Per.5 Ms. Fischer
Design your Lab: Action of an Enzyme
Problem: What effect will a change in temperature of hydrogen peroxide (°C) have on the activity of the enzyme Catalase in potatoes measured by the height of the bubbles created by the reaction in a test tube?
Hypothesis: All enzymes either breakdowns substances and\or they put substances together. An enzyme is a protein, folded into a complex three-dimensional shape. The active site is the part of the enzyme that allows it to be a catalyst and where substrates join and react. Anabolic reactions speed up the reactions were large molecules are built up from smaller molecules. This reaction usually needs an input of energy before reaction called the energy of activation. Catabolic reactions speed up the process of breaking down large molecules into smaller molecules. Catalase is a biological catalyst that helps speed up the breakdown of hydrogen peroxide into water and oxygen. Catalase is an enzyme and is the fastest enzyme known. In fact one molecule of Catalase can deal with six million molecules of hydrogen peroxide in 1 minute. The reaction we will be testing is catabolic which also means the reaction will give off some energy. Hydrogen Peroxide is often formed as a product of reactions in cells. It can be poisonous if it builds up, so Catalase has to work quickly so it does not build up to much poisoning the cells and killing them. The exact formula of this breakdown is shown here.
In a catabolic reaction, the enzyme molecule can bind with more molecules of substrate. Each enzyme may multiple times. The Substrate molecule fits into the active site of the enzyme. The active site splits the substrate molecule into smaller molecules. The substrate molecule can now reacts to form the product of two smaller molecules, which exit the active site. Temperature affects the activity of enzymes since an increase temperature speeds up the movement of substrate molecules, so that when they collide with the enzyme they have more energy and are more likely to bind with the active site speeding up the reaction more. The enzyme activity increases more with the increase of temperature up to a point. As the enzymes are proteins they will break down at high temperatures as the molecules start to vibrate and they could eventually lose their shape. The enzyme loses its three-dimensional shape and the substrate no longer fits into the active site. The enzyme is denatured. As of this high temperatures reduce enzyme activity. Every enzyme has an Optimum Temperature which is a balance between the two effects of temperature. Denaturalizing is sometimes irreversible, and living cells make great efforts to keep the conditions suitable for the enzymes to work. I.e. The body temperature is at 37°C which body enzymes work at best. This is their optimum temperature. As the temperature increases both the enzyme and substrate gain heat, causing them both to move around more, this means that the substrate
makes more successful collisions with the enzymes active site, thus the rate of reaction increases, once the optimum temperature is reached the rate of reaction falls rapidly, as shown on the graph above. (Arefin Khan, 2008) Based on the research above I think the enzymes will work best at 37 °C body temperature. The enzymes’ optimum temperature and will be able to react best with the substrate molecules as they would be moving about more and colliding more with the enzyme molecule increasing the chance of them reacting called a successful collision. At optimum temperature the Enzymes react quicker. In this experiment it will be a catabolic reaction as the Catalase enzymes will be breaking down the Hydrogen Peroxide molecules into water and oxygen molecules.