Metabolomics for the Quality Assessment of Lycium chinense Fruits

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, ³J_NHCαH coupling constants and amide hydrogen–deuterium (H–D) exchange rates show that the peptide consisted of two α-helices and a bent structure around a Pro-14 residue.