Spectral Assignment and Conformational Analysis of Cyclic Peptides by Carbon-13 Nuclear Magnetic Resonance

摘要: Abstract Tentative assignment for each carbon resonance in the natural abundance high resolution carbon-13 nuclear magnetic Fourier transform spectrum at 25.2 MHz of biologically active cyclic octapeptides, synthetic oxytocin (43 carbons) and lysine-vasopressin (46 dodecapeptide bacitracin (66 has been made using a number different techniques. The 13C assignments constituent amino acids were used to investigate conformation these peptides aqueous solution. chemical shift nonequivalence found end chain β-substituted methyl carbons 3 isoleucyl residues may result from environments imposed by this peptide. Furthermore, small differences (less than 2 ppm) shifts peptide resonances relative (correcting internal bond, N- C-terminal, pH effects) linear also reflect extent that are affected conformations.