Protocols for isolating and characterizing polysaccharides from plant cell walls: a case study using...

Area of Science:

• Plant cell wall biology
• Carbohydrate chemistry
• Biomass valorization

Background:

• Plant cell walls contain diverse polysaccharides like cellulose, hemicellulose, and pectin.
• Pectin valorization is gaining interest for biomass deconstruction and material science.
• Incomplete knowledge of pectin structure limits its utilization.

Purpose of the Study:

• To present a workflow for characterizing complex polysaccharide primary structures.
• To use rhamnogalacturonan-II (RG-II) as a model for polysaccharide analysis.
• To establish principles for relating saccharide structure to function.

Main Methods:

• Isolation of RG-II from plant sources (celery, duckweed) and red wine.
• Size-exclusion chromatography for purification.
• Mass spectrometry (MS)-based techniques for glycosyl composition and linkage analysis.
• Proton nuclear magnetic resonance (¹H-NMR) spectroscopy for structural investigation.

Main Results:

• Successfully isolated RG-II using chemical/enzymatic treatments and chromatography.
• Determined glycosyl residue and linkage compositions of RG-II and derived oligosaccharides.
• Identified non-glycosyl modifications (methyl-ethers, esters) on RG-II oligosaccharides.
• Characterized RG-II dimerization using size-exclusion chromatography.

Conclusions:

• Pectic polysaccharide complexity hinders valorization efforts.
• Demonstrated a workflow for isolating and characterizing polysaccharides using chromatography, MS, and NMR.
• The presented principles can be applied to other saccharide structures for functional analysis.