382 NITROGEN BASES 



The behaviour of the two acids on hydrolysis is substantially 

 the same except in regard to their final products, and it is, 

 therefore, proposed only to deal with plant nucleic acid. 



When hydrolysed with ammonia under pressure at a tem- 

 perature of 100-125°, yeast nucleic acid yields four so-called 

 mono-nucleotides as follows * : — 



HOs 

 Guanine nucleotide 0=^P— O . CjHgOa . C5H4N5O 



HOx 

 Adenine nucleotide 0==P — O . CgHgOa . C^H^Nb 

 HO/ 



HO>. 

 Cytosine nucleotide 0=;P— O . CjHgOa . C1H1N3O 

 HO/ 



HO\ 

 Uracil nucleotide O^P— O . C^HgOg . C4H3N2O2 



HO/ 



From which it may be concluded that the original nucleic acid 



is a tetra-nucleotide. 



If the hydrolyses of nucleic acid is carried out at a higher 



temperature, 145-155°, the mononucleotides above-mentioned 



undergo further hydrolysis, yielding products containing no 



phosphoric acid, which are known as nucleosides : — 



Nucleotide. Nucleoside formed on hydrolysis. 



Guanine nucleotides H3PO4 + Guanosine, C10H13N5O5 . 2H2O 



Adenine nucleotide -> H3PO4 + Adenosine, C10H13N5O4 . i^HjO 



Cytosine nucleotide -^ H.;P04 + Cytidine, CgHigNjOg 



Uracil nucleotide — > H;P04 + Uridine, C9H13N3O5 



These nucleosides are each composed of a carbohydrate, 



ribose, united to a nitrogen base which belongs either to the 



group of purines or of pyrimidines, and on hydrolysis break 



up into their constituents : — 



Guanosine -^ Ribose + Guanine ~l ^ . 



Adenosin -^ Ribose + Adenine j 



Cytidine — ^ Ribose + Cytosine) _, . 



Uridine -> Ribose + Uracil jPynmidme. 



These stages of the hydrolysis of a nucleotide may be illus- 

 trated by a single example of guanine nucleotide : — ■ 

 * See Jones : " The Nucleic Acids," London. 



