PENTOSE NUCLEIC ACIDS 15 



TABLE 6 



MOLAR PROPORTIONS OF PURINES AND PYRIMIDINES IN DEOXYPENTOSE 

 NUCLEIC ACIDS FROM DIFFERENT ORGANS OF ONE SPECIES 



Abbreviations: A = adenine, G = guanine, T = thymine, C = cytosine. 



8. COMPOSITION OF PENTOSE NUCLEIC ACIDS 



Here a sharp distinction must be drawn between the prototype 

 of all pentose nucleic acid investigations — the ribonucleic acid 

 of yeast — and the pentose nucleic acids of animal cells. Nothing 

 is known as yet about bacterial pentose nucleic acids. In view 

 of the incompleteness of our information on the homogeneity of 

 pentose nucleic acids, which I have stressed before, I feel that 

 the analytical results on these preparations do not command the 

 same degree of confidence as do those obtained for the deoxy- 

 pentose nucleic acids. 



Three procedures, to which reference is made in Tables 7 

 (Refs. 25, 28) and 8, were employed in our laboratory for the 

 analysis of pentose nucleic acids. 



In Procedure 1, the pentose nucleic acid was hydrolyzed to 

 the nucleotide stage with alkaU, at pH 13.5 and 30°, and the 

 nucleotides, following adjustment to about pH 5, separated by 

 chromatography with aqueous ammonium isobutyrate-isobutyric 

 acid as the solvent. Under these conditions, guanylic acid shares 

 its position on the chromatogram with uridylic acid; but it is pos- 

 sible to determine the concentrations of the two components in 

 the eluates by simultaneous equations based on the ultraviolet 



References p. 23 



