Inhibition of the hydration of CO2 catalyzed by carbonic anhydrase III from cat muscle.

摘要: Using stopped flow methods, we have measured the steady state rate constants and inhibition by N3- I- of hydration CO2 catalyzed carbonic anhydrase III from cat muscle. Also, using fluorescence quenching enzyme at 330 nm, binding sulfonamide chlorzolamide to III. Inhibition anions was uncompetitive pH 6.0 mixed higher values pH. The constant azide independent between 7.5 with a value KIintercept = 2 X 10(-5) M; also in range Kdiss 10(-6) M. Both these increased as above 8. There competition N-3 OCN- for sites on profiles kinetic can be explained an activity-controlling group pKa less than 6. Moreover, data suggest that like isozyme II, is limited step occurring outside actual interconversion HCO3- involving change bonding hydrogen exchangeable solvent water.