A complex polysaccharide originating from grape was purified from a re
d wine by size-exclusion and ion-exchange chromatography. This polysac
charide contained 2-O-methylfucose, rhamnose, fucose, 2-O-methylxylose
, arabinose, apiose, galactose, galacturonic and glucuronic acids, and
thiobarbituric acid assay-positive material, presumably 3-deoxy-D-man
no-2-octulosonic acid (Kdo) and 3-deoxy-D-lyxo-2-heptulosaric acid (Dh
a). Methylation structural analysis showed that this polysaccharide is
a typical rhamnogalacturonan II (RG-II), a structurally complex pecti
c polysaccharide that has been isolated previously from the primary ce
ll walls of sycamore. Red wine RG-II presented discrete differences fr
om previously described RG-II's, a greater richness in uronic acids an
d some additional glycosyl linkages, which might be related to the pat
tern of degradation of grape-wall pectic substances by endogenous pect
inolytic enzymes after pressing the berries and subsequent fermentatio
n to wine.