THK LECITHINS 437 



mastei'-^^ has recently reported a miei-odetermination method for a- and 

 /3-glycerophosphate based on the colorimetric measurement of orthophos- 

 phate produced by the action of periodate. The recent literature on 

 jllycerophosphates has brrn roA'ieued by Fischer and Baer. -•'•'' 



d. Glycerylphosphorylcholine. Another lecithin interniediate which 

 has been isolated from beef panci(>as, "'■'-" from the reaction mixture when 

 an extract of rice hulls acts upon lysolecithin/^^ and from the action of 

 minced intestine on lecithin, ^^^-^'^ is glycerylphosphor^vlcholine. Roth the 

 (X- and the /5-form have now been reported as isolated from pancreas. '-"•-'■■"'' 

 This compound results from the action of lecithinase B. 



HoCOH 



I 



HCOH ^Q^ ^C^^^ 



HX-0-P-OCH»CH»N-CH, 

 i CH3 



OH 



a-Gl.\cer.\ii)h(>splu)r.\lcholine 



Although a number of methods have been &uggesl;ed for the synthesis of 

 /3-glycerylphosphorylcholine/*^*"^^'"' Aloisi and Buffa'-^*^ have concluded 

 that the product obtained in each case was the choline salt of /3-gl.ycerophos- 

 phoric acid rather than the choline ester. The latter workers-^^ did, how- 

 ever, succeed in preparing choline a- and /^-glycerophosphate in beautiful 

 crystalline form. 



Pure glycerylphosphorylcholine is soluble in water and alcohol, but it does 

 not dissolve in acetone, et:her, or petroleum ether. It possesses a levo-rota- 

 tion {\otf^ = —4.8°).^^^ The eh oline-phosphoric acid linkage in glyceryl- 

 phosphorylcholine is very susceptible to rupture. Thus, when it is heated 

 with 1 iV HCl for 30 minutes on the water bath, a complete hydrolysis to 

 choline and glycerophosphate takes place. This behavior is in marked 

 contrast to that of phosphorylcholine, where the corresponding linkage is 

 very resistant toward acids.'-" Glycerylphosphorylcholine is hydrolyzed 

 by alkaline phosphatase, but the rate of hydrolysis is as much as 150 times 

 slower than that which occurs when glycerophosphate is the substrate. 

 Thannhauser and Schmidt^" state that glycerylphosphorylcholine is the 

 only intermediate of lecithin which has been identified in mammalian me- 

 tabolism. 



*" C. F. Burmaster, J. Biol. Chem., 164, 233-240 (1946). 



*» H. O. L. Fischer and E. Baer, Chem. Rers., 29, 287-316 (1941). 



"« M. Aloisi and P. Buffa, Biochem. J., 43, 157-160 (1948). 



^^ H. .-Vrnold, Ber., B73, 87-90 (1940). 



2^*' C. Ravazzoni and .V. Fonaroli, Ann. chim. opplicata, 30, 318-323 (1940); Chem. 

 Abst.,3o, 1765 (1941). 



''*'■ S. Belfanti, A. Erroli, and M. Franncioli, in E, Bamann and K. Myrbaclv, Die 

 Melhoden der Fermenlforschung, \o\. I, Thieme, Leipzig, 1941, pp. 80-110. 



"^ E. Baer and C. S. McArthur, J. Biol. Chem., 154, 451-460 (1944). 



