Cereal Chem 50:443 - 454.  |  VIEW ARTICLE
The Nature of the Starch-Protein Interface in Wheat Endosperm.

K. K. Barlow, M. S. Buttrose, D. H. Simmonds, and M. Vesk. Copyright 1973 by the American Association of Cereal Chemists, Inc. 

Wheat varieties differ in the vitreosity and hardness of their mature air-dry endosperms. Micropenetrometer hardness testing indicated little difference between either starch or protein from different varieties. The conclusion is that the nature of the starch and storage-protein interface differs between hard and soft varieties. Information on this interface has been obtained by light microscopy coupled with soluble protein extraction and protein staining, by transmission electron microscopy, by scanning electron microscopy, by freeze etching, and by fluorescent antibody staining. The entire area between starch granules is filled with material staining as protein. Water-soluble proteins are confined to a position immediately surrounding starch granules, and this area is capable of rapid swelling on hydration. There is evidence that residues of the original amyloplast membranes, as well as those of endoplasmic reticulum, exist around starch granules. The soluble proteins associated with starch granules form an electrophoretically complex group. Associated with them are carbohydrates giving rise to glucose on hydrolysis. The total water-soluble material appears to play the role of a cementing substance between starch granules and storage protein. It is likely that through the amount and composition of this material the genetic control of grain hardness is expressed.