The research of the nanoparticle (NP) delivery systems and the use of NPs both for diagnostic and therapeutic purposes have created a need for understanding the complex interactions of NPs with cells. Membrane-NP interactions are of crucial importance both for the cell uptake and toxicological investigations. For that reason, lipids that are the cell membrane building blocks, have been used as ...

Quantification of membrane partition potential of drug compounds is of great pharmaceutical interest. Here, a novel approach combining liquid-state NMR diffusion measurements and fast-tumbling lipid/detergent bicelles is used to measure accurately the partition coefficient K(p) of amantadine in phospholipid bilayers. Amantadine is found to have a strong membrane partition potential, with K(p) o...

The interaction of the fusogenic polypeptide segment "B18" from the fertilization protein binding with lipid membranes was investigated by solid state 2H and 31P NMR, and by differential scanning calorimetry. B18 is known to adopt different conformations depending on peptide concentration, ionic conditions, pH and lipid environment. Here, the peptide was studied in its beta-stranded amyloid con...

We have studied the lipid binding of apoC-III with two types of mixed vesicles of DMPC (dimyristoyl phosphatidylcholine) and DPPC (dipalmitoyl phosphatidyl-choline). DMPC vesicles mixed with those of DPPC produce a macroscopic mixture in which the DMPC and DPPC vesicles remain intact. The circular dichroism and fluorescence spectra of apoC-III in the presence of this macroscopic mixture exhibit...

Gramicidin A was incorporated at a peptide/lipid ratio of 1:10 mol/mol in aligned bilayers of dimyristoyl phosphatidylcholine (DMPC), phosphatidylserine (DMPS), phosphatidylglycerol (DMPG), and phosphatidylethanolamine (DMPE), from trifluoroethanol. Orientations of the peptide and lipid chains were determined by polarized attenuated total reflection infrared spectroscopy. Lipid-peptide interact...

Eukaryotic cells depend on external surface markers, such as gangliosides, to recognize and bind various other molecules as part of normal growth and maturation. The localization of gangliosides in the outer leaflet of the plasma membrane, also make them targets for pathogens trying to invade the host cells. Since ganglioside-mediated interactions are critical to both beneficial and pathologica...

Hydrophobic mismatch, which is the difference between the hydrophobic length of trans-membrane segments of a protein and the hydrophobic width of the surrounding lipid bilayer, is known to play a role in membrane protein function. We have performed molecular dynamics simulations of trans-membrane KALP peptides (sequence: GKK(LA)nLKKA) in phospholipid bilayers to investigate hydrophobic mismatch...

The membrane-bound conformation of a cell-penetrating peptide, penetratin, is investigated using solid-state NMR spectroscopy. The (13)C chemical shifts of (13)C, (15)N-labeled residues in the peptide indicate a reversible conformational change from beta-sheet at low temperature to coil-like at high temperature. This conformational change occurs for all residues examined between positions 3 and...

We present the performance of nanometer-range pulse electron paramagnetic resonance distance measurements (pulsed electron-electron double resonance/double electron-electron resonance, PELDOR/DEER) on a transmembrane WALP24 peptide labeled with the semirigid unnatural amino acid 4-(3,3,5,5-tetra-methyl-2,6-dioxo-4-oxylpiperazin-1-yl)-l-phenylglycine (TOPP). Distances reported by the TOPP label ...

The Hofmeister series illustrates how salts produce a wide range of effects in biological systems, which are not exclusively explained by ion charge. In lipid membranes, charged ions have been shown to bind to lipids and either hydrate or dehydrate lipid head groups, and also to swell the water layer in multi-lamellar systems. Typically, Hofmeister phenomena are explained by the interaction of ...