COMPOUNDS RELATED TO THE CEREBROSIDES 503 



acids and it gave a purple color when the Bial test was applied. On heating 

 with 16% sulfuric acid, a black humin-like precipitate was formed. In the 

 same year, Levene and Landsteiner^*'- also reported the presence of a simi- 

 lar compound in the brain. Since these compounds contain a sugar but no 

 phosphate, it is evident that they are more closely related to the cerebro- 

 sides than to other conjugated lipids such as the phosphatides. Blix'"^^ 

 confirmed the observations of Walz, and noted that a similar compound 

 occurred in the normal human brain. The sugar component was classified 

 as a hexosamine, since it gave a positive reaction with Ehrlich dimethyl- 

 aminobenzaldeh3'de reagent. 



Ivlenk^*'*''*^^ isolated a lipid, which he called "substance X," from the 

 tissues of an individual suffering from Niemann-Pick's disease. Later he 

 prepared the same compound from the tissues of an individual who had 

 died of the so-called Tay-Sachs disease, ^^^~^^^ where it had completely re- 

 placed the normall}'' occurring cerebroside. It is now evident that this 

 new lipid is closely allied to the cerebrosides. Since it occurs predominantly 

 in the ganglion cells of the nervous sj^stem, and because it possesses a gluco- 

 side structure, this substance has been named ganglioside.^*^ Under nor- 

 mal conditions the highest concentration is in the cerebral cortex, while 

 the white matter contains negligible amounts. ^^^ In the Tay-Sachs type of 

 infantile amaurotic idiocy, this lipid makes up ten times the normal content 

 in the cortex. A relatively high concentration likewise occurs in the whole 

 brain in the so-called Niemann-Pick's disease, but this is probably largely to 

 be ascribed to the more even distribution of the ganglioside throughout the 

 brain, due to the decreased proportion of ganglioside-deficient white matter 

 in this disease. Although gangliosides are present in the spinal cord, their 

 concentration is so small that it is impossible to separate them from other 

 components. Schuwirth^^° points out that these differences may be related 

 to the variations in structure of the two tissues. For this same reason, 

 also, the sphingomyelin content of the spinal cord is considerably higher 

 than that of the brain. ^^° Ivlenk and Rennkamp^^- have also isolated 

 gangliosides from normal beef spleen. 



The gangliosides are insoluble in ether, acetone, and ethyl acetate, and 

 are only slightly soluble in alfcohol. They readily dissolve in mixtures of 

 chloroform or benzene and alcohol. They form clear colloidal solutions in 

 water up to concentrations of 10%. Such solutions are non-dialyzable, 



^'2 p. A. Levene and K. Landsteiner, J. Biol. Chem., 75, 607-612 (1927). 



*8' G. Blix, Skand. Arch. Phi/siol, 80, 46-51 (1938). 



«* E. Klenk, Z. physiol. Chem., 235, 24-36 (1935). 



«s E. Klenk, Ber. ges. Phi/siol., exptl. Pharmakol, 96, 659-660 (1937). 



«« E. Klenk, Z. physiol. Chem., 262, 128-143 (1939). 



*«' E. Klenk, Z. phi/siol. Chem., 267, 128-144 (1940). 



«« E. Klenk and 11. LanRerbeins, Z. phi/siol. Chem., 270, 185-198 (1941). 



«9 E. Klenk, Z. physiol. Chem., 282, 84-88 (1947). 



♦*« K. Sc-huwiith, Z. physiol. Chem., 278, 1-6 (1943). 



