Enzyme action

• 1. Enzyme and substrate molecules have their own kinetic energy and are moving – they collide randomly
• 2. substrate molecule binds to the active site of the enzyme forming an enzyme-substrate complex (lock and key / induced fit)
• 3. Enzymes reduce activation energy by holding substrate in a way which causes reaction to occur more easily forming enzyme-product complex
• 4. The products no longer fit active site and move out – enzyme is free to catalyse same reaction with another substrate molecule
• Induced fit hypothesis - substrate molecule changes shape to fit enzyme molecule more closely as they bind, putting a strain on the substrate bonds.
• Induced fit hypothesis - Charges on amino acids at active site also hold substrate in place