Structural elucidation of plant cell wall polysaccharides and their derivatives using chromatographic and mass spectrometric techniques

The macromolecular structures of plant cell wall polysaccharides, especially heteropolysaccharides or hemicelluloses, are extremely complex due to the presence of different monosaccharides used as building blocks (that usually are isobaric stereoisomers) and the variations in sequence (e.g. linkage, branching, and distribution of side chains). This structure gets even more complicated in their chemical derivatives, when lack of regioselectivity of such chemical modification procedures is typical. Structural elucidation of polysaccharides involves obtaining data from numerous analytical approaches, each of which gives some structural information, and the assimilation/integration of this data into a chemical structure that rigorously and uniquely fits all the available structural information. The present work focused on developing a methodology for the analysis of plant polysaccharides (xyloglucans and galactoglucomannans) and their derivatives by integrating enzymatic approaches with chromatographic (hydrophilic interaction chromatography, HILIC) and mass spectrometric techniques (matrix-assisted laser desorption/ionization-time-of-flight MS, MALDI-TOF-MS, electrospray ionization MS, ESI-MS, and tandem MS). This methodology will be exploited towards the understanding the structural diversity of plant polysaccharides and the chemo-enzymatic modification mechanisms of their derivatives. Semi-quantitative information about the substitution pattern of these derivatives can also be obtained from this powerful approach. The macromolecular structures of plant cell wall polysaccharides, especially heteropolysaccharides or hemicelluloses, are extremely complex due to the presence of different monosaccharides used as building blocks (that usually are isobaric stereoisomers) and the variations in sequence (e.g. linkage, branching, and distribution of side chains). This structure gets even more complicated in their chemical derivatives, when lack of regioselectivity of such chemical modification procedures is typical. Structural elucidation of polysaccharides involves obtaining data from numerous analytical approaches, each of which gives some structural information, and the assimilation/integration of this data into a chemical structure that rigorously and uniquely fits all the available structural information. The present work focused on developing a methodology for the analysis of plant polysaccharides (xyloglucans and galactoglucomannans) and their derivatives by integrating enzymatic approaches with chromatographic (hydrophilic interaction chromatography, HILIC) and mass spectrometric techniques (matrix-assisted laser desorption/ionization-time-of-flight MS, MALDI-TOF-MS, electrospray ionization MS, ESI-MS, and tandem MS). This methodology will be exploited towards the understanding the structural diversity of plant polysaccharides and the chemo-enzymatic modification mechanisms of their derivatives. Semi-quantitative information about the substitution pattern of these derivatives can also be obtained from this powerful approach.