THE PROTEINS 41 



Aspartic acid, C 2 H 3 NH 2 (COOH) 2 , is amino-succinic acid: 



NH 2 



CH.COOH 



CH 2 COOH 



It is not present in large amounts among the protein products of 

 decomposition. Asparagin, the amide of. 'this acid, however, is very 

 widely distributed in the vegetable kingdom. 



Glutaminic acid, C 3 H 5 NH ( (COOH) 2 , is amino-glutaminic acid; 



NH, 



CH.COOH 

 CH 2 



is especially abundant in the proteins of seeds, although it occurs in 

 all the proteins yet examined, with the exception of protamines. 



Phenyl alanin is alanin in which a further Utom of hydrogen has 

 been replaced by the phenyl group (C 6 H 5 ). Its formula, therefore, 

 is C 2 H V CH.NH 2 .COOH (phenyl-a-amino-propionic acid), or more 

 graphically : 



CHjCH.NHjCOOH 



Tyrosin contains instead of the phenyl group the oxyphenyl 

 group C 6 H 4 OH. 'It is p - oxyphenyl - a - amino - propionic acid. 

 C 2 H 3 (C 6 HjOH)NH ;! COOO, or graphically: 



OH 



CH 2 CHNH 2 COOH 



It 'crystallizes easily in fine needles, and with leucin was the first 

 product of protein hydrolysis isolated. Millon's reaction is due to its. 

 presence. 



Adrenalin, the active substance of the suprarenal gland, has the 

 formula ^^^ 



OHf\CH(OH).CH 2 NCH 3 



OH 



U 



