Showing papers by "Anne Imberty published in 1988"
TL;DR: A new three-dimensional structure of the crystalline part of A-starch is described in which the unit cell contains 12 glucose residues located in two left-handed, parallel-stranded double helices packed in a parallel fashion; four water molecules are located between these helices.
561 citations
TL;DR: Wu et al. as mentioned in this paper proposed a new three-dimensional structure of B-starch in which the unit cell contains 12 glucose residues located in two left-handed, parallel-stranded double helices packed in a parallel register; 36 water molecules are located between these helices.
Abstract: A new three-dimensional structure of B-starch is proposed in which the unit cell contains 12 glucose residues located in two left-handed, parallel-stranded double helices packed in a parallel register; 36 water molecules are located between these helices. Chains are crystallized in the hexagonal space group P61, with lattice parameters a = b = 1.85 nm, c = 1.04 nm. The space group symmetry was derived from an exhaustive analysis of the large body of structural studies published so far. Diffraction data used in this work were taken from the previously reported x-ray fiber diffractogram [H.C. Wu and A. Sarko (1978), Carbohydrate Research, 61, 7–25] after adequate reindexing. The final R factor is 0.145 for the three-dimensional data. The repeating unit consists of a maltose molecule where the glucose residues have the 4C1 pyranose conformation and are α(1 → 4) linked. The conformation of the glycosidic linkage is characterized by torsion angles (Φ, Ψ) that take the values (83.8°, −144.6°) and (84.3°, −144.1°), whereas the valence angles at the glycosidic bridge have a magnitude of 115.8° and 116.5°, respectively. The primary hydroxyl groups exist in a gauche–gauche conformation. There is no intramolecular hydrogen bond. Within the double helix, interstrand stabilization is achieved without any steric conflict and through the occurrence of O(2)…O(6) type of hydrogen bonds. The model presented here, with an hydration around 27% w/w, corresponds to a well-ordered crystalline sample, since all the water molecules could be located with no apparent sign of a disorder. Half of the water molecules are tightly bound to the double helices; the remainder forms a complex network centered around the sixfold screw axis of the unit cell. The consistency of the present structural model, with both physicochemical and biochemical aspects of the crystalline component of tuber starch granules, is analyzed.
493 citations
TL;DR: The crystal structure of α-panose has been established by direct methods from 1491 independent reflections, and refined to a final R -value of 0.077 as discussed by the authors, which is made possible because of a unique, eclipsed orientation of the primary hydroxyl group at O-6″.
44 citations
15 Nov 1988
TL;DR: Three aspects of the specificity of oligosaccharide-protein interactions will be discussed and the thermodynamic model can be extended to the binding of glycoproteins to receptors and the high affinity of these interactions explained by either multivalency or fixation of the oligosACcharide in the 'correct' three-dimensional structure through interaction with the protein moiety.
20 citations