Enzymes usually function best at an optimal pH and temperature. The following graph shows the effectiveness of two enzymes at various temperatures. (c) From what you know about enzyme structure, explain why the rate of the reaction catalyzed by enzyme A slows down at temperatures above 40°C (140°F).

Verified step by step guidance

1. Understand that enzymes are proteins that catalyze biochemical reactions by lowering the activation energy required for the reaction to occur.
2. Recognize that enzyme structure is crucial for its function, and this structure is sensitive to changes in temperature.
3. Recall that enzymes have an optimal temperature range where they function most efficiently, and deviations from this range can affect their activity.
4. Explain that at temperatures above 40°C, the increased kinetic energy can cause the enzyme's structure to become unstable, leading to denaturation.
5. Denaturation involves the unfolding of the enzyme's three-dimensional structure, which can disrupt the active site and reduce the enzyme's ability to bind to substrates, thus slowing down the reaction rate.

Key Concepts

Enzyme Structure

Enzymes are proteins that have a specific three-dimensional structure essential for their function. This structure includes an active site where substrates bind, and it is maintained by various interactions, such as hydrogen bonds and hydrophobic interactions. Changes in temperature can disrupt these interactions, leading to denaturation, which alters the enzyme's shape and reduces its activity.

Optimal Temperature

Each enzyme has an optimal temperature range where it functions most effectively. At temperatures below this range, molecular movement is slower, leading to fewer collisions between enzymes and substrates. Conversely, at temperatures above the optimal range, increased kinetic energy can cause the enzyme's structure to destabilize, resulting in a decrease in reaction rate due to denaturation.

Denaturation

Denaturation refers to the process where an enzyme's structure is altered, typically due to extreme conditions such as high temperature or inappropriate pH. This structural change can lead to the loss of the enzyme's active site shape, rendering it unable to bind substrates effectively. As a result, the enzyme's catalytic activity diminishes, slowing down the reaction it catalyzes.