Pg:-25,26 Chapter-2

Enzymes are biological catalysts that speed up chemical reactions in living organisms. They are typically proteins, although some RNA molecules can act as enzymes (ribozymes).

Structure and Function:

Enzymes have a specific three-dimensional structure that allows them to bind to their substrates (the molecules they act upon). The region where the substrate binds is called the active site. The enzyme-substrate complex undergoes a reaction to form the product, which is then released, allowing the enzyme to bind to new substrate molecules.

Enzymes operate on the principle of lowering the activation energy of a reaction, making it easier for the reaction to proceed. This is achieved through various mechanisms, such as:

1. Proximity and Orientation: Enzymes bring substrates close together and in the correct orientation.

2. Strain and Distortion: Enzymes can distort substrate molecules to make the reaction more favorable.

3. Microenvironment: Enzymes can create a unique microenvironment, such as an acidic or basic pocket, to facilitate the reaction.

Types of Enzymes:

Enzymes are classified based on the type of reaction they catalyze. classes include:

1. Oxidoreductases: Catalyze oxidation-reduction reactions, where electrons are transferred between molecules. Examples include dehydrogenases and oxidases.

2. Transferases: Transfer functional groups from one molecule to another. Examples include kinases and transaminases.

3. Hydrolases: Catalyze the hydrolysis of various bonds, including ester, glycosidic, and peptide bonds. Examples include proteases and nucleases.

4. Lyases: Catalyze the addition or removal of groups to form double bonds, without hydrolysis or oxidation. Examples include decarboxylases and dehydratases.

5. Isomerases: Catalyze the rearrangement of atoms within a molecule. Examples include isomerases and epimerases.

6. Ligases: Catalyze the joining of two molecules with the simultaneous hydrolysis of a diphosphate bond in ATP or a similar molecule. Examples include DNA ligase and synthetases.

Uses of Enzymes:

Enzymes have a wide range of applications in various fields:

1. Biological Processes:

   • Metabolism: Enzymes are essential for metabolic pathways, including glycolysis, the citric acid cycle, and oxidative phosphorylation.

   • DNA Replication and Repair: Enzymes like DNA polymerases and ligases are crucial for DNA synthesis and repair.

   • Signal Transduction: Enzymes such as kinases and phosphatases regulate signaling pathways by adding or removing phosphate groups.

2. Industrial Applications:

   • Food Industry: Enzymes like amylases and proteases are used in brewing, baking, and cheese-making.

   • Detergents: Enzymes like lipases and proteases are added to detergents to break down stains.

   • Biofuels: Enzymes like cellulases are used to break down biomass into fermentable sugars for biofuel production.

3. Medical and Diagnostic Applications:

   • Therapeutics: Enzymes like asparaginase are used to treat certain types of cancer.

   • Diagnostics: Enzymes like glucose oxidase are used in biosensors to measure glucose levels in blood.

4. Research:

   • Molecular Biology: Enzymes such as restriction endonucleases, polymerases, and ligases are essential tools in genetic engineering and recombinant DNA technology.