774 



BIOCHEMISTRY: KORNBERG ET AL. 



Proc. N. a. S. 



Substrates. — Deoxynucleotides and samples of native and enzymatically syn- 

 thesized DNA were prepared as in earlier studies. ^^ ^ dHMC-5-P was synthesized 

 according to Flaks and Cohen^ using a 230-fold purified hydroxymethylase^^; C'"- 

 dHMC-5-P was obtained by using C'-formaldehyde (Volk Radiochemical Co.) 

 in the hydroxymethylation reaction, and P^2_jjj]y[Q_5_p ^y^s prepared by using 

 p32_(jQ_5_p The Em value determined for the nucleotide in this preparation 

 was 13.5 X 10^ at 284 m/x at pH 1. Since this value conflicts with that of 11.7 X 

 10^ given by Flaks and Cohen,' it is regarded as provisional and requires further 



20 30 



TIME - minutes 



Fig. 1 .— Appearance of pha{;e in T2- or T5-iiifected cells. In- 

 fected culture.s were prepared by Method I. Infectious units were 

 measured after "lysis from without." 



checking. C^^-glucose 6-phosphate was prepared by hexokinase action on uni- 

 formly labeled C^^-glucose (Isotope Specialties Co.). C^^-UDPG was prepared 

 from C ^"-glucose 6-phosphate and uridine triphosphate by the action of phospho- 

 glucomutase and UDPG pyrophosphorylase as outlined by Glaser and Brown. 2» 

 Unlabeled UDPG was a product of the Sigma Chemical Company. 



RESULTS 



An Enzyme which Phosphorylates dHMC-5-P. — At about 4 min after infection 

 of E. coli with phage T2, it was possible to detect in the extracts an enzyme w^hich 

 catalyzes the phosphorylation by ATP of dHMC-5-P (Fig. 2 A). This reaction was 



127 



