The methanol‐, ethanol‐, and 1‐propanol‐amylose “V” complexes have been prepared and their unit cell dimensions calculated from their x‐ray powder patterns. The small unit cell (with 13.0 A. helix diameter), previously reported to occur only after the complete removal of water, has been observed for the wet methanol and ethanol complexes. In fact, a methanol complex containing as much as one mole of water per glucose residue had the small unit cell. Residual water and residual complexing agent analyses have shown that complexes dried to constant weight under stringent conditions retain as much as one mole of water and one‐quarter mole of complexing agent per helix turn. It has been concluded that the specific organic complexing agent plays an important role in dictating the unit cell size.
SynopsisThis investigation has shown that it is possible to prepare V complexes of amylose from dimethyl sulfoxide solutions. Methanol, n-propanol, acetone, and methyl ethyl ketone complexes have been prepared and their unit cell dimensions calculated from their x-ray powder patterns. The small unit cell, with a helix diameter of 13.0 A., observed with a wet methanol complex from aqueous system, is also observed here. However, the wet and thoroughly dried ketone complexes prepared from DMSO have the larger helix diameter of 13.7 A. The results indicate that factors other than the size or type of complexing agent are important in determining the helix diameter of the amylose V complex. They also indicate that these factors are complex and probably interdependent. The effect of temperature on the helix diameter was explored.
SynopsisA dry form of amylose has been prepared that is easily soluble in water at all temperatures. It can go into solution even a t high concentrations (up to lo'%), forming very viscous liquids that are indistinguishable in appearance and properties from those prepared by autoclaving of retrograded amyloses. The solutions gel spontaneously upon standing. Two criteria were found to be important in the preparation of watersoluble amyloses: first, their molecular weight has to exceed 200,000; secondly, they must be dried from solution in a rapid manner, such as by drum-or spray-drying. Data from x-ray diffraction, infrared absorption, and iodine and water vapor absorption indicate the material to be an amorphous, substantially unbonded form of amylose, free of significant amounts of helical configuration. Data from @-amylase digestion limits and intrinsic viscosities on the water solutions of these amyloses indicate that they form true solutions in water and not merely dispersions.
The acetone‐ and methyl ethyl ketone‐amylose V complexes have been prepared and their unit cell dimensions calculated from their x‐ray powder patterns. This work demonstrates the size‐determining effect of these two ketones on the amylose V complex. The small unit cell, with a helix diameter of 13.0 A., observed with the wet methanol and ethanol complexes, is not found with the acetone and methyl ethyl ketone complexes. The wet ketone‐amylose V complexes and the thoroughly dried ketone complexes have the larger helix diameter of 13.7 A. This is the first report of an anhydrous amylose V complex with the expanded helix diameter. Thorough extraction of the methyl ethyl ketone‐amylose complex with methyl alcohol did not change the 13.7 A. helix diameter, although methyl alcohol‐extracted acetone‐amylose complex resulted in a mixture of the 13.0 A. and 13.7 A. helix diameter types. This work demonstrates the size effect of the lower molecular weight ketones on the amylose crystalline structure.
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