ISOLATION AND CHARACTERISATION OF A WATER-SOLUBLE WHEAT-FLOUR PROTEIN

The main component of the water‐soluble proteins of wheat flour has been isolated in sufficient quantity for chemical and physical characterisation. This was achieved by a combination of ion‐exchange chromatography on carboxymethyl cellulose and gel filtration through Sephadex G75. The protein isolated was judged to be 90% pure by zone electrophoresis. Sedimentation analysis yielded a single symmetrical peak with an S°20,w value of 2.45. The molecular weight was found to be 19,300 by gel filtration, and the diffusion coefficient estimated by the same method was 10.47 × 10−7. A molecular weight of 16,000 was calculated from sedimentation equilibrium analysis in a dissociating medium. The ultra‐violet spectrum of the isolated albumin exhibited a maximum at 278 nm and from this an E1%278 value of 13.1 was calculated. No free sulphydryl groups could be detected. Amino acid analysis showed that this protein has a composition similar to those of other soluble wheat‐flour preparations. A molecular weight of 16,300 was calculated from the amino acid analysis. End‐group analysis of the protein showed that serine is the N‐terminal amino acid. The C‐terminal amino acid was found to be resistant to release by both carboxypeptidase A and carboxypeptidase B. Copyright © 1969 John Wiley & Sons, Ltd