354 



ERWIN CHARGAFF 



TABLE VII 

 Selection of Data on Purine and Pyrimidine Contents of Sodium 



Deoxyribonucleate Preparations from Calf Thymus 



Proportions in moles of nitrogenous constituent per 100 g. -atoms of P in 



hydrolysate, corrected for a 100% recovery.* 



* When more than one value was reported for the same preparation, the average has been computed. 

 In Preparations 1 and 2, the first complete analyses reported in the literature, the purines and pyrimidines 

 were estimated in separate hydrolysates. For this reason, the total purines and the total pyrimidines were 

 adjusted individually to a 50% recovery. 



t Where no methylcytosine figures are given, the values for cytosine include methylcytosine in most 

 cases. For the calculation of ratios cytosine and methylcytosine were taken together. The average of all ratios 

 reported here is 1.30. A = adenine; G = guanine; C = cytosine; MC = methylcytosine; T = thymine. 



X A question mark indicates that the total recovery was below 85 mole %, or that the ratio of adenine to 

 thymine was below 0.95 or above 1.05. It has also been used when no recovery was reported or when other 

 factors rendered the results doubtful. 



§ This preparation was analyzed as the apurinic acid from calf thymus sodium deoxyribonucleate. 



References (Unless pointed out otherwise, the analytical methods were based on filter-paper chromatography.) 



" E. Chargaff et al. J. Biol. Chem. m, 405 (1949). 



* M. M. Daly et al., J. Gen. Physiol. 33, 497 (1950); chromatography of free bases on starch columns. 

 " A. Marshak and H. J. Vogel, J. Biol. Chem. 189, 597 (1951). 



'' G. R. Wyatt, Biochem. J. 48, 584 (1951). 

 ' C. Tamm et al., J. Biol. Chem. 195, 49 (1952). 

 ^ C. Tamm et al., J. Biol. Chem. 199, 313 (1952). 

 S. G. Laland et al., J. Chem. Soc. 1952, 3224. 



* R. L. Sinsheimer and J. F. Koerner, J. Biol. Chem. 198, 293 (1952); ion-exchange chromatography of 

 mononucleotides. 



"• R. O. Hurst et al., J. Biol. Chem. 204, 847 (1963); ion-exchange chromatography of mononucleotides. 



