8 



THE PROTEINS OF THE WHEAT KERNEL. 



Commaille 1 recognized, as protein constituents of flour, sitosin, soluble in 

 water and coagulable by heat ; imesin, soluble, after drying, only in water 

 containing o. i per cent hydrochloric acid ; sitesin, soluble in o. i per cent 

 hydrochloric acid ; glutin, nearly insoluble in dilute acid, easily in strong acid, 

 forming an emulsion with alcohol, which is separated by much water ; and 

 mucin, which dissolves easily, even after drying, in water and in cold 80 

 per cent alcohol. 



Ritthausen 2 next published the results of his extensive investigations in a 

 volume in which he discussed at length the proteins of the wheat kernel. 

 The composition, properties, and the proportions in which they occur in the 

 seed were given in detail, and also the evidence which he considered showed 

 the individuality of each. He recognized five proteins, namely, gluten-casein, 

 gluten-fibrin, plant-gelatin or gliadin, and mucedin, as constituents of the 

 gluten, and also albumin, which he found in the aqueous extracts of the 

 seed. 



The gluten-casein was not soluble in water, very slightly soluble in dilute 

 alcohol, and readily soluble in very dilute acids and alkalis. When decom- 

 posed by boiling with sulphuric acid it yielded tyrosine, leucine, 5.3 per 

 cent of glutaminic acid, and 0.33 per cent of aspartic acid. In the dry gluten 

 he found from 26 to 31.4 per cent of gluten-casein, which he considered to 

 be minimal quantities. 



Table giving results as ascertained by Ritthausen. 



The gluten-fibrin formed that fraction of the alcohol- soluble proteins 

 which was soluble in the strongest alcohol and separated from a hot con- 

 centrated solution in 50 to 60 per cent alcohol on cooling. Owing to the 

 difficulty encountered in separating gluten-fibrin from the other alcohol- 

 soluble proteins, it was impossible to determine its amount. Usually from 



1 Commaille, Journal de Pharmacie, 1866 (4), iv, p. 108. 



2 Ritthausen, Die Eiweisskorper, etc., Bonn, 1872. 



