Determination of carbonic anhydrase activity by a pCO2 sensor.

A potentiometric method capable of determining carbonic anhydrase (CA) activity in vitro and based on the use of a pCO2 sensor is presented. By means of the procedure described here it is possible to follow the rate of CO2 diffusion that takes place in a buffered solution of NaHCO3 in either the presence or the absence of CA. All experimental parameters that affect the speed of HCO3- dehydration, as well as the speed of CO2 diffusion, can be fixed and kept constant for the duration of every assay. The advantage of this method is that the overall dehydration plus diffusion process can be followed as it actually takes place in open thermodynamic systems far from equilibrium. The results obtained strongly confirm the hypothesis of a facilitating role of CA toward the rate of CO2 diffusion.