Protein Modification Alters Enzyme Binding

Steps:

• Replacing one amino acid changes the protein's primary structure.
• This alteration affects folding, resulting in a different tertiary structure (statement 1).
• The new tertiary structure disrupts shape complementarity with the enzyme's active site (statement 2).
• Without complementarity, the protein cannot induce the conformational change needed for enzyme binding (statement 3).

Why A is correct:

• All three statements align with the induced fit model of enzyme-substrate interaction, where structural changes prevent catalysis and degradation.

Why the others are wrong:

• B: Excludes 3, ignoring the role of induced fit in enzyme activation.
• C: Excludes 2, overlooking initial shape matching required for binding.
• D: Excludes 1, neglecting the foundational tertiary structure shift from amino acid substitution.

Final answer: A