)20 



G. H. BEAVEN, E. R. HOLIDAY, AND E. A. JOHNSON 



220 



240 



300 



260 280 



Wavelength, rriM 

 Fig. 20. Deoxy-5-methylcytidylic acid (Cohn'')- 



320 



the presence of this nucleotide, since the nondialyzable PNA cores obtained 

 by partial alkaline hydrolysis, which were rich rather in adenylic than in 

 guanylic acid, showed a much smaller hyperchromic effect than either the 

 parent PNA or the enzymic core. 



In the case of still smaller fragments there seems to be no evidence of anomalous 

 absorption. Merrifield and Woolley** have confirmed that a number of dinucleotides 

 and a trinucleotide derived from DNA show absorptivities which are within experi- 

 mental error the sums of those of their consistent mononucleotides (see also Elmore 

 and Todd^^), and Sinsheimer and Koerner*' make the same claim for di-deoxyribo- 



" R. B. Merrifield and D. W. Woolley, /. Biol. Chem. 197, 521 (1952). 



" D. T. Elmore and A. R. Todd, /. Chem. Soc. 1952, 3681. 



" R. L. Sinsheimer and J. F. Koerner, /. Am. Chem. Soc. 74, 283 (1952). 



