U 2 WALTER JONES 



HO\ 

 0=P O.C 5 H 8 3 .C 5 H 3 N 4 (1) 



HO/ 



O 



II 

 C 6 H 9 4 . P-0 . C 5 H 3 N 4 (2) 



OH 



/OH 



C 5 II 9 4 . C 5 H 2 N 4 . P-0 (3) 



\OH 



Inosinic acid is a dibasic acid, so that formula (2) is excluded. It 

 sets free its hypoxantliine much more easily than its phosphoric acid. 

 This would not be possible if the hypoxanthine group were internal to the 

 phosphoric acid group; so that formula (3) is excluded. The correct 

 formula (1) remains. The order of the groups in adenine nucleotide and 

 guanine nucleotide has been proven in a similar way. (Jones (d) 1920) 

 (Jones and Read, 1917.) 



Of the greatest interest is the hydrolytic action of ammonia on in- 

 osinic acid under pressure. When, so treated, the substance loses its 

 phosphoric acid completely, while the linkage between the pentose and 

 hypoxanthine groups is not disturbed, so that a phosphorus-free compound 

 is produced called inosine. (Levene and Jacobs (a) 1909.) 



HO\ HO\ 



0=P-0 . C 5 H 8 :i . C B H 8 N 4 0+H 2 0= O=P-OH+C 5 H 9 O 4 . O 5 H 3 N 4 

 HO/ HO/ 



Inosine is typical of a class of compounds called nucleosides. As from in- 

 osinic acid, so also from any nucleotide a nucleoside may be prepared by 

 hydrolysis with ammonia. 



Guanylic Acid. This substance is a strict analogue of inosinic acid. 

 It is found in animal tissues (principally the pancreas) and doubtless 

 originates from the plant food, for it is identical with guanine nucleotide 

 prepared from yeast nucleic acid. By mild acid hydrolysis, it splits easily 

 into phosphoric acid pentose and guanine, setting free the guanine much 

 more rapidly than the phosphoric acid. As with inosinic acid, guanylic 

 acid loses its phosphoric acid and forms its nucleoside by hydrolysis with 

 ammonia. 



Tlif chemical analogy between the two nucleotides is shown in the fol- 

 lowing equations: 



