CONFORMATION OF POLY[(1-]3)-ALPHA-D-MALTOTRIOSE], A MAJOR PART OF THEELSINAN MOLECULE, STUDIED BY X-RAY-DIFFRACTION COUPLED WITH CONFORMATIONAL-ANALYSIS

The molecular conformation of elsinan, consisting of (1 --> 3)-alpha-l inked maltotriose and alpha-maltotetraose units, was studied by X-ray diffraction coupled with conformational analysis. The quality of the X -ray fiber pattern obtained from elsinan was very poor, but the layer line spacing (45 angstrom), the probable presence of (005) reflection and a similar pattern with the powder pattern of a low molecular weigh t poly[(1 --> 3)-alpha-maltotriose] segment (DP about 35) suggested th at the poly[(1 --> 3)-linked-alpha-maltotriose] segment (MTR part) of elsinan chain took a five-fold helical structure with an asymmetric un it of maltotriose. Conformational analysis for the five-fold helix of the MTR part pointed out that two left handed helices, - 5/1 and - 5/2 , were energetically probable.