186 NUCLEIC ACIDS AND THE NITROGENOUS BASES 



Pyrrolidine, which should be formed by decarboxylization from 

 proline, oxypyrrolidine which should be formed from oxyproline, 

 amino-ethyldisulphide which should be formed from cystine, and 

 /3-hydroxyethylamine which should be formed from serin, have not 

 yet been found possible to prepare by bacterial decarboxylization. 



While a wide variety of bacilli, especially anaerobes, are able to 

 bring about the decarboxylization of amino-acids, this power would 

 seem to be possessed in an exceptional degree by a specific organism, 

 Bacillus aminophilus intestinalis which has been isolated by Bertrand 

 and Berthelot. 



The production of these bases, many of which are definitely toxic 

 is not necessarily accompanied by the production of the odor which 

 is commonly considered to be indicative of putrefaction. The odor 

 of putrefaction is due to Indol and Skatol or /3-methyl indol: 



CH C.CH 3 



/\ ' /\ 



C 6 H 4 CH C 6 H 4 CH 



\/ . \/ 



NH NH 



Indol. Skatol. 



and these substances which are derived from Tryptophane are the 

 products of a further stage of putrefactive decomposition, arising by 

 combined decarboxylization and deaminization succeeded by partial 

 (skatol) or complete (indol) oxidation of the aliphatic hydrocarbon 

 chain of the tryptophane molecule. 



The bases which are derived in this way from the proteins dis- 

 play the usual characteristic properties of the amines. They are very 

 much more basic than the amino-acids from which they are derived, 

 and yield crystalline salts with mineral acids. 



The aliphatic monamines (methylamine, ethylamine, isobutyl- 

 amine, isoamylamine, dimethylaminobutane) exert a physiological 

 action mimicking the effects of stimulation of the sympathetic nervous 

 system, they are therefore termed by Barger and Dale ''Sympathomi- 

 metic" bases. The lowest amine to produce a distinct rise in blood 

 pressure on intravenous injection is, however, Isobutylamine ; the 

 activity increases with increasing length of the aliphatic hydrocarbon 

 chain up to Hexylamine, and thereafter declines as the number of 

 carbon atoms increases. Very much more effective than mere increase 

 in the length of the chain is, however, the introduction of a ring- 

 structure as in the benzol and heterocyclic derivatives. Thus Phenyl- 

 ethylamine is at least five times as active, physiologically, as any 

 aliphatic amine. Two milligrammes of this substance when injected 

 intravenously may increase the blood-pressure of a cat no less than 

 six hundred per cent. (30 mm. to 180 mm.). The most active, however, 

 of the monamines derived from the amino-acid cleavage-products of 

 protein is parahydroxyphenylethylamine (Tyramine) which exerts an 



