13C-NMR chemical shift tensor and hydrogen-bonded structure of glycine-containing peptides in a single crystal

13C-nmr chemical shift tensor components are reported for a 13C-labeled Gly1 amide carbonyl carbon of a glycylglycine (Gly1Gly2) single crystal, a GlyGly · HNO3 single crystal and a GlyGly · HCl · H2O single crystal, for which the three-dimensional crystal structures have already been determined by x-ray diffraction. The tensor components were measured by changing the angle between the crystal plane and the applied magnetic field by using a goniometer designed in this work for use in conventional 13C cross-polarization/magic angle spinning nmr probe. From these experimental data, the principal values of the 13C chemical shift tensor and its directions for the Gly1 amide carbonyl carbon were determined. It was found that the 13C chemical shift tensor components (δ11, δ22, and δ33) for the Gly1 amide carbonyl carbon in GlyGly and GlyGly · HNO3 with a >NH · · · OC< type of hydrogen bond depend on the hydrogen-bond length and the directions of the δ22 components of these peptides are along the hydrogen-bonded >CO bond axis. In addition, the magnitude of the deviation from the bond axis depends on the hydrogen-bond angle. Further, the experimental result for GlyGly · HCl · H2O with a OH · · ·OC< type of hydrogen bond was discussed. © 1999 John Wiley & Sons, Inc. Biopoly 50: 61–69, 1999