The induced fit model of enzyme catalysis states that __________.

• A. the substrate must have a rigid, complementary shape to the enzyme's active site
• B. the enzyme's active site is unchanged by substrate binding
• C. the enzyme and substrate form a covalent bond during catalysis
• D. the enzyme changes its shape upon substrate binding to better fit the substrate

Answer: (D)

Verified step by step guidance

1. Understand the concept of the induced fit model: This model explains how enzymes interact with substrates. Unlike the lock-and-key model, the induced fit model suggests that the enzyme's active site is flexible and changes shape upon substrate binding to better accommodate the substrate.
2. Recognize the key feature of the induced fit model: The enzyme undergoes a conformational change when the substrate binds. This change enhances the enzyme's ability to catalyze the reaction by stabilizing the transition state.
3. Compare the induced fit model to other models: For example, the lock-and-key model assumes a rigid active site that perfectly matches the substrate's shape, while the induced fit model emphasizes flexibility and dynamic interaction.
4. Identify the incorrect statements in the options: The substrate does not need to have a rigid, complementary shape, the enzyme's active site is not unchanged, and covalent bonding between enzyme and substrate is not a general feature of catalysis.
5. Conclude that the correct answer aligns with the induced fit model: The enzyme changes its shape upon substrate binding to better fit the substrate, which is the defining characteristic of this model.