THE LECITHINS 419 



compound. The isoelectric point has been shown^''^- to be 7.5. On the 

 other hand, l)oth lecithin and cephalin arc able to bind one eciuivalent of 

 hydrogen ions when the pH. is sufficiently low.^^ 



The suggestion that lecithin is internally neutralized, so that the acidic 

 phosphoric acid hydrogen is bound with the strongly basic choline on the 

 alkaline side of the isoelectric point (and hence acts as a neutral salt), 

 would involve the following molecular structure: 



H,C-0-CR 



hc-o-cr' 



I ^0 



HjC-0-P-OCHbCHjN (ch,), 



Lec-.itliin (intenuil anhj-dride form) 



(7) Lysolecithins 



j^ygg93,94 discovered that when an aqueous solution of hooded African 

 cobra venom {Naja haye, the "spy-slange" of the Boers) was shaken with a 

 chloroform solution of lecithm, a new substance (cobralecithin) originated, 

 which could be distinguished from the original compound by its specific 

 solubihty and its marked hemolytic activity. Liidecke^^ demonstrated 

 that one fatty acid had been split from the molecule. The fatty acid so 

 lost was usually the unsaturated component. Further evidence of the 

 nature of this compound can be adduced from the work of Delezenne and 

 co-workers,^ ^'^^ who named it "l3^socithin." 



"Lysocithin" was sho\\Ti by Levene and Rolf^^-^* and later by Levene, 

 RoK, and Simms" to be composed of lecithin and cephalin components. 

 These were named lysolecithin and lysocephalin. The lysolecithin proved 

 to be a monostearolecithin, and no amino nitrogen was present. It was 

 more readily soluble than lysocephalin, and could be crystallized from 

 chloroform, acetic acid, pyridine, or methyl or ethyl alcohol, in needles 

 which melted at 100°C. and decomposed at 263 °C. Lysolecithin is in- 

 soluble in ether and acetone and, like lecithin, it is extremely hydroscopic. 

 It forms emulsions in water which dissolve on the addition of alkali; 



" H. Fischgold and E. Chain, Biochem. J., 28, 2044-2051 (1934). 



" H. Fischgold and I. Kemp, Biochem. J., 28, 2052-2055 (1934). 



" P. Kyes, Berlin, klin. Wochschr., 40, 956-959, 982-984 (1903). 



9^ P. Kyes, Biochem. Z., 4, 99-123 (1907). 



^5 K. Liidecke, "Zur Keuntnis der Glycerinphosphorsiiure und des Lecithins," Dis- 

 sertation, Miinch. philos. Fak., Sect. II. Cited from H. Thierfelder and E. Klenk, Die 

 Chemie der Cerebroside und Phosphatide, Springer, Berlin, 1930, p. 110. 



s« C. Delezenne and S. Ledebt, Compt. rend., 153, 81-84 (1911); 155, 1101-1103 

 (1912). 



" C. Delezenne and E. Foumeau, Bull. soc. chim. [4], 15, 421-434 (1914). 



»8 P. A. Levene and I. P. Ilolf, /. Biol. Chem., 55, 743-749 (1923), 



