D. I). HEXDLEY AND B. L. STREHLER 



595 



was washed with water ami KH._.P(), (0.005 M) , then resuspended 

 ill 50'r aqueous ethaiiol (ontaiiiiiig 0.5% v/v cone. NH;, and 0.2% 

 meihvl (elhdose. AHqiiots weie jihited on phuuhets, dried, and 

 coiniled with an end-window (;eiger-Miiller counter. 



ATP (Sigma, sodium salt) solutions were freshly prepared for each 

 run at pH 7.5. TPNH, TPN, FAIN, and PMS (phena/.ine metho- 

 siUfate) were obtained from the Sigma Chemical Company. 



Experimental Results 

 A. ATP-phospliate exchange in presence of TPN. The typical rate 

 of Pi^- incorporation into added ATP in the presence or absence of 

 TPN is shown as a function of the time of illumination in Fig. 1. 



8 

 2 7 



X 



uj 6 



I- 



3 



? 5 

 q: 



UJ 4 



a. 



CO 



o 

 o 







* — -hAMP + TPN 



PMS 



— Low ATPy 



+ tpn/^ ■'" ^P'^ "'" ^'^^ 



High ATP — 



TIME (Minutes) 

 Fig. 1. Incorporation of P,^- into ATP or AMP under various conditions. Each 

 tube contained, in fxmoles: K,HPO,. 1.18; ATP, 1.2 (■, Q. •• O), 3.2 (a). «.."> 

 (A), or AMP. 1.2 (*); TPN. 0.7.5 (*, A- O. V^ D)- or ^'^^^- (phenazine nietho- 

 sulfate) 0.05 (■); MgCl.,, 2.36; NaCi, 11.9; tris HCl, pH 8.0, 13.3. 0.1 ml chloro- 

 plast suspension containing 148 /xg chlorophyll, and P,-^^ 2.8 X 10-'' counts/min 

 were also added. Total volume, 1.6 ml, temp = 15°C. Ordinate values are 

 counts/min adsorbed on charcoal from aliquots corre.sponding to 0.174 ml reaction 

 mixture. 



