Determination of the Peptide Torsion Angle φ by15N Chemical Shift and13Cα-1HαDipolar Tensor Correlation in Solid-State MAS NMR

✍ Scribed by M. Hong; J.D. Gross; W. Hu; R.G. Griffin

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 214 KB
• Volume: 135
• Category: Article
• ISSN: 1090-7807
• DOI: 10.1006/jmre.1998.1573

✦ Synopsis

We demonstrate a dipolar-chemical shift correlation technique for sign-sensitive determination of the torsion angle in solid peptides and proteins under magic-angle spinning. The indirect dimension of the experiment is obtained by separate but synchronous evolution of the magnetization under the 15 N chemical shift and the C-H dipolar coupling. The resulting sum and difference spectrum of the two frequencies, with more than ten independent sidebands, depends strongly on the relative orientation of the 15 N chemical shift tensor and the C ␣ -H ␣ bond. This relative orientation reflects the C(O) i؊1 -N-C ␣ -C(O) i torsion angle. The technique can distinguish angles over the full range of 360°when the amide 15 N chemical shift tensor does not possess reflection symmetry with respect to the peptide plane. Thus it complements our previous HNCH experiment, in which two mirror-symmetric conformers of the H N -N bond relative to the C ␣ -H ␣ bond around the N-C ␣ axis cannot be distinguished.