518 



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



210 



230 



270 



290 



250 



Wavelength, rriA 

 Fig. 18. Uridine (Fox and Shugar'«). 



the values calculated from the summation of the absorptivities of the con- 

 tained purine and pyrimidine nucleotides. 



(b) Values of e(P) show poor reproducibility even from the same prepara- 

 tion of nucleic acid.^'*"'^^ It is of interest therefore to find out at what level 

 of hydrolytic degradation the anomalously low e(P) of nucleic acid is abol- 

 ished. 



Kunitz^^ had observed slight increases in the absorption maxima of 

 yeast PNA samples when depolymerized with ribonuclease, although here 

 the primary effect was a shift of the entire curve to shorter wavelengths. 

 Oster and Grimsson®" and Ogur and Rosen^^ found that other PNA Sam- 

 s' A. M. Marko and G. C. Butler, /. Biol. Chem. 190, 165 (1951). 

 69 M. Kunitz, /. Biol. Chem. 164, 563 (1946). 

 60 G. Oster and H. Grimsson, Arch. Biochem. 24, 119 (1949). 

 " M. Ogur and G. Rosen, Arch. Biochem. 25, 262 (1950). 



