Nuclear magnetic resonance study and secondary structure determination of the antibiotic peptide, aibellin

Aibellin is a 20-residue peptide antibiotic that has been isolated from the fungus Verticimonosporium ellipticum. Sequence-specific assignment of the 1H- and 13C-NMR signals of aibellin in a methanol solution was achieved by using the two-dimensional NMR technique. Furthermore, its secondary structure was characterized by circular dichroism (CD) and NOESY spectra. The observed NOEs, 3JNHC alpha H coupling constants and amide hydrogen-deuterium (H-D) exchange rates show that the peptide consisted of two alpha-helices and a bent structure around a Pro-14 residue.