336 



ERWIN CHARGAFF 



TABLE II 



Ultraviolet Absorption of Several Preparations of Sodium Deoxypentose 



Nucleate* 



* Preparations 1 to 8 were isolated bjr the procedures discussed in Section III.2.a; for Preparation 9 com- 

 pare Sections II.3.a.(2) and III.2.g. See also Chapter 14 and Section IV. 1 of this chapter. 



References 



° C. Tamm, M. E. Hodes, and E. Chargaff. J. Biol. Chem. 195, 49 (1952). 



*" E. Chargaff, E. Vischer, R. Doniger, C. Green, and F. Misani, J. Biol. Chem. 177, 405 (1949). 



" E. Chargafl and R. Lipshitz, J. Am. Chem. Soc. 75, 3658 (1953). 



^ E. Chargaff, R. Lipshitz, C. Green, and M. E. Hodes, J. Biol. Chem. 192, 223 (1951). 



^ E. Chargaff, R. Lipshitz, and C. Green, J. Biol. Chem. 195, 155 (1952). 



■'■ E. Chargaff and S. Zamenhnf, J. Biol. Chem. 173, 327 (1948). 



" E. Vischer, S. Zamenhof, and E. Chargaff, J. Biol. Chem. 177, 429 (1949). 



from the value of €(P) = 6600. In eight preparations of sodium deoxy- 

 ribonucleate from ox tissues (seven from thymus, one from spleen) the 

 absorption maximum was at 259 mn and c(P) = 6650 with a standard 

 error of ±50."^ A selection of data is presented in Table II. In contrast 

 to a statement in the literature/"^ I am inclined to consider an e(P) higher 

 than about 7200 as a sign of denaturation. (Compare the discussion of the 

 general problem of hyperchromic effects by Magasanik and Chargaff"*- and 

 in Chapter 14, and also Thomas. ^^^•'^^) 



While the absence of high viscosity indicates denaturation or degradation 

 of the sodium nucleate, no standard values can as yet be given for the 

 viscosity of carefully prepared specimens. [Compare the discussion by 

 Jordan, Chapter 13.] 



Surprisingly little is known about the optical activity of intact nucleic 

 acids. To indicate the order of magnitude, some measurements by Tamm 

 et al}'"^ may be quoted. With a preparation of calf thymus sodium deoxy- 



'«8 R. Thomas, Bull. soc. chirn. biol. 35, 609 (1953). 



'69 R. Thomas, Biochim. et Biophys. Acta 14, 231 (1954). 



i^» C. Tamm, M. E. Hodes, and E. Chargaff, J. Biol. Chem. 195, 49 (1952) . 



