CHEMISTRY OF Till-: PURINES 



()27 



that arc attached to this nucUnis. The structure of purine itself is 

 as shown below :- 



N = CH 



I I 



HC C-NH 



II II >" 

 N-C-N 



Purine 



The derivatives of purine are described by stating to which atom 

 of the purine nucleus the combining groups are attached. Thus, 

 adenine is referred to as 6-amino-purinc, and therefore has the follow- 

 ing formula : 



N = C-NHo 



I I 

 HC C-NH 



II I! >H 



N-C-N 



Adenine (G-amino-purine) 



Other important members of this group of "purine bodies," (also 

 called xanthine bodies, alloxuric bodies, and nuclein bodies) are built 

 up about the purine nucleus as shown below: 

 HN-C=0 



H2N-C C-NH 



,11 II ^ 

 N-C-N 



Guanine 

 (2-amino-6-oxy purine) 



HN-C=0 



CH 



HC 



C-NH 

 ^ CH 



l| i" ^ 

 N-C-N 



Hypoxanthine 

 (C-oxy purine) 



H3C-N-C=0 



! 



0=C C-N/ 



I II v 



CH3 



CH 



H3C-N-C-N 



Caffeine 

 (1-3-7 trimethyI-2-6 dioxy purine) 



HN-C=0 

 0=C C-NH 



J i: >CH 



HN-C-N 



Xanthine 

 (2, 6-dioxypurine) 



HN-C=0 

 0=C C-NH 



\c=o 



HN-C-NH 



Uric acid 

 (2-0-S-trioxy purine) 



HN-C = CH3 



i 1 / 



0=C C-N/. 



I II /^^ 



H,C-N-C-N 



Theobromine 

 (3-7-dinicthyI, 2-6 dioxy purine) 



As shown by their structural formulae, the pyrimidines present in 

 the nucleic acids are also closely related to the purines, viz: 

 N-CH N-C-NH2 HN-C=0 HN-C=0 



II II II- I ; 



0=C C-CH, 



HC CH 



.i> 



N = CH 



Pyrimidine 



= C CH 



I H 

 HN-CH 



Cytosine 



(2-oxy, G-amino- 



pyrimidine) 



0=C CH 



I ' 

 HN-CH 



Uracil 



(2-6-dioxy- 

 pyrimidine) 



HN-CH 



Thymine 



(5-methyl, 2-6-dioxy- 



pyrimidine) 



2 In these formula) the symbols of the atoms forming the purine nucleus are 

 in heavy type. 



