z Enzymes lower the free energy of activation by binding the transition state of the reaction better than the substrate z The enzyme must bind the substrate in the correct orientation otherwise there would be no reaction z Not a lock & key but induced fit – the enzyme and/or the substrate distort towards the transition statez Enzymes lower the free energy of activation by binding the transition state of the reaction better than the substrate z The enzyme must bind the substrate in the correct orientation otherwise there would be no reaction z Not a lock & key but induced fit – the enzyme and/or the substrate distort towards the transition state