Enzyme Lab

Introduction

Enzymes are the catalysts of biochemical reactions that are produced in the cell. It changes the rate of reaction but is not consumed by it. The reaction produced breaks up substrate molecules, and afterwarc, the enzyme is free to move on to another substrate molecule. The substrate molecule is the original molecule that the enzyme attaches to it active site where the substrate is changed.

There are several objectives to this lab. They are to be able to graph all the data that was taken from the experiment, understand how to determine enzyme activity, find the rates at which the enzymes affected the substrate, determine how the various variables affect the rate (such as the affect of temperature, pH, and concentration of the enzyme and the substrate) and design an experiment to determine the effect at which these variables are changed on the enzyme activity.

The lab is made of four tests, and two of them have their procedures written below. The first determines the effect on enzyme activity when H202 is added. The rest consist of using a chemical titration to measure and calculate the rate at which H2O2 is changed into O2 and H2O when the catalase is added.

Procedures

2B: Baseline:

1.) put 10mL of 1.5% H2 O2 in a beaker.

2.) Add 1mL of H2 O to the beaker.

3.) Add 10mL of H2 SO4. Be careful when using the H2 SO4.

4.) Swirl all contents of beaker well.

5.) With a burette, pour KMnO4 until approximately Ñ* full. Record initial reading.

6.) By using the burette, add one drop of the KMnO4 into the H2 O, H2 O2, and H2 SO4 solution.

7.) Swirl each time after adding a drop.

8.) Continue to add drops, and swirl, until a pink or brown color is seen.

9.) Record final reading of burette.

10.) Calculate the baseline by subtracting the initial from the final readings of KMnO4. Record.

2D: Rate of decomposition:

1.) Use the same baseline that was found in experiment 2B.

2.) Pour KMnO4 into the burette until approximately Ñ* full. Record initial reading

3.) In a 50mL glass beaker put 10mL of 1.5% H2O2.

4.) Add 1mL of catalase extract.

5.) Swirl this solution for 10 seconds.

6.) After swirling for 10 seconds, add 10mL of H2SO4

7.) Use a burette to add one drop of KMnO4 at a time to this solution, swirling each time. Add until a pink or brown color is seen.

8.) Record final reading of KMnO4 in the burette.

9.) In a clean beaker repeat steps three through seven, but swirling at the increments of 30, 60, 120, and then 180 seconds.

10.) Then proceed the titration of the KMnO4, after each time interval, into each solution until a pink or brown color is seen, and record the final reading.

Follow-Up Questions-

1.)Average rate (molecules/second) that H2O2 decomposed in 10 seconds.

2.) Catalase helps speed up chemical reactions, usually hydrogen peroxide. The structure of catalase contains four polypeptide chains. More than 500 amino acids make up each. Catalase has a molecular weight of approximately 240,000 daltons, and is found in all aerobic organisms. Catalase accumulates toxic levels of hydrogen peroxide within the cells formed from the metabolic process. Catalase speeds up the decomposition of hydrogen peroxide to water and oxygen gas.

The oxygen that is produced by catalase could be used in the cell at the end of the electron transport chain. This oxygen can also be used in the respiration of a living cell. It would be able to oxidize various molecules in the cell to aid in the production of energy.

3.) Average rate of decomposition during the