Cell walls periodate oxidation

Trifluoroacetic acid is volatile, and thus readily removed. This acid was used by Albersheim and coworkers for the hydrolysis of plant cell-walls,39 and has since been employed for cell walls,40-43 plant mucilages,44 blood-group oligosaccharides,45 peptidogalactoman-nans,46 heparin,47 and disaccharides in blood and urine.48,49 It has also been suggested as an alternative to 6 M hydrochloric acid in the determination of amino sugars,50 and for the hydrolysis of polyalcohols produced by periodate oxidation of polysaccharides.503 Lee... 

Poly(ribitol phosphate) synthetase has been found in particulate fractions from Staphylococcus aureus H, and Lactobacillus plantatrum.lt ll-m The bulk of the activity in Lactobacillus plantarum was in crude, cell-wall preparations, and the enzyme is apparently located in the membrane, although intimate association with the wall itself has been suggested. Unlike the natural teichoic acid, the enzymically synthesized ribitol phosphate polymer was readily extracted with phenol hydrolysis by acid and by alkali gave the expected products, and oxidation with periodate indicated a chain length of 5-9 units, a value which compares well with that of 8 units for the natural polymer in the walls of this organism. 

The use of controlled periodate oxidation in structural polysaccharide chemistry has been reviewed (Lindberg et al., 1975). In this section only its general application to plant cell walls will be considered. 

P-Mannan is water-insoluble and solubilizing it requires very strong alkali, cuprammonium or derivatization. X-ray and electron diffraction show that mannan has a ribbon-like conformation, similar to cellulose, with the 2-OH axial instead of equatorial. In seeds (palm, coffee, caraway) a few (<5%) of a-Gal groups are attached to the hydroxymethyl and in seaweeds a small percentage (<5) of Glc residues may occur in the chain. A pure P(l-4) mannan has been extracted from cell walls of the siphonous green alga Codium latum as the methylol mannan with paraformaldehyde dimethylsulphoxide. It was purified by size exclusion chromatography in dimethyl sulphoxide and recovered by the addition of water or methanol and could be re-dissolved in hot dimethyl sulphoxide. Infra-red and n.m.r. spectroscopy and periodate oxidation confirmed the unbranched P(l-4) structure [185]. 

TABLE 3- Periodate oxidation of the cell wall glucan of Pyricularia oryzae. 

The simplest possible structure proposed for the cell wall glucan of Pyricularia oryzae, based on the results of methylation, periodate oxidation and fragmentation analysis is shown in Fig. 1. 

The cell walls of Streptococcus pneumoniae contain a teichoic acid (C polysaccharide) composed of 2-acetamido-2-deoxy-D-galactose, 2-acetamido-4-amino-2,4,6-trideoxy-D-hexose, ribitol phosphate, choline phosphate, and D-glucose. From the results of periodate oxidation and methylation analysis, together with an examination of the n.m.r. spectra, the structure (1) has been proposed. It is speculated that the C-3 hydroxy-group of the chain terminal diaminotrideoxy-D-hexose unit is glycosylated with isomaltose. 

Methylation analysis of the tetra-arabinosides isolated from primary cell walls of tomato and sycamore indicates that the arabinosyl residues are terminal and 2- and 3-linked (71, 123). Akiyama and Kato (2) have studied the hydroxyproline arabinosides obtained from suspension-cultured cells of tobacco (Nicotiana tabacum). These workers used periodate oxidation (Smith degradation), methylation analyses, NMR, and optical rotation to show that the structure of the hydroxyproline tetra-arabinoside is Araf-(1 3)-Araf-(l - 2)-Arar(l - 2)-Arar(l - 4)-hydroxyproline. 

In continuous flow mode, the stability experiments were carried out for a total period of 48 and 100 h. Two different solutions (0.1 and 0.2 mmol l-1) of hydrogen peroxide were continuously passed in the wall-jet cell and the signal was first recorded for a total of 48 h. A decrease of around 10% and 15%, respectively, was detected at the end of 48 h of monitoring for 0.1 and 0.2 mM. Under these conditions (presence of hydrogen peroxide and an applied potential), PB is forced to continuously change its oxidative state according to the following equation (Eq. (24.1)) [28] ... 

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