Identify the two important classes of catalysts. Analyze the chemical reactions that take place when a biological catalyst combines with a reactant (substrate) to form an unstable intermediate
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The two important classes of catalysts are biological catalysts, known as enzymes, and non-biological catalysts, which include both homogeneous and heterogeneous catalysts.
To analyze the chemical reactions that take place when a biological catalyst (enzyme) combines with a reactant (substrate) to form an unstable intermediate, we need to consider the enzyme-substrate complex and the concept of enzyme specificity.
1. Enzyme-Substrate Complex Formation:
- The enzyme has a specific active site where the substrate molecule binds.
- The active site and the substrate have complementary shapes that allow them to fit together, similar to a lock and key.
- When the substrate enters the active site of the enzyme, it forms a temporary enzyme-substrate complex.
2. Induced Fit Model:
- According to the induced fit model, the active site of the enzyme is flexible and can slightly change its shape to accommodate the substrate.
- This interaction induces conformational changes in both the enzyme and substrate, enhancing the catalytic activity.
3. Transition State Formation:
- Once the substrate enters the active site and the enzyme-substrate complex is formed, the enzyme helps to lower the activation energy required for the reaction to occur.
- The enzyme provides an optimal microenvironment for the reaction to take place.
- The enzyme may stabilize the transition state (unstable intermediate) of the reaction by interacting with the substrate, forming bonds, and modifying the chemical structure of the reactants.
4. Catalysis and Product Formation:
- The enzyme catalyzes the reaction by facilitating the conversion of the reactants (substrates) into products.
- It does so by providing an alternative reaction pathway that has a lower activation energy.
- The catalytic effect of the enzyme allows the reaction to occur more rapidly, often increasing the reaction rate by several orders of magnitude.
It is important to note that different enzymes have different mechanisms for catalysis, depending on their specific functions and the reactions they facilitate. The precise details of the chemical reactions involved may vary depending on the specific enzyme and substrate involved.