Metabolism encompasses the complex network of chemical reactions that sustain life. These reactions are categorized into two main types: catabolism, which involves breaking down molecules to release energy, and anabolism, which builds up molecules to store energy or create cellular components. Enzymes, specialized protein catalysts, are indispensable for facilitating and regulating these metabolic processes. They accelerate reactions by lowering activation energy, ensuring efficiency and specificity in cellular activities.
Role of Enzymes in Metabolism
- Energy Conversion: Enzymes facilitate the transformation of food-derived energy into adenosine triphosphate (ATP), the primary energy currency of cells.
- Molecular Synthesis: They assist in synthesizing essential macromolecules like proteins, lipids, and nucleic acids.
- Waste Removal: Enzymatic activity ensures the breakdown and elimination of metabolic byproducts.
Mechanism of Enzyme Action
Enzymes operate by binding substrates at their active sites, forming an enzyme-substrate complex. This interaction stabilizes the transition state of the reaction, reducing the activation energy required for the process. The enzyme remains unchanged after the reaction and can be reused repeatedly. Specificity is a hallmark of enzyme function; each enzyme typically catalyzes only one type of reaction or acts on specific substrates.
Coenzymes and Their Role
- NAD+/NADH: Central to redox reactions in catabolism.
- FAD/FADH2: Participates in electron transport during energy extraction.
- ATP: Transfers phosphate groups in phosphorylation reactions.
