The inhibition of the carbon concentrating mechanism of the green alga Chlorella saccharophila by acetazolamide.
The effects of the carbonic anhydrase (CA) inhibitors acetazolamide (AZ) and dextran-bound sulfonamide (DBS) on HCO3--dependent O2 evolution in Chlorella saccharophila were evaluated. Addition of 4 µM AZ or 0.4 mg ml-1 DBS to photosynthesizing cells reduced the O2 evolution rate at low dissolved inorganic carbon (DIC) concentration, decreased the size of the intracellular acid-labile carbon pool, and decreased the apparent affinity of the cells for DIC. Measurement of the whole-cell affinity of cells for CO2 and HCO3- in the presence and absence of inhibitors indicated that active HCO3- transport was inhibited by AZ and DBS. The inhibition of HCO3- transport was independent of the inhibition of external and internal CA. These results suggest that the active uptake of HCO3- occurs initially by the interaction of HCO3- and a CA-like transporter.
Pollock
Steve Vincent
SV
Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA; Department of Biology, York University, 4700 Keele St., Toronto, Ontario, M3J 1P3, Canada.
Colman
Brian
B