VIRUS-INDUCED ACQUISITION OF METABOLIC FUNCTION 



23 



300-- 



1200- 



5900- 



1500 



900 



x 



/ 



100 105 



Tube no. 



i 



21 



41 



c 



LJ 



81 101 121 



TUBE NUMBER 



Figure 3. The isolation of the deoxycytidylate hydroxymethylase by elution 

 from a DEAE column. Dotted line = enzyme. 



mycin, the fractionation of DEAE cellulose was effected using two 

 linear-gradient elutions with phosphate buffer. 



As can be seen in Figure 3, a peak of enzyme activity is obtained at 

 a low point in the protein elution, and the central tubes of this peak 

 have a constant specific activity. The values presented in the graph 

 were obtained for the purified fractions in this peak about 16 days 

 after infection, and about nine days after separation on the column. 

 Specific activities of 2,200 were obtained by the column assay for key 

 tubes eight days before the time for the assays indicated on the chart. 

 Extrapolation to the earliest point in the fractionation suggests specific 

 activities for the enzyme of the order of 5,000, a value slightly lower 

 than that obtained by Komberg et al. (personal communication), 

 which was 6,000, using the original, less reliable assay of Flaks and 

 Cohen (1959a). 



The peak tubes were pooled, concentrated, and examined by ana- 

 lytical ultracentrifugation and electrophoresis in 0.02 M KPO4 buffer 

 pH 7.4, 0.1 M with respect to KCl. Two components of 85 per cent and 

 15 per cent were observed in both analyses. The major component had 

 an S2o,w of 4.4 and mobility of —5.4 x 10"^ cm^ volts"^ sec^ The minor 

 component had an S20.W of 25 and a mobihty of —9.3 x 10'^ cm^ volts"^ 



