Investigation of the effective interactions in stabilizing Ac-Pro-cisPro-Phe-NH2 peptide
کد مقاله : 1227-PHYSCHEM20
سارا فخرایی *، محبوبه مختاری
دانشگاه پیام نور
چکیده مقاله:
In the present study, the interactions playing a remarkable role in stability of cis isomer of peptide with Ac-Pro-cisPro-Phe-NH2 amino acid sequence (Phe=phenylalanine), as a typical model of Ac-Pro-cisPro-Xaa-NH2 peptides (Xaa=aromatic amino acid), were studied using density functional theory. The atoms in molecules (AIM) and natural bond orbital (NBO) analyses were applied to determine the electronic structure and nature of the interactions. The topological properties of electron density detected three bond critical points (BCPs) corresponding to CH•••π interactions between first Pro and Phe residues, and also, one BCP was detected between nitrogen atom of Pro interacting with Phe residue. The latter interaction has not been reported so far. The AIM descriptors at BCPs showed that all interactions are closed shell in nature. In support of these results, the NBO analyses were carried out to calculate the charge transfers affected on the stability of cis isomer. The NBO results showed π→σ^* transitions for CH•••π interactions, and also σ→n^* transition for predicted interaction between nitrogen atom of first Pro and C-C bond of Phe residue. Therefore, both analyses confirm the interaction of N atom of Pro with Phe group of side chain residue in cis conformational isomer of Pro...Xaa peptides.
کلیدواژه ها:
Cis isomer peptide; Proline; Phenylalanine; Atoms in molecules; Natural bond orbital.
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