424 V. CHEMISTRY OF PHOSPHATIDES AND CEREBROSTDKS 



proportional to the antilecithinase activity. Moreover, it has been 

 demonstrated that a general relationship obtains between the production 

 in vitro of a-toxin or lecithinase D and the virulence of the organism. ^"-^^s 

 Lecithinase D is activated by the calcium ion and mhibited by fluoride, 

 citrate, or phosphate; although relatively heat-stable, it was sho^^^l to be 

 readily inactivated by surface denaturation and by sodium dodecylsul- 

 fate.121 



(9) Chemistry and Properties of Hydrolysis Products 



2l. Fatty Acid Components of Lecithin. The fatty acids which have 

 been reported in various lecithin preparations include the saturated acids 

 palmitic and stearic and the unsaturated acids oleic, linoleic, linolenic, 

 arachidonic, and clupanodonic. Hart and HeyP^*'^-^ have suggested the 

 possibility that a triply unsaturated fatty acid wuth 20 carbon atoms occurs 

 in the phospholipid present in corpora lutea. A number of lecithins have 

 been separated from the same natural sources, so that it must be assumed 

 that a wide range of different compounds exists in nature. 



Levene and Rolf*® isolated a lecithin preparation from egg-yolk which 

 contained palmitic, stearic, and oleic acids. Since only two fatty acids 

 can occur in any single lecithin molecule, it is evident that the product 

 described above must have been a mixture of several different lecithins. 

 Moreover, these same workers later reported^-^ another preparation from 

 egg-yolk in which they isolated the three unsaturated acids oleic, linoleic, 

 and arachidonic acids. Still later, these investigators®* isolated palmitic, 

 stearic, and tetrabromostearic acids from a fraction of brominated lecithin. 

 This must have differed from the first preparation, in which the unsaturated 

 acid was oleic. Sueyoshi and Furukubo^" reported the presence of "iso- 

 palmitic" and clupanodonic acids in egg lecithin, as well as of oleic and 

 linoleic acids. Brain lecithin was shown in one case to contain palmitic, 

 stearic, and oleic acids, -'^ while the same workers later reported^^® a brain 

 lecithin devoid of saturated fatty acids and containing only oleic and 

 arachidonic acids. The lecithin preparations isolated from samples of liver 

 have shown even wider variations. Thus, Levene and Ingvaldsen^^' de- 

 monstrated the presence in one sample of only stearic acid and of an un- 

 saturated acid which was probably in the linoleic series; in another study 



122 D. G. Evans, /. Path. BacL, 57, 75-85 (1945). 



123 E. H. Kass, H. C. Lichstein, and B. A. Waisbren, Proc. Soc. Exptl. Biol. Med. ,58, 

 172-175 (1945). 



124 M. C. Hart and F. W. Heyl, /. Biol. Chem., 70, 663-674 (1926). 



125 M. C. Hart and F. W. Heyl, /. Biol. Chem., 72, 395-402 (1927). 



126 P. A. Levene and I. P. Rolf, /. Biol. Chem., 51, 507-513 (1922). 



127 Y. Sueyoshi and T. Furukubo, /. Biochem. Japan, 13, 155-175, 177-183 (1931). 



128 P. A. Levene and L P. Rolf, /. Biol. Chem., 64, 99-100 (1922). 



i2« P. A. Levene and T. Ingvaldsen, /. Biol. Chem., 43, 355-358, 359-378 (1920) 



