Steps in enzyme catalysis
Match each description with the appropriate step in this example of enzyme catalysis.
The binding of the substrate and enzyme places stress on the glucose-fructose bond, and the bond breaks.
The substrate, sucrose, consists of glucose and fructose bonded together.
Products are released, and the enzyme is free to bind other substrates.
The substrate binds to the active site of the enzyme, forming an enzyme-substrate complex.
The correct answer and explanation is :
Correct Matching of Steps in Enzyme Catalysis:
- The substrate, sucrose, consists of glucose and fructose bonded together. → Substrate Identification
- The substrate binds to the active site of the enzyme, forming an enzyme-substrate complex. → Enzyme-Substrate Complex Formation
- The binding of the substrate and enzyme places stress on the glucose-fructose bond, and the bond breaks. → Catalysis (Transition State and Bond Breaking)
- Products are released, and the enzyme is free to bind other substrates. → Product Release and Enzyme Recycling
Explanation:
Enzyme catalysis is a biochemical process that speeds up chemical reactions by lowering the activation energy required for a reaction to proceed. The breakdown of sucrose into glucose and fructose by an enzyme such as sucrase follows a series of steps:
- Substrate Identification: The process begins with recognizing the substrate. In this case, sucrose is composed of glucose and fructose linked by a glycosidic bond. Enzymes are highly specific and recognize particular substrates based on their shape and chemical properties.
- Enzyme-Substrate Complex Formation: The substrate binds to the enzyme’s active site, forming an enzyme-substrate complex. This binding is highly specific and often follows the lock-and-key model or induced fit model, where the enzyme slightly changes shape to fit the substrate.
- Catalysis (Transition State and Bond Breaking): The enzyme applies stress to the bond between glucose and fructose, reducing the energy required for the bond to break. This process occurs at the transition state, where the enzyme stabilizes the breaking of the glycosidic bond.
- Product Release and Enzyme Recycling: Once the bond is broken, the products (glucose and fructose) are released from the enzyme. The enzyme itself remains unchanged and can bind new sucrose molecules to repeat the process.
This cycle allows enzymes to function efficiently, catalyzing reactions multiple times without being consumed.