Vol. 45, 1959 BIOCHEMISTRY: KORNBERG ET AL 785 



librated with 0.02 M KPO4, pH 8.0, containing 0.01 M 2-mercapto(!thanol. Linear gradients 

 were applied and the purifications obtained are expressed relative to t'.ie supernatant fluid of the 

 sonic extract; all solutions contained 0.01 M 2-mercaptoethanol. Glucosylating enzyme: 

 gradient of 0.08 to 0.32 M NaCl in 0.02 M KPO4, pH 8.0-30 X purification; dCTPase: gradient 

 of 0.08 M to 0.32 M NaCl in 0.02 M KPO4, pH 8.0-24 X purification, rechromatographed with a 

 gradient of 0.06-0.32 M KPO4, pH 6.5-85X purification; dHMC-5-P kinase: gradient of 0.06 

 to 0.32 M KPO4, pH 6.5-20 X purification; hydroxymethylating enzyme: gradient of 0.3 M 

 KPO4, pH 6.5 to 1.0 Af KPO4, pH 6. 1-230 X purification. Fractions containing 2-mercapto- 

 ethanol were not frozen. Active fractions were concentrated by precipitation with solid (NH4)2- 

 SO4. Further details of the purification procedures will be published elsewhere. 



2" Glaser, L., and D. Brown, these Proceedings, 41, 253 (1955); Glaser, L., J. Biol. Chem., 

 232, 627 (1958). 



21 Personal communication from Dr. M. J. Bessman. 



22 We are indebted to Dr. R. L. Sinsheimer for the sample of <^X174 DNA. 

 "^ Personal communication from Dr. I. R. Lehman. 



** Chargaff, E., in Nucleic Acids, ed. E. Chargaff and J. N. Davidson (New York: Academic 

 Press, Inc., 1955), I, 307. 



« Dunn, D. B., and J. D. Smith, Nature, 174, 305 (1954); S. Zamenhof and G. GribofT, Nature, 

 174,306(1954). 



26 Burton, K., Biochem. J., 61, 473 (1955). 



2' Tomizawa, J., and S. Sunakawa, /. Gen. Physiol., 39, 553 (1956). 



28 Hershey, A. D., and N. E. Melechen, Virology, 3, 207 (1957). 



" Watanabe, L, Biochim. et Biophys. Acta, 25, 665 (1957); Watanabe, I., and Y. Kiho, Proc. 

 Int'l. Symp. Enzyme Chemistry (Tokyo-Kyoto, 1958), p. 418; Hershey, A. D., A. Garen, D. K. 

 Eraser, and J. D. Hudis, Carnegie Institution of Washington Year Book, 53, 210 (1953-1954). 



^ Cohen, S. S., Abstracts of the American Chemical Societj^, Meeting, September, 1958, p. 22C. 



31 Pardee, A. B., and R. E. Kunkee, J. Biol. Chem., 199, 9 (1952). Dr. Fred Bergmann has 

 found no changes, following T2 infection of E. coli B, in amino acid "activation" levels for valine, 

 isoleucine, methionine, leucine, phenylalanine, tryptophan, and tyrosine. We have observed that 

 levels of the following activities did not change ( ±20 per cent) within 15 min after E. coli B infec- 

 tion with phage T2: PRPP synthetase, orotate -|- PRPP conversion to uridylate, inorganic pyro- 

 phosphatase, adenine + PRPP conversion to adenylate, and adenylate kinase. 



32 Hogness, D. S., M. Cohn, and J. Monod, Biochim. et Biophys. Acta, 16, 99 (1955); Rotman, 

 B., and S. Spiegelman, J. BactenoL, 68, 419 (1954). 



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