclein in α-helical conformation at air–water interface: implication of conformation and orientation changes during its accumulation/aggregation

2010 ◽  
Vol 46 (36) ◽  
pp. 6702 ◽  
Author(s):  
Chengshan Wang ◽  
Nilam Shah ◽  
Garima Thakur ◽  
Feimeng Zhou ◽  
Roger M. Leblanc
Keyword(s):  
Helical Conformation ◽  
Water Interface ◽  
Air Water Interface

scholarly journals Multilayer formation by a compressed monolayer of poly-∈-benzyloxycarbonyl-l-lysine

1968 ◽  
Vol 110 (4) ◽  
pp. 733-737 ◽  
Author(s):  
B. R. Malcolm
Keyword(s):  
Infrared Spectroscopy ◽  
Electron Diffraction ◽  
Helical Conformation ◽  
Water Interface ◽  
Ordered Arrays ◽  
Molecular Monolayers ◽  
Air Water Interface ◽  
Polarized Infrared Spectroscopy ◽  
Multilayer Formation ◽  
Perfect Plastic

Molecular monolayers of poly-∈-benzyloxycarbonyl-l-lysine were studied at the air/water interface. Deuterium-exchange measurements and the surface area of the monolayer are consistent with a structure consisting of condensed ordered arrays of α-helices. Collapsed films removed from the surface and air-dried were examined by polarized infrared spectroscopy and electron diffraction and found to consist of molecules in the α-helical conformation. There is no indication of a conformational change during compression of the monolayer, and a series of transitions found in the force–area curve are interpreted as the consecutive formation of additional layers of molecules. Some of the factors that influence this almost perfect plastic behaviour are discussed.

The organization of poly-γ-benzyl-L-glutamate in the α-helical conformation at the air-water interface

1994 ◽  
Vol 242 (1-2) ◽  
pp. 229-233 ◽  
Author(s):  
Pierre Lavigne ◽  
Pierre Tancrède ◽  
François Lamarche ◽  
Michel Grandbois ◽  
Christian Salesse
Keyword(s):  
Helical Conformation ◽  
Water Interface ◽  
Air Water Interface

scholarly journals Characterization of the lipid-binding domain of the Plasmodium falciparum CTP:phosphocholine cytidylyltransferase through synthetic-peptide studies

2003 ◽  
Vol 375 (3) ◽  
pp. 653-661 ◽  
Author(s):  
Marie-Pierre LARVOR ◽  
Rachel CERDAN ◽  
Catherine GUMILA ◽  
Luc MAURIN ◽  
Patrick SETA ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Surface Pressure ◽  
Hydrophobic Interactions ◽  
Lipid Binding ◽  
Binding Domain ◽  
Helical Conformation ◽  
Initial Surface ◽  
Water Interface ◽  
Ctp:Phosphocholine Cytidylyltransferase ◽  
Air Water Interface

Phospholipid biosynthesis plays a key role in malarial infection and is regulated by CCT (CTP:phosphocholine cytidylyltransferase). This enzyme belongs to the group of amphitropic proteins which are regulated by reversible membrane interaction. To assess the role of the putative membrane-binding domain of Plasmodium falciparum CCT (PfCCT), we synthesized three peptides, K21, V20 and K54 corresponding to residues 274–294, 308–327 and 274–327 of PfCCT respectively. Conformational behaviour of the peptides, their ability to bind to liposomes and to destabilize lipid bilayers, and their insertion properties were investigated by different biophysical techniques. The intercalation mechanisms of the peptides were refined further by using surface-pressure measurements on various monolayers at the air/water interface. In the present study, we show that the three studied peptides are able to bind to anionic and neutral phospholipids, and that they present an α-helical conformation upon lipid binding. Peptides V20 and the full-length K54 intercalate their hydrophobic parts into an anionic bilayer and, to a lesser extent, a neutral one for V20. Peptide K21 interacts only superficially with both types of phospholipid vesicles. Adsorption experiments performed at the air/water interface revealed that peptide K54 is strongly surface-active in the absence of lipid. Peptide V20 presents an atypical behaviour in the presence of phosphatidylserine. Whatever the initial surface pressure of a phosphatidylserine film, peptide V20 and phosphatidylserine entities seem linked together in a special organization involving electrostatic and hydrophobic interactions. We showed that PfCCT presents different lipid-dependence properties from other studied CCTs. Although the lipid-binding domain seems to be located in the C-terminal region of the enzyme, as with the mammalian counterpart, the membrane anchorage, which plays a key role in the enzyme regulation, is driven by two α-helices, which behave differently from one another.

Sampling and analysis of the air-water interface with SEM and EDS of microlayers

1989 ◽  
Vol 47 ◽  
pp. 1004-1005
Author(s):  
Randall W. Smith ◽  
John Dash
Keyword(s):  
Heavy Metals ◽  
Surface Microlayer ◽  
Surface Films ◽  
Water Interface ◽  
Physical Processes ◽  
Infrared Spectroscopic Analysis ◽  
Eds Analysis ◽  
Air Water Interface ◽  
Significant Area ◽  
Bulk Chemical

The structure of the air-water interface forms a boundary layer that involves biological ,chemical geological and physical processes in its formation. Freshwater and sea surface microlayers form at the air-water interface and include a diverse assemblage of organic matter, detritus, microorganisms, plankton and heavy metals. The sampling of microlayers and the examination of components is presently a significant area of study because of the input of anthropogenic materials and their accumulation at the air-water interface. The neustonic organisms present in this environment may be sensitive to the toxic components of these inputs. Hardy reports that over 20 different methods have been developed for sampling of microlayers, primarily for bulk chemical analysis. We report here the examination of microlayer films for the documentation of structure and composition.Baier and Gucinski reported the use of Langmuir-Blogett films obtained on germanium prisms for infrared spectroscopic analysis (IR-ATR) of components. The sampling of microlayers has been done by collecting fi1ms on glass plates and teflon drums, We found that microlayers could be collected on 11 mm glass cover slips by pulling a Langmuir-Blogett film from a surface microlayer. Comparative collections were made on methylcel1ulose filter pads. The films could be air-dried or preserved in Lugol's Iodine Several slicks or surface films were sampled in September, 1987 in Chesapeake Bay, Maryland and in August, 1988 in Sequim Bay, Washington, For glass coverslips the films were air-dried, mounted on SEM pegs, ringed with colloidal silver, and sputter coated with Au-Pd, The Langmuir-Blogett film technique maintained the structure of the microlayer intact for examination, SEM observation and EDS analysis were then used to determine organisms and relative concentrations of heavy metals, using a Link AN 10000 EDS system with an ISI SS40 SEM unit. Typical heavy microlayer films are shown in Figure 3.

Temperature Dependence of the Air/Water Interface Revealed by Polarization Sensitive Sum-Frequency Generation Spectroscopy

2018 ◽  
Author(s):  
Daniel R. Moberg ◽  
Shelby C. Straight ◽  
Francesco Paesani
Keyword(s):  
Temperature Dependence ◽  
Low Frequency ◽  
Potential Energy Function ◽  
Md Simulations ◽  
Sum Frequency Generation ◽  
Water Molecules ◽  
Water Interface ◽  
Sum Frequency ◽  
Air Water Interface ◽  
Frequency Generation

<div> <div> <div> <p>The temperature dependence of the vibrational sum-frequency generation (vSFG) spectra of the the air/water interface is investigated using many-body molecular dynamics (MB-MD) simulations performed with the MB-pol potential energy function. The total vSFG spectra calculated for different polarization combinations are then analyzed in terms of molecular auto-correlation and cross-correlation contributions. To provide molecular-level insights into interfacial hydrogen-bonding topologies, which give rise to specific spectroscopic features, the vSFG spectra are further investigated by separating contributions associated with water molecules donating 0, 1, or 2 hydrogen bonds to neighboring water molecules. This analysis suggests that the low frequency shoulder of the free OH peak which appears at ∼3600 cm−1 is primarily due to intermolecular couplings between both singly and doubly hydrogen-bonded molecules. </p> </div> </div> </div>

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