CHEMISTRY OF NUCLEOSIDES AND NUCLEOTIDES 



187 



The uridine phosphate formed on hydrolysis consumes 1 mol. of periodate 

 and is identical with synthetic uridine-5'-phosphate.^^^ The product of 

 cautious acid hydrolysis is uridine-5'-pyrophosphate (LIII). The pyrophos- 



N: 



— o — 



OH OH OH OH 



II , , 



'-CH-CH-CH-CH-CHj-O-P-O-P-OH 



I II II 



N^ 



-0- 



N 



MeCMe 



/\ 

 O OCH^Ph 



I 

 LcH-CH-CH-CH-CH,-0-P-Cl 

 I II 



N^ 



OH 



LHI 



Uridine- 5'-pyrophosphate 



OH 



LIV 



2',3'-Isopropj'lidene uridine-5'- 

 benzylphospliorochioridate 



phate has been synthesized from 2',3'-isopropylidene-5'-iodo-5'-deoxyuri- 

 dine (formula, p. 177) by condensing the latter with silver tribenzyl pyro- 

 phosphate, then removing protecting groups.^''^ It may also be prepared 

 from 2',3'-isopropylidene uridine-5'-benzyl phosphorochloridate (LIV) and 

 dibenzyl phosphate.^^" 



The formula LV is established for UDPG : 



-O- 



OH OH 



OH OH 



OH 



OH 



^CH-CH-CH-CH-CH>-0-P-0-P-0-CH-CH-CH-CH-CH-CH,-OH 



I ' II II I 



N O OH 



o=r ■ 



OH 



LV 

 UDPG 



The linkage between the pyrophosphate and glucose residues must be a 

 since cautious alkaline hydrolysis gives glucose-1 ,2-hydrogen phosphate, 

 which can only be formed from an a- 1 -phosphate. 



Several other uridine diphosphate coenzymes have been encountered in 

 Nature. Staphylococcus aureus contains such substances bearing an amino 

 sugar and amino acids in the place of glucose.-^^ In addition to the galactose 

 analogue of UDPG there is some evidence for the presence in Nature of 

 UDP derivatives of other sugars.^®^- "^' "® 



"3 N. Anand. V. M. Clark, R. H. Hall, and A. R. Todd, /. Chein. Soc. 1952, 3665. 



"^ J. T. Park, /. Biol. Chem. 194, 877, 885, 897 (1952). 



"^ J. G. Buchanan, J. A. Bassham, A. A. Benson, D. F. Bradley, M. Calvin, L. L. 



Daus, M. Goodman, P. M. Hayes, V. H. Lynch, L. T. Norris, and A. T. Wilson, 



Phosphorus Metabolism 2, 440 (1952). 

 "• G. J. Dutton and I. D. E. Storey, Biochem. J. 53, XXXVII (1953). 



