470 V. CHEMISTRY OF PHOSPHATIDES AND CEREBROSIDES 



antigenic in viiro,^'^^-^'^^ Wadsworth et al^'^^ demonstrated that adequately 

 purified lecithin and cephalin are completely ineffective in the test. How- 

 ever, the active principle is also throun out of solution by cadmium chlo- 

 ride, since beef heart lipids from which all cadmium chloride-precipitable 

 material has been removed were found to be no longer active as antigens in 

 the complement-fixation test for syphilis.^'''' 



Pangborn^" demonstrated that a properly balanced mixture of cardio- 

 lipin, cholesterol, and lecithin functions in the same w^ay as beef heart ex- 

 tract to produce a complement-fixing action with the sera of syphilitics. 

 It was also proved that the system is inactivated if any one of the three 

 components is omitted from the mixture. Cardiolipin by itself possesses 

 no activity. 



The separation of cardiolipin from lecithin offers considerable difficulty. 

 However, it was accomplished by transforming the mixtures to their 

 barium salts, ^''^ from which the barium salt of cardiolipin could be sepa- 

 rated because of its insolubility in methanol. The use of sodium sulfate in 

 precipitation Avas later recommended for improving the yield of cardio- 

 lipin.^^* When this modified procedure was employed, 6.4 g. of purified 

 sodium cardiolipin was obtained from 5 hearts. A further improvement in 

 procedure for the preparation of cardiolipin has been reported more re- 

 cently. ^^^ 



Cardiolipin has been found to be a viscous yellow oil soluble in acetone or 

 alcohol, as well as in the other usual lipid solvents, but not in water. It 

 has a specific rotation of -f5.8° at 25°C. in ethanol. The iodine number 

 was found to be 119=^^8 (io6, 112, 126, 99.8, and 112 in later successive 

 preparations),^^" and the apparent molecular weight as determined by 

 titration was 726. The phosphorus content was found to be 4.31%, and 

 no chlorine or sodium was detected. Although the compound was origi- 

 nally believed to contain a polysaccharide group, ^'^^ this report was later 

 found to be in error. ^^^ Cardiolipin is believed to be a phosphatidic acid 



7. Acetal Phosphatides (Plasmalogens) 



Feulgen discovered a new group of phosphatides, as a result of peculiar 

 staining reactions which were observed when fuchsin sulfurous acid was 

 used. This reagent produces a purple color with aldehydes; if it is used 

 after a preliminary treatment of the cells with sulfuric acid, a selective 



"3 1. Sakakibara, /. Blochem. Japan, 24, 31-72 (1936). 



3'* J. W. Wellman and H. P. Lankelma, Venereal Dis. Inform., 22, 12-14 (1941). 

 3^5 A. Wadsworth, E. Maltaner, and F. Maltaner, J. Immunol, 26, No. 1, 25-48 (1934). 

 ''« F. Maltaner, in Ann. Rep. Div. Lab. Res., New York State Dept. Health, Albany, No. 

 54, 19(1933). 



3" M. C. Pangborn, Proc. Sac. Exptl. Biol. Med., 48, 484-48r) (1941 ). 

 3^8 M. C. Pangborn, /. Biol. Chem., 153, 343-348 (1944). 

 "9 M. C. Pangborn, J. Biol. Chem., 157, (591-692 (1945). 

 38" M. C. Pangborn, /. Biol. Chem., 161, 71-82 (1945). 



