Lee, HJ Song, JW Choi, YS Park, HM Lee, KB 2024-01-21T10:01:23Z 2024-01-21T10:01:23Z 2022-01-10 2002-10-09 0002-7863 https://pubs.kist.re.kr/handle/201004/139135 The conformational properties of azapeptide derivatives, Ac-azaGly-NHMe (1), Ac-azaAla-NHMe (2), Ac-NMe-azaGly-NHMe (3), Ac-NMe-azaAla-NHMe (4), Ac-azaGly-NMe2 (5), Ac-azaAla-NMe2 (6), Ac-NlMe-azaGly-NW2 (7), and Ac-NMe-azaAla-NMe2 (8), were systematically examined by using ab initio MO and DFT methods. Structural perturbations in azapeptides resulting from cyclic substitution of a methyl group at three N-positions of an azaamino acid were studied on the basis of the structure of the simplest model azapeptide, 1. Potential energy surfaces were generated at the HF/6-31 G* level for 1-4 and at the HF/6-31 G*//HF/3-21 G level for 5-8 by rotating two key dihedral angles (phi, psi) in increments of 30degrees. The backbone (phi, psi) angles of the minima for 1-4 are observed at the i + 2 position to form the betaI(I')-, betaII(II')-, betaVI-turns or the polyproline 11 structure according to the orientation of the acetyl group and the positions of the N-methyl groups. Compounds 5-8 coupled to a secondary amine were found to preferentially adopt polyproline II, betaI(III)-turn, or alpha-helical structure or even extended conformations depending on the orientation of the acetyl group and the positions of the N-methyl groups. Furthermore, N-methyl groups, depending on their positions, were found to affect the orientation of the amide group in the lowest energy conformations, the pyramidality of the N2 atom, and the bond length in azapeptice derivatives. These unique theoretical conformations of N-methyl azapeptide derivatives could be utilized in the definite design of secondary structure for peptides and proteins, and in the development of new drugs and molecular machines. English AMER CHEMICAL SOC SOLID-PHASE SYNTHESIS CIS PEPTIDE-BONDS LOW-ENERGY CONFORMERS SET MODEL CHEMISTRY X-RAY STRUCTURES AB-INITIO SCF CRYSTAL-STRUCTURES FORCE-FIELD SIDE-CHAIN INHIBITORS A theoretical study of conformational properties of N-methyl azapeptide derivatives Article 10.1021/ja026496x 1 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, v.124, no.40, pp.11881 - 11893 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 124 40 11881 11893 scie scopus 000178487100022 2-s2.0-0037048621 Chemistry, Multidisciplinary Chemistry Article SOLID-PHASE SYNTHESIS CIS PEPTIDE-BONDS LOW-ENERGY CONFORMERS SET MODEL CHEMISTRY X-RAY STRUCTURES AB-INITIO SCF CRYSTAL-STRUCTURES FORCE-FIELD SIDE-CHAIN INHIBITORS azapeptide computation structure