Table of Contents
International Journal of Carbohydrate Chemistry
Volume 2011, Article ID 964521, 11 pages
http://dx.doi.org/10.1155/2011/964521
Review Article

Pectin Rhamnogalacturonan II: On the “Small Stem with Four Branches” in the Primary Cell Walls of Plants

1Unit of Training and Research in Food Science and Technology (UFR-STA), University of Abobo-Adjamé (UAA), 22 BP 759 Abidjan 22, Cote D’Ivoire
2Unit of Pedagogy and Research in Biochemistry and Microbiology, Regional Unit of Higher Education (URES), BP 150, Daloa, Cote D’Ivoire

Received 11 June 2011; Accepted 25 September 2011

Academic Editor: J. F. Vliegenthart

Copyright © 2011 Beda M. Yapo. 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.

Abstract

Rhamnogalacturonan II (RG-II) is a type of block copolymer of complex pectins that represents a quantitatively minor component of the primary cell walls of land (vascular) plants. The structural composition of RG-II is almost totally sequenced and appears to be remarkably conserved in all tracheophytes so far examined. The backbone of RG-II, released from complex (cell wall) pectins by endo-polygalacturonase (Endo-PG) treatment, has been found to contain up to 15 (1→4)-linked-α-D-GalpA units, some of which carry four well-defined side chains, often referred to as A-, B-, C-, and D-side chains. Nevertheless, the relative locations on the backbone of these four branches, especially the A chain, remain to be ascertained. A combination of different data suggests that neither the terminal nonreducing GalA nor the contiguous GalA unit is likely to be the branching point of the A chain, but probably the ninth GalA residue from the reducing end, assuming a minimum backbone length of 11 (1→4)-linked-α-d-GalpA. The latest reports on RG-II are here highlighted, with a provided update for the macrostructure and array of functionalities.