Mutual orientation of three magnetic tensors in a polycrystalline dipeptide by dipole-modulated 15N chemical shift spectroscopy

Cynthia J Hartzell, T. K. Pratum, G. Drobny

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This study demonstrates the mutual orientation of three tensor interactions in a single NMR experiment. The orientation of the 15N chemical shift tensor relative to the molecular frame has thus been determined in polycrystalline L-[1-13C] alanyl-L-[15N] alanine. The 13C-15N and 15N-1H dipole interactions are determined using the 1H dipole-modulated, 13C dipole-coupled 15N spectrum obtained as a transform of the data in t2. From simulations of the experimental spectra, two sets of polar angles have been determined relating the 13C- 15N and 15N-1H dipoles to the 15N chemical shift tensor. The values determined are βCN = 106°, αCN = 5° and βNH = -19°, αNH = 12°. The experiment verifies, without reference to single crystal data, that σ33 lies in the peptide plane and σ22 is nearly perpendicular to the plane.

Original languageEnglish (US)
Pages (from-to)4324-4331
Number of pages8
JournalThe Journal of Chemical Physics
Issue number8
StatePublished - 1987
Externally publishedYes


ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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