146 H. GOBIND KHORANA 



purified the system to the point that net synthesis of DNA has been 

 achieved. 



c. Other Tissues 



Bollum and Potter 108 have found significant amounts of the polymerase 

 enzyme in a variety of rat tissues. The enzyme was also found in relatively 

 large amounts in extracts of Flexner-Jobling carcinoma and Walker 256 

 carcinoma. Harford and Romberg 1 ' 3 have shown the presence of polymerase 

 in extracts of HeLa cells, lymph glands, and leukemic blood cells. Mant- 

 savinos and Canellakis 117 have also reported on the preparation and proper- 

 ties of the soluble enzyme from mouse leukemic cells. Net synthesis of DNA 

 in soluble extracts of Ehrlich ascites cells has been demonstrated by David- 

 son and co-workers. 118, 119 



116 F. J. Bollum, Federation Proc. 18, 194 (1959). 



117 R. Mantsavinos and E. S. Canellakis, Cancer Research in press. 



118 J. N. Davidson, R. M. S. Smellie, H. M. Keir and A. H. McArdle, Nature, 182, 589 

 (1958). 



119 R. M. Smellie, H. M. Keir, E. D. Gray, D. Bell, J. Richards, and J. N. Davidson, 

 Biochem. J. 72, 17P (1959); Biochim. et Bwphys. Acta 37, 243 (1960). 



