LIPIDES (fats and RELATED SUBSTANCES) 



99 



(dissolve) red blood cells. Cobra snake venom contains Iccithinase A, 

 and presumably owes its deadly effect, at least in part, to the production 

 of lysolecithin. Still another hydrolysis i)roduct of lecithins (or cepha- 

 lins) are the phosphatidic acids, which are found in the form of metallic 

 salts in various plant and animal tissues. 



O 



II 



CH2 — — C — CisHai 







II 



CH— O-C-CnHaj 







'I 

 CHaO— PC^r^Ca 



A phosphatidic acid 

 (calcium salt) 



Cephalins 



The cephalins are found closely associated with lecithins in many 

 tissues, but particularly in brain tissue. A phospholipide preparation ob- 

 tained from ether-soluble brain lipides, by precipitation with alcohol, 

 has been called "brain cephalin." It was thought to differ from lecithin 

 only in containing ethanolamine, or cholamine (HOCHoCHoNHo), as 

 the basic constituent in place of choline. However, it has been demon- 

 strated that "brain cephalin" is actually a mixture of several phospho- 

 lipides, only one of which corresponds to the above structure. This com- 

 ponent of "brain cephalin" is now designated by the more specific name, 

 phosphatidyl ethanolamine. A second component is very similar in 

 structure but contains the amino acid serine, HOCHoCHCOOH, in place 



NHo 



of ethanolamine. It is named phosphatidyl serine. When obtained 

 from brain tissue, it contains oleic and stearic acids, as the only fatty 

 acids. The chemical formulas of these substances are as follows: 



O 



II 

 CH2 — — CC17H34 



o 



II 



CH — — CCnHas 



I 



CH2-0— p— OCH2CH2NH3 



I 



0- 



Phosphatidyl ethanolamine 

 (inner salt formula) 



O 



II 

 CHj — — CCkHss 







II 



CH-0— CCnHjj 

 



II 



CHj-O-P— OCH2CHCOOH 

 1 I 



ONa NH2 



Phosphatidyl serine 

 (sodium salt) 



