Pectic plant cell wall, arabinans

Zujovic et al investigated the mobility of veiy mobile polysaccharides in plant cell walls by NMR method. Mobility of such polysaccharides as arabinan and galactan side chains of pectic polysaccharide rhamnoga-lactouronan I in two apple cultivars was evaluated by the solid-state C NMR. The authors used two pulse phase modulation (TPPM) decoupling which improved the resolution of cross polarisation (CP) and single pulse excitation (SPE) NMR spectra. This methodology facilitated the mobility estimation of mobile polysaccharides in apples cell walls. 

Pectic substances are the glues to plant cells and exist predominately in middle lamella between cell walls. The American Chemical Society defined the terms protopectin, pectinic acid and pectic acid (21). The native protopectin is a long chain, alpha-1, 4-D-galacturonic acid polymer, interspersed with alpha-1,2-L-rhamnose residues. Shorter polymers, galactans and arabinans exist and are bonded covalently with the main chain (22). Many types and different amounts of side chains exist in various plant tissues. 

Galactans are found in association with galacturonans and arabinans in the pectic substances, which occur without exception in all the higher plants. These gelling factors occur in the cell walls, in the cell itself, and in the intercellular layers where they appear to promote cell adhesion. Citrus fruit... 

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