Among the following compounds most basic amino acid is :

Options

A. Asparagine
B. Lysine
C. Histidine
D. Serine

Explanation

To determine which of the given amino acids is the most basic, we need to analyze the structures and properties of the amino acids mentioned: Arginine, Histidine, and Lysine.

### Step-by-Step Solution:

1. **Identify the Amino Acids**:
The amino acids we are considering are Arginine, Histidine, and Lysine. All three have basic side chains.

**Hint**: Recall that basic amino acids typically have extra amine groups in their side chains.

2. **Analyze the Structures**:
- **Arginine**: Contains a guanidinium group which is highly basic due to the presence of three nitrogen atoms that can donate protons.
- **Lysine**: Contains a primary amine group in its side chain, which can accept protons, making it basic.
- **Histidine**: Contains an imidazole ring, which has a nitrogen that can be protonated, contributing to its basicity.

**Hint**: Look for functional groups that can accept protons (H+) to determine basicity.

3. **Compare Basicity**:
- **Arginine**: The guanidinium group is very stable and can easily donate a proton, making Arginine very basic.
- **Lysine**: While it is basic due to the amine group, it is less basic than Arginine.
- **Histidine**: Although it can be basic, its imidazole ring is less basic compared to the guanidinium group of Arginine.

**Hint**: Consider the stability of the protonated forms of these amino acids when determining which is the most basic.

4. **Conclusion**:
Among the three amino acids, Arginine is the most basic due to its guanidinium group, which is more capable of accepting protons compared to the other two.

**Final Answer**: Arginine is the most basic amino acid among the given options.