21 research outputs found
Reorganization of Ternary Lipid Mixtures of Non-Phosphorylated Phosphatidylinositol Interacting with Angiomotin
Phosphatidylinositol (PI) lipids are necessary for many cellular signaling pathways of membrane associated proteins, such as Angiomotin (Amot). The Amot family regulates cellular polarity, growth, and migration. Given the low concentration of PI lipids in these membranes, it is likely that such protein-membrane interactions are stabilized by lipid domains or small lipid clusters. By small-angle x-ray scattering, we show that non-phosphorylated PI lipids induce lipid de-mixing in ternary mixtures of phosphatidylcholine (PC) and phosphatidylethanolamine (PE), likely due to preferential interactions between the head groups of PE and PI. These results were obtained in the presence of buffer containing concentrations of Tris, HEPES, NaCl, EDTA, DTT, and Benzamidine at pH 8.0 that in previous work showed an ability to cause PC to phase separate but are necessary to stabilize Amot for in vitro experimentation. Collectively, this provided a framework for determining the effect of Amot on lipid organization. Using fluorescence spectroscopy, we were able to show that the association of Amot with this lipid platform causes significant reorganization of the lipid into a more homogenous organization. This reorganization mechanism could be the basis for Amot membrane association and fusigenic activity previously described in the literature and should be taken into consideration in future protein-membrane interaction studies
Bio-Lithography: A Novel Process for Modification and Patterning of Supported Lipid Bilayers using Lipopolysaccharide, a Biological Amphiphile
Electron Density Mapping of Triblock Copolymers Associated with Model Biomembranes: Insights into Conformational States and Effect on Bilayer Structure
Structure and Optical Properties of a Thermoresponsive Polymer-Grafted, Lipid-Based Complex Fluid
Film Architecture in Biomolecular Assemblies. Effect of Linker on the Orientation of Genetically Engineered Surface-Bound Proteins
Electrochemical Activity of Glucose Oxidase on a Poly(ionic liquid)–Au Nanoparticle Composite
Glucose oxidase (GOx) adsorbed on an ionic liquid-derived
polymer
containing internally organized columns of Au nanoparticles exhibits
direct electron transfer and bioelectrocatalytic properties towards
the oxidation of glucose. The cationic polyÂ(ionic liquid) provides
an ideal substrate for the electrostatic immobilization of GOx. The
encapsulated Au nanoparticles serve to both promote the direct electron
transfer with the recessed enzyme redox centers and impart electronic
conduction to the composite, allowing it to function as an electrode
for electrochemical detection
Reversible Lifting of Surface Supported Lipid Bilayers with a Membrane-Spanning Nonionic Triblock Copolymer
Neutron reflectometry was used to
monitor structural variations
in surface-supported dimyristoylphosphatidycholine (DMPC) bilayers
induced by the addition of Triton X-100, a surfactant commonly used
to aid solubilization of membrane proteins, and the coaddition of
a membrane spanning nonionic amphiphilic triblock copolymer, (PEO<sub>117</sub>–PPO<sub>47</sub>–PEO<sub>117</sub>, Pluronic
F98). Surfactant addition causes slight compression of the bilayer
thickness and the creation of a distinct EO layer that increases the
hydrophilic layer proximal to the supporting substrate (i.e., a water
and EO gap between the lipid bilayer and quartz) to 6.8 ± 0.4
Ã…. Addition of the triblock copolymer into the DMPC:Triton X-100
bilayer increases the complexity of (broadens) the lipid phase transition,
further compresses the bilayer, and continues to expand the proximal
hydrophilic layer thickness. The observed structural changes are temperature
dependent with transmembrane polymer insertion achieved at 37 °C,
leading to a compressed membrane thickness of 39.2 ± 0.2 Å
and proximal gap of 45.0 ± 0.2 Å. Temperature-driven exclusion
of the polymer at 15 °C causes partitioning of the polymer into
the proximal space generating a large hydrogel cushion 162 ±
16 Å thick. An intermediate gap width (10–27 Å) is
achieved at room temperature (22–25 °C). The temperature-driven
changes in the proximal hydrophilic gap dimensions are shown to be
reversible, but thermal history causes variation in magnitude. Temperature-driven
changes in polymer association with a supported lipid bilayer offer
a facile means to reversibly control both the membrane characteristics
as well as the separation between membrane and solid substrate