Examine the mechanism of carbonic anhydrase. If the Zn2 were removed from the active site, and replaced with either Cu , Cd2 , o

Question

stiks02 [169]

3 years ago

7

Examine the mechanism of carbonic anhydrase. If the Zn2 were removed from the active site, and replaced with either Cu , Cd2 , o

r Fe3 would you expect the enzyme to still be functional

Biology

1 answer:

Shkiper50 [21] · Answer 1 · 2022-04-20T03:33:06+03:00

Answer: No

Explanation:

Carbonic anhydrase (CA; carbonate hydro-lyase) is a zinc-containing enzyme that catalyzes the reversible hydration of carbon dioxide: CO2+ H2O<-->HCO3(-)+H+. The enzyme is the target for drugs, such as acetazolamide, methazolamide, and dichlorphenamide, for the treatment of glaucoma.

The zinc ion is located in a cone-shaped cavity and coordinated to three histidyl residues and a solvent molecule. Inhibitors bind at or near the metal center guided by a hydrogen-bonded system comprising Glu-106 and Thr-199. The catalytic mechanism of CA II has been studied in particular detail. It involves an attack of zinc-bound OH- on a CO2 molecule loosely bound in a hydrophobic pocket. The resulting zinc-coordinated HCO3- ion is displaced from the metal ion by H2O. The rate-limiting step is an intramolecular proton transfer from the zinc-bound water molecule to His-64, which serves as a proton shuttle between the metal center and buffer molecules in the reaction medium.