For each of the following metallo-proteins identify the metal-ion at the active-site and the function of the proteins: deoxy-hemoglobin, deoxy-myoglobin, oxy-hemocyanin, cytochrome-C and carbonic anhydrase.Correct answer is 'Deoxy-hemoglobin'. Can you explain this answer?

Question

Answer

Deoxy-hemoglobin:

Metal-ion at the active site: Iron (Fe)

Function of the protein: Oxygen transport

Details:
Deoxy-hemoglobin is a metalloprotein found in red blood cells and is responsible for carrying oxygen from the lungs to the tissues. It is composed of four protein subunits, each containing a heme group, which consists of an iron ion coordinated to a porphyrin ring.

The iron ion at the active site of deoxy-hemoglobin is in the ferrous (Fe2+) state, which allows it to bind to oxygen molecules. In the absence of oxygen, the iron ion remains in the reduced state, leading to the formation of deoxy-hemoglobin.

When deoxy-hemoglobin encounters oxygen in the lungs, the iron ion binds to the oxygen molecules, forming oxy-hemoglobin. This transformation is essential for the efficient transport of oxygen to the tissues. The binding of oxygen to the iron ion induces a conformational change in the protein, which promotes the release of carbon dioxide, a waste product of cellular respiration, from the tissues into the bloodstream.

During the delivery of oxygen to the tissues, oxy-hemoglobin dissociates into deoxy-hemoglobin, releasing the bound oxygen molecules to be utilized by cells. This reversible binding and release of oxygen by deoxy-hemoglobin allow for efficient oxygen transport in the bloodstream.

The presence of the iron ion in deoxy-hemoglobin is crucial for its oxygen-binding capacity. The coordination chemistry of the iron ion allows it to form reversible bonds with oxygen, ensuring the efficient transport of oxygen throughout the body.

In summary, deoxy-hemoglobin is a metalloprotein that contains an iron ion at its active site, allowing for the reversible binding and release of oxygen. Its function is vital for the transport of oxygen from the lungs to the tissues.

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