Regulation of Ribulose-l,5-bisphosphate Carboxylase Activity in Response to Changes in the Source/Sink Balance in Single-Rooted Soybean Leaves: The Role of Inorganic Orthophosphate in Activation of the Enzyme

(...) In the present study, the activity of RuBPcase in vivo was estimated by measuring the «initial» activity immediately after extraction from standard leaves (grown under a regime of 10 h of light and 14 h of darkness) and from sink-limited leaves (exposed for 6 or 7 d to continuous light to alter the source/sink balance). (...)