The preparation and susceptibility to hydrolysis of novel O-galacturonoyl derivatives of carbohydrates.
D-Galacturonic acid or (1-->4)-alpha-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 beta-D-glucopyranoside, methyl beta-D-galactopyranoside, and cellulose. D-Galacturonic acid itself readily gave an O-D-galacturonoyl-D-glacturonic acid. The proposed structure of one compound, methyl 6-O-D-galacturonoyl-beta-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 degrees 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 degrees 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
J A
JA
Division of Biological Sciences, University of Edinburgh, United Kingdom.
Fry
S C
SC
D002240:Carbohydrate Sequence; D002473:Cell Wall / Q000737:chemistry; D004187:Disaccharides / Q000138:chemical synthesis*; D004952:Esters / Q000138:chemical synthesis; D005697:Galactosides / Q000737:chemistry; D005960:Glucosides / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry*; D006868:Hydrolysis; D008969:Molecular Sequence Data; D010368:Pectins / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry; D014990:Xylans / Q000737:chemistry
D004187:Disaccharides; D004952:Esters; D005697:Galactosides; D005960:Glucosides; D006603:Hexuronic Acids; D011134:Polysaccharides; D014990:Xylans; C007819:galacturonic acid; D010368:Pectins