title: Isolation and sequence determination of trichorzianines A antifungal peptides from Trichoderma harzianum.
abstract: Trichorzianines A, membrane active peptides of the peptaibol class, were isolated from cultures of the mould Trichoderma harzianum. Trichorzianines A were separated into pure components by HPLC on octadecyl bonded and SiO2 phases successively. Nine trichorzianines A (IIa, IIIa, IIIb, IIIc, IVb, Vb, VIa, VIb and VII) were isolated from the complex microheterogeneous mixture. Their N-terminal amino acid is acetylated, the C-terminal amino alcohol is either tryptophanol or phenylalaninol, 7 to 8 of the 19 residues are alpha-aminoisobutyric acid. Gas chromatography on a chiral phase showed isovaline to have the D-configuration and all the other optically active amino acids and amino alcohols to have the L-configuration. The amino acid sequences were determined from their positive ion FAB mass spectra which exhibited the preferential cleavage of the Aib 12-Pro 13 amide bond as a main fragmentation. The resulting fragments subsequently underwent amide bond ruptures that generated two series of abundant acylium ions which enabled direct determination of the 1-19 sequence. The relative position of the isomeric amino acids in the sequence of trichorzianine AVII was assigned from analysis of the N- and C-terminal oligopeptides yielded by its selective acidic hydrolysis. The microheterogeneity of trichorzianines A results mainly from single or multiple substitution of amino acids at the specific positions 5, 14, 16 and 19.
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid; D013058:Mass Spectrometry; D003904:Mitosporic Fungi / Q000032:analysis*; D008970:Molecular Weight; D054848:Peptaibols; D010455:Peptides / Q000302:isolation & purification; D013329:Structure-Activity Relationship; D014242:Trichoderma / Q000032:analysis*
chemical_list: D000900:Anti-Bacterial Agents; D054848:Peptaibols; D010455:Peptides; C039715:trichorzianine