- The preparation and susceptibility to hydrolysis of novel O-galacturonoyl derivatives of carbohydrates
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D-Galacturonic acid or (1->4)-α-D-galacturonan reacted in aqueous pyridine in the presence of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide with alcohols to yield esters.The alcohols that gave high yields of D-galacturonoyl derivatives were primary and included methanol, ethanol, 1-propanol, D-glucose, D-galactose, methyl β-D-glucopyranoside, methyl β-D-galactopyranoside, and cellulose.D-Galacturonic acid itself readily gave an O-D-galacturonoyl-D-galacturonic acid.The proposed structure of one compound, methyl 6-O-D-galacturonoyl-β-D-glucopyranoside, was supported by 1H and 13C NMR data and the FAB mass-spectral data.Each ester was hydrolysed at pH 11 and 25 deg C within 1 h.O-D-Galacturonoyl-D-glucose was considerably more alkali labile than O-polygalacturonoyl-D-glucose, and O-D-galacturonoylcellulose had an intermediate stability.The esters were relatively stable to cold acid, but could be hydrolysed by M trifluoroacetic acid at 100 deg C for 1 h.The esters tested were resistant to digestion by "Driselase", although the glycosidic bonds of O-polygalacturonoyl D-glucose were hydrolysed to yield O-oligogalacturonoyl-D-glucoses of low molecular weight.The possible application of these analytical methods to the detection of O-uronoyl-type cross-links in cell-wall polysaccharides is discussed.
- Brown, John A.,Fry, Stephen C.
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