Carbonic anhydrase specificity constant

Aromatic sulfonamides are specific inhibitors of carbonic anhydrase (E). The apparent second-order rate constants for association of p-nitrobenzenesulfonamide with (a) carbonic anhydrase-B and (b) the carboxymethylated derivative of the enzyme are shown against pH in Figure 1.14. Estimate using equations (1.225) and (1.226) the values for pAig, and k and he two possible schemes shown for both carbonic... 

Thus although a protein can be made very specific for a particular metal, if it has a fold that generates matching properties to those possessed by the cation (e.g., carbonic anhydrase), this degree of matching is not required for the removal of heavy metals as they have such high binding constants to unconstrained sites. Clearly, there is a competition between two types of site for two metal ions ... 

Another simple addition reaction is the hydration of C02 to form the bicarbonate ion. Without catalysis the reaction may require several seconds,4 5 the apparent first-order rate constant being -0.03 s 1 at 25°C. Cells must often hasten die process. The specific catalyst carbonic anhydrase is widespread in its distribution... 

This oxidation of o-dianisidine by hydrogen peroxide catalyzed by CA[Mn] is only 60- to 75-fold less efficient than the hydration of carbon dioxide catalyzed by native carbonic anhydrase (Table 1). The kinetic constants for the oxidation show an unexceptional catalytic constant k J of 17 s , but a low apparent Michaelis constant (Ky) of 15 (iM. These values give an apparent specificity constant k JK of 1.1 X 10 M" s . Similarly CAll[Mn] showed a of 140 s , and a K of... 

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