Which statements are correct about the mixture of lysine `pI=9.6)` and glycine `(pI=5.97)`, sparated by electrophoresis method or by solubility method?

Options

A. At `pH=5.97`, glycine does not migrate while lysine moves to the cathode.
B. At `pH=5.97`, glycine does not migrate while lysine moves to the anode.
C. At `pH= 9.6`, lysine does not migrate while glycine moves to the anode.
D. At `pH=5.97` of the mmixture of the solution, glycine precipitates out while lysine remains in the solution.

Answer

To solve the problem regarding the mixture of lysine (pI = 9.6) and glycine (pI = 5.97) and their behavior during electrophoresis or solubility methods, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Isoelectric Point (pI)**:
- The isoelectric point (pI) is the pH at which an amino acid exists in a neutral dipolar form, meaning it does not migrate towards either electrode in an electric field.
- For glycine, the pI is 5.97, and for lysine, it is 9.6.

2. **Behavior of Glycine at pH 5.97**:
- At its isoelectric point (pH 5.97), glycine will not migrate towards either electrode because it is in its neutral dipolar form. Thus, it does not carry a net charge.

3. **Behavior of Lysine at pH 5.97**:
- At pH 5.97, lysine, which has a higher pI (9.6), will still be positively charged because the pH is below its pI. Therefore, lysine will migrate towards the cathode (negative electrode).

4. **Behavior of Lysine and Glycine at pH 9.6**:
- At pH 9.6, lysine will be at its isoelectric point, meaning it will not migrate towards either electrode as it is neutral.
- Glycine, on the other hand, will be negatively charged (since the pH is above its pI), and it will migrate towards the anode (positive electrode).

5. **Solubility at Isoelectric Points**:
- At their respective isoelectric points, amino acids have minimum solubility.
- At pH 5.97, glycine will precipitate out of the solution since it is at its isoelectric point, while lysine will remain soluble.

### Conclusion:
Based on the above analysis, we can evaluate the statements:

- **Statement A**: Correct - At pH 5.97, glycine does not migrate while lysine moves to the cathode.
- **Statement B**: Incorrect - At pH 5.97, lysine does not move to the anode; it moves to the cathode.
- **Statement C**: Correct - At pH 9.6, lysine does not migrate while glycine moves to the anode.
- **Statement D**: Correct - At pH 5.97, glycine precipitates out while lysine remains in solution.

### Final Answer:
The correct statements are A, C, and D.

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