The Effect of Substrate Concentration on the Activity of the Enzyme Catalase

Catalase is an important enzyme that protects cells from oxidative damage, which hydrogen peroxide can cause. It is an incredibly efficient enzyme where one catalase molecule can convert millions of hydrogen peroxide molecules each second.

In the experiment we used Turnip, Hydrogen Peroxide, Distilled Water, and Guaiacol as my substances. On the first activity, Effect of Enzyme concentration of Reaction Rate for low enzyme concentration, we tested three concentrations of the turnip extract, and hydrogen peroxide. For the Turnip Extract I used 0.5 ml, 1.0 ml, and 2.0 ml. For hydrogen peroxide we used 0.1 ml, 0.2 ml, and 0.4 ml. We used a control to see the standard, and used a control for each enzyme concentration used. The control contains turnip extract and the color reagent, Guaiacol. We prepared my substrate tubes separately from the enzyme tubes. My substrate tube

The topic of this lab is on biochemistry.This experiment was conducted to show how cells prevent the build of hydrogen peroxide in tissues. My group consisted of Lekha, Ruth, and Jason. There were used two different concentrations of hydrogen peroxide through this experiment , 1.5% and 3%. By testing two different types it is easier to understand how the H2O2 and catalase react with one another. To do this both the yeast, which was our catalase, and H2O2 were mixed together in a beaker. Each concentration was tested out twice for more accurate results . 1.5% concentrated H2O2 had an average reaction rate of 10.5 seconds while 3% concentrated H2O2 had an average reaction rate of 7.5 seconds. From this experiment we learned that by increasing the concentration of H2O2 and chemically combining it with a catalase it will speed up the reaction. Enzymes speed up chemical reactions . The independent variable in this experiment was the concentration of the H2O2. Some key vocabulary words are Catalase, enzyme, hydrogen peroxide ( H2O2), and concentration.

Enzymes are biological catalysts that speed up chemical reactions, without being used up or changed. Catalase is a globular protein molecule that is found in all living cells. A globular protein is a protein with its molecules curled up into a 'ball' shape. All enzymes have an active site. This is where another molecule(s) can bind with the enzyme. This molecule is known as the substrate. When the substrate binds with the enzyme, a product is produced. Enzymes are specific to their substrate, because the shape of their active site will only fit the shape of their substrate. It is said that the substrate is complimentary to their substrate.

This would be a suitable independent variable as it would be easy to change ourselves. If the concentration of the substrate increases the faster the rate of reaction, as more hydrogen peroxide molecules can collide with catalase molecules, so more reactions will take place. As you increase the concentration of substrate this will continue to occur up to a point where all the active sites on the enzyme are being used.

Hypothesis: If the concentration of an substrate is increased then the time it takes for the yeast spheres to rise will decrease because there is more substrate for the enzyme to break down, creating more oxygen, faster.

How does changing the substrate concentration affect the rate of a catalase reaction in an enzyme? Hydrogen peroxide was used as the substrate and the rate was measured by oxygen production.

The purpose of this experiment was to simply measure oxygen production rates released from decomposed hydrogen peroxide under different conditions (concentration of enzymes, temperature, and PH level).

4) It is likely that the rate of reaction would increase as substrate is added. It will probably follow classical michaelis-menten kinetics. See the attached picture for an example of this scheme for the rates (the picture of the hyperbola is the rate vs. the substrate concentration).

The null hypothesis for the first experiment was that substrate concentration would have no effect on the reaction rate. It was hypothesized that the reaction rate would increase with rising substrate concentrations, until all active sites were bound. The null hypothesis for the second experiment was that temperature would not have an effect on reaction rates. It was hypothesized that until the enzyme is denatured, as temperature increased, so would the reaction rate.

We hypothesized that a medium pH buffer added to the hydrogen peroxide an peroxidase reaction would be the best condition for the enzyme activity due to it being the more neutral than the high, being basic, and low, being acidic, pH.

The independent variable in this investigation is pH. Each individual enzyme has it’s own pH characteristic. This is because the hydrogen and ionic bonds between –NH2 and –COOH groups of the polypeptides that make up the enzyme, fix the exact arrangement of the active site of an enzyme. It is crucial to be aware of how even small changes in the

Substrate concentration also affects the rate of reaction as the greater the substrate concentration the faster the rate of reaction and all the active sites are filled. At this point the rate of reaction can only be increased if you add more enzymes in to make more active sites available.

An Enzyme is a protein, which is capable of starting a chemical reaction, which involves the formation or breakage of chemical bonds. A substrate is the surface or material on or from which an organism lives, grows, or obtains its nourishment. In this case it is hydrogen peroxide. This lab report will be explaining the experiment held to understand the effects of the changes in the amount of substrate on the enzyme’s reaction.

The chemical hydrogen peroxide(H₂O₂) is broken down by the enzyme catalase. Hydrogen peroxide is a byproduct formed in cellular reactions that, if not broken down, could inflict severe damage to the cell. Catalase is an enzyme that breaks down hydrogen peroxide in to water and oxygen. How efficient and strong the enzymes reaction to break down H₂O₂ determines largely on temperature and pH level. An enzyme only functions within a set pH and temperature range. Beyond that it becomes denatured, rendering it useless. The purpose of this lab is to determine at which temperature and pH level the enzyme catalase reacts best. Catalase in chicken and beef livers will be used to do the lab because enzymes still function after death as long as they are kept refrigerated at a low temperature.