Search results for " Fluidity"

Self-Assembling of Peptide/Membrane Complexes by Atomistic Molecular Dynamics Simulations

2007

Abstract Model biological membranes consisting of peptide/lipid-bilayer complexes can nowadays be studied by classical molecular dynamics (MD) simulations at atomic detail. In most cases, the simulation starts with an assumed state of a peptide in a preformed bilayer, from which equilibrium configurations are difficult to obtain due to a relatively slow molecular diffusion. As an alternative, we propose an extension of reported work on the self-organization of unordered lipids into bilayers, consisting of including a peptide molecule in the initial random configuration to obtain a membrane-bound peptide simultaneous to the formation of the lipid bilayer. This strategy takes advantage of the…

Incorporation of Membrane Proteins in Solid-Supported Lipid Layers

1995

Distinct amino acids of  the Oenococcus oeni small heat shock protein Lo18 are essential for damaged protein protection and membrane stabilization

2010

The small heat shock protein (smHsp) Lo18 from lactic acid bacteria Oenococcus oeni reduces in vitro thermal aggregation of proteins and modulates the membrane fluidity of native liposomes. An absence of information relating to the way in which the smHsp demonstrates a stabilizing effect for both proteins and membranes prompted this study. We expressed three Lo18 proteins with amino acid substitutions in Escherichia coli to investigate their ability to prevent E. coli protein aggregation and their capacity to stabilize E. coli whole-cell membranes. Our results showed that the alanine 123 to serine substitution induces a decrease in chaperone activity in denaturated proteins, and that the ty…

Solid State NMR Structure Analysis of the Antimicrobial Peptide Gramicidin S in Lipid Membranes: Concentration-Dependent Re-alignment and Self-Assemb…

2008

Antimicrobial peptides can kill bacteria by permeabilizing their cell membrane, as these amphiphilicmolecules interact favourably with lipid bilayers. This mechanism of action is attributed eitherto the formation of a peptide “carpet” on the membrane surface, or to a transmembranepore. However, the structure of such a pore has not yet been resolved under relevant conditions.Gramicidin S is a symmetrical cyclic β-sheet decapeptide, which has been previouslyshown by solid state NMR to lie flat on the membrane surface at low peptide:lipid ratios (≤ 1:80).Using highly sensitive 19F-NMR, supported by 15N-labelling,we found that gramicidin S can flip into an upright transmembrane alignment at hig…

Erythrocyte rheology in diabetes mellitus and hypertension

2009

Nitrated Fatty Acids Modulate the Physical Properties of Model Membranes and the Structure of Transmembrane Proteins

2017

Nitrated fatty acids (NO2 -FAs) act as anti-inflammatory signal mediators, albeit the molecular mechanisms behind NO2 -FAs' influence on diverse metabolic and signaling pathways in inflamed tissues are essentially elusive. Here, we combine fluorescence measurements with surface-specific sum frequency generation vibrational spectroscopy and coarse-grained computer simulations to demonstrate that NO2 -FAs alter lipid organization by accumulation at the membrane-water interface. As the function of membrane proteins strongly depends on both, protein structure as well as membrane properties, we consecutively follow the structural dynamics of an integral membrane protein in presence of NO2 -FAs. …

Type II diabetics with macrovascular complications: polymorphonuclear leukocyte (PMN) filtration, PMN membrane fluidity and cytosolic Ca2+ content af…

1998

We evaluated polymorphonuclear (PMN) filtration parameters, membrane fluidity and cytosolic Ca2+ content in 21 normal subjects and in 18 type II diabetics with macrovascular complications (MVC). Evaluations were carried out at baseline and after in vitro activation prolonged for 5 and 15 min. PMA (4-phorbol 12-myristate 13-acetate) and fMLP (N-formyl-methionyl-leucyl-phenylalanine) were used as stimulating agents. TMA-DPH (1-[4-(trimethylamino)phenyl]-6-phenyl-1,3,5-hexatriene) was used as fluorescent probe for the membrane fluidity tests and Fura 2-AM for the cytosolic Ca2+ content. A significant variation was evident in PMN filtration parameters at 5 and 15 min. No variation was present i…

Rheological and metabolic leucocyte determinants in diabetes mellitus

1995

In diabetics of type I and 2 we examined, in resting white blood cells (WBC), the filtration parameters (Initial Relative Flow Rate - lRFR, Clogging Rate - CR) employing the St. George Filtrometer, the polymorphonuclear cells (PMN) membrane fluidity, the PMN cytosolic Ca2+ content and the PMN membrane cholesterol/phospholipid ratio (C/PL). From the obtained data, it is evident that, while the lRFR of unfractionated WBC distinguishes normals from diabetics of type 1 and 2, the fIltration parameters of the PMN and mononuclear cells (MN) do not show any significant difference. PMN membrane fluidity, PMN cytosolic Ca2+ content and PMN C/PL do not discriminate normals from diabetics of type 1 an…

Platelet membrane fluidity and platelet membrane lipid pattern in several clinical conditions

1996

Platelet membrane fluidity, platelet membrane lipid pattern and platelet cytosolic Ca2+ content in subjects with vascular atherosclerotic disease

1994

In a group of subjects with vascular atherosclerotic disease (V AD) we examined the platelet membrane fluidity (obtained marking intact resting platelets with TMA-DPH), the platelet membrane cholesteroVphospholipid ratio (CIPL using column chromatography), the platelet membrane individual phospholipids (employing the thin layer chromatography) and the platelet cytosolic Ca2+ content (evaluated marking intact resting platelets with Fura 2-AM). From the obtained data, it is evident that platelet membrane fluidity differentiates normals from V AD subjects. Platelet membrane lipid pattern (CIPL and individual phospholipids) and cytosolic Ca2+ content do not discriminate normals from V AD subjec…