476 GASTRO-INTESTINAL "AUTOINTOXICATION" 



the presence of an NH 2 group attached to the carbon atom nearest 

 the acid radical, the a position ; thus, R CHNH 2 COOH. 

 A few of the ammo-acids contain an aromatic group, and the 

 relation of these to intestinal decomposition has been considered 

 above. The greater number have a simple fatty acid radical 

 (the simplest amino-acid being glycocoll, CH 2 NH 2 COOH), 

 and from them are derived by intestinal putrefaction substances 

 that are, for the most part, chemically simple and, as far as 

 known, pathologically unimportant. 



Fatty acids may readily be formed from them by splitting out 

 of the NH 2 group ; thus acetic acid may be formed from glycocoll, 

 propionic acid from alanin, etc. Apparently butyric and acetic 

 acid are the acids most commonly formed in this way. Gaseous 

 derivatives, such as hydrogen, ammonia, carbon dioxide, and 

 marsh-gas are also produced. Acetone is perhaps formed from 

 these fatty acids ; it is often present in the intestinal contents, 

 but may come from other sources. 



Diatnins. Of more interest are the substances that are 

 formed from the amino-acids by bacterial action, which still retain 

 their nitrogen radicals the plomains. Two of these, the diamins 

 putrescin, NH 2 (CH 2 ) 4 NH 2 , and cadaverin, NH 2 (CH 2 ) 5 NH 2 

 are of particular interest i because they have been observed in 

 the feces and urine of persons with cystinuria. The stools in 

 cholera also seem to contain these ptomains frequently. Their 

 etiological relation to the cystinuria is no longer accepted, how- 

 ever, and their toxicity is slight. They are probably derived 

 from the diamino-acids of the proteid molecule, putrescin being 

 closely related to ornithin? and is probably formed from it as 

 follows : 



NH 2 NH 2 NH 2 NH 2 



CH 2 CH 2 CH 2 CH COOH = CH 2 CH 2 CH 2 CH 2 + CO 2 , 



(ornithin) (putrescin) 



while cadaverin is probably formed from lysin, 



NH 2 NH 2 NH 2 NH 2 



CH 2 (CH 2 ) 3 CH COOH = CH 2 (CH 2 ) 3 CH 2 -f CO 2 . 



(lysin) (cadaverin) 



,NH 2 

 Eihylidendiamin, CH S CH/ which is somewhat toxic, 





1 For discussion of formation and properties of these two ptomains, see 

 Vaughn and Novy's " Cellular Toxins." 



2 Ornithin forms part of the arginin molecule, which is the most univer- 

 sally present of all the amino-acids, ornithin being formed when urea is split 

 from arginin. 



