74 THE CHEMICAL CONSTITUTION OF THE PROTEINS 

 The Vegetable Proteins. 



The vegetable proteins show no great difference from the animal 

 proteins in regard to the number of amino acids which they contain in 

 their molecule. The most noticeable features are their high content in 

 glutamic acid and in arginine. Their ammonia content is also high. 

 This is probably connected with the large amount of the dibasic 

 glutamic acid and is in harmony with the occurrence of asparagine 

 and glutamine in growing seedlings. 



Albumins. 



Only two vegetable albumins have so far been analysed, the 

 legumelin of the pea and the leucosin of wheat. The resemblance in 

 their composition extends not only to the general proportions of the 

 amino acids, but also to the quantity isolated. Leucosin occurs in 

 the embryo of wheat ; it is not possible to locate legumelin in any 

 particular part of the seed, but, from analogy, it may be supposed that 

 both these proteins are constituents of the physiologically active tissues 

 rather than a constituent of the reserve food-stuff for the embryo. 

 Legumelin is quite different in composition from legumin and vicilin, 

 two other proteins contained in the pea. These albumins show a 

 resemblance in their composition to the animal albumins. 



Globulins. 



All the globulins, which can be prepared in a crystalline state, 

 have a very similar composition. Excelsin contains the greatest amount 

 of arginine and edestin of glutamic acid. These proteins form the 

 best source of arginine. Their content in glutamic acid is about half 

 the content of the gliadins in this amino acid. It is unfortunate that 

 the analysis of edestin by Osborne and Liddle [1910, i] is incomplete. 

 Their figures are higher than those of Abderhalden [1902, 1903] and 

 they were unable to isolate oxyproline. 



No great difference is to be noted between the crystalline globulins 

 and the other vegetable globulins, except in the proportion of arginine 

 which is distinctly less in most of the non-crystalline ones. 



The legumins of the pea and vetch show no real difference in 

 their physical properties and elementary composition, but the analysis 

 shows that differences do exist, especially in the data for lysine and 

 histidine. Analysis has also shown that vignin differs from the other 

 legumins. 



The vicilin of the pea contains less sulphur (o*i-O'2 per cent.) than 



