Fungal metabolites. Part 3. Structural elucidation of antibiotic peptides, trichosporin-B-IIIb, -IIIc, -IVb, -IVc, -IVd, -VIa and -VIb from Trichoderma polysporum. Application of fast-atom bombardment mass spectrometry/mass spectrometry to peptides containing a unique Aib–Pro peptide bond

Abstract

Trichosporin-B-IIIb, -IIIc, -IVb, -IVc, -IVd, -VIa and -VIb are components of an antibiotic peptide mixture produced by Trichoderma polysporum. Each component was purified by reversed-phase high-performance liquid chromatography (HPLC). The amino acid sequences of these peptides, which have an unstable peptide bond, Aib–Pro, were elucidated by fast-atom bombardment mass spectrometry (FAB MS) and fast-atom bombardment mass spectrometry/mass spectrometry (FAB MS/MS) with the help of NMR spectroscopy. The molecular weights of these peptides were all ca. 2000 and the structures were very similar.