ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
X-ray investigation of a crystalline complex between dimethyl sulfoxide (DMSO) and amylose indicates a sevenfold helical structure having an orthogonal unit cell: a = 30.23 Å, b = 28.18 Å, and C = 7.91 Å (helix axis). This helical amylose results from precipitation of amylose in DMSO solutions under suitably dry conditions using toluene as a precipitating agent. Analyses show a molar ratio of 0.95:2:0.4:0.08 for DMSO, amylose glucose units, water, and toluene, respectively. DMSO and amylose combine in at least two crystalline conformations, sixfold and sevenfold helices. The amount of water present influences the resulting conformation. The existence of the sevenfold helical solid indicates that the amylose sevenfold helix has greater stability than previously recognized by conformational energy calculations. In general, potential energy calculations cannot be correct that ignore the influence of guest molecules and their effects upon the maltose residue conformation and that lead to a sixfold helix as the most probable structure.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.1972.360111216
