DEOXYPENTOSE NUCLEOPROTEINS 



49 



0.5 1.0 1.5 2.0 2.5 3.0 

 MNaCI 



Fig. 6. Successive extraction with NaCl solutions of increasing strength, 

 in the absence (curves 1-4) and in the presence (curves 5 and 6) of a 

 CHCI3 phase, of calf thymus nucleohistone (curves 1 and 2) or of artificial 

 histone complexes (curves 3-6) with calf thymus deoxyribonucleic acid. 

 Compare the text for experimental details. Co-ordinates as in Fig. 2. 

 (Taken from unpublished experiments with Miss Rakoma Lipshitz.) 



(curve 3) and in 3 M NaCl (curve 4) and extracted successively. 

 In another series, similarly produced complexes (curve 5 without, 

 curve 6 with 3 M NaCl) were extracted stepwise in the presence 

 of CHCls-pentanol. These experiments permit a comparison of 

 the behavior of nucleohistone and of histone nucleate com- 

 plexes, prepared at a low electrolyte concentration (curves 1 and 

 3), towards extraction with salt solutions in the absence of 

 chloroform with that of preparations that had initially been in 

 contact with a 3 M NaCl solution (curves 2 and 4). The effect 

 of chloroform on the rate of appearance of nucleic acid P in the 

 extracts is demonstrated by a comparison of curve 3 with 6 and 

 of curve 4 with 5. Certain characteristic differences between 

 nucleohistone and histone nucleate are brought out when curve 

 1 is compared with 3 and curve 2 with 4. 



References p. 60 



