Cell walls linkage analysis

Xylans as true homopolymers occur in seaweeds of the Palmariales and Nemaliales, however, their backbone consists of Xylp residues linked by -(1 3) (Type X3, Fig. la) or mixed -(1 3, 1 -> 4)-glycosidic linkages (Type Xmy Fig. lb). They are assumed mainly to have a structural function in the cell-wall architecture, but a reserve function cannot be ruled out [4]. From the microfibrils of green algae (Siphonales) such as Caulerpa and Bryop-sis sp., X3 was isolated and the structure confirmed by methylation analysis, C-NMR spectroscopy [7], as well as by mass spectrometry of enzymically released linear oligosaccharides up to a degree of polymerization (DP) of... 

The analysis of acidic cell wall polymers (notably pectins) can also be complicated by their tendency to precipitate in acidic media. Jermyn and Isherwood (1956) found that aqueous solutions of pectic polymers from pear cell walls precipitated on the addition of nitric acid. If, however, the sample was warmed prior to the slow addition of acid, precipitation could be avoided. Ford (1982) has shown that quantitative analysis of water-soluble pectic polysaccharides can be improved by depolymerization with a poly-( 1,4-a-D-galacturonide)-glycanohydrolase (EC 3.2.1.15). This treatment can also be used prior to acid hydrolysis to prevent polymer aggregation. Although the recovery of neutral monosaccharides is increased, the stability of the glycosiduronic linkage still prevents its complete hydrolysis. 

The question of how specific LCC preparations represent the whole plant LCC in situ is very important. The answer to this question is often pursued by studying various LCC fractions [18]. However, it is very difficult to extrapolate the information obtained from the analysis of these fractions to the analysis of the whole LCC, especially in a quantitative manner. Ideally, the most representative preparation to elucidate LCC linkages in wood in situ would be the one allowing for the isolation of all lignin/LCC present in wood with minimal alteration, such as completely dissolved cell wall preparations [43,44,82]. However, the structure of the preparations is very complex due to the presence of high amounts of various carbohydrate moieties, especially of those not involved in LCC linkages, which hinder the signals from the... 

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