CHEMISTRY OF NUCLEOSIDES AND NUCLEOTIDES 167 



3'-phosphates^^^' "- and strong support for this view is furnished by the 

 synthesis of the two isomers by phosphorylation of 5'-trityladenosine with 

 dibenzyl phosphorochloridate, followed by hydrogenolysis of protecting 

 groups"" (see p. 174). Also, the ready cyclization of adenylic acids a and b 

 to the same adenosine-2',3'-hydrogen phosphate'^^ can only be explained in 

 this way. It has been shown recently'^"* that adenylic acid a may be hy- 

 drolyzed by short boiling in water with an ion-exchange resin (sulfonic 

 acid type) to ribose-2-phosphate. Under these conditions isomerization of 

 nucleotides and ribose phosphates does not occur to any significant ex- 

 tent. After similar treatment adenylic acid b gives ribose-3-phosphate. The 

 structure of the ribose phosphates follows from periodate oxidation of their 

 methyl glycosides and reduction to ribitol phosphates. Ribose-3-phosphate 

 is reduced to an optically inactive ribitol-3-phosphate, whereas the 2-phos- 

 phate gives an optically active substance, the activity of which may be 

 enhanced by formation of a boric acid complex. It follows that adenylic 

 acid a is adenosine-2'-phosphate and adenylic acid b is adenosine-3'-phos- 

 phate. 



Adenosine-2',5'-diphosphate is obtained by enzymic hydrolysis of tri- 

 phosphopyridine nucleotide (p. 182) and the 3',5'-diphosphate is produced 

 in a similar manner from coenzyme A (p. 186). 



PO3H2 

 -\ — 



O OH OH 

 I I I 

 ^^ „ MeO • CH • CH • CH • CH • CH2 



I Q I (consumes 1 mol. lOr) 



OH 



-CH-CH-CH-CH-CHj-OH pQ^H^ 



/ 



N. ^N 



^ r > 



-o- 



OH OH 



NH2 ^ HO-CH-CH-CH-CH-CHj 



Adenylic acid a Ribose-2-phosphate 



\ 



P0,H2 



OH OH 



1 I I 

 H0-CH2- CH-CH-CH-CHrOH 



Ribitol-2-phosphate 



"2 D. M. Brown and A. R. Todd, /. Chem. Soc. 1952, 52. 

 1" D. M. Brown, D. I. Magrath, and A. R. Todd, J. Chem. Soc. 1952, 2708. 

 "* J. X. Khym, D. G. Doherty, E. Volkin, and W. E. Cohn, J. Am. Chem. Soc. 75, 

 1262 (1953). 



