NUCLEIC ACIDS 



143 



H0\ 



0-P-O . C 5 H 8 3 . C 

 HO/ 



inosinicacid 



H0\ 



0-P-O . C 5 H 8 3 . C 

 HO/ 



guanylic acid 



I. By acid hydrolysis 



10 5 +C 5 H 4 N 4 O 



pentose hypoxanthine 



pentose 



guanine 



II. By hydrolysis with ammonia 



HO\ 



0-P O . C 5 H 8 3 . 

 HO/ 



inosinic acid 



HO\ 



0-P O . C 5 H 8 3 . 

 HO/ 



guanylic acid 



nosne 



4 . C 5 II 4 K>O 



guanosine 



Thus, inosinic acid (from muscle) is hypoxanthine nucleotide, or 

 deaminized adciiinc nucleotide, one of the purine nucleotides of plant 

 nucleic acid. 



Guanylic acid (from pancreas) is guanine nucleotide, one of the nu- 

 cleotides of plant nucleic acid. 



The plant origin of both nucleotides is shown by the identity of their 

 characteristic pentose (d-ribose). 



The Nucleosides of Yeast Nucleic Acid. When yeast nucleic acid is 

 submitted to mild alkaline hydrolysis (as with ammonia at 110), 

 it easily decomposes into its four component nucleotides.. But when al- 

 kaline hydrolysis of the nucleic acid is effected at. higher temperatures 

 (as with ammonia at 150), the four nucleotides first formed lose their 

 phosphoric acid, and are converted into the corresponding four nucleosides. 

 (Levene arid Jacobs (e) (/) (h), 1900, 1910.) 



[The logical order of treatment is from nucleotides to nucleosides but 

 this is not the order of discovery as the nucleosides were discovered first. 

 A long period of time elapsed between Kossel's discovery of the funda- 

 mental decomposition products of nucleic acid and Levene's discovery of 

 the first partial decomposition products (the nucleosides). The isolation 

 of the nucleotides by Jones and by Thannhuusor came afterwards.] 



