Correct Option
The correct option is Carbonic anhydrase.
Explanation
The transport of carbon dioxide ($CO_2$) in the blood primarily occurs in the form of bicarbonate ions ($HCO_3^-$). This process relies on a specific enzyme found in high concentrations within erythrocytes (Red Blood Cells) to accelerate the reaction between carbon dioxide and water.
Detailed Analysis
- Carbonic anhydrase: This enzyme is predominantly present in Red Blood Cells. It catalyzes the reversible hydration of carbon dioxide to form carbonic acid ($H_2CO_3$), which subsequently dissociates into bicarbonate ($HCO_3^-$) and hydrogen ions ($H^+$). This reaction is essential for the transport of $CO_2$ from tissues to the lungs and for maintaining blood pH.
Reaction: $CO_2 + H_2O \rightleftharpoons H_2CO_3 \rightleftharpoons HCO_3^- + H^+$ - Carboxypeptidase: This is a proteolytic enzyme (protease) secreted by the pancreas. It is involved in the digestion of proteins in the small intestine, not in gas transport.
- Catalase: While present in RBCs and many other cells, its primary function is to protect the cell from oxidative damage by catalyzing the decomposition of hydrogen peroxide ($H_2O_2$) into water and oxygen. It does not catalyze bicarbonate formation.
- Aldolase: This is a glycolytic enzyme found in the cytoplasm of cells. It catalyzes the breakdown of fructose-1,6-bisphosphate during glycolysis and is not involved in gas transport.
Key Takeaway
Carbonic anhydrase is the zinc-containing enzyme in RBCs that drastically accelerates the formation of carbonic acid from carbon dioxide and water, facilitating $CO_2$ transport and acid-base balance.