Calix[8]arene-mediated self-assembly of tetrapeptide H-Leu-Leu-Ile-Leu-OMe

Conformational analysis of peptide 1, H-Leu-Leu-Ile-Leu-OMe on complexing with macro cycle calix[8]-arene has been carried out using 1H-NMR and FTIR spectroscopic techniques. Stoichiometry of the complex formed in the 1:8 ratio was evidenced by a Job plot NMR studies of the above peptide show a marked downfield shift and an increase in 3J values for NH resonances on complexing with calix[8]arene. The characteristic NOE connectivity between Ni+iH and CiαH confirm β-sheet conformation in the complexed state. Both 1H-NMR and FTIR results indicate that the α-amino group of Leu I is proximal to the macrocycle and is involved in hydrogen bond formation with phenolic hydrogen atom of the calix[8]arene. This suggests that calix[8]arene provides a suitable platform for peptide 1 to self-assemble in a parallel β-sheet conformation. The nature of calix[8]arene interaction with peptide 1 has been studied using dynamic NMR studies, which concludes that a bifurcated hydrogen bonding interaction exists in the molecular interfaces of the assembly. Copyright © 2003 John Wiley & Sons, Ltd.