58 



D. SHUGAR 



TABLE I 



Hyperchromicity of Some Nucleoside Diphosphates 



and Oligo- and Polynucleotides 



Hyperchromicity" 



Substance 



pH 2 



pH 7 l 



pH 9 



pH 13 



(d)pTp 

 (d)pCp 

 (d)A5'p3'T5'p 

 (d)pTpT 

 (d)pCpC 

 (d)pCpT 

 (d)pCpA 

 (d)pGpA 

 A2'p5'U 

 A2'(3')p5'T 

 A3'p5'C3'p 

 Diadenylic acid c 

 Triadenylic acid 

 Tetraadenylic acid 

 Pentaadenylic acid 

 Poly-A (13.6)'; 

 Poly-A (high) 

 Poly-U (3.5) c 

 Poly-U (6.6)' 

 Poly-U (12) c 

 Poly-U (high) 

 Poly-G (3.2) c 

 Poly-G (5.4) c 

 Poly-G (12. 5) c 

 Poly-AG (6.2) c 





 3 

 6 



12 







6.8 

 13.2 

 16.4 

 22.9 



4.8 

 7.5 

 7.5 



9.0 

 14.6 

 18.0 

 14.7 



9 

 18 



3 



1. 



3 

 25 



16 



4 

 2 



7 

 11 



36.7 

 50 



7.5 

 6.0 

 10.3 

 16.5 

 23.0 

 36.7 



12.8 

 12.7 

 7.2 

 15.1 

 22.8 

 30.7 

 32.9 

 36.7 



4.8 

 6.5 



8.6 















19.0 



References 



d 



d 



e 



e 

 d,f 

 d,f 

 d,f 



f 



9 



(I 



9 



9 



9 



9 



9 



9 



h 



9 



9 

 9 



h 



a Per cent increase in absorption following degradation to mononucleotides. 



6 Values in this column for oligo- and polynucleotides of Ap, Up, Gp.and ApGpare in unbuffered solution; 

 for influence of ionic strength on highly polymerized polynucleotides see Warner . 



c These refer to polymers containing a mixture of 2', 5' and 3', 5' internucleotide linkages (see Michelson") ; 

 figures in parentheses denote average chain lengths. 



d H. S. Shapiro and E. Chargaff, Biochim. et Biophys. Acta 26. 596 (1957). 



e P. T. Gilham and H. G. Khorana, J. Am. Chem. Soc. 80. 6212 (1958). 



f M. P. deGarilhe and M. Laskowski, J. Biol. Chem. 223. 661 (1956). 



» A. M. Michelson, Nature 182. 1502 (1958); J. Chem. Soc. p. 1371 (1959). 



h R. C. Warner, J. Biol. Chem. 229. 711 (1957). 



More recently there has been a tendency to use e(P) to express the extinction co- 

 efficients of such compounds as nucleoside diphosphates, dinucleotides, and dinucle- 

 oside monophosphates. 76 ' 82 It seems questionable to the writer whether such a pro- 

 cedure retains the simplification it was originally intended to have, when applied to 

 well-defined compounds; and comparisons of absorption spectra on this basis are, if 

 anything, rendered more complicated. Until some uniform procedure is adopted, it 



"* P. T. Gilham and H. G. Khorana, /. Am. Chem. Soc. 80, 6212 (1958). 



