Galactofuranosyl-containing glycans: occurrence, synthesis and biochemistry

CARLA MARINO; CAROLA GALLO -RODRIGUEZ; ROSA M. DE LEDERKREMER

Glycans: Biochemistry, Characterization and Applications

Nova Science Publishers

Año: 2012; p. 207 - 268

Galactofuranosyl units (Galf), mainly in the -configuration, are constituents of infectious microorganisms, such as the Mycobacteria, trypanosomatids like Trypanosoma cruzi and Leishmania, and fungi like Aspergillus fumigatus. The absence of Galf in mammalian cells points to Tthe metabolic pathways involved in the biosynthesis of the microbial glycoconjugates containing Galf areas attractive targets for the development of therapeutic agents, because Galf are absent in mammalian cells. The enzymes involved in the biosynthesis of Galf-containing molecules are the UDP-galactopyranosyl mutase, which catalyzes the interconversion of UDP-Galp into UDP-Galf, the donor of Galf units UDP-Galf, and the galactofuranosyltransferases, which are responsible for the incorporation of the sugar into the glycoconjugates. In some species, -D-galactofuranosidases have been identified as responsible for the degradation of the D-Galf containing glycoconjugates. Although the metabolism of -D-galactofuranosides has been extensively studied, the -D-Galf biosynthetic and metabolic machinery still remain unclear. The description of the enzymes involved in its metabolism is important, considering that glycoconjugates containing -D-Galf residues have been also described in several pathogenic microorganisms including bacteria, such as Escherichia coli and Streptococcus pneumoniae, and fungi, such as Paracoccidioides brasiliensis, the causative agent of paracoccidioidomycosis. It is interesting that in the latter Galf is present in both anomeric configurations. Recent methods for the synthesis of galactofuranosides are included in this chapter.