The polysaccharide gum obtained from Venezuelan Acacia tortuosa contai
ns galactose, arabinose, xylose as ti aces, glucuronic acid and its 4-
O-methyl analogue. C-13 NMR spectroscopy, in combination with chemical
methods, was applied in this study. The preparation of degraded produ
cts, via hydrolytic-and Smith-degradations, indicated interesting stru
ctural features of the polysaccharide. The core of the structure is es
sentially a branched beta-(1 --> 3) galactan. Arabinose, glucuronic ac
id and its 4-O-methyl analogue could not be totally removed from the c
ore. Arabinose (as furanose and pyranose residues) exist as terminal a
nd 3-O-linked, while xylose, glucuronic acid and its 4-O-methyl deriva
tive are probably terminal residues. The high content of proteinaceous
material in A. tortuosa gum must be investigated in order to determin
e whether there are many polysaccharide-protein covalent linkages. (C)
1997 Elsevier Science Ltd.