Search results for "Phosphatidylglycerol"
showing 6 items of 16 documents
Pulmonary surfactant protein C containing lipid films at the air-water interface as a model for the surface of lung alveoli.
1995
The pulmonary surfactant lines as a complex monolayer of lipids and proteins the alveolar epithelial surface. The monolayer dynamically adapts the surface tension of this interface to the varying surface areas during inhalation and exhalation. Its presence in the alveoli is thus a prerequisite for a proper lung function. The lipid moiety represents about 90% of the surfactant and contains mainly dipalmitoylphosphatidylcholine (DPPC) and phosphatidylglycerol (PG). The surfactant proteins involved in the surface tension adaption are called SP-A, SP-B and SP-C. The aim of the present investigation is to analyse the properties of monolayer films made from pure SP-C and from mixtures of DPPC, DP…
Interaction of Quinine with Model Lipid Membranes of Different Compositions
2002
The binding of a drug such as Quinine with neutral and negatively charged small unilamellar lipid vesicles at pH 7 and 37 degrees C was investigated. Changes in the fluorescence properties of the drug after association with the liposomes were used to obtain binding isotherms over a range of phospholipid compositions at different ionic strengths. Under such conditions, the association was strongly enhanced by the negative net charge of the bilayer but diminished by the increasing presence of electrolytes in the aqueous media. Binding data were analyzed in terms of a surface partition equilibrium without and after correcting for electrostatic effects by means of the Gouy-Chapman theory. The i…
Plasmonic Nanosensors for the Label-Free Imaging of Dynamic Protein Patterns.
2020
We introduce a new approach to monitor the dynamics and spatial patterns of biological molecular assemblies. Our molecular imaging method relies on plasmonic gold nanoparticles as point-like detectors and requires no labeling of the molecules. We show spatial resolution of up to 5 μm and 30 ms temporal resolution, which is comparable to wide-field fluorescence microscopy, while requiring only readily available gold nanoparticles and a dark-field optical microscope. We demonstrate the method on MinDE proteins attaching to and detaching from lipid membranes of different composition for 24 h. We foresee our new imaging method as an indispensable tool in advanced molecular biology and biophysic…
The Escherichia coli Envelope Stress Sensor CpxA Responds to Changes in Lipid Bilayer Properties
2015
The Cpx stress response system is induced by various environmental and cellular stimuli. It is also activated in Escherichia coli strains lacking the major phospholipid, phosphatidylethanolamine (PE). However, it is not known whether CpxA directly senses changes in the lipid bilayer or the presence of misfolded proteins due to the lack of PE in their membranes. To address this question, we used an in vitro reconstitution system and vesicles with different lipid compositions to track modulations in the activity of CpxA in different lipid bilayers. Moreover, the Cpx response was validated in vivo by monitoring expression of a PcpxP-gfp reporter in lipid-engineered strains of E. coli. Our comb…
Binding of water-soluble, globular proteins to anionic model membranes
2009
Abstract The role of electrostatics is studied in the adsorption of proteins to negatively charged (phosphatidylcholine/phosphatidylglycerol, PC/PG) and neutral (PC) small unilamellar vesicles (SUVs). For model proteins the interaction is monitored vs . pH at low ionic strength. The adsorption behaviour of lysozyme, myoglobin and albumin (isoelectronic point, p I 5–11) is investigated in SUVs, along with changes of the fluorescence emission spectra of the charged proteins, via their adsorption on SUVs. Significant adsorption of the proteins to negatively charged SUVs is found only at pH values, where the number of positive charge moieties exceeds the number of negative charge moieties on th…
Ligand requirement for LHC I reconstitution
1998
Knowledge of the structure of photosynthetic light harvesting complexes is essential for understanding their function. Reconstitution of light harvesting complexes proved to be a very powerful tool for such structure analyses. In this way evidence was obtained for the central role of lutein and chlorophylls for LHCII structure (1) which was later confirmed by electron crystallographic analyses (2). Employing mutated, bacterial overexpressed LHCII apoproteins, amino acids could be identified which are involved in trimerization of LHCII and probably in binding of phosphatidylglycerol (3).