400 V. CIIEMISTEY OF PIIOSrHATIDES AND CEREBROSIDES 



for enabling the normal metabolic reactions of the carbohydrates to take 

 place in nervous tissue. 



The analogy between the phosphorus-containing carbohydrates and 

 lipids is not too close in other respects. For example, only the phosphate 

 ion is attached to the sugars, and this is in an ester linkage. This allows 

 the phosphate to be easily detached or to be transferred to other com- 

 pounds by simple chemical or biochemical means. Such carbohydrates 

 can readily act as phosphate acceptors or phosphate donors. In the case 

 of all the phosphatides except the phosphatidic acids, a second non-fatty 

 component is combined w"ith the phosphoric acid in such a way that these 

 compounds cannot effectively act in phosphate transfer without hydrolysis 

 of the molecule. It is true that the glycerol phosphate, which may be an 

 intermediate, may act as the sugar phosphate compound. 



Thudichum^ originally assigned the name phosphatide to the compounds 

 now more frequently referred to as phospholipids. He included in this 

 group those substances which contained phosphoric acid, glycerol, higher 

 fatty acids, and an organic base. Leathes^ coined the term phospholipines 

 for these products, and this terminology was also adopted by H. and I. S. 

 MacLean,^ although the latter workers dropped the terminal "e." How- 

 ever, Thierf elder and Klenk^ prefer to retain the original Thudielium usage, 

 since this includes the nitrogen-free phosphatidic acids, along with the 

 nitrogen-containing phospholipids. In line with the preponderant current 

 American practice, the term phospholipid^ will be used to connote all 

 phosphorus-containing lipids, including the phosphatidic acids. 



Specific monographs dealing entirely or largely with the phospholipids 

 include the volume entitled Lecithin and Allied Suhstaiices by MacLean 

 and MacLean,^ and Die Chemie der Cerebroside und Phosphatide by Thier- 

 f elder and Klenk.'* Among the various monographs on lipids, those of 

 Bloor^ and of Schonfeld-Hefter^ present especially good discussions of the 



1 J. L. W. Thudichum, Researches on the Chemical Constitution of the Brain, Report 

 of the Medical Officer of the Privy Council and Loral Government Board [n.s.], 3, No. 

 5, 113-247 (1874). Cited by H." Thierf elder and E. Klenk, Die Chemie der Cerebroside 

 und Phosphatide, Springer, Berlin, 1930, p. 63. 



* J. B. Leathes, The Fats, Longmans, Green & Co., 1st ed., London (1910). Cited 

 by H. Thierfelder and E. Henk, Die Chemie der Cerebroside und Phosphatide, Springer, 

 Berlin, 1930. 2nd ed., with H. S. Roper, London, 1925, p. 61. 



' H. MacLean and I. S. MacLean, Lecithin and Allied Substances, 2nd ed., Long- 

 mans, Green & Co., London, 1927. 



* H. Thierfelder and E. Klenk, Die Chemie der Cerebroside und Phosphatide. 



* Although the majority of publications employ this spelling, some authors prefer 

 to include a terminal "e" (phospholipide). Since this revised spelling would appear to 

 offer no additional clarity of expression, the shorter term has been employed here. 



8 W. R. Bloor, Biochemistry of the Fatty Acids and Their Compounds, the Lipids, 

 Reinhold, New York, 1943. 



^ A. Griin, in H. Schonfeld and G. Hefter, Die Chemie und Technologic der Fette und 

 Fettprodukte, Vol. I, Springer, Vienna, 1936, pp. 456-516. 



