140 WALTER JONES 



HO\ 



0=P O . C 5 H 8 3 . C 4 H 3 No0 2 

 HO/ 



Uracil Xucleotide (Levene (d) , 1919) 



They are crystalline dibasic acids which closely resemble phosphoric acid 

 in their acidic conduct. They form crystalline dibrucine salts which differ 

 from one another in their solubilities, thus making possible the purification 

 of the nucleotides and their separation from one another. 



The two purine nucleotides easily undergo acid hydrolysis, giving rise 

 to phosphoric acid pentose and purine base: but the pyrimidine nucleotides 

 are very stable, and must be treated severely before hydrolysis is effected. 

 This explains the conduct of nucleic acid toward hydrolytic agents. 



It will be seen that a thermostable physiological agent (a ferment ?) 

 is present in the pancreas, which at the body temperature causes a decom- 

 position of yeast nucleic acid into its four component nucleotides. 



The Nucleotide Linkages of Yeast Nucleic Acid. It has been pointed 

 out that the work of the earliest investigators indicated the nucleotide 

 structure of yeast nucleic acid. But this work gave no suggestion of the 

 points where the four nucleotides are united to one another in yeast nucleic . 

 acid, or in other words, the location of the nucleotide linkages. The loca- 

 tion was later assumed, without any evidence, to be through the phosphoric 

 acid groups, but this assumption is not correct. The nucleotide linkages 

 involve neither the phosphoric acid groups, nor purine groups, and prob- 

 ably not the pyrimidine groups. This conclusion is based principally upon 

 the following. 



I. The conversion of yeast nucleic acid into simpler nucleotides is 

 not attended J?y an increase in acidity. (Jones (e), 1020.) There would 

 bo a marked increase in acidity if the nucleotide linkages involved the 

 phosphoric acid groups. 



II. The laws governing the liberation of phosphoric acid from the 

 nucleotides are the same, whether the nucleotides are free or combined in 

 nucleic acid. The same is true for the purines, and also for the pyrim- 

 idines, so far as experiments with the latter are possible. (Jones (d) 

 1920.) 



If the nucleotide linkages involve neither the phosphoric acid groups, 

 the purine groups nor the pyrimidine groups, they can only involve the 

 carbohydrate groups. Nucleic acid should therefore probably have" the 

 following formula which represents the substances as a polysaccharide. 



[It should be noted that this formula is arrived at by exclusion and is 

 intended primarily to indicate the points at which the nucleotide linkages 

 do not exist.'] 



