Cereal Chem 55:180 - 187. | VIEW
Chemistry and Ultrastructure of a Major Aleurone Protein of Rapeseed Meal.
T. A. Gill and M. A. Tung. Copyright 1978 by the American Association of Cereal Chemists, Inc.
A major storage protein extracted from commercial rapeseed meal (Brassica campestris L. var. Span) was characterized both chemically and ultrastructurally. The 12S glycoprotein was found to contain 12.9% (w/w) carbohydrate consisting of arabinose, galactose, glucose, inositol, glucosamine, and mannose. The rapeseed aleurone grains contain globoid bodies which suggest the presence of phytic acid. This observation may be related to the presence of inositol in the 12S oligomer. It may be that the sugars are added to the protein backbone some time after protein synthesis or perhaps could be complexed with the protein by way of a Maillard condensation reaction in the meal during lipid removal. It is also possible that the differences observed between the carbohydrate contents of the 12S protein recovered from commercial meal and that obtained from seed could have resulted from nonenzymatic browning reactions. The amino acid profile of the 12S globulin was dominated by the acidic amino acids, glutamic and aspartic, which is typical for an oilseed aleurin. There was a scarcity of the sulfur-containing amino acids 1/2 cystine and methionine. Tryptophan was not detected from a p-toluenesulfonic acid hydrolyzate of protein. The protein aggregate was found to be morula-like with a maximum particle diameter of 120 angstroms as determined from electronmicrographs of negatively stained specimens.