334 BACTERIOLOGICAL CHEMISTRY 



bases cytosine and either uracil or thymine. These facts 

 are summarised in the following scheme : — 



Nucleoprotein 



I 



I 

 Protein + Nudein 



Acid j hydrolysis 



I 

 Protein + Nucleic acid (polytetranucleotides) 

 Cold alkaline | hydrolysis 



I 

 Tetra-nucleotides 

 Alkaline | hydrolysis 



Phosphoric acid + nucleosides 



Acid I hydrolysis 



From yeast nucleic acid From animal nucleic acid 



Adenine \p^^^-j^p ^^ggg Adenine 



Guanine J Guanine 



Cytosine "1 ^^ . . ,. , Cytosine 



Uracil )Pyrm^idme bases Thymine 



Ribose Desoxyribose 



The molecular weight of the ribonucleic acids from 

 various sources corresponds to the presence of from eight 

 to eighteen tetranucleotide units. Careful deamination 

 of the nucleic acids does not cause a lowering of the 

 molecular weight, suggesting that phospho -amide groups 

 are not involved in the linkage of the nucleotides. Elec- 

 trometric titration of the poly-tetranucleotides shows 

 that four acid dissociations are present for each tetra- 

 nucleotide, three of which correspond to primary phos- 

 phoric acid dissociations and one to a secondary phos- 

 phoric acid dissociation. The deaminated nucleic acids 

 show similar dissociation behaviour. Mild hydrolysis of 

 the polj^etranucleotides and the deaminated compounds 

 causes a lowering of the molecular weight with the 

 liberation of further secondary phosphoric acid groups. 

 It is suggested, on the basis of these facts, that the 



