Related ArticlesDifference in the structures of alanine tri- and tetra-peptides with antiparallel ?-sheet assessed by X-ray diffraction, solid-state NMR and chemical shift calculations by GIPAW.
Biopolymers. 2014 Jan;101(1):13-20
Authors: Asakura T, Yazawa K, Horiguchi K, Suzuki F, Nishiyama Y, Nishimura K, Kaji H
Alanine oligomers provide a key structure for silk fibers from spider and wild silkworms.We report on structural analysis of L-alanyl-L-alanyl-L-alanyl-L-alanine (Ala)4 with anti-parallel (AP) ?-structures using X-ray and solid-state NMR. All of the Ala residues in the (Ala)4 are in equivalent positions, whereas for alanine trimer (Ala)3 there are two alternative locations in a unit cell as reported previously (Fawcett and Camerman, Acta Cryst., 1975, 31, 658-665). (Ala)4 with AP ?-structure is more stable than AP-(Ala)3 due to formation of the stronger hydrogen bonds. The intermolecular structure of (Ala)4 is also different from polyalanine fiber structure, indicating that the interchain arrangement of AP ?-structure changes with increasing alanine sequencelength. Furthermore the precise (1)H positions, which are usually inaccesible by X-ray diffraction method, are determined by high resolution (1)H solid state NMR combined with the chemical shift calculations by the gauge-including projector augmented wave method.
[Question from NMRWiki Q&A forum] Capillary vs bulk solvent chemical shift difference
Capillary vs bulk solvent chemical shift difference
I have prepared a sealed DMSO-d6 capillary tube (3mmOD) to use as an internal reference for an undergraduate prac using Evans method.
When I run the capillary with DMSO-d6 only in the outer tube (ie no sample) there is a small difference in the shift of the residual DMSO solvent peak of the outer tube vs the capillary (~0.005ppm, 300MHz). The difference is not great enough to effect the result of the experiment but I would like to be able to explain the discrepancy to the students.
Due to the large number of samples it is...
[NMR paper] Transmembrane 19F NMR chemical shift difference of fluorinated solutes in liposomes,
Transmembrane 19F NMR chemical shift difference of fluorinated solutes in liposomes, erythrocytes and erythrocyte ghosts.
Related Articles Transmembrane 19F NMR chemical shift difference of fluorinated solutes in liposomes, erythrocytes and erythrocyte ghosts.
NMR Biomed. 1993 Mar-Apr;6(2):136-43
Authors: Xu AS, Waldeck AR, Kuchel PW
In erythrocytes suspended in isotonic medium, a number of fluorinated anions showed well resolved 19F NMR resonances from the solute populations in the intra- and extracellular compartments; the intracellular...