Pectic rhamnogalacturonan

Fig. 1.—Proposed Structure for Pectic Rhamnogalacturonan (I) of Primary Cell-Walls of Dicots (After Alberslieim5-64). [Linear sequences of galacturonic acid (Gal) are interrupted by rhamnosyl (Rha) residues, half of the latter being covalently attached to arabinogalactans.]... 

The first paper on the bioactive polysaccharides from Glycyrrhiza uralensis roots was published in 1996 by Kiyohara et al. [57]. They isolated a pectic type polymer with anti-complementary and mitogenic activity that was an acidic pectin, possibly containing rhamnogalacturonan type I as part of the total structure. Degradation of the uronic acid part of the molecule decreased both types of bio activities. The neutral oligosaccharide chains were shown to retain some of the activities of the native polymer, but it was suggested that they should be attached to the acidic core to retain maximum activity. 

Rhamnogalacturonan 11 (RG-11) is a structurally complex, pectic polysaccharide that is present in the primary cell-walls of higher plants. It is composed of 60 glycosyl residues, and is a very complex molecule indeed. For example, on acid hydrolysis, at least ten different monosaccharides are formed, including the novel aceric acid (30), which is the only branched-... 

There are three pectic polysaccharides in all primary cell walls that have been studied these are rhamnogalacturonan n, rhamnogalacturonan I, and homogalacturonan. 

The Pectic Polysaccharide Rhamnogalacturonan II is a major Component of the Polysaccharides present in Fruit-derived Products. 

The polysaccharide composition and structure of pectic polysaccharides present in fruit-derived products have been the aim of numerous studies [14-19]. However, the attention of scientists was focused on the analysis of rhamnogalacturonan I or so-called pectic hairy regions. As far as we know, the presence of RG-II in fruit juices has not been reported. 

Fig 2 Immunogold negative staining, with a monoclonal antibody (JIM 5 (13)) that recognises a relatively unesterified pectic epitope, of rhamnogalacturonans extracted from onion cell walls. Arrows indicate 5 nm colloidal gold particles. Scale bar represents 200nm. 

An, J., O Neill, M.A., Albersheim, P., and Darvill, A.G. (1995) Isolation and structural characterization of B-D-glucosyluronic acid-containing oligosaccarides from the cell-wall pectic polysaccharide, rhamnogalacturonan I. CarbohydrMes. 252 235-243. 

Echinacea-polysaccharide II consists of arabino-3,6-P-galactan part, rhamnogalacturonan part and arabinan part [5], therefore it is suggested that the polysaccharide may be certain ramified region of pectic polysaccharide. 

Schols HA, Voragen AGJ, Colquhoun IJ (1994) Isolation and characterization of rhamnogalacturonan-oligomers, liberated during degradation of pectic hairy regions by rhamnogalacturonase. Carbohydr Res 256 97-111... 

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