Fungal metabolites. Part 6. Nuclear magnetic resonance study of antibiotic peptides, trichosporin Bs, from Trichoderma polysporum

Abstract

Sequence-specific ¹H- and ¹³C-nuclear magnetic resonance assignments of an antibiotic peptide, trichosporin B-V isolated from fungus Trichoderma polysporum, were achieved in methanol by using two dimensional NMR techniques. The ¹H NMR spectra recorded at various concentrations (1–60 mmol dm^–1) suggested that the peptide behaves predominantly as a monomer in methanol and that its conformation is not affected by its concentration. Furthermore, complete or partial ¹H-resonance assignments of trichosporin B-la, -IIIa, -IVd and -VIb were carried out similarly. Comparison of the ¹H NMR parameters for the amide groups of trichosporin Bs suggested that their backbone conformations are very similar to each other. It is proposed that the significant differences in the biological activity of trichosporin Bs result from the lipophilicity of the individual molecules.