Microheterogeneity characterization of a trichorzianine-A mixture from Trichoderma harzianum

The microheterogeneity of trichorzianine-A (TA) from Trichoderma harzianum was studied using single-stage mass spectrometry and high-energy collision-induced dissociation (CID) tandem mass spectrometry. Based on the electrospray ionization and the liquid secondary ion single-state mass spectra, the main components with eight different molecular masses were identified in the mixture. Five contain phenylalaninol and three a tryptophanol C-terminal amino alcohol residue. The tandem mass spectra taken on the protonated molecular ion of these components (MH+) show that most of them contain one main and one or more minor sequence analogues. For the microheterogeneity characterization of this mixture, a previously described method was used based on high-energy CID studies of the different MH+, y(7), b(12) ions and their satellite ions with +/-14 and +/-28 mass number differences. In addition to the nine known sequence variants, five new trichorzianines were sequenced from the mixture. It was found, furthermore, that amino acid exchange can occur not only at positions 5, 14, 16 and 19 but also at positions 2, 3, 4, 7, 8 and 9. (C) 1998 John Wiley & Sons, Ltd.