Spectroscopic studies of lipids and biological membranes: carbon-13 and proton magic-angle sample-spinning nuclear magnetic resonance study of glycolipid-water systems

Abstract

We have obtained 1H and 13C magic-angle sample-spinning (MAS) nuclear magnetic resonance (NMR) spectra of three glycosyldiacylglycerol-water (1:1, weight ratio) mesophases, at 11.7 T, as a function of temperature, in order to probe lipid headgroup, backbone, and acyl chain dynamics by using natural-abundance NMR probes. The systems investigated were monogalactosyldiacyldiglyceride [MGDG; primarily 1,2-di[(9Z,12Z,15Z)octadec-9,12,15-trienoyl++ +]-3-beta-D-galactopyranosyl- sn-glycerol]; digalactosyldiacyldiglyceride [DGDG; primarily 1,2-di[(9Z,12Z,15Z)octadec-9,12,15-trienoyl++ +]-3- (alpha-D-galactopyranosyl-1-6-beta-D-glactopyranosyl)-sn-glycerol] ; and sulfoquinovosyldiacyldiglyceride [SQDG; primarily 1-[(9Z,12Z,15Z)octadec-9,12,15-trienoyl]-2 -hexadecanoyl-3-(6-deoxyl-6- sulfono-alpha-D-glucopyranosyl)-sn-glycerol]. At approximately 22 degrees C, all three lipid-water systems give well-resoled 13C and 1H MAS NMR spectra, characteristic of fluid, liquid-crystalline mesophases. 13C spin-lattice relaxation times of the headgroup and glycerol backbone carbons of all three materials give, within experimental error, the same NT1 values (approximately 400 ms), implying similar high-frequency motions, independent of headgroup size and charge. Upon cooling, pronounced line broadenings are observed, due to an increase in slow motional behavior. For each lipid, the onset of line broadening is seen with the glycosyl headgroup, glycerol backbone, and the first two or three carbons of the acyl chains. By approximately -20 degrees, all headgroup carbon resonances are broadened beyond detection. Both galactose moieties in DGDG "freeze out" together, implying a rigid-body motion of the disaccharide unit. Upon further cooling, the bulk polymethylene chain resonances in all three systems (in both 13C and 1H MAS) broaden greatly, followed by the olefinic and allylic carbon resonances.(ABSTRACT TRUNCATED AT 250 WORDS)

Location of Cholesterol in Model Membranes by Magic‐Angle‐Sample‐Spinning NMR

“…At the same time, X-ray crystallography is hampered by the fact that the system is far from being in its natural hydrated state. Recent work using solid-state NMR instrumentation has permitted the obtaining of very-high-resolution NMR spectra of multilamellar model and natural membrane systems, which has opened the way to obtain direct information on membrane structure and dynamics, and it has made it possible to determine specific properties of lipids and peptides incorporated into the phospholipid lamellar phase (Abebodun et al, 1992;Bouchard et al, 1995;Davies et al, 1995;Forbes et al, 1988a, b;Guo and Hamilton, 1995;Hamilton et al, 1991;Oldfield et al, 1987;Salgado et al, 1993). In this work we aimed to exactly localize the molecule of cholesterol when incorporated into well-hydrated non-perturbed phospholipid multilamellar vesicles by using MAS-NMR.…”

“…MAS l3C-NMR spectra were obtained in the Fourier transform mode on a Varian Unity 300 spectrometer (Varian Instruments), operating at 75.429 MHz for carbon, using a Jakobsen 7-mm room-temperature MAS probe from Varian. I' C MAS experiments (high-power decoupling during the data acquisition and variable delay, 100 W) were recorded using (typically) 8 ps 13C 90" pulse widths and spinning rates of 1.5-2 kHz (Abebodun et al, 1992). Total sample volume was about 1 0 0~1 and it was possible to introduce about 60-70mg of lipids into the rotor.…”

In Vivo Detection of Apoptosis

“…With the advent of magic angle spinning (MAS) proton spectroscopy in the early 1990s, the problems with obtaining high-resolution spectra from whole-tissue samples have largely been overcome (118)(119)(120). It is known that if a sample is spun mechanically, at a rate faster than the spectral broadening originating from these interactions (about 2.5 kHz) and at the ''magic angle'' of 54°449 with respect to the main magnetic field, then the contribution from these interactions to the MR spectral broadening can be significantly reduced.…”

Magic angle spinning 13C-NMR spin-lattice relaxation study of the location and effects of ?-tocopherol, ubiquinone-10 and ubiquinol-10 in unsonicated model membranes

“…~aC MAS experiments (dipolar decoupled during data acquisition, 100 W) were recorded using (typically) 8 gs a3C 90 ° pulse widths and spinning rates of ~ 1-1.2 KHz (Abebodun et al 1992). The number of scans for each delay was typically 1 000.…”

“…Recently, the application of magic angle sample spinning (MAS) NMR to model and natural membrane systems yielded very highly resolved spectra, enabling detailed studies of their structure and dynamics (Oldfield et al 1987;Hamilton et al 1991;Abebodun et al 1992).…”