Describe enzymes as proteins that are involved in all metabolic reactions, where they function as biological catalysts

Enzymes are specialized proteins that play a crucial role in facilitating and regulating metabolic reactions within living organisms. Here’s a detailed description of enzymes and their functions:

Characteristics of Enzymes

1. Proteins: Enzymes are primarily composed of amino acids, which are linked together in specific sequences to form polypeptide chains. The unique sequence and structure of these amino acids determine the enzyme’s specific function.
2. Biological Catalysts: Enzymes act as biological catalysts, meaning they speed up chemical reactions without being consumed in the process. They achieve this by lowering the activation energy required for reactions to occur, allowing metabolic processes to proceed efficiently at the temperatures and conditions found in living organisms.
3. Specificity: Each enzyme is highly specific to its substrate (the reactant it acts upon). This specificity is due to the unique shape of the enzyme’s active site, where substrate molecules bind. The “lock-and-key” model or the “induced fit” model describes how substrates fit into the active site, leading to a reaction.
4. Involvement in Metabolic Reactions: Enzymes are involved in all metabolic pathways, including:
   • Catabolic Reactions: Breaking down complex molecules into simpler ones (e.g., digestion).
   • Anabolic Reactions: Building complex molecules from simpler ones (e.g., protein synthesis).
5. Regulation: Enzyme activity can be regulated by various factors, including:
   • Temperature and pH: Each enzyme has an optimal temperature and pH at which it functions best.
   • Cofactors and Coenzymes: Some enzymes require additional non-protein molecules (cofactors) or organic molecules (coenzymes) to be active.
   • Inhibitors: Certain substances can inhibit enzyme activity, either reversibly or irreversibly, affecting metabolic pathways.
6. Reusability: After catalyzing a reaction, enzymes remain unchanged and can participate in subsequent reactions. This makes them highly efficient catalysts within biological systems.