Brunner, Henri and Ikeshita, Masahiro and Tsuno, Takashi (2024) Pyramidalization of the Carboxamide sp<SUP>2</SUP>-Center in Peptide Structures. JOURNAL OF ORGANIC CHEMISTRY, 89 (8). pp. 5511-5517. ISSN 0022-3263, 1520-6904
Full text not available from this repository. (Request a copy)Abstract
A CSD search in the Cambridge Crystallographic Database for the substructure N-C alpha H-C'(= O)-N gave 24,180 peptide structures for analysis of the pyramidalization of the sp(2)-hybridized carboxamide group C'(= O)NC alpha, which had not been investigated before. The dependence of the pyramidalization theta = O-N-C'-C alpha on the rotation angle psi = O= C'-C-alpha-N about bond C'-C-alpha resulted in a curve with three maxima, three minima, and six zero-crossings. Surprisingly, the psi/theta analysis of the individual amino acid building blocks showed that all of them exhibited similar curves, irrespective of their different R substituents. This unusual behavior is explained by a 3-fold short-range potential set up by the three covalent bonds, emanating from C-alpha. The tie-up of the rotation angle psi and the pyramidalization theta in a rigid coupling is remarkable. In the 24,180 peptide structures, subjected to X-ray crystallography, there is no dynamics. For peptides in solution, the rotation/pyramidalization curve psi/theta(av) determines the degree of pyramidalization theta, when the rotation angle psi runs through a full 360(degrees) circle. Density functional theory (DFT) calculations of alaninamide supported the analysis.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | DENSITY; DISTORTION; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Anorganische Chemie > Alumni or Retired Professors > Prof. Dr. Henri Brunner |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 29 Jul 2025 09:36 |
| Last Modified: | 29 Jul 2025 09:36 |
| URI: | https://pred.uni-regensburg.de/id/eprint/64192 |
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