Starch phosphates complexation with proteins

The saturated HpHb complex of type 1-1 was formed in solution and mixed with a pure solution of globin. The proteins were then separated by starch gel electrophoresis with a neutral phosphate buffer. The procedure was afterward repeated, but with a solution of Hp-globin complex mixed with an Hb solution. 

Specific interactions between starch and proteins were observed as early as the beginning of the twentieth century. Berczeller996 noted that the surface tension of aqueous soap solutions did not decrease with the addition of protein (egg albumin) alone, but it did decrease when starch and protein were added. This effect was observed to increase with time. Sorption of albumin on starch is inhibited by bi- and trivalent ions and at the isoelectric point. Below the isoelectric point, bonding between starch and albumin is ionic in character, whereas nonionic interactions are expected above the isoelectric point.997 The Terayama hypothesis998 predicts the formation of protein complexes with starch, provided that starch exhibits the properties of a polyelectrolyte. Apart from chemically modified anionic starches (such as starch sulfate, starch phosphate, and various cross-linked starch derivatives bearing ionized functions), potato starch is the only variety that behaves as a polyelectrolyte. Its random phosphate ester moieties permit proteins to form complexes with it. Takeuchi et a/.999-1002 demonstrated such a possibility with various proteins and a 4% gel of potato starch. 

The reaction of starch phosphate with such proteins as soybean protein and casein was used to produce protective colloids for insolubilization of pigments in coatings and paper.1684 The complexation of starch phosphate with protein insolubilizes the latter, particularly when starch phosphate is in the form of an ammonium salt.1685... 

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