Temperature and pH

Temperature and pH

Every enzyme has a temperature at which it works best, called its optimum temperature; for most enzymes in the human body this lies close to normal body temperature. As temperature rises from a low value towards the optimum, molecules move faster and collide more often, so the reaction rate increases. Beyond the optimum, however, the rate falls away sharply, because the heat begins to disrupt the precise three-dimensional folding of the enzyme protein (denaturation), distorting or destroying the active site so that it can no longer bind its substrate properly. At the other extreme, very low temperatures do not usually destroy the enzyme but simply slow molecular motion so much that the reaction becomes very sluggish. …