300 PRACTICAL ORGANIC AND BIO-CHEMISTRY 



ascertained, but the following formulae have been provisionally 

 assigned : 



Animal Nucleic Acid. 



Plant Nucleic Acid. 1 



0-V 



HO 



HO 



H0 





O C 6 H 10 O 4 guanine group. 



\ 



O = P O C 5 H 7 O 2 guanine group. 

 HO/ 



O = P O C 6 H 8 O 2 thymine group. 



H 



\ 



I 



O = P O C 6 H 8 O 2 - 

 HO/ 



O 



H0 \ 



:ytosine group. 



O = P O C 6 H 6 O cytosine group. 

 HO/ 



O 



H0 \ I 



O = P O C 6 H 6 O uracil group. 



HO 



HO 



/ 



\ 



O = P O C 6 H 10 O 4 adenine group. O = P O C C H 7 O 2 adenine group* 



HO/ HO/ 



The combination of phosphoric acid with carbohydrate in each 

 case has been proved by the isolation of a carbohydrate ester of phos- 

 phoric acid, and the combination of purine base with carbohydrate by 

 the isolation of such a compound. This compound is a glucoside and 

 glucosides of carbohydrate and purine have been synthesised by Emil 

 Fischer. There is as yet no evidence as to how the groups are con> 

 bined together. 



Each of the groupings phosphoric acid + carbohydrate -f- purine 

 or pyrimidine base is termed a mononucleotide. Nucleic acid is thus 

 a tetranucleotide. The carbohydrate and purine base or pyrimidine 

 combination is known as a nucleoside. 



a-N ucleoproteins. 



If aqueous extracts of various organs be made and these extracts 

 be acidified with acetic acid, a precipitate consisting of protein and 

 nucleic acid is formed. It has been termed nucleoprotein. 



These a-nucleoproteins must be regarded as salts or of combinations 

 of nucleic acid and protein ; as salts on account of the occurrence 

 of protamine nucleate in spermatozoa, their easy separation, and on 

 account of the property of nucleic acid of precipitating protein from 

 solution when a solution of sodium nucleate in a solution of protein 

 is acidified. 



/?-Nucleoproteins. Mononucleotides. 



If organs, especially the pancreas, be suspended in water, the sus- 

 pension raised to the boiling-point and filtered from the coagulum of 

 protein which is formed, a clear yellow liquid is obtaind. If this 

 1 Jones and Read, J. Biol. Chem., 1917, 31, 40. 



