82 ERWIN CHARGAFF 



TABLE VI 



Differential Distribution Analysis of E. coli DNA 



Produced in the Absence and Presence of 5-Bromouracil: 



Frequency of Solitary and Coupled Pyrimidine Nucleotide Units* 



Growth supplements Thymine Thymine + 5 -bromouracil 



B C [CC] [TC] T B C [CC] [TC] 



Total pyrimidine, as 



mole % P 24-8 — 25-5 16-4 9-0 25-1 



Solitary pyrimidine, as 

 mole % of total con- 

 stituent in DNA i5"4 — 7-0 18-4 32-9 14-3 



Solitary or bunched 

 pyrimidines, as 

 mole % P 3 '82 • — I 78 o- 37 I • 13 3 -CI 2-96 3 -60 0-58 I -38 



Total solitary 

 pyrimidines, as 



* Based on previously published results [42]. Compare Table V for the 

 composition of the DNA preparations and also Tables I and IV for explanations 

 of the designations used. 



Summarizing remarks 



SEQUENCE CHARACTERISTICS COMMON TO ALL DEOXYRIBONUCLEIC ACIDS 



Though the first application of the procedure for the ditferential 

 analysis of pyrimidine distribution served to demonstrate that deoxy- 

 ribonucleic acids from difi^erent species, even those showing identical 



