102 THE CLEAVAGE PRODUCTS OF THE NUCLEOPROTEIDS. 



HN CO 



-NH X CO C N.CH 3 . 



I II >CH | 



CH 3 .N C N * CH 3 .N 



Theophyllin = C 7 H 8 N 4 O 2 . Theobromin = C 7 H 8 N 4 O 2 . 



NH CO 



NH 2 .C C. N.CH, 



Epiguanin = C 6 H 7 N 5 O. 



Carnin is apparently closely related to hypoxanthin, as on treatment 

 with bromine it yields methyl bromide, carbon dioxide, and the brom- 

 hydrate of hypoxanthin, according to the equation : 



C 7 H 8 N 4 O 3 + 2Br = C 5 H 4 N 4 O.HBr -f- CH 3 Br -f CO 2 . 

 Its structural formula is thus possibly the following : 

 CH 3 .N CO 



CHOH C NH v 



I II X CH 



HN CO = CO N ^ 



Episarcin is but little known. Its formula is given as C 4 H 6 N 3 O, 

 but it is possible that this is not correct. The substance has un- 

 doubtedly many properties in common with epiguanin, and future 

 researches indeed may possibly show that the two are identical. 



The various purin bases, which Gautier once designated the 

 xantkin leucomains, have the character of feeble alkaloids, and com- 

 bine with hydrochloric acid and platinum chloride to form crys- 

 talline salts, which are dissociated only very slowly or not at all 

 by water. When fused with alkalies they lose the greater portion 

 of their nitrogen in the form of cyanogen, and, as a matter of fact, 

 we find that all of them contain the group HCN. Adenin, indeed, 

 is a polymeric compound of hydrocyanic acid, and xanthin can be 

 obtained by direct hydration of the same body (Gautier). On heat- 

 ing with alkalies or with water the nucleinic bases generally do not 

 give rise to the formation of urea, and they cannot hence be re- 

 garded as ureids, although a close relationship exists between them. 

 By a simultaneous process of oxidation and hydration guanin thus 

 gives rise to parabanic acid, and it is possible indeed to pass from 

 guanin to xanthin and hypoxanthin by a series of simple reactions 

 without the intervention of urea. These changes are represented by 

 the equations : 



/NH 2 CO NH X 



C 5 H 5 N 5 O + 3O -f- H 2 O = C(NH)< + I >CO -f CO 2 



Guanin 5 . \NH 2 CO-NH/ 



Guanidin. Parabanic acid. 



C 5 H 5 N 5 + HN0 2 = C 5 H 4 N 4 2 -f 2N + H 2 O. 

 Guanin. Xanthin. 



C 5 H 4 N 4 O 2 + 2H = C 5 H 4 N 4 O -f H 2 O. 

 Xanthin. Hypoxanthin. 



