Glucuronic acid directly linked to galacturonic acid in the rhamnogalacturonan backbone of beet pectins.
Sugar-beet pulp was de-esterified and submitted to 72 h hydrolysis by 0.1 M HCl at 80 degrees C. Oligomers containing a single glucuronic acid (GlcA) moiety in addition to n(>/= 2) repeats of the dimer -->4)-alpha-D-GalpA-(1-->2)-alpha-L-Rhap-(1--> were isolated from the hydrolysate by ion-exchange and gel-permeation. Glycosyl linkage composition analysis and 1H NMR studies indicated that the GlcA was attached to O-3 of a galacturonic acid (GalA) residue, as shown for the two pentamers beta-D-GlcpA-(1-->3)-alpha-D-GalpA-(1-->2)-alpha-L-Rhap-(1-->4)-alpha-D-GalpA-(1-->2)-L-Rhap and alpha-D-GalpA-(1-->2)-alpha-L-Rhap-(1-->4)-[beta-D-GlcpA-(1-->3)]-alpha-D-GalpA-(1-->2)-L-Rhap. Substitution by GlcA was estimated as occurring on one GalA residue out of 72 in the rhamnogalacturonan fraction of the backbone of beet pectins.
Renard
C M
CM
Unité de Recherches sur de Polysaccharides, leurs Organisations et Interactions, Institut National de la Recherches Agronomique, Centre de Recherche Agro-Alimentaire de Nantes, France. crenard@rennes.inra.fr
Crépeau
M J
MJ
Thibault
J F
JF
D027461:Beta vulgaris / Q000378:metabolism*; D002852:Chromatography, Ion Exchange; D005965:Glucuronates / Q000737:chemistry* / Q000378:metabolism; D020723:Glucuronic Acid / Q000737:chemistry*; D006027:Glycosides / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry*; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D010368:Pectins / Q000737:chemistry* / Q000378:metabolism; D013997:Time Factors
D005965:Glucuronates; D006027:Glycosides; D006603:Hexuronic Acids; C007819:galacturonic acid; D010368:Pectins; D020723:Glucuronic Acid