Energy sources for photosynthetic carbon dioxide fixation

Photophosphorylation In Vivo

“…The question of whether high-energy intermediates instead of ATP may be used directly for CO2 assimilation in vivo, which has been concluded from experiments especially with phloridzin and Dio-9 in vitro (262) and in vivo (64,173,178,252), is still unanswered. But it has to be considered that these inhibitors could show an additional effect possibly on the transport ATPase in cellular membranes (98, 173,178).…”

Cyclic Photophosphorylation in Vivo and its Relation to Photosynthetic CO2-Fixation

“…Noncyclic photophosphorylation does not seem to inhibit respiration (9), possibly because no free ATP is generated but an energy rich intermediate is used directly for photosynthetic CO. fixation (33 (4,14).…”

“…Rathel-it seemiis to be an ATI'P generating system, comparable in capacity with respiration (maximally [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] finmoles ATP per img chloropllyll per 1r) anld also competing with the respiratory system for ADP (9,22). Noncyclic photophosphorylation does not seem to inhibit respiration (9), possibly because no free ATP is generated but an energy rich intermediate is used directly for photosynthetic CO. fixation (33 (4,14).…”

Exchange reaction between ATP and labelled pyrophosphate by isolated spinach chloroplasts

“…Recently several reports have referred to the role of P -P in photosynthesis. Vose and Spencer [6] found in photosynthetic CO2 fmation, that P-P could replace ATP (see also [7,8]); H. Baltscheffsky [9] showed the formation of P-P instead of ATP in the absence of nucleotides by photosynthetic active bacterial chromatophores and M. Baltscheffsky [lo] pointed to the close linkage of P m P to the phosphorylation step between cyt. b and cyt.…”