We discuss the difference between osmotic permeability pf and diffusion permeability pd of single-file water channels and demonstrate that the pf/pd ratio corresponds to the number of effective steps a water molecule needs to take to permeate a channel. While pd can be directly obtained from equilibrium molecular dynamics simulations, pf can be best determined from simulations in which a chemic...

The surface forces apparatus and atomic force microscope were used to study the effects of lipid composition and concentrations of myelin basic protein (MBP) on the structure of model lipid bilayers, as well as the interaction forces and adhesion between them. The lipid bilayers had a lipid composition characteristic of the cytoplasmic leaflets of myelin from "normal" (healthy) and "disease-lik...

Structures of the prokaryotic homologue of rhomboid proteases reveal a core of six transmembrane helices, with the active-site residues residing in a hydrophilic cavity. The native environment of rhomboid protease is a lipid bilayer, yet all the structures determined thus far are in a nonnative detergent environment. There remains a possibility of structural artefacts arising from the use of de...

Alamethicin is an amphipathic alpha-helical peptide that forms ion channels. An early event in channel formation is believed to be the binding of alamethicin to the surface of a lipid bilayer. Molecular dynamics simulations are used to compare the structural and dynamic properties of alamethicin in water and alamethicin bound to the surface of a phosphatidylcholine bilayer. The bilayer surface ...

In molecular structure, both UQs and MKs consist of a polar head group and a hydrophobic side chain. The latter part provides the molecules with a lipid-soluble character to allow them to perform vital functions in membrane lipid bilayers, whereas the former group enables interaction with membrane proteins. The quinone ring of the head group has a crucial activity by a two-step reversible reduc...

The architecture of cells, with various membrane-bound compartments and with the protein synthesizing machinery confined to one location, dictates that many proteins have to be transported through one or more membranes during their biogenesis. A lot of progress has been made on the identification of protein translocation machineries and their sorting signals in various organelles and organisms....

The membrane-binding properties and pore-forming potential of the tumor-lysing and antibacterial polypeptide NK-lysin were investigated. Fluorescence quenching experiments show a drastic change of accessibility to Trp58 in solution and in association with a lipid membrane. Calcein release from large unilamellar vesicles and fluctuating conductivity observed across a planar lipid bilayer of asol...

Prostasomes are found in high concentrations in seminal plasma. Under electron microscopy there appear to be two distinct morphological types: smaller, ‘dark’ prostasomes with tightly packed electron-dense contents, and larger ‘light’ less dense structures (Fig. 1). Their diameter is 40–500 nm [1]. They have a lipid bilayer membrane which may be arranged in a multilamellar fashion, and has a ch...

Obtaining an understanding, at the atomic level, of the interaction of nanomaterials with biological systems has recently become an issue of great research interest. Here we report on the molecular dynamics study of the translocation of fullerene C60 and its derivative C60(OH)20 across a model cell membrane (dipalmitoylphosphatidylcholine or DPPC bilayer). The simulation results indicate that, ...

Lipid bilayer membranes are important as fundamental structures in biology and possess characteristic water-permeability, stability, and mechanical properties. Water permeation through a lipid bilayer membrane occurs readily, and more readily at higher temperature, which is largely due to an enthalpy cost of the liquid-to-gas phase transition of water. A fullerene bilayer membrane formed by dis...