Haemoglobin is having maximum affinity with

Options

A. `NH_(3)`
B. `O_(23)`
C. `CO`
D. `CO_(2)`

Answer

To determine which molecule hemoglobin has the maximum affinity for, let's analyze the options provided: ammonia, oxygen, carbon monoxide, and carbon dioxide.

### Step-by-Step Solution:

1. **Understanding Hemoglobin**:
- Hemoglobin (Hb) is a globular protein composed of two main components: heme groups and globin proteins. The heme group contains iron, which is crucial for binding gases.

2. **Identifying the Binding Affinities**:
- Hemoglobin can bind to various gases, but the strength of this binding varies. The options we have are:
- Ammonia (NH3)
- Oxygen (O2)
- Carbon Monoxide (CO)
- Carbon Dioxide (CO2)

3. **Analyzing Each Option**:
- **Ammonia**: Hemoglobin does not have a significant affinity for ammonia.
- **Oxygen**: Hemoglobin binds oxygen, but it is not the molecule with the highest affinity.
- **Carbon Monoxide**: Hemoglobin has a very high affinity for carbon monoxide. When CO binds to hemoglobin, it forms carboxyhemoglobin, which is a stable compound.
- **Carbon Dioxide**: Hemoglobin can bind carbon dioxide, but again, the affinity is lower compared to carbon monoxide.

4. **Reason for High Affinity with Carbon Monoxide**:
- The binding of carbon monoxide to hemoglobin is more stable than the binding of other gases due to the electron coordination between the heme group and the carbon monoxide molecule. This coordination is perpendicular, which minimizes steric hindrance, allowing for a stronger and more stable bond.

5. **Conclusion**:
- Based on the analysis, hemoglobin has the maximum affinity for carbon monoxide (CO).

### Final Answer:
- **Hemoglobin has maximum affinity with Carbon Monoxide (CO)**.