Fungal metabolites. XVIII. New membrane-modifying peptides, trichorozins I-IV, from the fungus Trichoderma harzianum

New membrane-modifying peptides, trichorozins I-IV, have been isolated from conidia of the fungus Trichoderma harzianum. Their amino acid sequences were clearly determined by spectrometric methods and, furthermore, they were synthesized by the solution-phase method. Trichorozins are a family of the class of peptaibols and are composed of 11 residues including an amino alcohol. Trichorozins exhibited voltage-dependent ion channel-like activity in lipid bilayers.

Fungal metabolites. XVI. Structures of new peptaibols, trichokindins I-VII, from the fungus Trichoderma harzianum

New peptaibols, trichokindins I-VII, have been isolated from the fungus Trichoderma harzianum. Their structures were characterized by spectrometric methods. Trichokindins, which are 18-residue peptides containing one to three isovaline residues, were found to induce Ca(2+)-dependent catecholamine secretion from bovine adrenal medullary chromaffin cells.

Carbohydrate structures of the cell adhesion molecule, contact site A, from Dictyostelium discoideum

We determined the carbohydrate structures of contact site A from Dictyostelium discoideum. The carbohydrate moieties of contact site A were released by hydrazinolysis. Fractionation of the deacidified oligosaccharide mixture by Bio-Gel P-4 column chromatography revealed that it was composed of four major oligosaccharides. Their respective structures were determined by sequential exoglycosidase digestion. It is known that contact site A consists of two kinds of carbohydrates, I and II. Taking together the previous and the present results, it was deduced that carbohydrate I comprises N-linked oligosaccharides and carbohydrate II O-linked ones. Furthermore, the relative molar contents of GalNAc and GlcNAc in reducing terminal suggested that contact site A contains 67% of N-linked and 33% of O-linked oligosaccharides.

Identification of sialic acids in cell adhesion molecule, contact site A from Dictyostelium discoideum

It has been believed that Dictyostelium discoideum cell membranes contain no sialic acid. In this study, however, we found that contact site A, the cell adhesion molecule of D. discoideum, is a major glycoprotein containing sialic acids. This suggests that sialic acid in non-reducing terminal plays an important role in the cell adhesion in which contact site A is involved.