A Water-soluble Arabinogalactan-Peptide From Wheat Endosperm

Abstract

The water-soluble polymeric components of wheat endosperm have been extracted by two different procedures and their chemical composition studied in detail. Water extracts of wheat flour that had first been treated with hot 80% ethanol contained only 2% protein, but if the ethanol treatment was omitted up to 20% of the extracted polymeric fraction was low-molecular-weight non-dialysable protein material. Density-gradient ultracentrifugation in caesium chloride solutions indicated that most of this protein was free, whereas the 2% protein in the water extract of ethanol-treated flottr was firmly bound to a polysaccharide. This bound protein (a peptide) was characterized by high levels of hydroxyproline (16-20% of the amino acids present).