RESUMO
Conformational analysis of peptide 1, H-Leu-Leu-Ile-Leu-OMe on complexing with macro cycle calix[8]arene has been carried out using (1)H-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 (3)J values for NH resonances on complexing with calix[8]arene. The characteristic NOE connectivity between N(i+1)H and C(ialpha)H confirm beta-sheet conformation in the complexed state. Both (1)H-NMR and FTIR results indicate that the alpha-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 beta-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.
Assuntos
Oligopeptídeos/química , Compostos Policíclicos/farmacologia , Calixarenos , Ligação de Hidrogênio , Espectroscopia de Ressonância Magnética , Compostos Policíclicos/química , Conformação Proteica/efeitos dos fármacos , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , TitulometriaRESUMO
Proton magnetic resonance Spectroscopy (PMRS) has been used to study the differences between immortalized fibroblasts and fibrosarcoma cells of different grade. One and two dimensional purged correlation spectroscopy (PCOSY) have been used to assess intact viable fibroblast and fibrosarcoma cells, and differences in the triglyceride, cellular metabolite, and cell surface fucosylation patterns between the three cell lines have been observed. The clinical implication of this study is the potential use of PMRS as an adjunct to conventional histopathology.
