110 PHYSIOLOGICAL CHEMISTRY 



H H 



C C 



HC C CCH 3 HC C CH 



I II II I II II 



HC C CH HC C CH 



\/\/ \/\/ . 



C N C N 



H H H H 



Skatol Indol 



From amino acids, by removal of C0 2 from the carboxyl group 

 various amines are produced, e.g., from tyrosine, tyramine 



H H 



C C 



// \ // \ 



HC C CH 2 CH NH 2 COOH HC C CH 2 CH 2 NH 2 



HOC CH - HO C CH 



\ / \ / 



C C 



H H 



From histidine, histamine is produced in a similar way. Such 

 compounds are known by the name "ptomaines," and they are 

 extremely toxic. Cystine and cystein give rise to hydrogen sul- 

 phide and other sulphur compounds. A condition of constipa- 

 tion, in which intestinal contents are retained unduly long in 

 the body, and putrefaction thus prolonged, favors the produc- 

 tion of such substances. On absorption into the blood they give 

 rise to headaches, general debility and in time, to more serious 

 disorders. Undoubtedly certain compounds of this type are 

 produced normally by the enzymes of the tissue cells them- 

 selves, and it is probable that some of them are of importance 

 for the regulation of certain body processes. Adrenaline is 

 such a substance. 



Individual Groups. Simple Proteins 



The important characteristics of the proteins as a class have 

 been considered. Let us now review the properties of groups 

 and of individual proteins. 



