PRODUCTS FROM NITROGENOUS COMPOUNDS 91 



Vaughan considers that beta-imidazole-ethylamin is the active 

 principle of the protein molecule. Some of these amins are strong 

 stimulants of the heart or vasodilators. It is quite likely that their 

 liberation by bacterial activity in the intestinal tract and their 

 subsequent absorption may result in severe constitutional symptoms. 

 These compounds belong to a group of substances called "ptomains." 

 They are alkaloid-like bodies of basic character and of more or less 

 well-known structure. Some of them are harmless, while others are 

 apparently violent poisons. It is interesting to note that in the 

 majority of cases the poisonous properties decrease or at times 

 entirely disappear as purification proceeds thus indicating that the 

 poisonous principle in some cases at least is an impurity associated 

 with them. Their production is not limited to any one special class 

 of bacteria, for Zinsser defines ptomains as "poisons elaborated 

 by all bacteria that are capable of producing protein cleavage, if 

 planted on suitable nutrient materials under conditions favoring 

 growth. The matrix of these poisons is the protein nutriment; they 

 are not products of intracellular metabolism specifically characteris- 

 tic of the bacteria which produce them." 



Bacterial toxins, in contradistinction to the ptomains, are specific 

 bacterial poisons which are characteristic of each individual species 

 of bacteria and are truly the products of bacterial metabolism in 

 that they emanate from the cell itself either as a secretion or excre- 

 tion during cell life, or as an inherent element of the cytoplasm 

 liberated after death. 



Enzymes which are true products of bacterial metabolism have 

 been considered in detail in the preceding chapter. % 



Urea, uric acid, and hippuric acid are the forms in which the 

 waste nitrogen is excreted by the higher animals. There are a 

 great number of organisms occurring widely distributed which 

 possess the power of changing urea into ammonium carbonate. 

 This is a simple hydrolysis. 



NH 2 NH 4 



\ \ 



CO + 2H 2 O = CO 



NH 2 NH 4 



Uric acid can be changed in several ways by bacteria, that is, it 

 may be hydrolyzed with the formation of dialuric acid and urea. 



HN C O HN CO NH 2 



O = C C NH V + 2H 2 -* OC CHOH + CO 



>C = O / 



HN-C NH/ HN-CO NH 2 



Uric acid. Dialuric acid. Urea. 



On oxidation uric acid yields various substances, alloxan, urea, 

 oxalic acid, carbonic acid, tartronic acid, allantoinic and uroxanic 



