513 Pyrimidrnes 



and seem to be nearly ubiquitous, although so far they 

 have not been reported from other microorganisms. 

 CDP-Glycerol and CDP-ribitol have been isolated only 

 from lactobacilU,''' but probably such substances will be 

 found elsewhere. 



CDP-Choline and CDP-ethanolamine are coenzymes es- 

 sential to the biosynthesis of lecithin and phosphotidyl- 

 ethanolamine.'^ The stages in the biosynthesis of lecithin 

 may be outlined : 



2R— CO— S— CoA 



HOCH2CH2N®(CH3)3 

 ATP^ 



r^ADP 



POCH2CH2N©(CH3)3 

 Cyt— P— P— p«->jr 



ppHI 



Cyt— P— P— OCH2CH2N ® (CHsls 



Cytidine— P + CH2— OCOR 



I 

 RCOO— CH O 



I T 



CH2O— P— O— CH2CH2N ® (CHsla 



The cytidine monophosphate can then be rephosphoryl- 



35 J. Baddiley and A. P. Mathias, /. Chem. Soc, 2723 (1954); 

 J. Baddiley, J. G. Buchanan, B. Cares, A. P. Mathias and A. R. San- 

 derson, Biochem. J. 64 599 (1956). 



