THE PROTEINS ,, 



It can be synthetised by fusing together in a sealed tube trichlorolactamide 

 and urea. Thus : 



NH 2 CONH 2 NH-CO 



II II 



CO + CHOH + NH 2X = CO C-NH + NH 4 C1. + 2HC1 



/CO || \co 



NH, CC1 3 NH/ NH C NH/ 



The relation of xanthine, hypoxanthine, guanine, and adenine to uric acid 

 is shown by the following formulae : 



NH CO HN CO 



I' II 



CO C NH, CO-C^-NH X 



I II >0 I II >H 



NH C NH 7 HN C N 



Uric acid Xanthine 



2-6-8-trioxypurine 2-6-dioxypurine 



HN CO N = C.NH 2 NH-CO 



II II II 



HC C NH\ HC C NH X NH 2 C C NH\ 



II II >H || \CH || || VjH 



N C N '- N C N ' N C N ' 



Hypoxanthine Adenine Guanine 



6-oxypurine 6-amino-purine 2-amino 6-oxypurine 



Closely allied to this group of bodies are the chief constituents of tea, 

 coffee, and cocoa, namely caffeine, which is trimethyl dioxypurine, and 

 theobromine, which is dimethyl dioxypurine. From the structural formulae 

 given it will be seen that the purine radical contains two nuclei. The 

 nucleus N C 



I i 



C C 



u 



is spoken of as the pyrimidine nucleus, pyrimidine having the formula 



iN= 6 CH 



2 HC 5 CH 



I II 

 3N 4 CH 



The other is the radical which we have met with already in histidine, a 

 disintegration product of proteins, namely iminazol : 



HC NH 



II > CH 



HC N ' 



Besides the purine bases proper, we find among the disintegration products 

 of nucleic acid a series of bases derived from the pyrimidine ring, 

 are uracil, thymine, and cytosine. 



URACIL is 2-6-dioxypyrimidine, NH CO 



i i 



CO CH 



I II 

 NH CH 



