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Titolo:
A two-dimensional magic-angle decoupling and magic-angle turning solid-state NMR method: An application to study chemical shift tensors from peptidesthat are nonselectively labeled with N-15 isotope
Autore:
Lee, DK; Wei, YF; Ramamoorthy, A;
Indirizzi:
Univ Michigan, Dept Chem & Macromol Sci & Engn, Div Biophys Res, Ann Arbor, MI 48109 USA Univ Michigan Ann Arbor MI USA 48109 Biophys Res, Ann Arbor, MI 48109 USA
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 20, volume: 105, anno: 2001,
pagine: 4752 - 4762
SICI:
1520-6106(20010524)105:20<4752:ATMDAM>2.0.ZU;2-E
Fonte:
ISI
Lingua:
ENG
Soggetto:
NUCLEAR-MAGNETIC-RESONANCE; COUPLED POWDER PATTERNS; SECONDARY STRUCTURE; BACKBONE DYNAMICS; QUANTITATIVE MEASUREMENT; POLYPEPTIDE BACKBONE; CROSS-CORRELATION; ROTATING SOLIDS; MODEL PEPTIDES; DIPOLAR;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
67
Recensione:
Indirizzi per estratti:
Indirizzo: Ramamoorthy, A Univ Michigan, Dept Chem & Macromol Sci & Engn, Div BiophysRes, Ann Arbor, MI 48109 USA Univ Michigan Ann Arbor MI USA 48109 n Arbor, MI 48109 USA
Citazione:
D.K. Lee et al., "A two-dimensional magic-angle decoupling and magic-angle turning solid-state NMR method: An application to study chemical shift tensors from peptidesthat are nonselectively labeled with N-15 isotope", J PHYS CH B, 105(20), 2001, pp. 4752-4762

Abstract

A two-dimensional solid-state NMR technique is presented that can be used to determine the N-15 chemical shift and H-1-N-15 dipolar coupling tensors in powder samples of polypeptides containing 15N isotopes at multiple sites. By combining the magic-angle rf decoupling in one time period and the magic-angle turning pulse sequence in another time period of a 2D experiment, we obtain 2D spectra in which the convoluted chemical shift anisotropy (CSA) and dipolar coupling line shapes appear along one axis and the normal MASspectrum appears along the other axis. The magnitudes of the principal elements of the 15N CSA tensors and their orientations in the molecular frame for n-acetyl-N-15-L-Val-N-15-L-Leu (NAVL) and n-acetyl-N-15-D,L-Val (NAV) powder samples are determined using this method. The magnitudes of the N-15 CSA tensors are 60.2 +/- 1,87.1 +/- 1, and 230.1 +/- 1 ppm for the Val residue in NAVL; 58.7 +/- 1, 93.7 +/- 1, and 232.8 +/- 1 ppm for the Leu residue in NAVL; 59.6 +/- 1, 80.5 +/- 1, and 235.3 +/- 1 ppm for site I in NAV; and 57.5 +/- 2, 81.0 +/- 2, and 227.0 +/- 2 ppm for site II in NAV. The experimental results also suggest that the most-shielded axis, sigma (11N), andthe sigma (22N) axis of the N-15 CSA tenser are significantly tilted away from the peptide plane and the normal to the peptide plane, respectively. The tilt angles (alpha (N)) are 34 +/- 12 degrees for Val and 36 +/- 11 degrees for Leu in NAVL, whereas it is 5 +/- 22 degrees in NAV. The angles (beta (N)) between the least-shielded axis of the N-15 CSA tensor, sigma (33N),in the peptide plane and-the N-H bond are determined to be 20 +/- 2 degrees for Val and 18 +/- 2 degrees for Leu in NAVL and 21 +/- 2 degrees for NAV. The values are in good agreement with some of the recent solid-state NMR experimental studies on peptides. The values for the PN angle reported in this study are also, in agreement with the solution NMR studies on water-soluble proteins.

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Documento generato il 05/04/20 alle ore 07:00:39