Carboxylase and oxygenase activities of ribulose bisphosphate carboxylase purified from wheat were measured over the temperature range 5 to 35°C either at constant 02 and CO2 concentrations or where the 02 and CO2 simulated the concentrations in water equilibrated at each temperature with the same gaseous phase. At constant CO2 (14 micromolar) and 02 (0.34 millimolar), the oxygenase to carboxyl...

A novel framework is presented for the analysis of ecophysiological field measurements and modelling. The hypothesis 'leaves minimise the summed unit costs of transpiration and carboxylation' predicts leaf-internal/ambient CO2 ratios (ci /ca ) and slopes of maximum carboxylation rate (Vcmax ) or leaf nitrogen (Narea ) vs. stomatal conductance. Analysis of data on woody species from contrasting ...

Incubating isolated soybean leaf mesophyll cells with glyoxylate increased the rates of CO(2) fixation by as much as 150%. In order to cause this stimulation, the glyoxylate must be presented to the cells before the NaHCO(3). Significant stimulation was observed 15 seconds after beginning the glyoxylate treatment. The glyoxylate-dependent stimulation was increased by high O(2) concentrations an...