2!>4 



H. li. KOBERTS, R. .1. HHITTKN. AND H. J. MCCARTHY 



dissociated into two coiupoiK'Hts of about 60S and 408 when the mag- 

 nesium concentration of the sut^pending fluid was reduced from 10'^ M 

 (Chao, 1957). Bolton et at. independently found a similar effect in the 

 ril)08omes of Escherichia coli (Bolton et al, 1958). Ts'O et al. reported 



the dissoeiatit)n of the SOS coinponciit of iiI)Osomcs of pea seedHngs into 



L A J 



Ribosome pellet in I0~ M Mg. 



i 



Fig. 2. Centrifugation pattern of ribosome pellet in 10 ' M Mg. Only 50S and 

 30S ribosomes appear. 



components of 60S, 40S, and 26S (Ts'O et al., 1958). A Mg/P ratio of 

 0.3 was required to preserve the integrity of SOS particles from pea 

 seedlings (Edelman et al., 1960). 



The sedimentation coefficient.-^ reported in early jiapers vary widely; 

 most of the values were not corrected for viscosity or concentration. 



