Yusuke Edashige

Rhamnogalacturonan II from cell walls of Cryptomeria japonica

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.

Xyloglucan from xylem-differentiating zones of Cryptomeria japonica

Xyloglucan was isolated from xylem-differentiating zones of Cryptomeria japonica. Endo-1,4-beta-glucanase digestion of the xyloglucan gave a series of oligosaccharides. These oligosaccharides were purified by gel permeation chromatography and normal-phase HPLC. Glycosyl-residue composition and glycosyl-linkage composition analyses. 1H NMR spectroscopy and FAB-mass spectrometry of the oligosaccharides showed that the xyloglucan was composed of five kinds of oligosaccharide. These oligosaccharides are commonly found in xyloglucan from dicot plants and are characterized as XXXG, XXLG, XXFG, XLLG and XLFG. These results suggest that xyloglucan from gymnosperms has similar structure to that of dicots.

Rhamnogalacturonan I from xylem differentiating zones of Cryptomeria japonica

Rhamnogalacturonan I (RG-I) was isolated from the pectin of the cell wall of xylem differentiating zones of sugi (Cryptomeria japonica D. Don, gymnosperm) by digesting with endo-alpha-1,4-polygalacturonase followed by gel-permeation chromatography. Structure of RG-I was characterized by glycosyl composition and glycosyl linkage analyses, partial acid hydrolysis, and lithium (Li)-treatment in ethylenediamine. The oligosaccharides produced by partial acid hydrolysis showed the backbone of RG-I to be a disaccharide repeating unit of --> 4)-alpha-D-GalpA-(1-->2)-alpha-L-Rhap-(1-->. Arabian and oligogalactosyl side chains were attached at O-4 of rhamnosyl residues of the backbone. Glycosyl composition and glycosyl linkage analyses suggested that the structures and/or the distribution of the arabinan sidechains of sugi RG-I were different from those of sycamore (angiosperm) RG-I.