In primary structure of a protein, methionine is located at left end of amino acid chain while glutamic acid is located at right end. Which of the following statement is ture with respect to above mentioned protein?

Options

A. Methionine is a C-terminal amino acid
B. Glutamic acid is the first amino acid of the chain
C. Glutamic acid is N-terminal amino acid
D. Methionine is the first amino acid of the chain

Answer

To solve the question regarding the primary structure of a protein where methionine is at the left end and glutamic acid is at the right end, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Position of Amino Acids**:
- In the given protein structure, methionine (Met) is located at the left end of the amino acid chain, and glutamic acid (Glu) is at the right end.

2. **Understand the Terminology**:
- The left end of a protein chain is referred to as the N-terminal (amino terminus), where the amino group (-NH2) of the first amino acid is free.
- The right end is referred to as the C-terminal (carboxyl terminus), where the carboxyl group (-COOH) of the last amino acid is free.

3. **Identify the Role of Methionine**:
- Methionine is known to be the first amino acid in protein synthesis and is coded by the start codon AUG. This means that methionine is always the first amino acid in the sequence of proteins.

4. **Identify the Role of Glutamic Acid**:
- Glutamic acid, being at the right end of the chain, is the last amino acid in this particular sequence.

5. **Evaluate the Statements**:
- **Statement 1**: Methionine is a C-terminal amino acid. (False, because it is N-terminal)
- **Statement 2**: Glutamic acid is the first amino acid of the chain. (False, because methionine is the first)
- **Statement 3**: Glutamic acid is an N-terminal amino acid. (False, because it is C-terminal)
- **Statement 4**: Methionine is the first amino acid of the chain. (True, as it is at the N-terminal)

6. **Conclusion**:
- The correct statement with respect to the protein structure is that methionine is the first amino acid of the chain.

### Final Answer:
The correct statement is: **Methionine is the first amino acid of the chain.**