Lipids resonant frequency

The NMR experiments were performed using the quadrupolar echo pulse sequence 7i/2x—Ti—7i/2y—T2—acquisition with phase-cycling and quadrature detection. A Bruker MSL 400 spectrometer was used for the high pressure studies operating at a resonance frequency of 61.4 MHz. In the liquid-crystalline phase, perdeuterated lipids display NMR spectra, which are superpositions of axially symmetric quadrupolar powder patterns of all C-D bonds.From the sharp edges, the quadrupolar splittings... 

Fig. 7. Theoretically calculated line widths for the 13C-choline nuclear magnetic resonance signals for dipalmitoylphosphatidylcholine (A) and dielaidoylphosphatidylcholine (O) in a 50 mol% binary mixture of the two lipids. Calculation appropriate for a 13C resonance frequency of 25.2 MHz.

Assignments of C resonance frequencies to individual carbon atoms have been achieved following several strategies (Levy and Nelson, 1972 Stothers, 1972a,b). C chemical shifts, relative to methyl carbons of tetramethylsilane (TMS) of the most common functional groups in lipids, are given in Table 9.9. Available compilations of C-NMR frequencies (Johnson and Jankowski, 1972 Breit-maier and Voelter, 1974 Rosenthal and Fendler, 1976) should also be consulted. 

A new method for the simultaneous suppression of water and lipid resonances using a series of dual-band frequency-selective radiofrequency pulses with associated dephasing gradients is presented." By optimizing the nutation angles of the individual pulses, the water and lipid suppression is... 

The normal H spectrum of tissue consists of the dominant resonance of water at about 4.7 ppm and a weaker resonance from the methylene of lipid (fat) at about 0.9 ppm. This spectrum never changes significantly and is therefore usually uninteresting. However, by suppressing these resonances, many others, much weaker in intensity but far more diagnostically useful, are revealed. There are a number of suppression techniques. A frequency-selective pulse may first be applied to saturate the unwanted resonances. Water, being by far the... 

The high-resolution and the high scaling factor of 2D PISEMA, for the first time, enabled the use of the dipolar dimension to resolve resonances from non-selectively or uniformly labeled proteins. Three-Dimensional experiments were used to enhance the resolution of resonances from uniformly N-labeled peptides and proteins embedded in lipid bilayers. This was successfully demonstrated on aligned samples containing uniformly N-labeled membrane-associated peptides and proteins. Two-dimensional PISEMA spectra of some of these systems showed limited resolution due to a small frequency dispersion of resonances from a-helices oriented on the surface of the bilayer in both N chemical shift and H- N dipolar coupling dimensions. However, when an additional H chemical shift dimension was invoked, the 3D H chemical shift/ H- N dipolar coupling/ N chemical shift spectra of these systems considerably increased the resolution of peaks. ... 

Single-pulse spectra of human blood plasma are very complex, and resonances of metabolites, proteins, lipids and lipoproteins are heavily overlapped even at 800 MHz H observation frequency (Fig. 1). Most blood plasma samples are quite viscous and this gives rise to relatively short Ti... 

Planar supported lipid membranes were first prepared and studied as simplified structural models of cell membranes [4,6, 32], and more recently as biocompatible coatings for sensor transducers and other synthetic materials [33-37], A major advantage of the planar geometry relative to vesicles, and a major contributor to the expansion of this field, is the availability of powerful surface-sensitive analyti-cal/physical techniques. Confining a lipid membrane to the near-surface region of a solid substrate makes it possible to study its structural and functional properties in detail using a variety of techniques such as surface plasmon resonance, AFM, TIRF, attenuated total reflection, and sum frequency vibrational spectroscopy [38 -2]. 

Fig. 5 Frequency response (dots) of a 5-MHz quartz resonator after addition of DPPC/ biotinyl Cap DOPE vesicles with varying amounts of biotinylated lipid. The solid black line is the result of the dynamic MC simulation. The images in the insets are snapshots of the MC simulation taken at the end of the simulation given by the experiment. The final bilayer coverage is also depicted, a /biotin = 0-02, kon = 2.4 x 10 ms k b Xbiotin = 0.1,A on = 1.3 X 10 ms A rup = 2 x 10 s c /biotin = 0.2,A on = 6.0 x 10 ms ...

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