NMR study of the galactomannans of Trichophyton mentagrophytes and trichophyton rubrum

Kyoko Ikuta, Nobuyuki Shibata, John S. Blake, Mark V. Dahl, Robert D. Nelson, Kanehiko Hisamichi, Hidemitsu Kobayashi, Shigeo Suzuki, Yoshio Okawa

Research output: Contribution to journalArticlepeer-review

51 Scopus citations

Abstract

Around 90% of chronic dermatophyte infections are caused by the fungi Trichophyton mentagrophytes and Trichophyton rubrum. One of the causes of the chronic infection resides in the immunosuppressive effects of the cell-wall components of these organisms. Therefore we have attempted to identify the chemical structure of galactomannan, one of the major cell-wall components. The cell-wall polysaccharides secreted by T. mentagrophytes and T. rubrum were isolated from the culture medium and fractionated into three subfractions by DEAE-Sephadex chromatography. Analysis of each subfraction by NMR indicated that there are two kinds of polysaccharides present, i.e. mannan and galactomannan. The mannan has a linear backbone consisting of α1,6-linked mannose units, with α1,2-linked mannose units as side chains. The core mannan moiety of the galactomannan was analysed by a sequential NMR assignment method after removing the galactofuranose units by acid treatment. The result indicates that the mannan moiety has a linear repeating structure of α1,2-linked mannotetraose units connected by an α1,6 linkage. The H-1 signals of the two intermediary α1,2-linked mannoses of the tetraose unit showed a significant upheld shift (Δδ = 0.05-0.08 p.p.m.), due to the steric effect of an α1,6-linked mannose unit. The attachment point of the galactofuranose units was determined at C-3 of the core mannan by the assignment of the downfield-shifted 13C signals of the galactomannan compared with those of the acid-modified product. In these galactomannans there were no polygalactofuranosyl chains which have been found in Penicillium charlesii and Aspergillus fumigatus.

Original languageEnglish (US)
Pages (from-to)297-305
Number of pages9
JournalBiochemical Journal
Volume323
Issue number1
DOIs
StatePublished - Apr 1 1997

Fingerprint Dive into the research topics of 'NMR study of the galactomannans of Trichophyton mentagrophytes and trichophyton rubrum'. Together they form a unique fingerprint.

Cite this