PHOSPHORYLATION IN Chlorclla 



337 



to exist between these curves and bioluminescence curves as reported 

 by Strehler and Arnold (7, see Fig. 3), which suggests that the time 

 constants of their cell material are nmch the same as in ours. On the 

 other hand, the ATP time curve in Strehler's material (8) fails to 

 show a transient maximum corresponding to the phosphate fixation 

 maximum after 5 to 10 seconds, shown in our curves (see Fig. 3). 

 This led us to the conclusion that this maximum represents a phos- 

 phate other than ATP. Its nature is now under investigation in our 

 laboratory. In view of the fact that sulfhj'dryl-containing phosphates 

 recently have been reported on (Krall, this symposium) and sulf- 

 hydryl compounds have been postulated to be closely connected with 



RHOH + 



dari( 



(+ROH) 



x + 



(a) 



hv 

 H +E ^Tt EH -t- PO, r:*- 'V^ PO, 

 • "reducing •• "pool" 



»g«nt " 



u 



• • "pool" 



+ C02 — ► photosynthat* + -^ 



+ sugar (+ 02?)-*assimilat» ■♦•COi + 

 + nothing — ► polyphosphate 



(b) 



(c) 



Fig. 4. Scheme, representing the relations between photosynthesis and poly- 

 phosphate formation. (Original.) Dots (• and ••) indicate corresponding com- 

 pounds in the subsequent Hnes of the scheme. 



the energy transfer from chlorophyll (9), it will be of interest to inquire 

 into the possible sulfhydryl content of the "10 sec." phosphate. 



The w^ay in which the light-dependent polyphosphate formation is 

 linked with photosynthesis may be visualized as follows (see Fig. 4). 

 The scheme also contains a suggestion concerning some reactions 

 connected with the energy transfer. The first hne (a) of Fig. 4 ex- 

 presses the possible feeding in of hydrogen from the ultimate hydro- 

 gen donor (water) into the light-sensitive redox system E ^ EH, 

 acting as energy acceptor. The step E ;=^ EH is considered to require 

 light energy (or excited chlorophyll). The possibility of an intermedi- 

 ate step (X ^ XH) is expressed. Possibly, EH combines with phos- 

 phate, giving rise to the 10-second phosphate, or one or two inter- 

 mediate hydrogen transfers (EH + F -> FH -f- G -► GH, etc.) may 



