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Abstract
The pectic polysaccharides isolated from cell walls of xylem-differentiating zones
of sugi (Cryptomeria japononica) were degraded with endo-alpha-(1-->4)-polygalacturonase
and the polysaccharides, composed mainly of rhamnogalacturonan II (RG-II), were obtained
from the degradation products. These polysaccharides consisted of rhamnosyl, fucosyl,
arabinosyl, xylosyl, galactosyl, glucosyl, galacturonic acid, glucuronic acid and
the characteristic sugars of RG-II, namely, 2-O-methylfucose, 2-O-methylxylose, apiose,
aceric acid and thiobarbituric acid assay-positive glycosyl ¿probably, 3-deoxy-D-manno-2-octulosonic
acid (Kdo) and 3-deoxy-D-lyxo-heptulosaric acid (Dha)¿. The polysaccharides contained
the glycosyl residues of RG-II, besides small amounts of the glycosyl linkages of
RG-I. The RG-II was structurally analysed by partial acid hydrolysis and lithium treatment
in ethylenediamine. The glycosyl sequences of three compounds generated by partial
hydrolysis were not identical to the partial structure of the sycamore (Acer pseudoplatanus)
RG-I and RG-II structures previously proposed by Albersheim et al. Furthermore, five
novel glycosyl sequences were detected in the products from lithium treatment. The
results suggest that the structure of sugi RG-II is somewhat different from that of
sycamore RG-II.