Apparatus for rapid adjustment of the degree of alignment of NMR samples in aqueous media: Verification with residual quadrupolar splittings in ²³Na and ¹³³Cs spectra
Date
2006
Authors
Kuchel, Philip William
Chapman, B E
Muller, Norbert
Bubb, William A
Philp, David
Torres, Allan M
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Publisher
Academic Press
Abstract
NMR spectra of 23Na+ and 133Cs+ in gelatine in a silicone rubber tube that was stretched to various extents showed remarkably reproducible resonance multiplicity. The relative intensities of the components of the split peaks had ratios, 3:4:3, and 7:12:15:16:15:12:7, respectively, that conformed with those predicted using a Mathematica program. The silicone-rubber tube was sealed at its lower end by a small rubber stopper and placed inside a thick-walled glass tube. Gelatine was injected in solution into the silicone tube and 'set' by cooling below 30 °C. A plastic thumb-screw held the silicone tube at various degrees of extension, up to ∼2-fold. After constituting the gel in buffers containing NaCl and CsCl, both 23Na and 133Cs NMR spectroscopy revealed that after stretching the initial single Lorentzian line was split into a well-resolved triplet and a heptet, respectively. This was interpreted as being due to coupling between the electric quadrupoles of the nuclei and the average electric field gradient tensor of the collagen molecules of gelatine; these molecules became progressively more aligned in the direction of the main magnetic field, B0, of the vertical bore magnet, as the gel was stretched. This apparatus provides a simple way of demonstrating fundamental physical characteristics of quadrupolar cations, some characteristics of gelatine under stretching, and a way to invoke static distortion of red blood cells. It should be useful with these and other cell types, for studies of metabolic and membrane transport characteristics that may change when the cells are distorted, and possibly for structural studies of macromolecules.
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Keywords
Keywords: Gelation; Mathematical instruments; Positive ions; Problem solving; Resonance; Rubber; Silicones; Sodium chloride; 133-Caesium; 23-Sodium; Alignment tensors; Electric field tensors; Erythrocytes; Quadrupolar splitting; Relative intensities; Resonance mult 133-Caesium; 23-Sodium; Alignment tensor; Electric field tensor; Erythrocytes; Gel; Gelatine; Quadrupolar splitting
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Source
Journal of Magnetic Resonance
Type
Journal article
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2037-12-31
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