496 



VICTOR C. MYERS 



Nucleic Acid 

 (nuclease) 



I 

 Nucleotjda 



(nucleotidase) 



4 



Nucleosids 

 | nucleosidase) 



Adenin Guanin 



Nucleoprotein 

 (protease) 



Protein 



(adenase) 



I 

 Hypoxanthin 



(oxidase) 



(guanase) 



I 

 > Xanthin 



(oxidase) 



Uric Acid 



We are familiar with the chemical structure of the purins owing 

 chiefly to the researches of Emil Fischer and his pupils, An apprecia- 

 tion of the chemical structure of this group of compounds is of material 

 aid in obtaining an adequate understanding of purin metabolism. 



N = C(NH 2 ) 



HN CO 



IN 60 



II II II 



20 5C N7\ HC C NH (NH 2 )C C NH 



| | C8 || || \CH || || \CH 



3N 4C N9/ N C N/ N~ C N/ 



Purin Nucleus or Adenin Guanin 



Skeleton (G-amino-puriii) (2-amino-6-oxy purin) 



4 4 



HN CO HNCO HN 



11-11 II 



HC C NH OC C NH -> OO C NH\ 

 || || \CH | || \CII | || - CO 



N C N/ HN C N/ HN C NH/ 

 Hypoxanthin Xanthin Uric Acid 



(C-oxypurin) (2, G-dioxypurin) 2, 6, 8-trioxy-purin 



It has been claimed that in man about half the uric acid is subject to 

 a further enzymatic change (uricolysis). This, however, is still a dis- 

 puted question although in animals the greater part of the uric acid is 

 undoubtedly converted to allantoin. 



