ISOLATION AND COMPOSITION OF DEOXYPENTOSE NUCLEIC ACIDS 



355 



that the adenine and thymine contents increase, and the guanine and 

 cytosine contents decrease, in the following order: ox, sheep, pig, man. 

 The differences between two adjoining columns are, in general, not signifi- 

 cant or of doubtful significance, when analyzed statistically ; but the prob- 

 ability of identity becomes very small, when the specimens from bovine 

 and human tissues are compared. 



Table V includes information on the results of an analysis of 21 different 

 preparations of calf thymus sodium deoxyribonucleate. Many individual 

 analy.ses of calf thymus preparations are compiled in Table VII. It will be 

 seen that the agreement is, on the whole, better than would have been 

 anticipated. Table VIII collects data on other bovine tissues, Tables IX 

 and X on the nucleic acids from mammalian and other animal sources, 

 respectively. 



The high content of 5-methylcytosine in the sodium deoxypentose nucle- 



TABLE VIII 

 Selection of D.\ta on Purine and Pyrimidine Content.s of Sodiu.m 



Deoxypentose Nucleate Preparations from Bovine Tissues 



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



hydrolysate, corrected for a 100% recovery.* 



• Compare footnotes in Table VII. 



t The average of all ratios reported here is 1.29. 



Referevces 



" E. Chargaff et al., J. Biol. Chem. 177, 405 (1949). 

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

 ' S. G. Laland et at.. J. Chem. Svc. 1952, 3224. 

 ■^ G. R. Wyatt and S. S. Cohen, Biochem. J. 55, 774 (1953). 



' R. O. Hur.st etal., J. Biol. Chem. 204, 847 (1953); ion-exchange chromatography of mononucleotides. 

 /£. Chargaff and R. Lipshitz, J. Am. Chem. Soc. 75, 3658 (1953). 

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



