Structure of the repeating units in the rhamnogalacturonic backbone of apple, beet and citrus pectins

✍ Scribed by Catherine M.G.C. Renard; Marie-Jeanne Crépeau; Jean-François Thibault

• Book ID: 102991686
• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 512 KB
• Volume: 275
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(95)00140-o

✦ Synopsis

After controlled acid hydrolysis of de-esterified apple, beet and citrus pectins, a fraction rich in galacturonic acid and rhamnose was isolated and further fractionated by ion-exchange chromatography. The main peaks, representing for each pectin > 30% of the rhamnose-rich fraction, and 50-78% of its rhamnose, were composed of rhamnose and galacturonic acid in equimolar proportions. Gel-permeation chromatography showed series of homologous oligomers with polymerisation degrees of 6 to 20. NMR data indicated a repetitive structure based on the ~ 4)-a-D-GalpA-(1 ~ 2)-a-L-Rhap-(1 ~ unit, where the reducing ends were rhamnose units and the non-reducing ends galacturonic acid residues. The same rhamnogalacturonan oligomers were obtained from apple, beet and citrus pectins.