Investigating the Effect of Substrate Concentration on Catalase Reaction

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Investigating the Effect of Substrate Concentration on Catalase Reaction Planning -Aim: The aim of the experiment is to examine how the concentration of the substrate (Hydrogen Peroxide, H2O2) affects the rate of reaction of the enzyme (Catalase). -Background information: Enzyme Enzymes are protein molecules that act as the biological catalysts. A catalyst is a molecule which can speed up chemical reaction but remains unchanged at the end of the reaction. Enzymes catalyze most of the metabolic reactions which take place within a living organism. They speed up the metabolic reactions by lowering the amount of energy needed to activate the reacting molecules. They are specific that usually act on only one type of substrate, so each of them just perform one particular reaction. Furthermore, only small amount of enzyme is needed every time to speed up a reaction. Enzymes are globular proteins that have a precise three-dimensional shape. Their hydrophilic side-chains on the outside of the molecule make them soluble in water. Enzymes can catalyze both anabolic and catabolic reactions within an organism. That means by the interaction between the side-chains of the enzyme and the atoms of the substrate, the enzyme can encourage the formation or breaking of bonds in a substrate molecule. Each enzyme possesses an active site. The active site is a region of enzyme which allows a substrate to bind with it. The configuration of the active site gives the specificity of enzyme. That means the active site and the substrate should be exactly complementary so that the substrate can fit in perfectly. Once they collide, the substrate and some of the side-chains of the enzyme’s amino acids form a temporary bond so that the substrate can be held in the active site. They combine to from an enzyme-substrate complex and the enzyme can start its work. It is called the “lock and key” hypothesis. (Lock: enzyme, key: substrate) There is another hypothesis called “induced fit”. That is when the substrate molecule combines with the enzyme it may induce a small

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