Transient Pores
Mostrando 1-12 de 27 artigos, teses e dissertações.
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1. Propriedades de vesículas unilamelares gigantes / Properties of Giant Unillamelar Vesicles
The stability of giant unilamellar vesicles (GUVs) has been monitored by phase contrast and fluorescence microscopy, using sugar gradients, sodium 1,3,6,8 pirene tetrasulfonate (PTS) as fluorescent probe, 1,1-dimethyl-4,4-bipiridinium chloride (MV) as fluorescence quencher and 2-(12-(7-nitrobenz-2-oxa-1,3-diazol-4-il) amino) dodecanoyl-1-hexadecanoyl-sn-glic
Publicado em: 2006
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2. Modeling and simulation of hydrodemetallation and hydrodesulfurization processes with transient catalytic efficiency
A model is presented for the description of the concentration behavior of organometallic and sulfurated compounds in hydrodemetallation and hydrodesulfurization catalytic processes, where catalyst effectiveness decreases with time. Due to the complexity of the mixture, an approach based on pseudocomponents was adopted. The system is modeled as an isothermal
Brazilian Journal of Chemical Engineering. Publicado em: 2000-06
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3. Arginine-Rich Peptides Destabilize the Plasma Membrane, Consistent with a Pore Formation Translocation Mechanism of Cell-Penetrating Peptides
Recent molecular-dynamics simulations have suggested that the arginine-rich HIV Tat peptides translocate by destabilizing and inducing transient pores in phospholipid bilayers. In this pathway for peptide translocation, Arg residues play a fundamental role not only in the binding of the peptide to the surface of the membrane, but also in the destabilization
The Biophysical Society.
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4. Dynamics of transient pores in stretched vesicles
We image macroscopic transient pores in mechanically stretched giant vesicles. Holes open above a critical radius rc1, grow up to a radius rc2, and close. We interpret the upper limit rc2 by a relaxation of the membrane tension as the holes expand. The closing of the holes is caused by a further relaxation of the surface tension when the internal liqui
The National Academy of Sciences.
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5. Theory of electroporation of planar bilayer membranes: predictions of the aqueous area, change in capacitance, and pore-pore separation.
A large increase in the transmembrane voltage, U(t), of a fluid bilayer membrane is believed to result in the occurrence of temporary aqueous pathways ("pores") across the membrane. The number, size, and evolution dynamics of these pores are expected to be crucial to the transport of water-soluble species ranging from small ions to macromolecules such as pro
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6. High-efficiency transformation of bacterial cells by electroporation.
We have developed a method for efficiently generating transient pores in the outer membranes of Escherichia coli K-12 derivatives by using a new type of electroporation apparatus. The pores are large enough and persist long enough to facilitate the equilibration of plasmid molecules between the intracellular and extracellular spaces. The method has been used
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7. Proton transport across transient single-file water pores in a lipid membrane studied by molecular dynamics simulations.
To test the hypothesis that water pores in a lipid membrane mediate the proton transport, molecular dynamic simulations of a phospholipid membrane, in which the formation of a water pore is induced, are reported. The probability density of such a pore in the membrane was obtained from the free energy of formation of the pore, which was computed from the aver
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8. Hemolysis of human erythrocytes by transient electric field.
Exposure of human erythrocytes, under isotonic conditions, to a high voltage pulse of a few kV/cm leads to total hemolysis of the red cells. Experiments described herein demonstrate that the hemolysis is due to the effect of electric field. Neither the effect of current nor the extent of the rapid Joule-heating to the suspending medium shows a direct correla
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9. Energetic constraints on the creation of cell membrane pores by magnetic particles.
Naturally occurring and contaminant ferromagnetic and ferrimagnetic particles have been found within or near cells, and might allow pulsed magnetic fields to create transient cell membrane opening ("pores"). We show that this possibility is significantly constrained by the maximum rotational energy that can be transferred to the cell membrane. For single bio
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10. Effect of calcium ions on staphylococcal alpha-toxin-induced hemolysis of rabbit erythrocytes.
Calcium in millimolar concentrations protected rabbit erythrocytes from hemolysis caused by staphylococcal alpha-toxin. This effect was maximal at 30 mM CaCl2 and required the continued presence of calcium. The protection was not absolute and could be overcome by increased concentrations of alpha-toxin. Calcium did not block the binding of alpha-toxin to ery
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11. Rational combinatorial design of pore-forming β-sheet peptides
Exogenous polypeptides that self-assemble on biological membranes into pores are abundant and structurally diverse, functioning as transporters, toxins, ion channels, and antibiotics. A means for designing novel pore-forming sequences would unlock new opportunities for the development and engineering of protein function in membranes. Toward this goal, we des
National Academy of Sciences.
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12. Iron uptake in ferritin is blocked by binding of [Cr(TREN)(H2O)(OH)]2+, a slow dissociating model for [Fe(H2O)6]2+
Ferritin concentrates iron as a hydrous ferric oxide in a protein cavity (8 nm in diameter) by using eight pores along the threefold symmetry axes of the octahedral supramolecular structure. The role of ligand exchange in the entry of Fe(II) hexahydrate into ferritin protein has been studied with [Cr(TREN)(H2O)(OH)]2+ [TREN = N(CH2CH2NH2)3], a model for Fe(H
National Academy of Sciences.