156 



NUCLEOPROTEINS, NUCLEIC ACIDS, RELATED SUBSTANCES 



in the tubercle bacillus, has now been found in small quantities in desoxy- 

 ribonucleic acids from cattle spleen, fish sperm, and wheat germ, but 

 not in the desoxyribonucleic acids from bacteria and viruses. To date, 

 none has been found in ribonucleic acids. The vitamin, thiamine, is a 

 pyrimidinethiazole combination. Its pyrimidine can be designated as 

 2,5-dimethyl-6-aminopyrimidine. 



Nucleosides and nucleotides 



If the hydrolysis of a nucleic acid is done under suitable conditions, 

 the breakdo\Mi may be stopped before it is complete and nucleosides and 

 nucleotides obtained. A nucleoside is a purine or pyrimidine-pentose 

 combination, and a nucleotide is a nucleoside-phosphoric acid complex. 

 The various bases, and the corresponding well-known nucleosides and 

 nucleotides, are listed in the following tabulation: 



The nucleosides are designated, according to the sugar contained in 

 them, as ribosides (adenosine, guanosine, cytidine and uridine) or as 

 desoxyriboside (thymidine) . The corresponding mononucleotides contain 

 the same sugars as the nucleosides. There are obviously other nucleosides 

 and nucleotides of desoxyribose, but, to date, these have not been given 

 specific names. They are often designated by prefixing the term desoxy 

 to the i>ames of the ribose-containing compounds: desoxyadenosine, des- 

 oxyadenylic acid, etc. 



The structural formula of one of the mononucleotides, adenylic acid, 

 will be given to show the order of the components and the linkages that 

 join the parts together. 



(6) 



0) N=C— NHj 



HC C- 



(7) 



■N 

 \\ 



OH 



I 

 0— P=0 



I 



OH 



CH 



(3) N— C-N- 



(4) (9) 



Adenine 

 Adenosine 



— 

 OH 



-C— C— C— C— CH2OH 

 H H H H 



(!') (20 (30 (40 (5') 



R 



i 



b 

 o 



s 

 -e 



Ribose phosphoric acid 

 >-i 



Adenosine-3-phosphoric acid 



Adenylic acid (adenosine monophosphate) 



