Role of catalysts, enzymes in biochemical reactions

1. Introduction to Catalysts

1. A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process.
2. Catalysts provide an alternative pathway with a lower activation energy.
3. They do not alter the equilibrium position of a reversible reaction.
4. Catalysts are classified as homogeneous (same phase as reactants) or heterogeneous (different phase).

2. Mechanism of Catalysis

1. The reactants bind to the catalyst surface, forming intermediate complexes.
2. These complexes require less energy to convert into products.
3. After the reaction, the catalyst is regenerated and ready for reuse.

3. Enzymes as Biological Catalysts

1. Enzymes are protein-based catalysts that accelerate biochemical reactions in living organisms.
2. They exhibit high specificity, acting only on specific substrates.
3. Enzymes operate under mild conditions of temperature and pH.
4. Their activity can be regulated by inhibitors or activators.

4. Factors Affecting Enzyme Activity

1. Temperature: Enzymes have an optimum temperature, beyond which they denature.
2. pH: Extreme pH levels can alter the enzyme structure, affecting its function.
3. Substrate Concentration: Higher substrate concentration increases reaction rate until the enzyme becomes saturated.
4. Cofactors: Non-protein molecules or ions that assist enzyme function.

5. Industrial Applications of Catalysts

1. Haber process: Catalysts like iron are used to synthesize ammonia.
2. Contact process: Vanadium pentoxide (V₂O₅) is used in sulfuric acid production.
3. Platinum and palladium are used in automobile catalytic converters to reduce emissions.
4. Zeolites are used in petroleum refining for cracking hydrocarbons.

6. Biological Importance of Enzymes

1. Enzymes catalyze crucial biochemical reactions like photosynthesis, respiration, and DNA replication.
2. They are involved in breaking down food into nutrients for absorption.
3. Enzymes regulate metabolic pathways, ensuring proper cellular function.
4. Deficiency or malfunction of enzymes can lead to metabolic disorders.

7. Enzyme Inhibition

1. Competitive inhibitors: Compete with the substrate for the enzyme’s active site.
2. Non-competitive inhibitors: Bind to a site other than the active site, altering enzyme function.
3. Inhibition can be reversible or irreversible.

8. Key Points

1. Catalysts increase reaction rates by lowering activation energy.
2. Enzymes are highly specific biological catalysts that operate under mild conditions.
3. Homogeneous catalysts are in the same phase as reactants, while heterogeneous catalysts are in a different phase.
4. Examples of industrial catalysts include iron (Haber process) and V₂O₅ (Contact process).
5. Enzyme activity is influenced by factors like temperature, pH, and substrate concentration.
6. Inhibitors can regulate or inhibit enzyme activity in biochemical reactions.
7. Catalysts do not alter the equilibrium constant of a reaction.