ION-EXCHANGE CHROMATOGRAPHY 



233 



3. Polynucleotides 



a. Ionic Properties and Molecular Size 



The polynucleotides derived from nucleic acid by the action of enzymes, 

 e.g., deoxyribonuclease on DNA^^ '*'' or ribonuclease on PNA,^^'*" or by 

 brief acid treatment^" can be separated by ion-exchange, if consideration 

 is given to their greater size and charge. These properties influence the rates 



02 09 

 LITERS THROUGH COLUMN 



Fig. 17. Separation of various phosphates by anion exchange in cliloiide system." 

 Exchanger: Dowex-l-chloride, 200-400 mesh, 10 cm. X 0.76 cm.''. 

 Solution: HCI + NaCl as shown, 1 ml./min. 



Sorbed material: 2-5 mg. of each substance shown. (Substances with peak posi- 

 tions indicated by arrows onh' were not included in the separation shown, but 

 were examined on similar columns or the same column independently.) 



of diffusion and the distribution coefficients. The latter must be compen- 

 sated for, as in the simpler polyphosphates, by increased acidity or ionic 

 strength. To accommodate the large size, it has been found advantage- 

 ous,^^' ''^ in ^vorking \vith polynucleotides, to utilize anion exchangers of a 

 lower degree of cross-linking (divinylbenzene content) than the so-called 

 "standard" resins although successful separations have been reported using 



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



" R. L. Sinsheimer. ./. Biol. Chem. 208, 445 (1954). 



^» W. E. Cohn, D. G. Doherty, and E. Volkin, in "Phosphorus Metabolism" (Mc- 



Elroy and Glass, eds.) Vol. II. Johns Hopkins Press, Baltimore, 1952. 

 ^9 E. Volkin and W. E. Cohn, ,/. Biol. Chem.. 205, 767 (1953). 

 '» R. B. Merrifield and D. W. Woolley, J. Biol. Chem. 197, 521 (1952). 



