Uridine diphosphate α- d -galactofuranose, an intermediate in the biosynthesis of galactofuranosyl residues

An increasing number of oligo-and poly-saccha- rides from a variety of micro-organisms have been shown to contain D-galactose in the 1,4-furanose ring form.It is noteworthy that several of the type-specific substances of Pneumococcus spp.contain this unit (Roberts, Buchanan & Baddiley, 1963; Rao, Buchanan & Baddiley, 1966; Rao, Watson, Buchanan & Baddiley, 1969).More recently a galactofuranosyl residue has been found in the 0-antigenic portion of a lipopolysaccharide (Berst et al. 1969).Other micro-organisms known to produce polysaccharides containing such residues in- clude Mycoplasma mycoides var.mycoides (Plackett & Buttery, 1964), Gibberella fujikuroi (Siddiqui & Adams, 1961), Peltigera horizontalis (Lindberg, Silvander & Wachtmeister, 1964), Bacteroides symbiosus (Reeves, Latour & Lousteau, 1964) and Penicillium chrysogenum (Myazaki & Yadomae, 1969).Galactocarolose, an extracellular ,B-D- (1 --5)-linked polygalactofuranose, produced by Penicillium charlesii G. Smith (Haworth, Raistrick & Stacey, 1937; Gorin & Spencer, 1959) was the first polysaccharide found to be composed of these units.So far little is known about the biosynthesis of galactofuranosyl residues, but if they are transferred to polymer chains from nucleotide intermediates in the manner usual for glycoside biosynthesis then their origin presents a particularly interesting problem, as the only known nucleotide containing galactose is UDP-galactopyranose.Investigations on the biosynthesis of galactocarolose have now led to the isolation and characterization of a new nucleotide containing galactofuranose and this has been shown to be an intermediate for the introduction of these units into the polymer.Hexofuranose nucleotides were hitherto unknown.A cell-free enzyme preparation from finely ground mycelia of Penicillium charlesii G. Smith, grown for 14 days on the Raulin-Thom medium, was prepared