400 V. CHEMISTRY OF PHOSPHATIDES AND CEREBROSIDES 



ions in basic solution. No buffering action of sphingomyelin could l)e 

 demonstrated over a wide range of pH. by Christensen and Hastings^^^; 

 these authors also failed to demonstrate any appreciable combination of 

 sphingomyelin with chloride or sodium ions. 



(o) Ifydrolysifi of SphitigomycUn 



There is general agreement that glycerol is not present as a hydrolysis 

 product of sphingomyelin. '-•''-• ^■^" Choline has been proved to l)e a compo- 

 nent, irrespective of whether hydrolysis was brought about by barium hy- 

 droxide or by dilute sulfuric acid-^'^^-"^-^^* Sphingosine is always pres- 

 ent,'-^-'^"'"'* while Thudichum-^- also reported that an alcohol — sphingol, 

 C18H36O2 — is found. This has been confirmed by Rosenheim and Tebb,^^" 

 although Levene failed to find it in the hydrolysis products. ^^^ According 

 to Levene, ^^^ about 40-50% of the hydrolysis products consist of fatty 

 acids. The nature of these has already been discussed (see Section 5(1). 

 When a less complete hydrolysis was carried out, lignocerylsphingosine was 

 found. ^1' This compound possesses no basic character, and the nitrogen is 

 not present as the free amino group. 



Magistris^" reported that lignoceric acid is split from sphingomyelin by 

 bee venom, yielding a so-called lysosphingomyelin. Thierf elder and Klenk'' 

 consider that the experiments are not convincing, and they suggest that the 

 isolated lignoceric acid might well have originated through acid hydrolysis 

 from sphingomyelin during the analytical procedures. 



Little is known about the pathways of enzymic breakdown of sphingo- 

 myelin. Lignocerylsphingosine has been identified as a product arising 

 during the incubation of a preparation of liver extract. ^^"^ 



(6) Chemistry of Hydrolysis Products of the Sphingomyelins and Their 



Derivatives 



a. Lignocerylsphingosine. Levene^^^ first isolated lignocerylsphingo- 

 sine from a partially hydrolyzed preparation of hydrogenated sphingo- 

 myelin. Thannhauser and FrankeP^^ prepared this compound from pig 

 liver by the use of a mild hydrolyzing agent such as methyl alcoholic so- 

 dium hydroxide. The term cer amides has been coined to identify this class 

 of compounds.''^'- The presence of free lignocerylsphingosine in pig liver 

 and beef spleen is indicated by the fact that the ceramide has been prepared 

 from these organs without preliminary saponification. ^^--^'^ Klenk and 

 von Schoenebeck^^^ also separated lignocerylsphingosine from unhydro- 



329 H. N. Christensen and A. B. Hasting.s, J. Biol. Chem., 136, 387-398 (1940). 



330 O. Rosenheim and M. C. Tebb, J. Physiol., 88, Proc, U-Hii, liv-lvi (1909). 



331 S. J. Thannhauser and E. Frankel, Z. physiol. Cfiem., 203, 183-188 (1931), 



332 E. Frankel and F. Bielschowsky, Z. physiol. Chem., 213, 58-62 (1932). 



333 C. Tropp and V. Wiedersheim, Z. -physiol. Chem., 222, 39-43 (1933). 



334 E. Klenk and O. von Schoenebeck, Z. physiol. Chem., 209, 112-133 (1932). 



