Galactofuranosyl-containing Glycans: Occurrence, Synthesis and Biochemistry

MARINO, CARLA; GALLO-RODRIGUEZ, C.; MUCHNIK DE LEDERKREMER, R

Glycans: Biochemistry, Characterization and Applications

Nova Science Publishers

Año: 2012; p. 207 - 268

Galactofuranosyl  units  (Galf),  mainly  in  the  â-configuration,  are  constituents  of infectious microorganisms, such as the Mycobacteria, trypanosomatids like Trypanosoma cruzi and Leishmania, and fungi  like Aspergillus fumigatus.  The  metabolic pathways involved  in  the  biosynthesis  of  the  microbial  glycoconjugates  containing  Galf  are attractive targets for the development of  therapeutic agents, because Galf is 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, and the galactofuranosyltransferases, which are responsible for the incorporation of the sugar into the glycoconjugates. In some species, â-D-galactofuranosidases have been identified as responsible for the degradation of the D-Galf containing glycoconjugates. Although the metabolism of â-D-galactofuranosides  has been extensively  studied, the á-D-Galf biosynthetic and metabolic machinery still remain unclear. The description of the enzymes involved in its metabolism is important, considering that glycoconjugates containing   á-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.