What is the typical optimum temperature for many human enzymes, and what happens if temperature rises above this range?

• A. Optimum around 0°C; heat denatures.
• B. Optimum around 25°C; higher temps have no effect.
• C. Optimum around 37°C; above this range enzymes can denature.
• D. Optimum around 100°C; heat increases activity indefinitely.

Answer: (C)

Temperature strongly affects both how fast an enzyme works and whether the enzyme keeps its proper shape. For many human enzymes, the best activity is right around 37°C, which matches normal body temperature. At this point the enzyme’s active site has the correct shape for catalysis, and molecular collisions occur at an efficient rate.

If the temperature rises above this range, increased molecular motion disrupts the weak bonds and interactions that hold the enzyme’s folded structure together. The enzyme can lose its precise shape, especially around the active site, leading to a loss of function (denaturation). At very high temperatures, this damage is often irreversible, so the enzyme stops working altogether.

Other statements aren’t accurate for human enzymes: around 0°C is far too cold for optimal activity and would slow reactions; 25°C is cooler than body temperature and not the usual optimum for most human enzymes; 100°C is well beyond what proteins can tolerate and would cause complete denaturation, not increased activity.