Three-dimensional structure of guaran

The galactosyl side chains were inadvertently fixed in the improper β-d configuration in a previously reported morphology of guaran [R. Chandrasekaran, A. Radha, and K. Okuyama, Carbohydr. Res. 306 (1998) 243–255]. This defect has now been rectified. In the correct α-d configuration, the 2-fold guaran helix is stabilized by periodic intramolecular hydrogen bonds between the galactosyl side chains and the mannan main chain. Ordered water molecules are responsible for the formation and association of sheets of guaran helices in the crystalline lattice. The crystallographic R-value is 0.14 for the revised model. The guaran molecular structure and packing arrangement are readily amenable to the entire galactomannan family.