• Bulletin of the Korean Chemical Society
• /
• v.35 no.3
• /
• pp.783-792
• /
• 2014

The binding interaction between a hemolytic peptide ${\delta}$-lysin and a zwitterionic lipid bilayer POPC was investigated through a series of molecular dynamics (MD) simulations. ${\delta}$-Lysin is a 26-residue, amphipathic, ${\alpha}$-helical peptide toxin secreted by Staphylococcus aureus. Unlike typical antimicrobial peptides, ${\delta}$-lysin has no net charge and it is often found in aggregated forms in solution even at low concentration. Our study showed that only the monomer, not dimer, inserts into the bilayer interior. The monomer is preferentially attracted toward the membrane with its hydrophilic side facing the bilayer surface. However, peptide insertion requires the opposite orientation where the hydrophobic side of peptide points toward the membrane interior. Such orientation allows the charged residues, Lys and Asp, to have stable salt bridges with the lipid head-group while the hydrophobic residues are buried deeper in the hydrophobic lipid interior. Our simulations suggest that breaking these salt bridges is the key step for the monomer to be fully inserted into the center of lipid bilayer and, possibly, to translocate across the membrane.

• Archives of Pharmacal Research
• /
• v.16 no.2
• /
• pp.147-151
• /
• 1993

In diabetes, the abnormal increase of the membrane cholesterol/phospholipid ratio (C/PL) is consdered to be the main reason for the decreased membrane fluidity, which then results in impaired erythrocyte deformability and subsequent microcirculatory disturbances. In this study, we examined the effects of brazilin on lipid and phosphatidyl fatty acid composition of erythrocyte membranes in streptozotocin induced diabetic rats. Treatment of brazilin (10mg/kg or 100 mg/kg for 2 weeks, i.p) altered and cholesterol contents in diabetic erythrocyte membranes. The C/PL ratio of brazilin treated groups decreased compared with that of diabetic control group while no change was observed in normal erythrocytes. In streptozotocin induced diabetic rats, alterations in phosphatidyl fatty acid compositioin of erythrocyte membranes were observed and brazilin could reverse these alterations. Arachidonic acid level reumed to a normal level while linoleic acid level remained unchanged by the treatment of brazilin. The results suggest that brazilin might increase erythrocyte membrane fluidity which plays a key role inregulating erythrocyte deformability, thereby it could exert positive effects on microdiculatory disturbances.

• Korean Journal of Environmental Agriculture
• /
• v.11 no.3
• /
• pp.261-268
• /
• 1992

The membranes of mitochondria and chloroplasts contain a number of pigments that can act as endogenous sensitizers to produce activated oxygen species, most efficiently in blue light, which, in turn, attack functional targets in membranes. Therefore, intense blue light from the sun can exert various adverse effects on the functional and structural integrity of the membranes: one of the biochemical events of these negative effects could be the oxidative degradation of the unsaturated fatty acid constituents of membrane polar lipid. It may be assumed that as a strategy to avoid the light induced fatty acid degradation in membranes plant cells, responding to high intensity blue light, change the fatty acid compositions of membrane lipid in such that more-unsaturated fatty acid constituents are replaced by lessunsaturated fatty acid constituents. The results obtained in the present study, most importantly the measurements of double bond index of membrane polar lipid in concert with other measurements such as light quaility-dependent membrane peroxidation and the activities of membrane-bound proteins, seem to support this assumption.

• Archives of Pharmacal Research
• /
• v.27 no.6
• /
• pp.653-661
• /
• 2004

Fluorescence probes located in different membrane regions were used to evaluate the effect of dopamine$.$HCI on the structural parameters (transbilayer lateral mobility, annular lipid fluidity, protein distribution, and thickness of the lipid bilayer) of synaptosomal plasma membrane vesicles (SPMV), which were obtained from the bovine cerebral cortex. An experimental procedure was used based on selective quenching of 1,3-di(1-pyrenyl)propane (Py-3-Py) by trinitrophenyl groups, and radiationless energy transfer from the tryptophan of membrane pro-teins to Py-3-Py and energy transfer from Py-3-Py monomers to 1-anilinonaphthalene-8-sulfonic acid (ANS) was also utilized. Dopamine$.$HCI increased both the bulk lateral mobility and annular lipid fluidity, and it had a greater fluidizing effect on the inner monolayer than on the outer monolayer. Furthermore, the drug had a clustering effect on membrane proteins.

• Coupled systems mechanics
• /
• v.6 no.2
• /
• pp.141-155
• /
• 2017

We present relatively simple derivations of the Helfrich energy potential that has been widely adopted in the analysis of lipid membranes without detailed explanations. Through the energy variation methods (within the limit of Helfrich energy potential), we obtained series of analytical solutions in the case when the lipid membranes are excited through their edges. These affordable solutions can be readily applied in the related membrane experiments. In particular, it is shown that, in case of an elliptic cross section of a rigid substrate differing slightly from a circle and subjected to the incremental deformations, exact analytical expressions describing deformed configurations of lipid membranes can be obtained without the extensive use of Mathieu's function.

• YAKHAK HOEJI
• /
• v.46 no.4
• /
• pp.242-246
• /
• 2002

The rhizoma of Polygonatum odoratum (Liliaceae) promotes the production of body fluid and relives dryness symptoms and has hypoglycemic effect. In order to evaluate the prevention of lipid peroxidative efficacy of P. odoratum, its extracts (Et$_2$O and MeOH ex.) and its fractions ($H_2O$, 20％ MeOH, 40％ MeOH, 60％ MeOH and 100％ MeOH fr.) were measured by TBARS assay on rat liver S9 and human erythrocyte ghost membrane. The order of anti-lipid peroxidative effect was as follows: Et$_2$O ex. ＞40％ MeOH fr. ＞60％ MeOH fr.＞100％ MeOH fr. Based on these results, we conclude that membrane lipid peroxidation is inhibited in vitro by addition of P. odoratum ether extract and its gradient MeOH fractions excepts $H_2O$ fr., and which have significant hepatoprotective activity in $CCl_4$-treated rats.

• Bulletin of the Korean Chemical Society
• /
• v.24 no.9
• /
• pp.1281-1283
• /
• 2003

Proteins in highly oriented lipid bilayer samples are useful to study membrane protein structure determination. Planar lipid bilayers aligned and supported on glass slide were prepared. These stack of glass slide with planar lipid bilayers are not well fit for commercial solid-state NMR probe with round coil. Therefore, homebuilt solid-state NMR probe was built and used for a stack of thin glass plates and RF coil is wrapping directly around the flat square sample. The overall filling factor of the coil is much better and the large surface area enhances the extent to orientation by providing uniform environments for the phospholipids and the high ratio of circumference to area reduces edge effects. $^1H\;and\;^{15}N$ double resonance probe for 400 MHz NMR (9.4T) with a flat coil (coil size: 11 mm ${\times}$ 20 mm ${\times}$ 4 mm) is constructed and tested.

• Electrical & Electronic Materials
• /
• v.10 no.6
• /
• pp.548-554
• /
• 1997

We fabricated the sample of ultra thin lipid membrane(L-$\alpha$-DLPC) by LB method. The $\pi$-A isotherm of the DLPC was measured at the air-water interface varying with the compressing speed and amounts of solutions for spreading. For the good property of lipid monolayer film, it was necessary to prepare at the lower speed of compressing, with an appropriate volume of solutions for spreading. Absorption, transmitance and intensity with the UV spectrophotometer were measured. The Z-type multilayers showed good characteristics better than Y-type. So we found building-up of structurally high quality LB films is essential to study properties of the films and to get reproducible data.

• Molecules and Cells
• /
• v.26 no.6
• /
• pp.517-529
• /
• 2008

Porosomes are supramolecular, lipoprotein structures at the cell plasma membrane, where membrane-bound secretory vesicles transiently dock and fuse to release inravesicular contents to the outside during cell secretion. The mouth of the porosome opening to the outside, range in size from 150 nm in diameter in acinar cells of the exocrine pancreas, to 12 nm in neurons, which dilates during cell secretion, returning to its resting size following completion of the process. In the past decade, the composition of the porosome, its structure and dynamics at nm resolution and in real time, and its functional reconstitution into artificial lipid membrane, have all been elucidated. In this mini review, the discovery of the porosome, its structure, function, isolation, chemistry, and reconstitution into lipid membrane, the molecular mechanism of secretory vesicle swelling and fusion at the base of porosomes, and how this new information provides a paradigm shift in our understanding of cell secretion, is discussed.

• Journal of Life Science
• /
• v.33 no.2
• /
• pp.191-198
• /
• 2023

As a member of the focal adhesion complex of the plasma membrane, Src is a nonreceptor tyrosine kinase that controls cell adhesion and motility. However, how Src activity is regulated in the plasma membrane microdomain in response to components of the extracellular matrix (ECM) remains unclear. This study compared and investigated the activity of Src in response to three representative ECM proteins: collagen type 1, fibronectin, and laminin. Genetically encoded FRET-based Src biosensors for plasma membrane subdomains were used. FRET-based biosensors allow the real-time analysis of protein activity in living cells based on their high spatiotemporal resolution. The results showed that Src activity was maintained at a high level under all ECM conditions of the lipid raft, and there was no significant difference between the ECM conditions. In contrast, Src activity was maintained at a low level in the non-lipid raft membrane. In addition, the Src activity of lipid rafts remained significantly higher than that of non-lipid raft regions under the same ECM conditions. In conclusion, this study demonstrates that Src activity can be controlled differently by lipid rafts and non-lipid raft microdomains.