3.6 enzymes Enzymes have specific shape and it need specific enzyme substrate to match the active site. They are specific to each other. Active substrate: the binding site on the surface of an enzyme where the substrate molecule binds. Enzyme influences the rate of reaction. It lowers the activation energy of reaction. There are three main factors which affecting enzyme-catalyses reaction. 1. Effect of temperature Reaction with or without enzymes will increase their reaction rate as temperature increase. Those enzyme used in reaction have an upper limit. When an enzyme loses its shape, it’s being denatured. Denaturation is changing the structure of an enzyme so it can no longer carry out its function. 2. Effect of pH Enzymes usually have an optimum pH at which they work most efficiently. As the pH diverges from the optimum, enzyme activity decreases. Both acid and alkali environments can denature enzymes. 3. Effect of concentration If there is constant amount of enzyme, as the concentration of a substrate increases, the rate of reaction will increase as well. At the optimum concentration of substrate molecules, all active sites are full and working at maximum efficiency. Any increase in concentration beyond the optimum will have no added effect as there are no extra active sited to be used. Lactose is the sugar found in milk. It can be broken down by enzyme lactase to glucose and galactose. However some people lack this enzyme and so cannot break down lactose leading to lactose intolerance. Lactose intolerant people need to drink milk that has been lactose reduced. Lactose-free milk is made by two different methods: add lactase to milk and run milk through apparatus with immobilized lactase.