gen-define-enzyme-catalysis-and-give-one-short-worked-example-6082

Define enzyme catalysis and give one short worked example.

# Enzyme Catalysis **Definition:** Enzyme catalysis is the process by which biological catalysts (enzymes) increase the rate of biochemical reactions by lowering the activation energy required for the reaction to proceed, without being permanently consumed in the process. ## Key Features: - Enzymes bind substrates at their active site - Form an enzyme-substrate complex - Lower activation energy (Ea) - Increase reaction rate by factors of 10⁶ to 10¹⁷ - Remain unchanged after the reaction --- ## Worked Example: Catalase and Hydrogen Peroxide Decomposition **Reaction:** 2H₂O₂ → 2H₂O + O₂ **Without enzyme (spontaneous):** - Activation energy: ~75 kJ/mol - Reaction rate: very slow at body temperature **With catalase enzyme:** - Activation energy: ~23 kJ/mol - Reaction rate: ~200,000 times faster - One catalase molecule can decompose ~6 million H₂O₂ molecules per second **Mechanism:** 1. H₂O₂ binds to catalase active site (Fe-heme group) 2. Enzyme-substrate complex forms 3. First H₂O₂ is split → H₂O + O (bound to enzyme) 4. Second H₂O₂ reacts with bound O → H₂O + O₂ 5. Products release; enzyme regenerated This prevents toxic buildup of hydrogen peroxide in cells!