Which of the following is an example of ''irreversible denaturation'' of a protein ?

Options

A. boiling egg
B. change of amino acid
C. enzymatic action
D. its synthesis

Answer

To determine which of the given options represents an example of "irreversible denaturation" of a protein, we need to analyze each option carefully.

### Step-by-Step Solution:

1. **Understanding Denaturation**: Denaturation refers to the process where proteins lose their native structure due to external stress or compounds, leading to a loss of function. Denaturation can be reversible or irreversible.

2. **Analyzing the Options**:
- **Option 1: Boiling of Egg**: When an egg is boiled, the proteins in the egg white (albumin) denature and coagulate. Once boiled, these proteins cannot revert to their original state. This process is irreversible.
- **Option 2: Change of Amino Acids**: Changing amino acids can refer to various processes, including mutations or modifications. However, amino acids themselves can often be restored to their original form, making this a reversible process.
- **Option 3: Enzymatic Action**: Enzymatic reactions typically involve the binding of substrates to enzymes, which can be reversed. The enzyme can return to its original state after the reaction, indicating that this is a reversible process.
- **Option 4: Its Synthesis**: The synthesis of proteins involves the assembly of amino acids into polypeptides. This process is also reversible, as proteins can be broken down into their constituent amino acids.

3. **Conclusion**: Based on the analysis, the only option that represents irreversible denaturation of a protein is the **boiling of an egg**.

### Final Answer:
The example of "irreversible denaturation" of a protein is **boiling of egg**.

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