Strained-cyclophane-induced beta-turn template: design, synthesis, and spectroscopic characterization.
[structure: see text] Three tetrapeptides incorporating a 14-membered (R(i+1), S(i+2)) cycloisodityrosine at the i + 1 and i + 2 positions were designed and synthesized. Conformational analysis by (1)H NMR and CD spectra as well as molecular modeling indicated that they all adopt a beta-turn conformation. While the CD spectrum of compound 2 is characteristic of the typical type-II beta-turn (maximum at approximately 200 nm and a minimum at approximately 220 nm), that of 1a (atropisomer of 2) is opposite in sign to the expected spectrum of the type-II beta-turn.
Cristau
Pierre
P
Institut de Chimie des Substances Naturelles, CNRS, 91198 Gif-sur-Yvette Cedex, France.
Martin
Marie-Thérèse
MT
Tran Huu Dau
Marie-Elise
ME
Vors
Jean-Pierre
JP
Zhu
Jieping
J
D002942:Circular Dichroism; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D009842:Oligopeptides / Q000138:chemical synthesis* / Q000737:chemistry*; D010456:Peptides, Cyclic / Q000737:chemistry*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D014443:Tyrosine / Q000737:chemistry*
D009842:Oligopeptides; D010456:Peptides, Cyclic; D014443:Tyrosine; C043548:RA VII