Changes in membrane elasticity caused by the hydrophobic surfactant proteins correlate poorly with adsorption of lipid vesicles

Soft Matter ◽  
2021 ◽  
Author(s):  
Ryan W. Loney ◽  
Bret Brandner ◽  
Maayan P. Dagan ◽  
Paige N. Smith ◽  
Megan Roche ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Order Parameter ◽  
Diffuse Scattering ◽  
Lipid Vesicles ◽  
Surfactant Proteins ◽  
Membrane Elasticity ◽  
X Ray ◽  
Bending Modulus ◽  
Air Water Interface ◽  
Acyl Chains

We used X-ray diffuse scattering to determine the bending modulus of lipid bilayers and an order parameter of the acyl chains to establish how the hydrophobic surfactant proteins, SP-B and SP-C, promote adsorption of lipids to an air/water interface.

scholarly journals Dielectric Properties of Phosphatidylcholine Membranes and the Effect of Sugars

Membranes ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 847
Author(s):  
Victoria Vitkova ◽  
Vesela Yordanova ◽  
Galya Staneva ◽  
Ognyan Petkov ◽  
Angelina Stoyanova-Ivanova ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Specific Capacitance ◽  
Lipid Bilayers ◽  
Electric Fields ◽  
Order Parameter ◽  
Molecular Mechanisms ◽  
Electrochemical Impedance ◽  
Lipid Vesicles ◽  
Sucrose Solutions ◽  
Simple Carbohydrates

Simple carbohydrates are associated with the enhanced risk of cardiovascular disease and adverse changes in lipoproteins in the organism. Conversely, sugars are known to exert a stabilizing effect on biological membranes, and this effect is widely exploited in medicine and industry for cryopreservation of tissues and materials. In view of elucidating molecular mechanisms involved in the interaction of mono- and disaccharides with biomimetic lipid systems, we study the alteration of dielectric properties, the degree of hydration, and the rotational order parameter and dipole potential of lipid bilayers in the presence of sugars. Frequency-dependent deformation of cell-size unilamellar lipid vesicles in alternating electric fields and fast Fourier transform electrochemical impedance spectroscopy are applied to measure the specific capacitance of phosphatidylcholine lipid bilayers in sucrose, glucose and fructose aqueous solutions. Alteration of membrane specific capacitance is reported in sucrose solutions, while preservation of membrane dielectric properties is established in the presence of glucose and fructose. We address the effect of sugars on the hydration and the rotational order parameter for 1-palmitoyl-2-oleoyl-sn-glycero-3- phosphocholine (POPC) and 1-stearoyl-2-oleoyl-sn-glycero-3- phosphocholine (SOPC). An increased degree of lipid packing is reported in sucrose solutions. The obtained results provide evidence that some small carbohydrates are able to change membrane dielectric properties, structure, and order related to membrane homeostasis. The reported data are also relevant to future developments based on the response of lipid bilayers to external physical stimuli such as electric fields and temperature changes.

scholarly journals Mechanical and Electrical Interaction of Biological Membranes with Nanoparticles and Nanostructured Surfaces

Membranes ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 533
Author(s):  
Jeel Raval ◽  
Ekaterina Gongadze ◽  
Metka Benčina ◽  
Ita Junkar ◽  
Niharika Rawat ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Electrostatic Interactions ◽  
Chemical Properties ◽  
Lipid Vesicles ◽  
Solid Surfaces ◽  
Electrochemical Anodization ◽  
Nanostructured Surfaces ◽  
Charged Surfaces ◽  
Bending Modulus ◽  
Head Groups

In this review paper, we theoretically explain the origin of electrostatic interactions between lipid bilayers and charged solid surfaces using a statistical mechanics approach, where the orientational degree of freedom of lipid head groups and the orientational ordering of the water dipoles are considered. Within the modified Langevin Poisson–Boltzmann model of an electric double layer, we derived an analytical expression for the osmotic pressure between the planar zwitterionic lipid bilayer and charged solid planar surface. We also show that the electrostatic interaction between the zwitterionic lipid head groups of the proximal leaflet and the negatively charged solid surface is accompanied with a more perpendicular average orientation of the lipid head-groups. We further highlight the important role of the surfaces’ nanostructured topography in their interactions with biological material. As an example of nanostructured surfaces, we describe the synthesis of TiO2 nanotubular and octahedral surfaces by using the electrochemical anodization method and hydrothermal method, respectively. The physical and chemical properties of these nanostructured surfaces are described in order to elucidate the influence of the surface topography and other physical properties on the behavior of human cells adhered to TiO2 nanostructured surfaces. In the last part of the paper, we theoretically explain the interplay of elastic and adhesive contributions to the adsorption of lipid vesicles on the solid surfaces. We show the numerically predicted shapes of adhered lipid vesicles corresponding to the minimum of the membrane free energy to describe the influence of the vesicle size, bending modulus, and adhesion strength on the adhesion of lipid vesicles on solid charged surfaces.

scholarly journals Elastic behavior of model membranes with antimicrobial peptides depends on lipid specificity and d-enantiomers

Soft Matter ◽  
2019 ◽  
Vol 15 (8) ◽  
pp. 1860-1868 ◽  
Author(s):  
Akari Kumagai ◽  
Fernando G. Dupuy ◽  
Zoran Arsov ◽  
Yasmene Elhady ◽  
Diamond Moody ◽  
...  
Keyword(s):  
Order Parameter ◽  
Model Membranes ◽  
Elastic Behavior ◽  
X Ray ◽  
Bending Modulus ◽  
X Ray Scattering ◽  
Chain Order ◽  
Lipid Chain ◽  
Lipid Specificity ◽  
Ray Scattering

(A) Low-angle X-ray scattering (LAXS) of oriented, fully hydrated model membranes yields bending modulus (KC) and (B) wide-angle X-ray scattering (WAXS) yields lipid chain order parameter (SX-ray).

Determination of the thermodynamic factor for the B2 FeAl phase from X-ray diffuse scattering data

1998 ◽  
Vol 527 ◽  
Author(s):  
Vlad Liubich ◽  
Simon Dorfman ◽  
David Fuks ◽  
Helmut Mehrert
Keyword(s):  
Interdiffusion Coefficient ◽  
Order Parameter ◽  
Diffuse Scattering ◽  
Al Alloys ◽  
Scattering Data ◽  
Thermodynamic Factor ◽  
X Ray ◽  
X Ray Scattering ◽  
Feal Phase

ABSTRACTThe interdiffusion coefficient is related via the modified Darken equation to the tracer diffusivities of the constituents. The thermodynamic factor Φ entering the Darken equation for the interdiffusion coefficient is expressed in terms of the energy parameters which describe the ordering process in the binary alloy. Our calculations for Fe-Al alloys yield the dependence of Φ on the long-range order parameter. These calculations are performed with the parameters extracted from diffuse X-ray scattering data on FeAl.

scholarly journals Reproducibility of protein x-ray diffuse scattering and potential utility for modeling atomic displacement parameters

2021 ◽  
Vol 8 (4) ◽  
pp. 044701
Author(s):  
Zhen Su ◽  
Medhanjali Dasgupta ◽  
Frédéric Poitevin ◽  
Irimpan I. Mathews ◽  
Henry van den Bedem ◽  
...  
Keyword(s):  
Diffuse Scattering ◽  
Atomic Displacement ◽  
Potential Utility ◽  
X Ray ◽  
Protein X ◽  
Atomic Displacement Parameters

Quantification of Starch Order in Physically Modified Rice Flours Using Small-Angle X-ray Scattering (SAXS) and Fourier Transform Infrared (FT-IR) Spectroscopy

2021 ◽  
pp. 000370282110282
Author(s):  
Daitaro Ishikawa ◽  
Jiamin Yang ◽  
Tomoyuki Fujii
Keyword(s):  
Infrared Spectroscopy ◽  
Small Angle ◽  
Water Sorption ◽  
Order Parameter ◽  
Rice Flour ◽  
Ordered Structure ◽  
X Ray ◽  
Glucose Unit ◽  
X Ray Scattering ◽  
Ray Scattering

The purpose of this study was to understand the ordered structure of starch in rice flour based on a physical modification with non-heating, milling, and water sorption through the structural evaluation of rice flour using small-angle X-ray scattering (SAXS) and infrared spectroscopy within the 4000–100 cm−1 region. The SAXS pattern of the samples with low moisture contents subjected to milling yield a band within the 0.4–0.9 nm−1 of the q range owing to a lamellar repeat of starch with an ordered structure in rice flour. We proposed an order parameter using the intensity of the SAXS band to quantify the order structure of starch in rice flour, and the true density was negatively correlated with the order parameter. Infrared band at 990 cm−1 in COH bending mode applied to the hydroxyl group of C6 shifted to a low wavenumber corresponding to the order parameter. A linear correlation was found between the order parameter and the 990 cm−1 and band at 861 cm−1 owing to COC symmetrical stretching of glycoside bond and CH2 deformation of the glucose unit of starch, 572, 472, and 436 cm−1, owing to the pyranose ring in the glucose unit of starch. The identified infrared bands are effective for quantifying the ordered structure of starch at the lamellar level. When subjected to water sorption, the band position at 990 cm−1 shifted to a higher wavenumber above a water activity of 0.7. This result revealed that the water-induced transition of glass to rubber of starch in rice flour can be clearly evaluated through infrared spectroscopy using the band at 990 cm−1. In addition, the band at 861 cm−1 also shifted to a higher wavenumber, whereas those at 572 and 436 cm−1 did not show a significant shift. These results indicate that water sorption slightly affects the internal structure and may mainly affect the surface of starch.

scholarly journals Diethylstilbestrol Modifies the Structure of Model Membranes and Is Localized Close to the First Carbons of the Fatty Acyl Chains

Biomolecules ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 220
Author(s):  
Alessio Ausili ◽  
Inés Rodríguez-González ◽  
Alejandro Torrecillas ◽  
José A. Teruel ◽  
Juan C. Gómez-Fernández
Keyword(s):  
Membrane Surface ◽  
Water Layer ◽  
Fatty Acyl ◽  
31P Nmr Spectroscopy ◽  
Relaxation Rates ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Acyl Chains ◽  
Dynamics Simulations

The synthetic estrogen diethylstilbestrol (DES) is used to treat metastatic carcinomas and prostate cancer. We studied its interaction with membranes and its localization to understand its mechanism of action and side-effects. We used differential scanning calorimetry (DSC) showing that DES fluidized the membrane and has poor solubility in DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) in the fluid state. Using small-angle X-ray diffraction (SAXD), it was observed that DES increased the thickness of the water layer between phospholipid membranes, indicating effects on the membrane surface. DSC, X-ray diffraction, and 31P-NMR spectroscopy were used to study the effect of DES on the Lα-to-HII phase transition, and it was observed that negative curvature of the membrane is promoted by DES, and this effect may be significant to understand its action on membrane enzymes. Using the 1H-NOESY-NMR-MAS technique, cross-relaxation rates for different protons of DES with POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) protons were calculated, suggesting that the most likely location of DES in the membrane is with the main axis parallel to the surface and close to the first carbons of the fatty acyl chains of POPC. Molecular dynamics simulations were in close agreements with the experimental results regarding the location of DES in phospholipids bilayers.

Evolution of Interfacial Roughness Correlations of Fe Au Films Grown on Mgo(001) Substrates

1996 ◽  
Vol 440 ◽  
Author(s):  
P. C. Chow ◽  
R. Paniago ◽  
R. Forrest ◽  
S. C. Moss ◽  
S. S. P. Parkin ◽  
...  
Keyword(s):  
Thin Films ◽  
Diffuse Scattering ◽  
Perfect Match ◽  
Grazing Incidence ◽  
Interface Roughness ◽  
Metallic Structures ◽  
X Ray ◽  
Dimensional Image ◽  
X Ray Scattering ◽  
Image Plate Detector

AbstractThe growth by sputtering of a series of thin films of Fe/Au on MgO(001) substrates was analyzed using Bragg and diffuse X-ray scattering. The Fe (bcc) layer grows rotated by 45° with respect to the MgO – Au(fcc) (001) epitaxial orientation, resulting in an almost perfect match between the two metallic structures. By collecting the X-ray diffuse scattering under grazing incidence using a 2-dimensional image plate detector, we mapped the reciprocal space of these films. We characterized the correlated interface roughness starting with a buffer of Fe in which only three interfaces are present. The propagation of the roughness was subsequently characterized for Fe/Au multilayers with 40 and 100 bilayers. We observe an enlargement of the surface features as a function of time, evidenced by the longer lateral cutoff length measured for thicker films.

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