scholarly journals Stable Polymer Bilayers for Protein Channel Recordings at High Guanidinium Chloride Concentrations

2020 ◽  
Author(s):  
Luning Yu ◽  
Xinqi Kang ◽  
Mohammad Amin Alibakhshi ◽  
Mikhail Pavlenok ◽  
Michael Niederweis ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Transmembrane Protein ◽  
Bilayer Membrane ◽  
Guanidinium Chloride ◽  
Planar Bilayers ◽  
Dna Hairpins ◽  
Polymer Bilayers ◽  
Protein Channel ◽  
The Stability ◽  
Chloride Concentrations

AbstractUse of chaotropic reagents is common in biophysical characterization of biomolecules. When the study involves transmembrane protein channels, the stability of the protein channel and supporting bilayer membrane must be considered. In this letter we show that planar bilayers composed of poly(1,2-butadiene)-b-poly(ethylene oxide) diblock copolymer are stable and leak-free at high guanidinium chloride concentrations, in contrast to diphytanoyl phosphatidylcholine bilayers which exhibit deleterious leakage under similar conditions. Further, insertion and functional analysis of channels such as α-hemolysin and MspA are straightforward in these polymer membranes. Finally, we demonstrate that α-hemolysin channels maintain their structural integrity at 2M guanidinium chloride concentrations using blunt DNA hairpins as molecular reporters.

scholarly journals Stable polymer bilayers for protein channel recordings at high guanidinium chloride concentrations

2021 ◽  
Author(s):  
Luning Yu ◽  
Xinqi Kang ◽  
Mohammad Amin Alibakhshi ◽  
Mikhail Pavlenok ◽  
Michael Niederweis ◽  
...  
Keyword(s):  
Guanidinium Chloride ◽  
Polymer Bilayers ◽  
Protein Channel ◽  
Chloride Concentrations

scholarly journals Probing the effects of nonannular lipid binding on the stability of the calcium pump SERCA

2018 ◽  
Author(s):  
L. Michel Espinoza-Fonseca
Keyword(s):  
Structural Integrity ◽  
Transmembrane Protein ◽  
Md Simulations ◽  
Lipid Binding ◽  
Calcium Pump ◽  
Lipid Molecule ◽  
Allosteric Control ◽  
Functional Dynamics ◽  
The Stability ◽  
And Function

AbstractThe calcium pump SERCA is a transmembrane protein that is critical for calcium transport in cells. SERCA resides in an environment made up largely by the lipid bilayer, so lipids play a central role on its stability and function. Studies have provided insights into the effects of annular and bulk lipids on SERCA activation, but the role of a nonannular lipid site in the E2 intermediate state remains elusive. Here, we have performed microsecond molecular dynamics (MD) simulations to probe the effects of nonannular lipid binding on the stability and structural dynamics of the E2 state of SERCA. We found that the structural integrity and stability of the E2 state is independent of nonannular lipid binding, and that occupancy of a lipid molecule at this site does not modulate destabilization of the E2 state, a step required to initiate the transition toward the competent E1 state. We also found that binding of the nonannular lipid does not induce direct allosteric control of the intrinsic functional dynamics the E2 state. We conclude that nonannular lipid binding is not necessary for the stability of the E2 state, but we speculate that it becomes functionally significant during the E2-to-E1 transition of the pump.

Destabilizing the Structural Integrity of SARS-CoV2 Receptor Proteins by Curcumin Along with Hydroxychloroquine: An Insilco Approach for a Combination Therapy

2020 ◽  
Author(s):  
Akhileshwar Srivastava ◽  
Divya Singh
Keyword(s):  
Binding Energy ◽  
Combination Therapy ◽  
Receptor Binding ◽  
Structural Integrity ◽  
Binding Domain ◽  
Receptor Binding Domain ◽  
Receptor Proteins ◽  
Main Protease ◽  
The Stability ◽  
Therapeutic Activities

Presently, an emerging disease (COVID-19) has been spreading across the world due to coronavirus (SARS-CoV2). For treatment of SARS-CoV2 infection, currently hydroxychloroquine has been suggested by researchers, but it has not been found enough effective against this virus. The present study based on in silico approaches was designed to enhance the therapeutic activities of hydroxychloroquine by using curcumin as an adjunct drug against SARS-CoV2 receptor proteins: main-protease and S1 receptor binding domain (RBD). The webserver (ANCHOR) showed the higher protein stability for both receptors with disordered score (<0.5). The molecular docking analysis revealed that the binding energy (-24.58 kcal/mol) of hydroxychloroquine was higher than curcumin (-20.47 kcal/mol) for receptor main-protease, whereas binding energy of curcumin (<a>-38.84</a> kcal/mol) had greater than hydroxychloroquine<a> (-35.87</a> kcal/mol) in case of S1 receptor binding domain. Therefore, this study suggested that the curcumin could be used as combination therapy along with hydroxychloroquine for disrupting the stability of SARS-CoV2 receptor proteins

scholarly journals Prediction of Functional Consequences of Missense Mutations in ANO4 Gene

2021 ◽  
Vol 22 (5) ◽  
pp. 2732
Author(s):  
Nadine Reichhart ◽  
Vladimir M. Milenkovic ◽  
Christian H. Wetzel ◽  
Olaf Strauß
Keyword(s):  
Transmembrane Protein ◽  
Functional Characterization ◽  
Missense Mutations ◽  
Mutant Proteins ◽  
Functional Consequences ◽  
New Perspective ◽  
The Stability ◽  
Dynamics Simulations ◽  
And Function

The anoctamin (TMEM16) family of transmembrane protein consists of ten members in vertebrates, which act as Ca2+-dependent ion channels and/or Ca2+-dependent scramblases. ANO4 which is primarily expressed in the CNS and certain endocrine glands, has been associated with various neuronal disorders. Therefore, we focused our study on prioritizing missense mutations that are assumed to alter the structure and stability of ANO4 protein. We employed a wide array of evolution and structure based in silico prediction methods to identify potentially deleterious missense mutations in the ANO4 gene. Identified pathogenic mutations were then mapped to the modeled human ANO4 structure and the effects of missense mutations were studied on the atomic level using molecular dynamics simulations. Our data show that the G80A and A500T mutations significantly alter the stability of the mutant proteins, thus providing new perspective on the role of missense mutations in ANO4 gene. Results obtained in this study may help to identify disease associated mutations which affect ANO4 protein structure and function and might facilitate future functional characterization of ANO4.

On the Design of Contact Member Surface Shape of Bolted Joints to Minimize Clamping Load Loss

2018 ◽  
Author(s):  
Linbo Zhu ◽  
Yifei Hou ◽  
Abdel-Hakim Bouzid ◽  
Jun Hong
Keyword(s):  
Contact Surface ◽  
High Performance ◽  
Thermal Loading ◽  
Structural Integrity ◽  
Bolted Joints ◽  
Surface Shape ◽  
Geometrical Shape ◽  
Joint Surfaces ◽  
Joint Contact ◽  
The Stability

Metal to metal contact between joint surfaces is widely used in bolted joints to obtain a rigid and a high performance connection. However, a significant amount of clamping load is lost when the joint is subjected to mechanical and thermal loading including creep and fatigue. In practice, to prevent bolt loosening, additional parts such as spring washers, double nut, spring lock washers, Nyloc nut and so on are used. Those methods are costly and influence the stability of the joint and affect its structural integrity. It is well established that a small compression displacement in clamping parts leads to a big clamping load loss in stiff joints. This paper discusses the relationship between connection stiffness and clamping load and presents a method that improves clamping load retention during operation by a careful design of the member contact surface shape. A single bolted joint with two clamping parts is modeled using finite element method (FEM). A method is proposed to obtain a specific stiffness by an optimized geometrical shape of the joint contact surfaces. The result shows that the contact surface shape based on a gradually varying gap can improve the retention of the initial clamping load. Furthermore, a formula of the connection stiffness based on the curve fitting technique is proposed to predict residual clamping load under different external load and loosening.

scholarly journals Stability Tests of Agricultural and Operating Machines by Means of an Installation Composed by a Rotating Platform (the “Turntable”) with Four Weighting Quadrants

2020 ◽  
Vol 10 (11) ◽  
pp. 3786
Author(s):  
Marco Bietresato ◽  
Fabrizio Mazzetto
Keyword(s):  
Degrees Of Freedom ◽  
Structural Integrity ◽  
Support Surface ◽  
Rotating Platform ◽  
Technical Standards ◽  
Stability Tests ◽  
Support Plane ◽  
Stability Performance ◽  
Inclination Angles ◽  
The Stability

The stability of agricultural machines, earth-moving machines, snow-compaction machines and, in general, of all vehicles that may operate on sloping terrains is a very important technical feature and should not be underestimated. In fact, it is correlated, above all, to the safety of the operators, but also to the preservation of the structural integrity of these vehicles, to the prosecution of the activities and to the preservation of the economic investment. Although these facts are well-known, the international legislation and technical standards do not yet have a sufficient level of detail to give an all-inclusive quantification of the stability of the vehicle under examination in all its working conditions, e.g., at different inclination angles of the support surface, at different climbing angles of the vehicle on the slope, with different tires and inflating pressures, and on different terrains. Actual standards limit the stability tests to the experimental measurement of the lateral rollover angle only. Furthermore, the realization of unconventional test equipment able to widen the usually-tested scenarios could not be simple, due to the necessary size that such equipment should have (to perform tests not in scale) and to the related difficulties of handling full-scale vehicles. This work illustrates the applications of a new rig for testing the stability of vehicles, able to address all the above-illustrated issues and of possible future adoption to certify the stability performance of machines and perform homologations. This installation, named “rotating platform” or “turntable”, has the peculiarity of being able to move the machine positioned on it according to two rotational degrees of freedom: (1) overall inclination of the support plane, (2) rotation of the support plane around an axis perpendicular to the plane. The same installation is also designed to record the weight supported by each wheel of the machine placed on it (by means of four sensorized quadrants), both when the platform is motionless and while the above-described movements of tilt and rotation are being carried out, thus locating precisely the spatial position of the vehicle center of gravity. The presented physical-mathematical models highlight the great potential of this facility, anticipate the outcomes of the recordings that the experimenters will have at disposal when the test rig will be effectively active, and help the future understanding of trends of data, thus maximizing the available information content.

scholarly journals Freeze-fracture analysis of the membrane lesion of human complement.

1983 ◽  
Vol 97 (3) ◽  
pp. 618-626 ◽  
Author(s):  
J Tranum-Jensen ◽  
S Bhakdi
Keyword(s):  
Transmembrane Protein ◽  
Freeze Fracture ◽  
Fracture Analysis ◽  
Membrane Insertion ◽  
Membrane Bilayer ◽  
Face Ring ◽  
Circular Structure ◽  
Protein Channel ◽  
Classical Ring ◽  
Membrane Lesion

The structure and membrane insertion of the human C5b-9(m) complex, generated by lysis of antibody-coated sheep erythrocytes with whole human serum under conditions where high numbers of classical ring-shaped lesions form, were studied in single and complementary freeze-fracture replicas prepared by unidirectional and rotary shadowing. The intramembrane portion of the C5b-9(m) cylinder was seen on EF-faces as an elevated, circular structure. In nonetched fractures it appeared as a solid stub; in etched fractures a central pit confirmed the existence of a central, water-filled pore in the molecule. Complementary replicas showed that each EF-face ring corresponded to a hole in the lipid plateau of the PF-face. Etched fractures of proteolytically stripped membranes revealed the extramembrane annulus of the C5b-9(m) cylinder on ES-faces and putative internal openings on PS-faces. Allowing for the measured thickness of deposited Pt/C, the dimensions of EF-face rings and ES-face annuli conformed to anticipations derived from negatively stained preparations. Our results support the concept that the hollow cylindrical C5b-9(m) complex penetrates into the inner leaflet of the target erythrocyte membrane bilayer, forming a stable transmembrane protein channel.

The stability of acid-soluble chromosomal proteins from avian erythrocytes

1968 ◽  
Vol 46 (8) ◽  
pp. 781-788 ◽  
Author(s):  
G. Vidali ◽  
J. M. Neelin
Keyword(s):  
Acetic Acid ◽  
Room Temperature ◽  
Starch Gel Electrophoresis ◽  
Guanidinium Chloride ◽  
Chromosomal Proteins ◽  
Avian Erythrocytes ◽  
Starch Gel ◽  
Avian Erythrocyte ◽  
The Stability ◽  
And Storage

The stability of avian erythrocyte histones was examined under the conditions of extraction, chromatography, electrophoresis, and storage, in order to avoid degradation during these operations. Since turbidity in trichloroacetic acid (TCA) was used as a measure of histone integrity, optimal conditions for quantitative assay were established as follows. One volume of histone sample was mixed with five volumes of 1.1 M TCA at room temperature, and the optical density at 400 mμ was measured after 25 min. The relation between turbidity and protein concentration was linear from 0.03 to at least 0.3 mg histone per milliliter and was not related to the kind of histone, except for the lysine-rich fraction which showed slightly less specific turbidity. Under these conditions turbidity was not sensitive to concomitant solutes such as guanidinium chloride, acetic acid, and dilute buffers and acids.With turbidity as the criterion of protein integrity, it was confirmed that brief manipulation in the cold is desirable in most media, including the dilute acids used for extraction. Nevertheless, chromatography at room temperature in concentrated solutions of guanidinium chloride or acetic acid appears to be tolerably safe. The effect of these conditions of manipulation and storage on histone fractions was substantiated by chromatography and starch-gel electrophoresis. Prolonged extraction of avian erythrocyte nuclei at acid pH released additional non-histone basic protein without alteration of authentic histone fractions.

AE Damage Assessment in the Bell Tower of the Turin Cathedral

2019 ◽  
Vol 817 ◽  
pp. 579-585
Author(s):  
Amedeo Manuello ◽  
Davide Masera ◽  
Alberto Carpinteri
Keyword(s):  
Damage Assessment ◽  
Structural Integrity ◽  
Cumulative Number ◽  
Height Ratio ◽  
Value Analysis ◽  
Integrity Assessment ◽  
Bell Tower ◽  
The Stability ◽  
Good Agreement

Historical churches, masonry towers and bell towers are structures subjected to high risk, due to their age, elevation and low base area on height ratio. In this work, an innovative monitoring technique for structural integrity assessment of historical buildings is reported. At the same time, the emblematic case study of the Turin Cathedral Bell tower is presented. The damage evolution in the tall masonry structure is described by the evaluation of the cumulative number of AE and by different parameters able to predict the time dependence of damage. In particular, since environmental disturbances have been minimized, and instrumental noises have been filtered out. The b-value analysis shows a downward trend to values compatible with the growth of localized macro-cracks at the base of the tower. These results seem to be in good agreement with the numerical analysis. Extension to longer monitoring periods and, later, investigation of different segments are strongly recommended to assess the stability of the monument.

Gore-Tex® ePTFE in Nasal Surgery and Review of Long-Term Results

1994 ◽  
Vol 11 (3) ◽  
pp. 179-182 ◽  
Author(s):  
Mark Berman
Keyword(s):  
Silicone Rubber ◽  
Structural Integrity ◽  
Subcutaneous Tissue ◽  
Long Term Results ◽  
Vacuum Impregnation ◽  
Nasal Surgery ◽  
Implant Material ◽  
Fda Approval ◽  
Antibiotic Solution ◽  
The Stability

More than 10 years have passed since the author first used Gore-Tex® expanded polytetrafluoroethylene (ePTFE) as a facial implant material. To date, the material has been tolerated very successfully without any signs of degradation or alteration. Previous research studies have confirmed the stability of the material. It has become increasingly popular and has recently received FDA approval as Subcutaneous Tissue Augmentation Material (SAM®) for use as a soft tissue filler of the face. More importantly, this author has documented two specific areas for consideration. First, the material does not need to be used by itself as an independent implant material. It can be bonded to other materials, such as silicone rubber, and thus be used for its unique surface properties while enjoying the structural integrity of the silicone rubber. (This use has not received FDA approval.) Secondly, as an added precaution, it is wise to prepare the material before implantation by vacuum impregnation with an antibiotic solution. Before use of this type of preparation was started in June 1989, the author experienced 9 infections out of 67 facial implants with Gore-Tex (13%). Since vacuum impregnation was initiated, there has been 1 infection out of 165 implantations (0.61%). There have been no infections or extrusions with nasal surgery since antibiotic impregnation was started.

Sign in / Sign up

Export Citation Format

Share Document