118 CHEMISTRY OF BACTERIA AND THEIR PRODUCTS 



The source of the ptomains in the various amino-acids is usuall}' easily traced 

 through their chemical structure, and Ackermann and Kutscher" have classified 

 them in this relation under the name " aporrhegma." 



When we examine the structural formulae of some of the larger ptomaln mole- 

 cules and compare them with the formula" of the amino-acids that form the protein 

 molecule, the relation is apparent, e. g., compare iso-amylamine with leucine. 

 CHav CH3\ 



^CH-CHj-CHo-NH, ^CH-CHo-CH-XH, 



CH/ . CH3 aeucine) ^COOH. 



(iso-amylamine) 



Putrescine, C4H12N2, structural formula, 



NH2-CH,-CH2-CH2-CH2-XH2, 

 and cadaverine, C5H14N2, structural formula, 



XH2 - CH2 - CH2 - CH2 - CH2 - CH2 - XHo, 



are of interest because they have been found in the intestinal contents, arising from 

 putrefaction of proteins, and also are sometimes present in the urine in cystinuriaJ^ 

 They are closely related to the diamino-acids, lysine and ornithine. Thej' are 

 but slightly toxic, although capable of causing local necrosis Avhen injected sub- 

 cutaneously. (See further discu.ssion on these and the Pressor Bases in Chap, xxi.) 



The Choline Group. — Another group of ptomains, including cho- 

 line and closely related substances, is also of interest. These ptomains 

 are: 



Chohne, CH2OH— CH2— X(CH3)3— OH 



Xeurine, CH2=CH— X(CH3)3— OH 



Muscarine, CH(0H)2— CH>— X (CH3).-r-0H 



Betaine, COOH— CH,— X(CH3)3— OH 



The first point of importance is that choline is present in every 

 cell normally, forming the nitrogenous portion of the lecithin mole- 

 cule. Its source in putrefaction of tissues is, therefore, plain. It is 

 possible that choline is liberated from nerve tissues when they break 

 down in the body during hfe," and there is a considerable literature 

 on the supposed finding of choline in the blood and cerebrospinal 

 fluid in diseases of the central nervous system and experimental 

 lesions in nervous tissues. At present it seems probable that these 

 observations depend upon faulty methods of analj'sis, and it is ex- 

 tremely doubtful if enough choline is ever set free at one time from 

 even severe acute nervous lesions to be detected in the body fluids by 

 chemical means. ^^ Hunt^^ has devised a physiological test that per- 

 mits of the detection of as little as 0.00001 mg.. but he was unable to 



" Zeit. physiol. Chem., 1910 (69), 2G5. 



2«Udrdnsky and Baumann, Zeit. physiol. Choiii., 1889 (13), 562; 1889 (15) 

 77. 



" Coriat (Amer. Jour, of Physiol., 1904 (12), 353) has studied the conditions 

 under which choline may be produced from lecithin. Putrefaction of lecithin 

 or lecithin-ridi tissues liberates choline as also does aut()ly.-;is of brain tissue; 

 neither pcjisin nor trypsin, however, splits it from the lecitliin. In brain tissue, 

 therefore;, there seems to be an enzyme different from trypsin, which splits choline 

 out of tlie lecithin molecule. 



-"Sec Wehstcr, liioclicm. .lour., 1900 (4), 123 ; Kajiura. (.luart. Jour. Exper. 

 Physiol.. 190.S (1), 291; llandel.sniuiin, Deu). Zeit. Nervenheilk., 1908 (35), 428; 

 Dori'c and (Jolla, Biochem. Jour., 1910 (5), 306. 



-"Jour. I'liurmacol., 1915 (7), 301. 



