Cereal Chem 62:284-289 | VIEW
Gluten Proteins with High Affinity to Flour Lipids.
U. Zawistowska, F. Bekes, and W. Bushuk. Copyright 1985 by the American Association of Cereal Chemists, Inc.
Gluten proteins were fractionated by pH precipitation (method A) and ammonium sulfate precipitation (method B) to determine primarily if the association of lipids with the gliadin fraction prepared by method A results from mutual solubility of the lipids and the proteins in 70% aqueous ethanol. The distributions of lipids and proteins among fractions obtained by the two methods were different. For method A, 56% of the gluten lipid was associated with the gliadin fraction and 44% with the glutenin fraction. Almost all of the polar lipid in gliadin A, which contained 75% of glycolipid of the original gluten, coeluted with fraction I when gliadin A was fractionated by gel filtration chromatography on Sephadex G-200. For method B, acetic acid-soluble gluten lipid was distributed almost entirely between two fractions, the first precipitate, P1 and the supernatant, S. Most of the polar lipid of P1 was associated with its ethanol-soluble subfraction, P1S. The two fractions of method B, P1S and S, seemed to have a particularly strong affinity for polar lipid; they contained 69% of the polar lipid present in the acetic acid-soluble gluten that was fractionated. Sodium dodecyl sulfate-polacrylamide gel electrophoresis and solubility characteristics showed that fraction P1S of method B and fraction I of gliadin A contained common protein components that appear to be responsible for binding polar lipid. The results suggest an intrinsic affinity of specific gluten proteins for specific lipids. The presence of the lipids in gliadin is not influenced entirely by use of the ethanol as solvent, because both gliadin subfractions P1S and I contained similar lipids.