scholarly journals Molecular Simulation of Nonfacilitated Membrane Permeation

2015 ◽  
Author(s):  
Ernest Awoonor-Williams ◽  
Christopher Rowley
Keyword(s):  
Molecular Simulation ◽  
Lipid Bilayer ◽  
Permeability Coefficient ◽  
Chemical Properties ◽  
Bilayer Membrane ◽  
Pharmaceutical Chemistry ◽  
Coarse Grain ◽  
Membrane Permeation ◽  
Membrane Composition ◽  
Quantitative Calculation

This is a review. Non-electrolytic compounds typically cross cell membranes by passive diffusion. The rate of permeation is dependent on the chemical properties of the solute and the composition of the lipid bilayer membrane. Predicting the permeability coefficient of a solute is important in pharmaceutical chemistry and toxicology. Molecular simulation has proven to be a valuable tool for modeling permeation of solutes through a lipid bilayer. In particular, the solubility-diffusion model has allowed for the quantitative calculation of permeability coefficients. The underlying theory and computational methods used to calculate membrane permeability are reviewed. We also discuss applications of these methods to examine the permeability of solutes and the effect of membrane composition on permeability. The application of coarse grain and polarizable models is discussed.

scholarly journals Transmembrane signal transduction by cofactor transport

2021 ◽  
Author(s):  
Istvan Kocsis ◽  
Yudi Ding ◽  
Nicholas H. Williams ◽  
Christopher A. Hunter
Keyword(s):  
Signal Transduction ◽  
Lipid Bilayer ◽  
Metal Ion ◽  
Bilayer Membrane ◽  
Ester Hydrolysis ◽  
Lipid Bilayer Membrane ◽  
Metal Ion Cofactors

Synthetic transducers transport externally added metal ion cofactors across the lipid bilayer membrane of vesicles to trigger catalysis of ester hydrolysis in the inner compartment. Signal transduction activity is modulated by hydrazone formation.

scholarly journals Evaluation of the correlation between porphyrin accumulation in cancer cells and functional positions for application as a drug carrier

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Koshi Nishida ◽  
Toshifumi Tojo ◽  
Takeshi Kondo ◽  
Makoto Yuasa
Keyword(s):  
Cancer Cells ◽  
Drug Carrier ◽  
Bilayer Membrane ◽  
Phospholipid Bilayer ◽  
Membrane Permeation ◽  
Porphyrin Derivatives ◽  
Phospholipid Bilayer Membrane ◽  
Meso Position ◽  
Tumor Accumulation ◽  
Binding Position

AbstractPorphyrin derivatives accumulate selectively in cancer cells and are can be used as carriers of drugs. Until now, the substituents that bind to porphyrins (mainly at the meso-position) have been actively investigated, but the effect of the functional porphyrin positions (β-, meso-position) on tumor accumulation has not been investigated. Therefore, we investigated the correlation between the functional position of substituents and the accumulation of porphyrins in cancer cells using cancer cells. We found that the meso-derivative showed higher accumulation in cancer cells than the β-derivative, and porphyrins with less bulky substituent actively accumulate in cancer cells. When evaluating the intracellular distribution of porphyrin, we found that porphyrin was internalized by endocytosis and direct membrane permeation. As factors involved in these two permeation mechanisms, we evaluated the affinity between porphyrin-protein (endocytosis) and the permeability to the phospholipid bilayer membrane (direct membrane permeation). We found that the binding position of porphyrin affects the factors involved in the transmembrane permeation mechanisms and impacts the accumulation in cancer cells.

scholarly journals Protein Sensing Device with Multi-Recognition Ability Composed of Self-Organized Glycopeptide Bundle

2020 ◽  
Vol 22 (1) ◽  
pp. 366
Author(s):  
Mao Arai ◽  
Tomohiro Miura ◽  
Yuriko Ito ◽  
Takatoshi Kinoshita ◽  
Masahiro Higuchi
Keyword(s):  
Binding Site ◽  
Lipid Bilayer ◽  
Structural Changes ◽  
Bilayer Membrane ◽  
Lipid Bilayer Membrane ◽  
Target Protein ◽  
Self Organization ◽  
Specific Response ◽  
Target Proteins ◽  
Recognition Ability

We designed and synthesized amphiphilic glycopeptides with glucose or galactose at the C-terminals. We observed the protein-induced structural changes of the amphiphilic glycopeptide assembly in the lipid bilayer membrane using transmission electron microscopy (TEM) and Fourier transform infrared reflection-absorption spectra (FTIR-RAS) measurements. The glycopeptides re-arranged to form a bundle that acted as an ion channel due to the interaction among the target protein and the terminal sugar groups of the glycopeptides. The bundle in the lipid bilayer membrane was fixed on a gold-deposited quartz crystal microbalance (QCM) electrode by the membrane fusion method. The protein-induced re-arrangement of the terminal sugar groups formed a binding site that acted as a receptor, and the re-binding of the target protein to the binding site induced the closing of the channel. We monitored the detection of target proteins by the changes of the electrochemical properties of the membrane. The response current of the membrane induced by the target protein recognition was expressed by an equivalent circuit consisting of resistors and capacitors when a triangular voltage was applied. We used peanut lectin (PNA) and concanavalin A (ConA) as target proteins. The sensing membrane induced by PNA shows the specific response to PNA, and the ConA-induced membrane responded selectively to ConA. Furthermore, PNA-induced sensing membranes showed relatively low recognition ability for lectin from Ricinus Agglutinin (RCA120) and mushroom lectin (ABA), which have galactose binding sites. The protein-induced self-organization formed the spatial arrangement of the sugar chains specific to the binding site of the target protein. These findings demonstrate the possibility of fabricating a sensing device with multi-recognition ability that can recognize proteins even if the structure is unknown, by the protein-induced self-organization process.

Voltage-induced gating of the mechanosensitive MscL ion channel reconstituted in a tethered lipid bilayer membrane

2008 ◽  
Vol 23 (6) ◽  
pp. 919-923 ◽  
Author(s):  
Martin Andersson ◽  
George Okeyo ◽  
Danyell Wilson ◽  
Henk Keizer ◽  
Paul Moe ◽  
...  
Keyword(s):  
Ion Channel ◽  
Lipid Bilayer ◽  
Bilayer Membrane ◽  
Lipid Bilayer Membrane

Nano-Process of SiC Ceramics by Molecular Simulation

2011 ◽  
Vol 189-193 ◽  
pp. 3097-3102 ◽  
Author(s):  
Guo Zhi Liu ◽  
Ke Zhang ◽  
Yu Lan Tang ◽  
Hong Sun ◽  
Hai Yan Gao
Keyword(s):  
Kinetic Energy ◽  
Molecular Simulation ◽  
Molecular Model ◽  
Cutting Speed ◽  
Chemical Properties ◽  
Cutting Depth ◽  
Sic Ceramics ◽  
Ultra Precision ◽  
Physical And Chemical ◽  
And Chemical Properties

SiC ceramics have been widely used in a variety of areas due to the excellent physical and chemical properties. However, the process of SiC ceramics is difficult and high-cost, molecular simulation is an effective and feasible method to study the nano-process of SiC ceramics. In this paper, a molecular model is presented to simulate the stress and energy in the nano-cutting of SiC ceramics. The influences of the cutting depth and cutting speed on the kinetic energy and potential are analyzed. The results show that potential energy increases with the decrease of the cutting depth. Kinetic energy increases with the increase of the cutting speed. The results are very helpful for improvement the level of ultra-precision processing and nano-processing of brittle ceramics.

scholarly journals Fatty Acid Fueled Transmembrane Chloride Transport

2019 ◽  
Author(s):  
Ethan N.W. Howe ◽  
Philip Gale
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Lipid Bilayer ◽  
Chloride Transport ◽  
Bilayer Membrane ◽  
Lipid Bilayer Membrane ◽  
Ph Gradient ◽  
Pumping System ◽  
Membrane Addition

We report an example of the use of fatty acids to drive chloride transport by creating a pH gradient across a vesicular lipid bilayer membrane. Addition of an unselective squaramide-based chloride transporter (which transports both H<sup>+</sup>and Cl<sup>-</sup>) facilitates the transport of HCl from the vesicle (driven by the pH gradient) so creating a chloride gradient. Addition of further aliquots of fatty acid ‘fuel’ can initiate further transport of chloride out of the vesicle by re-establishing the pH gradient. This is an example of a prototypical chloride pumping system.

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