86 



MICROSOMAL PARTICLES 



centrifuge shows that the bottom layers are rich in the heavy particles and lack 

 the light particles, whereas the top layers show the opposite distribution. 



Quite a different type of fractionation results from chromatography on col- 

 umns of diethylaminoethyl cellulose (DEAE) [9, 10]. Extremely high reso- 

 lution can be achieved giving a separation of various proteins as shown in 

 figure 2. Nucleoprotein appears as a prominent peak in the elution diagram 

 of the total cell juice but not in the diagram obtained with the 100,000^ super- 

 natant fluid (fig. 3). The corresponding ultraviolet diagrams show that there 

 are in fact two nucleoprotein peaks: the first peak consists of nucleoprotein of 

 high molecular weight which can be spun down in the centrifuge; the second 



40 60 80 100 



Fraction number 



Fig. 2. Cell suspension washed and broken as described by Bolton et al. [8] ; 0.5 g wet 

 weight of cell juice adsorbed on DEAE column (1 cm 2 X 20 cm) and eluted with con- 

 centration gradient to 0.7 M of NaCl in tris-succinate buffer plus magnesium. Lower 

 curve, total protein indicated by Folin reaction; upper curve, assay for activity of three 

 different enzymes. One-milliliter samples collected in fraction collector. 



