Table of Contents
International Journal of Carbohydrate Chemistry
Volume 2014 (2014), Article ID 347381, 6 pages
Research Article

Structure of a Rhamnogalacturonan Fragment from Apple Pectin: Implications for Pectin Architecture

Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078-3035, USA

Received 21 July 2014; Revised 15 October 2014; Accepted 25 October 2014; Published 14 December 2014

Academic Editor: John F. Kennedy

Copyright © 2014 Xiangmei Wu and Andrew Mort. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A commercial apple pectin was sequentially digested with the cloned enzymes endopolygalacturonase, galactanase, arabinofuranosidase, xylogalacturonase, and rhamnogalacturonan hydrolase. The rhamnogalacturonan hydrolase-generated oligosaccharides were separated by ultrafiltration, anion exchange, and size-exclusion chromatography. Fractions from the ion exchange chromatography were pooled, lyophilized, and screened by MALDI-TOF MS. An oligosaccharide (RGP14P3) was identified and its structure, α-D-GalpA--α-L-Rhap--α-D-GalpA--α-L-Rhap--α-D-GalpA, determined by 1D and 2D NMR spectrometry. This oligosaccharide probably represents a direct connection between homogalacturonan and rhamnogalacturonan in pectin. Alternatively, it could indicate that the nonreducing end of rhamnogalacturonan starts with a galacturonic acid residue.