New sequences and new fungal producers of peptaibol antibiotics antiamoebins

Mixtures of the microheterogeneous 16-mer peptaibol antibiotics called anti amoebins (AAM) have been isolated from the culture broths of strains of the filamentous fungi Stilbella erythrocephala ATCC 28144, Stilbeila fimetaria CBS 548.84 and Gliocladium catenulatum CBS 511.66. Sequences were determin ed using on-line HPLC together with positive- and negative-ion electrospray ionization mass spectrometry. Some characteristic features are recognized in the mass spectrometric fragmentation pattern of AAM. From a sample origi nally used for sequencing AAM (from Hindustan Antibiotics, Ltd., Pimpri, Po ona-411018, India), and a sample of AAM commercially available (from Sigma Chemicals, St. Louis, MO, USA) HPLC elution profiles and sequences were ass igned. Further, sequences of AAM previously isolated from Emericellopsis sy nnematicola CBS 176.60 and Emericellopsis salmosynnemata CBS 382.62 were de termined. The peptide designated AAM I was the most abundant in all isolate s and its structure could be confirmed. AAM II was detectable as a minor co mponent (1.9%) only in the original sample of AAM, but not in the other iso lates. The structures of AAM III, IV and V, which had previously been partl y assigned, were definitely established, and the new sequences AAM VI-XVI w ere elucidated. AAM showing Phe(1)/Leu(1) or Phe(1)/Val(1) exchange, respec tively, are produced in amounts only by S. erythrocephala. Sequences, HPLC elution profiles ('fingerprints') and relative amounts of peptides of all i solates were correlated. Copyright (C) 2000 European Peptide Society and Jo hn Wiley & Sons, Ltd.