8 



MAUKIOE .1. BESSMAN 



acid. In Fig. 2, (looxyuridyiate is seen to cleave the methylene group at 

 N= with the formation of a labile intermediate between this methylene 

 group and the 5-position of the uracil ring. An intramolecular oxidation- 

 reduction would yield thymidylate and dihydrofolate in equal amounts. 



I 



deoxyribose phosphote 



H 



I 





C-glut 



II 







J^ CH. 



I 



deoxyribose phosphate 



i 



H 



C-glut 



OH 







0' ^N* 



I 



deoxyribose phosphate 



Fig. 2. Postulated mechanism for the synthesis of thymidylate. (From Fried- 

 kin, 1959b.) 



Humphreys and Greenberg (1958) independently proposed a similar 

 mechanism for this reaction. 



An interesting aspect of the synthesis of thymidylic acid is the 

 increase in the capacity of E. coli infected with certain bacteriophages 

 to convert deoxyuridylate to thymidylate. Flaks and Cohen (1957) 



