186 J. BADDILEY 



it must be at position 3' (h). This is confirmed by the demonstration that 

 one of the products of pyrophosphatase action on CoA is adenosine-3',5'- 

 diphosphate (LI), different from the diphosphate obtained from TPN.^^s 



POjHa 



-0-1- 



OH 

 I I 

 '-CH-CH-CH-CH-CH2-OP03H2 



o::> 



LI 



Adenosine-3' , 5'-diphosphate 



OH 



I 

 H203PO-CH2-CMe2-CH-CO-NH-CH2-CH2-CO-NH-CH2-CH2-SH 



LII 



Pantetheine- 4'-phosphate 



Strong support for the formula assigned to CoA comes from the synthesis of 

 pantetheine-4'-phosphate (LII) by phosphorylation of pantetheine-0'',*S 

 dibenzyl ether with dibenzyl phosphorochloridate, then removal of benzyl 

 groups with sodium in liquid ammonia.^^^ This compound is identical with 

 the other product of pyrophosphatase action on the coenzyme, and is con- 

 verted into CoA by liver enzymes in the presence of ATP."" 



The "trans-acetylation" function of CoA involves the thiol group which, 

 as its thiolacetate, is capable of donating an acetyl group to a variety of sub- 

 strates."^ CoA is also involved in the transfer of other important acyl resi- 

 dues in biological systems. 



e. Uridine Diphosphate Glucose (UDPG) 



The intercon version of glucose- 1 -phosphate and galactose- 1 -phosphate 

 requires an enzyme "galactowaldenase." The coenzyme for this transfor- 

 mation is known as uridine diphosphate glucose (UDPG)."^ It gives on 

 hydrolysis uridine, glucose, and 2 mol. of phosphoric acid. Titration indi- 

 cates the presence of two primary and no- secondary phosphate acidic groups 

 and cautious acid hydrolysis liberates one secondary acidic group, together 

 with glucose. Further hydrolysis liberates 1 mol. of inorganic phosphate. 



268 T. p. Wang, L. Schuster, and N. O. Kaplan, J. Am. Chem. Soc. 74, 3204 (1952). 

 "9 J. Baddiley and E. M. Thain, /. Chein. Soc. 1953, 1610. 



"0 J. Baddiley, E. M. Thain, G. D. Novelli, and F. Lipmann, Nature 171, 76 (1953). 

 "1 F. Lynen, E. Reichert, and L. Rueff, Ann. 574, 1 (1951). 



"2 R. Caputto, L. F. Leloir, C. E. Cardini, and A. C. Paladini, J. Biol. Chcm. 184, 333 

 (1950). 



