According to the lock-and-key model of enzyme action, why does heating an enzyme solution above 60°C result in permanent loss of catalytic activity?
Answer and explanation
Correct answer: A. high thermal kinetic energy disrupts non-covalent bonds, permanently denaturing the active site
- Step 1: Enzymes are globular proteins whose catalytic function depends on the precise 3D tertiary conformation of their active site. Step 2. Excessive heat breaks hydrogen bonds and hydrophobic interactions, unfolding the tertiary structure (denaturation) so substrates no longer fit. Answer: high thermal kinetic energy disrupts non-covalent bonds, permanently denaturing the active site. Why not the others: Denaturation does not require inhibitors, peptide bond cleavage into amino acids, or hydrogen peroxide formation.
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