Fungal metabolites. Part 7. Solution structure of an antibiotic peptide, trichosporin B-V, from Trichoderma polysporum

Abstract

The secondary structure of the peptaibol trichosporin B-V in methanol was investigated in detail by 600 MHz nuclear magnetic resonance spectroscopy. Its fundamental secondary structure was characterized as a helix by the circular dichroism spectrum. Inter-residual nuclear Overhauser effect patterns, ³J_NH-CaH amide coupling constants, hydrogen–deuterium (H–D) exchange rates of the amide protons, and inspection of molecular models showed that the secondary structure of this peptide consists of two major α-helical structures because of a bent structure around a Pro residue, and that the first three amino acid residues of the N-terminal α-helix are arranged predominantly in a 3₁₀-helical fashion.