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Nucleation of β-Hairpin Structures with Cis Amide Bonds in E-Vinylogous Proline-Containing Peptides
figure
posted on 2003-07-12, 00:00 authored by Tushar K. Chakraborty, Animesh Ghosh, S. Kiran Kumar, Ajit C. KunwarSynthesis and conformational studies of peptides
containing the E-vinylogous prolines 1 (VPro1) and 2
(VPro2), Boc-Ala-Val-VPro1-Xaa-Leu-OMe (3, Xaa = Gly; 4,
Xaa = Phe), Boc-Ala-Val-VPro2-Xaa-Leu-OMe (5, Xaa = Gly;
6, Xaa = Phe), Boc-Leu-Ile-Val-VPro1-Xaa-Leu-OMe (7, Xaa
= Gly; 8, Xaa = Phe), and Boc-Leu-Ile-Val-VPro2-Xaa-Leu-OMe (9, Xaa = Gly; 10, Xaa = Phe), were carried out. It has
been shown that both VPro1 and VPro2 lead to the formation
of 12-membered intramolecularly hydrogen bonded structures very similar to type VI β-turns with a cis Xaa−VPro
amide bond in the major conformers in all the peptides 3−10,
resulting in the nucleation of β-hairpin type structures in
these molecules in CDCl3.