Pfizer Handbook of Microbial Metabolites 532 



Azaserine, a glutamine antagonist, inhibits purine syn- 

 thesis in some bacteria, and causes accumulation of for- 

 mylglycinamide ribotide in E. coli.-* Another antibiotic, 

 6-diazo-5-oxo-L-norleucine, also inhibits purine biosynthe- 

 sis at this stage. Purine-requiring mutants of E. coli and 

 A. aerogenes accumulate the following compounds or 

 derivatives : aminoimidazole,-'^ 5-aminoimidazolecarboxa- 

 mide,-'' 5-amino-4-imidazole-N-succinocarboxamide-^ and 

 xanthine.-' Yeast grown on a biotin-deficient medium 

 gives off aminoimidazole riboside and hypoxanthine.-^ 



Cell-free extracts of Neiirospora crassa are able to pro- 

 mote all the reactions shown in the biosynthetic scheme 

 above. All these facts as well as other evidence indicate 

 that this is the principal biosynthetic route to purines in 

 bacteria and fungi, and probably is quite general. 



Inosinic acid is an intermediate in the biosynthetic 

 route to the other purines as shown in the formula se- 

 quence on page 533. 



Extracts of Aerobacter aerogenes convert inosinic acid 

 to xanthylic acid, and there is other evidence that the 

 final stages of purine biosynthesis follow this route in 

 many bacteria and fungi as well as in animal cells. 



Other references can be found in some of the reviews 

 of this subject.-"' ^^ 



There are indications that methylated purines may be 

 minor constituents of yeast and bacterial nucleic acids. 

 Traces of 6-methylaminopurine, 6-hydroxy-2-methylami- 

 nopurine and 1-methylguanine were detected in yeast 

 RNA.-^ Small amounts of 6-methylaminopurine, 6,6-di- 



-^A. J. Tomisek, H. J. Kelley and H. E. Skipper, Abstr., 128th 

 Meeting, Am. Chem. Soc, 5C, Minneapolis, Sept., 1955. 



25 Samuel H. Love and Joseph S. Gots, J. Biol. Chem. 212 647 

 (1955). 



26 Joseph S. Gots, ibid. 228 57 (1957). 



2^ Boris Magasanik, H. S. Moyed and Lois B. Gehring, ibid. 226 

 339 (1957). 



2* D. P. Lones, C. Rainbow and J. D. Woodward, /. Gen. Microbiol. 

 19 146 (1958). 



2^^ Max Adler, Bernard Weissmann and Alexander B. Gutman, 

 ;. Biol. Chem. 230 717 (1958). 



