An enzyme can perform its catalytic activity in ________ structure

Options

A. Primary
B. Secondary
C. Tertiary
D. Quarternary

Answer

To answer the question "An enzyme can perform its catalytic activity in ________ structure," we need to analyze the different structural levels of proteins, particularly enzymes.

### Step-by-Step Solution:

1. **Understanding Protein Structure**:
- Proteins have four levels of structure: primary, secondary, tertiary, and quaternary.
- Each level of structure plays a role in the overall function of the protein.

2. **Primary Structure**:
- The primary structure is a linear sequence of amino acids linked by peptide bonds.
- This structure does not have the three-dimensional shape required for catalytic activity.

3. **Secondary Structure**:
- The secondary structure involves local folding of the polypeptide chain into structures such as alpha helices and beta sheets, stabilized by hydrogen bonds.
- While important, this level alone does not provide the functional conformation needed for enzyme activity.

4. **Tertiary Structure**:
- The tertiary structure is the overall three-dimensional shape of a single polypeptide chain, formed by the folding of the secondary structures.
- This structure is crucial for the enzyme's function as it creates the active site where substrate binding occurs.
- Most enzymes are functional in their tertiary structure, which allows for the necessary interactions with substrates and cofactors.

5. **Quaternary Structure**:
- The quaternary structure involves multiple polypeptide chains (subunits) coming together to form a functional protein.
- While some enzymes have quaternary structures, the functional form for many enzymes is primarily in the tertiary structure.

6. **Conclusion**:
- Based on the analysis, the correct answer is that an enzyme can perform its catalytic activity in its **tertiary structure**.

### Final Answer:
An enzyme can perform its catalytic activity in **tertiary structure**.

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