The true statement(s) regarding the carbonic anhydrase enzyme is/area)It is involved in peptide bond cleavage.b)Redox inactive Zn2+ ion is involved in the catalytic activity of this enzyme.c)Activated M-OH2 (M = metal ion) acts as the nucleophile in the enzyme.d)The metal ion is coordinated to the side chain of histidine residues.Correct answer is option 'B,C,D'. Can you explain this answer?

Question

Answer

The active site of this enzyme contains zn ion.they are metalloenzymes.mainly catalyze interconversion of co2 and h20.

Answer

Carbonic anhydrase is an enzyme that plays a crucial role in the regulation of pH in the body. It catalyzes the reversible hydration of carbon dioxide to bicarbonate and protons. The correct statements regarding the carbonic anhydrase enzyme are:

b) Redox inactive Zn2+ ion is involved in the catalytic activity of this enzyme.
c) Activated M-OH2 (M = metal ion) acts as the nucleophile in the enzyme.
d) The metal ion is coordinated to the side chain of histidine residues.

Explanation:

b) Redox inactive Zn2+ ion is involved in the catalytic activity of this enzyme:
Carbonic anhydrase contains a zinc ion (Zn2+) at its active site, which is essential for its catalytic activity. The zinc ion plays a crucial role in coordinating the water molecules and facilitating the hydration of carbon dioxide. It is important to note that the zinc ion in carbonic anhydrase is redox inactive, meaning it does not undergo oxidation-reduction reactions during the catalytic cycle.

c) Activated M-OH2 (M = metal ion) acts as the nucleophile in the enzyme:
In the catalytic mechanism of carbonic anhydrase, the zinc ion coordinated to a water molecule (M-OH2) acts as a nucleophile. It attacks the carbon dioxide molecule, forming a bicarbonate ion. This nucleophilic attack is facilitated by the activation of the zinc-bound water molecule, which is deprotonated by a nearby histidine residue. The nucleophilic attack results in the formation of a tetrahedral intermediate that eventually leads to the production of bicarbonate and protons.

d) The metal ion is coordinated to the side chain of histidine residues:
The zinc ion in carbonic anhydrase is coordinated to the side chain of histidine residues. Specifically, it forms a coordination bond with the imidazole nitrogen of histidine residues in the active site of the enzyme. These histidine residues play a crucial role in the catalytic mechanism by assisting in the deprotonation of the zinc-bound water molecule, thereby activating it for nucleophilic attack on carbon dioxide.

In summary, carbonic anhydrase utilizes a redox inactive zinc ion coordinated to histidine residues for its catalytic activity. The activated zinc-bound water molecule acts as a nucleophile, attacking carbon dioxide and facilitating the reversible hydration reaction.

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