The 'slow' pH-induced conformational transition of chloroplast fructose 1,6-bisphosphatase and the control of the Calvin cycle.
A slow conformation change of chloroplastic reduced fructose bisphosphatase is detected upon raising the pH from 7 to 8 or upon lowering the pH from 8 to 7. These conformation changes are fully reversible. In the time scale investigated these processes occur in one step. Their time constants and their amplitudes have been determined and analyzed as a function of proton concentration. The results obtained are consistent with the view that upon ionization or protonation of a strategic ionizable group the protein undergoes a 'slow' conformational transition that may be followed by conventional fluorescence techniques. Since illumination brings about a pH rise of chloroplastic stroma from 7 to 8, the above results suggest that light activation of fructose bisphosphatase is at least in part due to a slow conformation change of this enzyme.
D002736:Chloroplasts / Q000201:enzymology*; D006597:Fructose-Bisphosphatase / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008027:Light; D008956:Models, Chemical; D010944:Plants / Q000201:enzymology; D011487:Protein Conformation; D011489:Protein Denaturation; D011522:Protons
D011522:Protons; D006597:Fructose-Bisphosphatase