Structural Studies of Hydrogen-bonded Peptides and Polypeptides by Solid-state NMR

Enantiotropically-related polymorphs of {4-(4-chloro-3-fluorophenyl)-2-[4-(methyloxy)phenyl]-1,3-thiazol-5-yl} acetic acid: Crystal structures and multinuclear solid-state NMR

“…In Form 2, the C11 resonance is observed at 178.94 ppm and is deshielded relative to the Form 1 signals, an effect known to correlate with shorter and stronger hydrogen-bonding interactions. 54 The polymorphs also show other notable differences in their 13 C spectra. For example, a change in the isotropic chemical shift of C8 suggests that conformational changes may have occurred nearby.…”

Some aspects of the NMR chemical shift/structure correlation in the structural characterization of polymers and biopolymers

“…Therefore, the chemical shifts of the amide carbonyl carbon, amide nitrogen, amide carbonyl oxygen and amide hydrogen of the aminoacid residues associated with hydrogen bonding have provided useful information about the secondary structure of polypeptides. 85 The NMR chemical shift is one of the most important parameters for providing information about molecular structures including hydrogen bonds. Because the electronic structure around the amide carbonyl-carbon and nitrogen in peptides and polypeptides is greatly affected by the nature of the hydrogen bond, the NMR chemical shifts for the nuclei involved are sensitive to the spatial arrangement of the nuclei comprising the hydrogen bond.…”

“…Taking advantage of this, systematic studies have been performed on the effect of hydrogen bonding on the chemical shifts of the amide carbonyl carbon, amide nitrogen, amide oxygen and amide hydrogen of the amino acid residues for peptides and polypeptides in the solid state to obtain detailed information about the hydrogen-bonded structure. 85 In this section, some of the studies on the hydrogen-bonded structure of peptides and polypeptides in the solid state based on measurements and theoretical calculations of NMR chemical shifts will be discussed. 59,[85][86][87] Isotropic 13 C chemical shifts and chemical shift tensor components The effect of hydrogen bonding on the 13 C chemical shift of the carbonyl carbon has been studied in several amino-acid residues.…”

“…85 In this section, some of the studies on the hydrogen-bonded structure of peptides and polypeptides in the solid state based on measurements and theoretical calculations of NMR chemical shifts will be discussed. 59,[85][86][87] Isotropic 13 C chemical shifts and chemical shift tensor components The effect of hydrogen bonding on the 13 C chemical shift of the carbonyl carbon has been studied in several amino-acid residues. [88][89][90][91][92] The observed isotropic chemical shifts (d iso ) These relationships indicate that the hydrogen bond length can be determined through the observation of the 13 C chemical shift of the carbonyl carbon in the amino acid residues in peptides and polypeptides.…”

Solid state NMR study of hydrogen bonding, miscibility, and dynamics in multiphase polymer systems

“…Several excellent reviews on hydrogen bonds and their effects on the microstructures [77,78] and physical properties of various materials such as polymer blends [79][80][81], peptides and polypeptides [78], and crystal supramolecular systems [82] and so on, are available. Here we briefly present some new experimental and theoretical NMR studies on the main parameters related to the hydrogen bonding interactions in the solid state: (a) chemical shift, (b) double quantum transitions, (c) chemical shift anisotropy (CSA), (d) ab initio calculations.…”