THE CRYSTAL AND MOLECULAR-STRUCTURE OF THE TRISACCHARIDE ERLOSE TRIHYDRATE

Erlose [beta-D-fructofuranosyl O-alpha-D-glucopyranosyl-(1 --> 4)-D-gl ucopyranoside] trihydrate, C18H32 d2O(16).3H(2),O, M(r)=558.48, is ort horhombic, P2(1)2(1)2(1) with a=31.164(7), b=13.111(5), c=11.636(5) An gstrom, and Z=8. The structure was solved by direct methods, and refin ed to R=0.035 for 3926 observed reflections. The unit cell contains tw o independent molecules having a similar conformation. The conformatio n of the alpha-(1 --> 2) glycosidic linkage is similar to that observe d in erlose monohydrate, whereas the conformation of the alpha-(1 --> 4) glycosidic linkage differs significantly. The molecule has no intra molecular hydrogen-bonds except for the minor components of three-cent er bonds, but indirect intramolecular hydrogen-bonds through the water molecules are formed. The hydrogen-bond system in the crystal structu re consists of infinite and finite chains crosslinked by water molecul es.