THE EFFECT OF CO2 UPTAKE BY PEA PROTOPLASTS ON O-2 EVOLUTION RATE ANDPARAMETERS OF CHLOROPHYLL FLUORESCENCE QUENCHING

Using simultaneous measurements of O2 evolution rate and chlorophyll f luorescence parameters in pea leaves protoplasts, the response of PS I I to rapid alteration of outside CO2 concentration was studied. Measur ements of carbonic anhydrase (CA) activity of intact and broken protop lasts showed die existence of CA connected with protoplast surface. Ex periments with acetazolamide demonstrated die involvement of surface l ocalized CA in the process of penetration of CO2 into the cell, that m anifested only in the case of the millimolar CO2 concentrations in the liquid medium. The hypothetic role of CA in plasmalemma as a proton c onductor was suggested.