Cereal Chem 61:69 - 73.  |  VIEW ARTICLE
Sorghum Protein Body Composition and Ultrastructure.

J. R. N. Taylor, L. Novellie, and N. v. d. W. Liebenberg. Copyright 1984 by the American Association of Cereal Chemists, Inc. 

The protein composition and ultrastructure of sorghum protein bodies isolated from mature starchy endosperm material were studied. Transmission electron microscopy showed that the protein bodies were largely circular in section and varied between 0.4 and 2.0 micro-m across. The isolated protein bodies were subjected to an Osborne-type protein-fractionation procedure, which revealed that they are composed mainly of prolamin protein. Protein body prolamin had a virtually identical amino acid composition and gave the same electrophoretic pattern as kafirin (sorghum prolamin). This proves that starchy endosperm protein bodies are the site of kafirin storage in sorghum, as was suggested by electron microscope observations. The protein bodies were embedded in and, in some cases, penetrated by a matrix of mainly glutelin protein. This matrix protein consisted of many proteins, none of which predominated. Maltase activity was associated with the protein, and the matrix may function as a source of certain hydrolytic enzymes involved in the mobilization of endosperm reserves during germination.