Chemical shift and electric field gradient tensors for the amide and carboxyl hydrogens in the model peptide N-acetyl-D,L-valine. Single-crystal deuterium NMR study

Abstract

Single-crystal samples of the peptide N-acetyl-D,L-valine (NAV) with the exchangeable amide and carboxyl hydrogens replaced by deuterons were investigated by deuterium NMR spectroscopy. The electric field gradient (EFG) and chemical shift (CS) tensors for the amide and the carboxyl hydrogens, both of which are involved in intermolecular hydrogen bonds, were determined. The relationship of these tensors to the structure of NAV is discussed. The orientations of the EFG and the CS tensors of the amide hydrogen in a protein can provide information about the polypeptide backbone structure. For NAV the eigenvector of the largest eigenvalue of the EFG tensor coincides with the NH bond direction, as found by X-ray crystallography, within 2°, and the eigenvector of the intermediate eigenvalue with the normal (n peptide) to the peptide plane within 1°. The directions of largest and smallest shielding are similarly aligned with NH and n peptide respectively. However, the deviations are considerably larger, namely 9° and 11°, respectively. The anisotropy of the CS tensor is determined to be 13.4 +− 2.7 ppm, confirming that the amide hydrogen is involved in a weak hydrogen bond

NMR scalar couplings across Watson–Crick base pair hydrogen bonds in DNA observed by transverse relaxation-optimized spectroscopy

“…1 C and D), precise values for h J NN were obtained by inverse Fourier transformation of the in-phase multiplets (22). Table 1 shows that there are sizeable variations in the h J NN couplings among the AAT base pairs, e.g., T 10 and T 16 ( Fig. 1C), as well as among the G'C base pairs (Fig.…”

Deuterium Quadrupole-Coupling and Chemical-Shielding Tensors in the Model Dipeptide Glycylglycine Monohydrochloride Monohydrate

“…The other molecules biologically important peptide group. These are N-acetylvaare related by inversion through the (010) plane and, in line (11) and N-acetylglycine (12). Both molecules considgeneral, give rise to separate peaks.…”

The combination of X-ray diffraction and nuclear quadrupole resonance studies of crystals

“…Chemical shift and EFGT for the amide and carboxyl H atoms in N-acetyl-D.L-valine by single-crystal D NMR have been studied by Gerald II, Bernhard, Haeberlen, Rendell & Opella (1993). The structure is known (Carroll, Stewart & Opella, 1990).…”