160 J. BADDILEY 



h. Puromycin 



An antibiotic, puromycin, is produced by Streptomyces alhoniger. On 

 alcoholysis it yields a 6-dimethylaminopurine, 0-methyl-L-tyrosine and 

 D-3-amino-3-deoxyribose. Its ultraviolet absorption spectrum indicates 

 that the carbohydrate residue is attached to the purine at position 9. Two 

 hydroxyls and an amino group are present and it does not consume period- 

 ate. These properties are consistent with the partial formula XX. "^* It is 

 not known whether the carbohydrate residue is in the furanose or pyranose 

 configuration. 



NHs 



CO-CH-CHjf 70Me 



n< 



OH NH O 

 I I I I 

 CH-CH-CH-CH-CHj 





r 





a> 



XX 



Puromycin 



II. Nucleotides 

 1. Introduction 



Nucleotides are the phosphoric acid esters of nucleosides. They may be 

 prepared by chemical or enzymic hydrolysis of nucleic acids provided that 

 the conditions chosen do not effect hydrolysis of phosphomonoester groups. 

 Nucleotides are also formed during hydrolysis of certain coenzymes, but 

 nucleic acids are the most convenient source for these substances. The first 

 nucleotide to be isolated, inosinic acid,"^ is probably exceptional in this 

 respect. It was obtained from meat by fairly direct methods of extraction 

 and purification and is believed to be an artifact arising through deamina- 

 tion of "muscle adenylic acid" (adenosine-5'-phosphate), which occurs in 

 the free state in muscle tissues.^-" 



Ribonucleotides may be obtained from ribonucleic acid by gentle chem- 

 ical or enzymic hydrolysis. Enzymic hydrolysis^'* is incomplete, however, 

 and chemical methods 'are generally employed for preparative purposes. 

 Hydrolysis of yeast ribonucleic acid with dilute ammonia gives the nucleo- 



"8» C. W. Waller, P. W. Fryth, B. L. Hutchings, and J. H. Williams. /. Am. Chem. Soc. 



75, 2025 (1953). 

 "9 J. von Liebig, Ann. 62, 257 (1847). 



120 G. Embden andM. Zimmermann, Z. physiol. Chem. 167, 137 (1927). 



121 H. S. Loring and F. H. Carpenter. J. Biol. Chem. 150, 381 (1943). 



