Harzianin HB I, an 11-residue peptaibol from Trichoderma harzianum: isolation, sequence, solution synthesis and membrane activity

Harzianin HB I is a minor component of the peptaibol mixture biosynthesized by a Trichoderma harzianum strain. It is isolated by a multi-step chromatography procedure, including HPLC; its sequence has been elucidated by LSIMS and two-dimensional 1H NMR experiments. This 11-residue peptaibol is an analogue of the 14-residue peptaibol harzianin HC IX, resulting from the deletion of the tripeptide Aib-Pro-Ala. The CD and NMR data (NOE data and amide proton temperature coefficients) are similar to those of HC IX, suggesting a right-handed helix-type conformation for the two peptides. Harzianin HB I was synthesized by the solution-phase method using BOP as coupling reagent. The membrane properties examined on liposomes are compared with those of other known peptaibols.