The conformation of cyclodecapeptide loloatin C with obvious antibiotic activity has been investigated in 2,2,2-trifluoroethanol/sodium acetate buffer solution and then characterized by FT-IR, CD and NMR spectrum. T...The conformation of cyclodecapeptide loloatin C with obvious antibiotic activity has been investigated in 2,2,2-trifluoroethanol/sodium acetate buffer solution and then characterized by FT-IR, CD and NMR spectrum. The results of FT-IR show that there exists β-strand or β-turn secondary structure in the molecule. According to the CD spectrum, the helical turn is dominant but the β-turn structure also exists. Conformation of the whole molecule is probably a helical β-turn. The chemical shifts and coupling constants prove the existence of a β-structure in the regions of Val1, Orn2 and Leu3. NOESY data and temperature gradients of amide protons suggest that the molecular conformation is a dumbbell-like structure with the waist located between ornithyl (position 2) and D-phenylalanyl (position 7) and β-turn on both ends.展开更多
Two dimensional 1H NMR techniques were used to determine the solution structure of C10, a cyclopeptide synthesized in the laboratory. Complete proton resonance assignments were obtained using 2 D DQF COSY, TOC...Two dimensional 1H NMR techniques were used to determine the solution structure of C10, a cyclopeptide synthesized in the laboratory. Complete proton resonance assignments were obtained using 2 D DQF COSY, TOCSY, and NOESY experiments. The cross peak volumes in the NOESY spectra were used to calculate the C10 structure. The conformation showed that the four side chains of the lysine residues faced the same side of the cyclopeptide ring.展开更多
文摘The conformation of cyclodecapeptide loloatin C with obvious antibiotic activity has been investigated in 2,2,2-trifluoroethanol/sodium acetate buffer solution and then characterized by FT-IR, CD and NMR spectrum. The results of FT-IR show that there exists β-strand or β-turn secondary structure in the molecule. According to the CD spectrum, the helical turn is dominant but the β-turn structure also exists. Conformation of the whole molecule is probably a helical β-turn. The chemical shifts and coupling constants prove the existence of a β-structure in the regions of Val1, Orn2 and Leu3. NOESY data and temperature gradients of amide protons suggest that the molecular conformation is a dumbbell-like structure with the waist located between ornithyl (position 2) and D-phenylalanyl (position 7) and β-turn on both ends.
文摘Two dimensional 1H NMR techniques were used to determine the solution structure of C10, a cyclopeptide synthesized in the laboratory. Complete proton resonance assignments were obtained using 2 D DQF COSY, TOCSY, and NOESY experiments. The cross peak volumes in the NOESY spectra were used to calculate the C10 structure. The conformation showed that the four side chains of the lysine residues faced the same side of the cyclopeptide ring.
