The effect of substrate concentration, pH and other factors upon the activity of carbonic anhydrase.

calculating the extra rate in this unit at a series of instants during the course of the manometric experiment. These extra rates are then extrapolated to zero time so as to eliminate changes in the activity of the enzyme during the actual experiment owing to (i) progressive alterations in pH, substrate and buffer concentrations as C02 is taken up or evolved, (ii) destruction brought about bytheviolent shaking. The extrapolated rates are finally corrected for the limiting effect of diffusion by means of extensions of the equations previously developed by Roughton, on the basis of the application of the stationary film theory to gas-enzymic reactions. 3. Detailed examples of the computation of enzymic activity are given for CO2 uptake experiments both below and above pH 8-0 and also for C02 output experiments. 4. Applications of the methods to the study of the kinetics of carbonic anhydrase under varied conditions are given in the following paper.