CONFORMATION OF (1-]3)-ALPHA-D-GLUCAN TRIBENZOATE

The molecular conformation of (1 --> 3)-alpha-D-glucan tribenzoate (TB G) was studied by X-ray diffraction measurements coupled with a confor mational analysis. Although the fiber pattern obtained was of very low crystallinity, the presence of a meridional reflection at the 5th lay er line indicated that the TBG molecule took a five-fold helical confo rmation with a 19.63 angstrom fiber repeat. A conformational analysis on the five-fold helix, which was done by calculating van der Waals' r epulsion energy between non-bonded atoms comprising the TBG chain, sug gested that the most preferable energy-based conformation was -5/1, a left-handed five-fold helix.