South African Journal of Chemistry
On-line version ISSN 1996-840X
Print version ISSN 0379-4350
PAWAR, Sachin A et al. Conformational Comparison of Cyclic α3β Tetrapeptide vs. α3β Pentapeptide. S.Afr.j.chem. (Online) [online]. 2014, vol.67. ISSN 1996-840X.
The γ-turn inducing sugar β-amino acid plays an important role in the formation of well-defined secondary structures of cyclic tetra- and pentapeptide. Two tetra- and one novel pentapeptide were synthesized from a sugar β-amino acid and the conformations of the compounds were established by NMR spectroscopy (EASY-ROESY) and compared with CD spectroscopic data. Although the γ-turn conformation was dominant for both tetra- and pentapeptide according to NMR spectroscopic analysis in DMSO, the pentapeptide exhibited the presence of a second conformation. CD spectroscopic results in methanol showed that the tetrapeptides have a γ-turn conformation, while the pentapeptide has a random structure.
Keywords : Cyclic peptide; tetrapeptide; pentapeptide; conformational analysis; NMR spectroscopy; CD spectroscopy.