title: On the active species in bicarbonate stimulation of Hill reaction in thylakoid membranes.
abstract: At 5 degree C addition of CO2 or HCO3- to CO (HCO3-)-depleted thylakoids (containing 100 mM formate) initiates, within 10 s, the activation of the Hill reaction in light. In contrast to HCO3- addition, where there is a lag of 6-8 s, the activation by CO2 addition is almost instantaneous. With CO2, prior addition of carbonic anhydrase produces a lag of about 6 s that approaches the lag observed by the HCO3- addition. These data suggest that CO2 is an active species involved in stimulating the Hill reaction. Binding of CO2 (HCO3-) to a component on the external side of the thylakoid membranes is supported by the present study.
mesh_terms: D001639:Bicarbonates / Q000494:pharmacology*; D002736:Chloroplasts / Q000378:metabolism*; D004579:Electron Transport / Q000187:drug effects; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D010788:Photosynthesis / Q000187:drug effects*; D010944:Plants / Q000378:metabolism
chemical_list: D001639:Bicarbonates