PHYSICAL PROPERTIES OF NUCLEIC ACIDS 



485 



1 — \ — \ — r 



23456789 lO 



Concentration gx IO/ti'- 



Fig. 18. Variation of Vsp./c with concentration of sodium deoxypentose nucleate 

 at different concentrations of sodium chloride (Conway and Butler''^). 

 • 10-» N O 10-3 A^ 



3 10-" N € No added salt 



viscosity of deoxypentose nucleate solutions at low rates of shear in a 

 Couette viscometer and has interpreted his results as indicating that at 

 infinite dilution of nucleate there is no influence of ionic strength on the 

 viscosity of these solutions. This view has been supported by the more ex- 

 tensive results of Conway and Butler/^^ A\ho determined \-iscosities at 

 sufficiently low rates of shear to permit extrapolation to zero shear (Fig. 

 18). These conclusions would indicate that the deoxj^pentose nucleate ion 

 does not show a contraction, as was suggested by Jordan/^° on the addition 

 of electrolyte, and Conway and Butler'^^ consider that the variation of 

 viscosity is due entirely to electrostatic interaction l^etween the nucleate 

 ions, which would be reduced by the addition of sodium ions. 



The problem of the fall in viscosity on the increase of ionic strength is 

 clearly intimately related to the rigidity of the deoxypentose nucleate ion. 

 Further evidence on this problem comes from streaming birefringence 

 studies. '^^"'^^ Schwander and Cerf" find that the streaming birefringence 



1" B. E. Conway and J. A. V. Butler, /. Polymer Sci., 12, 199 (1954). 



'3^ O. Snellman and G. Widstrom, Arkiv Kemi Mineral. Geol. A19, No. 31 (1945). 



>" H. Schwander and R. Cerf, Helv. Chim. Acta 32, 2356 (1949). 



138 H. Schwander, J. chim. -phys. 47, 718 (1950). 



139 H. Schwander and R. Cerf, Helv. Chim. Acta 34, 436 (1951). 

 i^» H. Schwander and R. Cerf, Experientia 7, 95 (1951). 



"1 IL Schwander and R. Signer, Helv. Chim. Acta 34, 1344 (1951). 



