Effect of Carbonic Anhydrase Inhibitors on Inorganic Carbon Accumulation by Chlamydomonas reinhardtii

摘要: Membrane-permeable and impermeable inhibitors of carbonic anhydrase have been used to assess the roles extracellular intracellular on inorganic carbon concentrating system in Chlamydomonas reinhardtii. Acetazolamide, ethoxzolamide, a membrane-impermeable, dextran-bound sulfonamide were potent measured with intact cells. At pH 5.1, where CO2 is predominant species carbon, both acetazolamide had no effect concentration required for half-maximal rate photosynthetic O2 evolution (K0.5[CO2]) or accumulation. However, more permeable inhibitor, inhibited fixation but increased accumulation as compared untreated 8, K0.5(CO2) was from 0.6 micromolar about 2 3 sulfonamide, higher value 60 ethoxzolamide. These results are consistent hypothesis that which crosses plasmalemma replenish HCO3− at high pH. data also implicate role accumulating system, indicate inhibit only enzyme. It suggested transport internal might occur level chloroplast envelope.