X-ray diffraction studies of oriented lipid bilayers.

J Katsaras

doi:10.1139/o95-025

Home/Archive/PubMed

PubMed · 8829365

X-ray diffraction studies of oriented lipid bilayers.

J Katsaras

View original source ↗Export metadata ↓

Abstract

This brief review of the X-ray diffraction technique used to study oriented lipid bilayer systems is primarily intended to demonstrate to the nonspecialist in the lipid field the amount of detailed information that can be obtained simply by visually inspecting the diffraction pattern and making some measurements with a rule and protractor. The information that can be extracted from X-ray diffraction data is illustrated by selected examples of our most recent work.

Explore related subjects

Lipid Bilayers X-Ray Diffraction Journal Article Review

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

J Katsaras. X-ray diffraction studies of oriented lipid bilayers.. https://doi.org/10.1139/o95-025

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

Molecular motion at soft and hard interfaces: from phospholipid bilayers to polymers and lubricants.

Spatially resolved and time-resolved understanding of complex fluid situations compose a new frontier in physical chemistry. Here we draw attention to the significance of spatially resolving systems whose ensemble average differs fundamentally from the spatially resolved individual elements. We take examples from the field of fluid phospholipid bilayers, to which macromolecules adsorb; the field of polymer physics, when flexible chains adsorb to the solid-liquid interface; and from the field of lubrication, when two solids are squeezed close together with confined fluid retained between them.

Lipid Bilayers↗

PubMed2006

Fluorescence lifetime correlation spectroscopy combined with lifetime tuning: new perspectives in supported phospholipid bilayer research.

A new concept based on fluorescence lifetime correlation spectroscopy (FLCS) is presented allowing the simultaneous determination of diffusion coefficients of identical molecules located in different environments. The difference in fluorescence lifetimes, which is the main prerequisite for FLCS, is reached by locating one population of the dye close to a light-absorbing surface. Since such surfaces quench fluorescence, the fluorescence lifetime of chromophores located close to these surfaces can be tuned in a specific manner. This approach has been demonstrated for a BODIPY-tail-labeled lipid in supported phospholipid bilayers (SPBs) as well as in phospholipid multilayers adsorbed onto solid supports. In particular, the effect of the solid support type on the fluorescence lifetime as well as its dependence on the BODIPY-support distance has been characterized and verified by theoretical considerations based on precise determination of refractive indices of the used supports. While the fluorescence lifetime of BODIPY dye is 5.6 ns in small unilamellar vesicles (SUVs) composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dioleoyl-sn-glycero-3-[phospho-L-serine] (DOPS), the lifetime is 1.8 ns in DOPC/DOPS SPBs adsorbed onto ITO-covered glass or 3.0 ns in a DOPC/DOPS monolayer adsorbed onto seven 1,2-dipalmitoyl-sn-glycero-3-phosphate (DPPA) layers on oxidized silicon. Using these particular systems, we demonstrated that FLCS enables one to characterize simultaneously two-dimensional lipid diffusion in the planar lipid layers and three-dimensional vesicle diffusion in bulk above the lipid layers using single dye labeling. The autocorrelation functions obtained by this new approach do agree with those obtained by standard FCS on isolated SPBs or vesicles. Possible applications of this virtual two-channel measurement using single dye labeling as well as one detection channel are discussed.

Lipid Bilayers↗

PubMed2006

Sensitivity and resolution enhancement in solid-state NMR spectroscopy of bicelles.

Magnetically aligned bicelles are becoming attractive model membranes to investigate the structure, dynamics, geometry, and interaction of membrane-associated peptides and proteins using solution- and solid-state NMR experiments. Recent studies have shown that bicelles are more suitable than mechanically aligned bilayers for multidimensional solid-state NMR experiments. In this work, we describe experimental aspects of the natural abundance (13)C and (14)N NMR spectroscopy of DMPC/DHPC bicelles. In particular, approaches to enhance the sensitivity and resolution and to quantify radio-frequency heating effects are presented. Sensitivity of (13)C detection using single pulse excitation, conventional cross-polarization (CP), ramp-CP, and NOE techniques are compared. Our results suggest that the proton decoupling efficiency of the FLOPSY pulse sequence is better than that of continuous wave decoupling, TPPM, SPINAL, and WALTZ sequences. A simple method of monitoring the water proton chemical shift is demonstrated for the measurement of sample temperature and calibration of the radio-frequency-induced heating in the sample. The possibility of using (14)N experiments on bicelles is also discussed.

Lipid Bilayers↗