Glutamic acid has lower isoelectric point while glutamine `H_(2)N-overset(overset(O)(||))(C)-CH_(2)-CH_(2)- underset(underset(NH_(2))(|)) overset(overset(H)(|))(C)-COOH` has higher isoelectric `pH`. Explain ?

Explanation

To explain why glutamic acid has a lower isoelectric point while glutamine has a higher isoelectric pH, we can follow these steps:

### Step 1: Understand the Structures of Glutamic Acid and Glutamine
- **Glutamic Acid (C5H9NO4)**: It has two carboxylic acid groups (-COOH) and one amino group (-NH2). The structure can be represented as:
```
HOOC-CH2-CH2-CH(NH2)-COOH
```
- **Glutamine (C5H10N2O3)**: It has one carboxylic acid group and two amino groups (one as part of the amide). The structure can be represented as:
```
HOOC-CH2-CH2-CH(NH2)-CONH2
```

### Step 2: Identify the Functional Groups
- Glutamic acid has two acidic functional groups (COOH), which can donate protons (H+).
- Glutamine has one acidic group (COOH) and one amide group (CONH2), which does not donate protons.

### Step 3: Define Isoelectric Point (pI)
- The isoelectric point is the pH at which the amino acid exists predominantly in its zwitterionic form, where the overall charge is neutral.

### Step 4: Analyze the Zwitterionic Forms
- **Zwitterionic Form of Glutamic Acid**:
- At its isoelectric point, glutamic acid will have one carboxyl group deprotonated (COO-) and the amino group protonated (NH3+).
- This results in a net negative charge due to the presence of an additional COO- group, leading to a lower pI.

- **Zwitterionic Form of Glutamine**:
- At its isoelectric point, glutamine will have its carboxyl group deprotonated (COO-) and the amino group protonated (NH3+).
- There is no extra acidic group to contribute to a negative charge, resulting in a higher pI.

### Step 5: Conclusion
- Glutamic acid has a lower isoelectric point because it has two acidic groups that can lose protons, leading to a net negative charge at a lower pH.
- Glutamine has a higher isoelectric point because it has fewer acidic groups, resulting in a more neutral zwitterionic form at a higher pH.

### Summary
- **Glutamic Acid**: Lower isoelectric point due to two -COOH groups.
- **Glutamine**: Higher isoelectric point due to one -COOH group and one amide group.