The electrophoretic mobility and fractionation of complexes of hydrolysis products of amylose with iodine and potassium iodide

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Abstract
Partial hydrolysates of amylose are resolved into 4 separate colored zones by zone electrophoresis in agar jelly in the presence of I-iodide. Effects on the resolution of varying the I-iodide concentration are described. N-2:4-Dinitrophenylethanolamine was used as a marker of electroendosmotic movement. Continuous electrophoretic fractionation of alpha-amylase-hydrolyzed amylose in the presence of iodine-iodide was carried out in an apparatus similar to that of Svensson and Brattsten (1949). Four fractions were isolated in salt-free state, viz. material from (a) a non-staining zone having degree of polymerization (DP) < 10; (b) an orange - staining zone DP 19-25; (c) a red-staining zone DP 25-40; (d) a blue-staining zone DP 40-130 (the upper limit depending on the degree of hydrolysis). With improvement of technique, fraction (d) could probably be further fractionated The method is applicable to the study of enzymic breakdown of high-molecular starch-like polysaccharides and possibly to the fractionation of polydisperse substances such as amylopectin or glycogen. Possible structures of the various I-iodide-dextrin complexes are discussed, and it is suggested that there is a sudden change in the type of complex formed at DP of approximately 40. The purple-staining complexes formed by dextrins in the range DP 40-50 may be a mixture of red- and blue-staining complexes.