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-α-1,4-polygalacturonase followed by gel-permeation chromatography. Structure of RG-1 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)-α-d-GalpA-(1 → 2)-α-l-Rhap-(1 →. Arabinan 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. The backbone of sugi (Cryptomeria japonica D. Don, gymnosperm) rhamnogalacturonan I (RG-I) comprises a disaccharide repeating unit → 4)-α-d-Galp A-(1 → 2)-α-l-Rha p-(1 →. Arabinan and oligogalactosyl sidechainds are attached at O-4 of rhamnosyl residues of the backbones