Enzyme inactivation tends to occur at which temperature range?

• A. 60–65 C
• B. 40–50 C
• C. 70–80 C
• D. 20–25 C

Answer: (A)

High temperatures destabilize the folded shape of enzymes. They are proteins whose activity depends on maintaining a precise three‑dimensional structure; heat disrupts the noncovalent bonds that hold that structure, causing unfolding of the active site and loss of catalytic function. For many enzymes, this denaturation begins around 60–65 °C, so this range is where inactivation tends to occur. Lower ranges like 40–50 °C or room temperature 20–25 °C keep the enzyme in its active form, while even higher temperatures such as 70–80 °C would cause rapid inactivation, but the onset is at the 60–65 °C range.