CHEMISTRY OF PURINES AND PYRIMIDINES 107 



clue to the mechanism of the inhibitory activity of this agent (and possibly 

 others) is furnished by the reports of its apparent incorporation into the 

 nucleic acids of T. geleii^^* and the normal and tumor tissue nucleic acids 

 of mice;-^^'^^^ its incorporation into tobacco mosaic virus nucleic acid is 

 supported by the isolation therefrom of a and b isomers of 8-azaguanylic 

 acid.^^^ Other instances of this type of phenomenon are the incorporation 

 of the inhibitors 5-bromouracil into the nucleic acids of S. faecalis-^^ and 

 2,6-diaminopurine into the nucleoside phosphates of the mouse.^^^ 



A new series of analogues in which carbon 2 of the purines is replaced by 

 nitrogen, i.e., the imidazo-1 ,2,3-triazines, has been developed.^"" A product 

 of the acid degradation of adenine, i-amino-S-imidazolecarboxamidine^"' 

 is converted upon reaction with nitrous acid into 2-azaadenine (XXXIV) i^"" 

 in a similar fashion, 2-azahypoxanthine is obtained from the carboxamide. 

 The adenine analogue exerts a powerful inhibitory effect on a number of 

 microorganisms,^"" and mouse sarcoma 180 cells in tissue culture,^"^ and 

 these actions could be blocked by adenine. 2-Azaadenine also inhibits xan- 

 thine oxidase.^"^ 



II. General Properties of Purines and Pyrimidines 



Many diverse techniques have been used to study the physical and chemi- 

 cal properties of the purines and pyrimidines and some of the&e are sum- 

 marized in this section. Detailed aspects of X-ray, infrared, and ultraviolet 

 studies are considered elsewhere (cf. Jordan, Chapter 13; Beaven, Holiday, 

 and Johnson, Chapter 14). 



1. Physical Properties 



a. Solubility; Distribution Studies; Chromatography 



The pyrimidines and purines which are dealt with here should be classi- 

 fied as aqueous-soluble (rather than organic-soluble) despite the fact that 



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 "5 R. E. F. Matthews, Nature 167, 892 (1951); J. Gen. Microbiol. 8, 277 (1953). 

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197, 199 (1952). 

 "5 J. H. Mitchell, Jr., H. E. Skipper, and L. L. Bennett, Jr., Cancer Research 10, G47 



(1950). 

 "« L. L. Bennett, Jr., H. E. Skipper, and L. W. Law, Federation Proc. 12, 300 (1953). 

 "^ R. E. F. Matthews, Nature 171, 1061 (1953). 



298 F. Weygand, A. Wacker, and H. Dellweg, Z. Naturforsch. 7b, 19 (1952). 

 "9 G. P. Wheeler and H. E. Skipper, Federation Proc. 12, 289 (1953). 

 300 D. W. Woolley and E. Shaw, J. Biol. Chem. 189, 401 (1951). 

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302 J. J. Biesele, Cancer 5, 787 (1952). 



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