TABLE 2.

Susceptibility of the H. neapolitanus carboxysomal carbonic anhydrase rCsoSCA to inhibitors

InhibitorIC50 (M)a
Dithiothreitol2.4 × 10−4
2-Mercaptoethanol3.4 × 10−3
Ethoxyzolamide1.9 × 10−3
KCl (<100 mM)No effect
Na2SO4 (<100 mM)No effect
Sodium azide4.1 × 10−3
Sodium cyanide2 × 10−6
  • a IC50 is the molar inhibitor concentration that reduced the CO2 hydration activity of rCsoSCA by 50% at pH 8. Initial rates of CO2 hydration activity were determined by stopped-flow spectrophotometry in the presence of the indicated inhibitors. The IC50 values were calculated from plots of relative activity versus inhibitor concentrations. Individual data points were averaged from three to five independent determinations that did not vary more than 10%.