Question

Binding of a substrate to the enzyme to yield the product is possible only when

• A. Active site of the enzyme is denatured
• B. Allosteric site of the enzyme is intact
• C. An inhibitor is occupying the active site
• D. The active site of the enzyme is intact

Hint:

Enzyme active site integrity is essential for substrate binding ($ES$ complex formation) and catalytic lowering of activation energy ($E_a$).

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Enzymatic catalysis requires precise stereochemical and electronic fit of substrate molecules into the catalytic active site cleft.
Key Formula or Approach:
\[ E + S \rightleftharpoons [ES] \longrightarrow E + P \]

Step 2: Detailed Explanation:
An enzyme's catalytic efficiency depends on the native three-dimensional tertiary conformation of its active site (the specific pocket containing binding and catalytic amino acid residues).
If the active site is denatured, occupied by a competitive inhibitor, or chemically altered, substrate binding cannot occur and no product is formed.
Therefore, productive catalytic conversion requires the active site of the enzyme to be intact.

Step 3: Final Answer:
Thus, product formation is possible only when The active site of the enzyme is intact, corresponding to option (D).