112 THE PROTEINS OF THE WHEAT KERNEL. 



GLUTENIN. 



This protein was first described by Taddei under the name of zymom. 

 I,iebig, as well as Dumas & Cahours, named it " plant-fibrin ; " Ritthausen 

 called it ' ' gluten-casein ; ' ' Weyl & Bischoff considered it to be an albumi- 

 nate form of a myosin-like globulin. On the ground of priority and the fact 

 that the relations to animal proteins, which gave rise to the various names 

 subsequently applied to this body, have been proved to have no foundation, 

 it would be desirable to return to Taddei 's original name and in future call 

 this protein zymom. Unfortunately this name is derived from the Greek 

 word Ct>/7, a ferment, and as the results of this and all other subsequent 

 investigations of this subject show that the supposed ferment-changes do not 

 occur in the formation of gluten, it seems appropriate to call it glutenin, a 

 name suggested by S. W. Johnson. Glutenin is next in importance to 

 gliadin, for in most varieties of flour it is present in nearly equal amount. It 

 is so nearly insoluble in water and alcohol that it is a question whether the 

 slight traces that are dissolved by these solvents from carefully purified prep- 

 arations are not due to traces of gliadin, which it is very difficult to separate 

 from it. In hot dilute alcohol glutenin is slightly soluble and separates 

 from such solutions on cooling. When freshly precipitated and in the 

 hydrated condition, it is very readily dissolved by extremely dilute acids or 

 alkalis and is precipitated from such solutions on neutralization. Glutenin 

 can be separated from the other constituents of the seed only by solution in 

 dilute alkalis or acids, and it is necessary to filter the solutions, from which 

 it is finally precipitated, perfectly clear in order to separate the associated 

 non- protein substances. This filtration is accomplished with great difficulty 

 unless it is preceded by thorough extraction of the crude glutenin with 

 alcohol and ether, whereby fats and lecithins are removed. 



Glutenin contains all the groups which give rise to the usual color reac- 

 tions of the proteins. No protein similar to glutenin in physical and chem- 

 ical properties has yet been found in any other seed. Although its ultimate 

 composition is nearly the same as gliadin, the proportion of the various 

 products of hydrolysis which it yields is very different, as may be seen from 

 the following analyses : 



The ultimate composition of glutenin. 



P.ct. 



Carbon 52.34 



Hydrogen 6.83 



Nitrogen 17-49 



Sulphur i. 08 



Oxygen 22.26 



