Figure 3.

Basic structure of the homogalacturonan (left) and rhamnogalacturonan-I (right) backbones. In homogalacturonan, the carboxyl groups in C-6 are partially methylesterified (blue). The hydroxyl groups in C-2 and C-3 are partially acetylated (green). In rhamnogalacturonan-I, Rhap residues are substituted at C-4, indicated in yellow. The backbone residues of GalpA may be O-acetylated on C-2 and/or C-3, indicated in purple.