The Km of carbonic anhydrase for CO2 is 8000 uM. Why is that? Doesn't this enzyme one of the fastest enzymes? How come low affinity will give you high efficiency?
Thanks!
The reaction of carbonic anhydrase is reversible. When CO2 and H+ concentrations are high, as in the tissues, the conversion of CO2 to bicarbonate is favored. When CO2 concentration is low, as in the lungs, the conversion of bicarbonate to CO2 is favored.
The function of the enzyme is to allow the equilibrium between CO2 and bicarbonate to be established rapidly, much faster than would occur spontaneously. The enzyme has a very high rate of catalysis (kcat over 105/s), allowing it to achieve this outcome.
The substrate Kms are similar in magnitude to their physiological concentrations, which makes it possible for the enzyme to catalyze the establishment of the physiological equilibrium, rather than driving the reaction in one direction or the other.
Carbonic anhydrase carries out the hydration of carbon dioxide and dehydration of HCO3 .
It is an enzyme involved in rapid processes like transport process.
(The high km makes the substrate stick to the enzyme)
This means I make sure the product is turned by improving the circumstances. Maybe a question on efficiency and not speed.
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