TABLE 2 

 P^ Incorporation foi i owino Various Dark Incubation Periods 



Dark 

 Exp. conditions incubation Illumination Counts/min 



mm 



min 



Exp. A +PMS at min 



+ PMS at min 

 Exp. B +PMS at min, 0.05 /u moles 

 -HPMS at min, 0.05 m moles 

 4-PMS at 20 min, 0.05 n moles 

 + PMS at min + .28 ^ix moles 



ATP at 20 min 

 +TPN, 0.2 n moles 

 +TPNH, 0.2 M moles 

 +TPN, 0.2 /i moles 



P?- incorporation following: various dark incubation periods. 



Expt. A: Each tube contained, in pinoles: K.HPOj, 1.18; ATP, 0.4; PM.S, 0.05; 

 MgCl... 2.3(3; NaCl, 11.9 and tris-HCl, pH 8.0, 13.3. 0.1 ml chloroplast suspension 

 containing 66 jug chlorophyll and Pp, 1.46 X 10^ counts/min were also added. Final 

 volume, 1.0 ml. Counts are recorded for aliquots corresponding to 0.167 ml of reaction 

 mixture. Temp = 15°G. 



Evpt B: Each tube contained in /imoles: KoHFOi, 1.68; ATP, 0.6; PMS, 1 PN 

 TPNH, or additional ATP as indicated, Mgd, 3.38; NaCl, 170; tris-HCl, pH 8.0, 

 19.0. 0.15 ml chloroplast suspension containing 100 jug chlorophyll and P?-, 1.2 X 10^ 

 counts/min were also added. Final volume, 1.6 mi. Counts are recorded for aliquots 

 corresponding to 0.192 ml of reaction mixture. Temp = 15°C. 



.32 



EFFECT OF DARK PERIOD ATP-Pi EXCHANGE 



10 



20 30 40 



TIME (Minutes) 



50 



Each 



Fig. 4. Effect of dark incubation on subsequent .\TP-P,^= exchange in the light. 

 ich 1.0 ml aliquot contained, in /xmoies: K.Hl'O,, 1.05; ATP. 0.37 (curves), or AD!'. 



0.37 (single point, as indicated): PMS, 0.30; MgCl,, 2.1; NaCl, 10.4; tris-HCl, pH 

 8.0, 11.6. Chloroplasts containing 72 Mg chlorophyll and P,''=, 1.15 X 10^ counts/ 

 min were also present. Ordinate values refer to total counts/min adsorbable on 

 charcoal. Illumination started at zero time (O, ■) or at 20 min (•). 



