i>i:in\ .\Ti\ i:s of siu'iiiu rosTAisisa I'ifOTEiN radicals 581 



from tlio ainino-aeids by bacterial action, wliich still retain their nitro- 

 gen radicals — the ptoindins. Two of these, the diamines putrescine, 

 NII2 (CIIn)4 NIL, and cadaverine, Nil, (0X12)5 NIIj are of particular 

 interest,^^ because they have been observed in the feces and urine of 

 persons with cystinurw. The stools in cholera also seem to contain 

 these ptoma'i'ns frequently. Their etiological relation to the cystinuria 

 is no longer accepted, however, and their toxicity is slight. They are 

 probably derived from the diamino-acids of the protein molecule, pu- 

 trescine being closelj' related to ornithine,''^'' and is probably formed 

 from it as follows : 



NHa NHj NHo XH, 



CH2 — CH, — CH, — CH — COOH p=, CH, — CTI, — CH, — CH, + CO, 

 ( ornithine ) ( putrescine ) 



while cadaverine is probably formed from, lysine, 



NH„ NHo NH2 NH, 



CH,— (CH,), — CH — COOH .=. CH,— (CH,), — CH, + CO, 

 (lysine) (cadaverine) 



.NH, 

 Ethylidendiamine, CH^-CH < which is somewhat toxic, has also 



^NH,, 

 been detected in the contents of the gastro-intestinal tract. 



Apparently these substances are absent from normal feces, but 

 this does not exclude the possibility of their normal formation, ab- 

 sorption, and destnietion. There is no evidence that they ever cause 

 symptoms or pathological alterations. 



(3) SUBSTANCES ARISING FROM THE SULPHUR-CONTAINING RADICAL 



OF PROTEINS 



Most if not all of the sulphur in the protein molecule seems to be 

 contained in the amino-acid. cystine, which has the following compo- 

 sition : 



S — CH, — CHXH, — COOH 



S — CH, — CHNH, — COOH. 



From this is formed the hydrogen sulphide of the intestinal gases, of 

 which about 0.058-0.066 gram is present in each one hundred grams 

 of normal colon contents. Although Senator has described a case in 

 which an intoxication with HoS of intestinal origin occurred, this 

 gas seems not to be a frequent cause of intoxication, and Senator's 

 case stands almost alone. Under normal conditions H^S does not 

 appear in the urine, any that may be absorbed probabh^ being oxidized 



51 For discussion of formation and properties of these t\vo ptomains, see 

 Vanghan and No\'\''s ''Cellular Toxins." 



51a Ornithine forms part of tlie arginine molecule, which is the most universally 

 present (in proteins) of all tlie amino-acids, ornithine being formed when urea 

 is split from arginine. 



