PHYSIOLOGICAL CHEMISTRY. 



protamines and some of the albuminoids. The yield of this body 

 from the decomposition of proteins is frequently greater than the 



Frr,. 21. 



PHENYLALANINE. 



yield of tyrosine. The crystalline form of phenylalanine is shown 

 in Fig. 21. 



Tyrosine, CgHnNOg. Tyrosine, one of the first discovered end- 

 products of protein decomposition, is the amino acid, p-oxyphenyl- 

 a-ammo-propionic acid. It has the following formula: 



H NH 



The tyrosine which results from protein decomposition is usually 

 Isevo-rotatory although the dextro-rotatory form sometimes occurs. 

 Tyrosine is one of the end-products of tryptic digestion and usually 

 separates in conspicuous amount early in the process of digestion. 

 It does not occur, however, as an end-product of the decomposition 

 of gelatin. 



Tyrosine is found in old cheese, and derives its name from this fact. 

 It crystallizes in tufts, sheaves or balls of fine needles, which decom- 

 pose at 295 C. and are sparingly soluble in cold (1-2454) water, 



