STRUCTURE OF THE NUCLEIC ACIDS 



183 



O = P O.C 5 H7O 2 .C 6 H4N 6 







O = P O.C 5 H6O.C 4 H3N 2 O 2 

 HO/ 



O 



II 



O = P O.C 5 H 6 O.C 4 H 4 N 3 O 

 HO/ 







HOv 



\ 

 O = P O.C5H7O 2 .C 6 H 4 N 6 O 



Yeast nucleic acid. 



Tritico-nucleic Acid from the wheat embryo is identical in physical 

 behavior and in the products it yields on hydrolysis, with yeast nucleic 

 acid. They are therefore believed to be identical substances, and it 

 is considered probable that this is the only vegetable tetranucleotid. 



Thymus Nucleic Acid, it will be recollected, is yielded by the partial 

 hydrolysis of all nucleoproteins of animal origin. It contains a hexose 

 radical which has not yet been positively identified and it yields 

 thy mine instead of uracil. Levene and Jacobs consider that thymus 

 nucleic acid probably possesses the following structure: 



HOv 



O = PO C 6 HioO 4 C 6 H4N 6 O 

 / Guanine group 



0/ 



HO 



O 



II 



PO C 6 H 8 O 2 C 6 H 6 N 2 O2 



Thymine group 



O 



O = PO CeHsO:! C 4 H 4 N 3 O 



Cytosine group 



H 



O = PO C 6 Hio0 4 C 5 H4N B 

 / Adenine group 



HO/ 



