THE NUCLEINIO ACIDS. 103 



Xanthin, however, on oxidation and hydratio/n yields urea and 

 alloxan, which latter is further oxidized to parabanic acid and 

 carbon dioxide, as shown in the equations : 



CO NH, 

 I \ /NH 2 



C 5 H 4 N 4 2 -f 2O + H 2 O = CO >CO + CO< 



Xanthin. / \NH 2 



CO NH/ Urea. 



Alloxan. 



CO NHs 



\ CO NH, 



x v/vx xi J-^-x 



CO \CO + 0=| >CO + C0 2 



I / CO-NH/ 



CO NH/ 



Alloxan. Parabanic acid. 



The close relationship which exists between uric acid and the nucle- 

 inic bases thus becomes apparent, as uric acid on oxidation and 

 hydration gives rise to the same products as xanthin : 



C 5 H 4 N 4 3 + O + H 2 = C 4 H 2 N 2 O 4 + CON 2 H 4 . 

 Uric acid. Alloxan. Urea. 



As a matter of fact, it is now known that uric acid is formed from 

 the purin bases in the mammalian organism through the agency 

 of a specific ferment. Guanin thus gives rise to xanthin, and this 

 to uric acid, while adenin is transformed into hypoxanthin, and the 

 latter into uric acid with the intermediary production of xanthin. 

 In the transformation of guanin into xanthin a desamidizing ferment 

 is active, while the subsequent transformation into uric acid is refer- 

 able to an oxidizing ferment. This relationship is further shown by 

 decomposing the primary xanthin bases and uric acid with fuming 

 hydrochloric acid or hydriodic acid under high pressure. Qualita- 

 tively the same products are thus obtained, viz., ammonia, carbon 

 dioxide, glycocoll, and formic acid, while the quantitative relations, 

 of course, vary with the nature of the individual substance. 



C 5 H 3 N 5 + 8H 2 O = 4NH 3 -f CO 2 4- CH 2 .NH 2 .COOH + 2H.COOH. 

 Adenin. Glycocoll. Formic acid. 



C 5 H 4 N 4 O ^7H 2 = 3NH 3 + CO 2 + CH 2 .NH 2 .COOH + 2H.COOH. 



Hypoxanthin. 



C 5 H 5 N 5 O + 7H 2 O == 4NH, -f 2CO 2 -f CH 2 .NH 2 .COOH + H.COOH. 

 Guanin. 



C 5 H 4 N 4 O 2 -f 6H 2 = 3NH 3 + 2CO 2 + CH 2 .NH 2 .COOH -f H.COOH. 

 Xanthin. 



C 5 H 4 N 4 O 3 + 5H 2 O = 3NH 3 + 3CO 2 + CH 2 .NH 2 .COOH. 

 Uric acid. 



According to Emil Fischer, the structural formula of uric acid can 

 be represented as follows : 



HN CO 



CO C-NH X 



I II >co 



HN C NH X 



Uric acid. 



