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Table 1 Structural properties and occurrence of different O-acetylated pectin structures reported below were retrieved from (Pawar et al. 2013)

From: Structural and functional properties of pectin and lignin–carbohydrate complexes de-esterases: a review

Acetylated forms of polysaccharides Properties and occurrence
Rhamnogalacturonan I
Rhamnogalacturonan I, a group of structurally complex pectic polysaccharides. With a repeating backbone composed of diglycosyl [→ 2)-α-l-Rhap-(1 → 4)-α-d-GalpA-(1 →], branched at O-4/O-3 positions by four different side chain types: (1 → 5)-α-l-arabinan, (1 → 4)-β-d-galactan, arabinogalactan-I, and sometimes with arabinogalactan-II (Pawar et al. 2013; Yapo 2011). It is present in primary cell walls of soft and hardwoods (Pawar et al. 2013)
Rhamnogalacturonan II
Rhamnogalacturonan II is a low-molecular weight pectic polysaccharide with 5–10 kDa released upon treatment with endo-α-1,4-polygalacturonases. Structurally, rhamnogalacturonan II is a homogalacturonan backbone containing at least 7–9 residues containing five oligosaccharide side chains such as A–E [as described in Pérez et al. (2003)]. Naturally, rhamnogalacturonan II was found to occur in primary cell walls of soft and hard wood, also in cell walls of growing plant cell walls (Pérez et al. 2003)
Homogalacturonan
Homogalacturonan is one of the major constituents of the pectic polysaccharides. Structurally, it contains long chains of d-galacturonic acid units linked through α-(1 → 4) bonds, which are methyl or acetyl esterified at C-6 position with acetyl/methyl group on O-2 or O-3 positions. It is synthesized from the nucleotide sugars in the Golgi apparatus and are then transported to cell wall in fully methylesterified forms (Sénéchal et al. 2014)