Pg:- 70,71,72,73

Ch:- 5

Enzyme action describes how enzymes function as biological catalysts to speed up chemical reactions in living organisms. They do this by lowering the activation energy required for a reaction, making the process faster and more efficient.

Substrate Binding:

Enzymes bind to specific molecules called substrates. This occurs at the enzyme's active site, a specially shaped region that matches the substrate's shape. This interaction can be explained by two models:

• Lock and Key Model: The substrate fits the enzyme like a key fits into a lock.

• Induced Fit Model: The enzyme changes shape slightly to better accommodate the substrate.

Formation of the Enzyme-Substrate Complex:

Once the substrate binds to the active site, an enzyme-substrate complex is formed. This temporary complex aligns the substrate molecules in a way that facilitates the reaction.

Catalysis:

The enzyme catalyzes the conversion of substrates into products. It achieves this by:

• Lowering activation energy: Reducing the energy barrier needed for the reaction to proceed.

• Stabilizing transition states: Making intermediate stages of the reaction more stable.

Product Formation:

The chemical reaction takes place, and the substrate is transformed into the final product(s). For example:

• Hydrolysis: Breaking down a molecule into smaller parts (e.g., breaking a protein into amino acids).

• Synthesis: Joining smaller molecules into a larger product.

Product Release:

After the reaction, the enzyme releases the product(s) from the active site. The enzyme itself remains unchanged and can catalyze additional reactions.

Recycling:

The enzyme is free to repeat the process with new substrate molecules. This makes enzymes highly efficient—they can catalyze many reactions without being consumed.

Factors Affecting Enzyme Action:

Several factors influence how well enzymes function:

• Temperature: Too high or too low can denature the enzyme or slow its activity.