Which amino acid has imidazole ring

Options

A. alanine
B. Leucine
C. Tyrosine
D. Histidine

Explanation

To determine which amino acid contains an imidazole ring, we can follow these steps:

### Step 1: Understand the Structure of Amino Acids
Amino acids are organic compounds that serve as the building blocks of proteins. Each amino acid has a central carbon atom bonded to an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom, and a variable side chain (R group) that determines the characteristics of the amino acid.

### Step 2: Identify the Amino Acids Listed
The question provides a list of amino acids: alanine, leucine, tryptophan, and histidine. We need to analyze each of these amino acids to see if any contain an imidazole ring.

### Step 3: Analyze Each Amino Acid
- **Alanine**: Has a simple side chain (methyl group, -CH3) and does not contain an imidazole ring.
- **Leucine**: Has a branched side chain and does not contain an imidazole ring.
- **Tryptophan**: Contains an indole ring, which is different from an imidazole ring.
- **Histidine**: Contains an imidazole ring in its side chain, making it unique among the listed amino acids.

### Step 4: Conclusion
Based on the analysis, the amino acid that contains an imidazole ring is **histidine**.

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