MICROHETEROGENEITY CHARACTERIZATION OF A TRICHORZIANINE-A MIXTURE FROM TRICHODERMA-HARZIANUM

The microheterogeneity of trichorzianine-A (TA) from Trichoderma harzi anum was studied using single-stage mass spectrometry and high-energy collision-induced dissociation (CID) tandem mass spectrometry. Based o n the electrospray ionization and the liquid secondary ion single-stat e mass spectra, the main components with eight different molecular mas ses were identified in the mixture. Five contain phenylalaninol and th ree a tryptophanol C-terminal amino alcohol residue. The tandem mass s pectra taken on the protonated molecular ion of these components (MH+) show that most of them contain one main and one or more minor sequenc e analogues. For the microheterogeneity characterization of this mixtu re, a previously described method was used based on high-energy CID st udies 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 o ccur 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.