E Science Lab 9

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Procedure 1
1) The substrate for this procedure was hydrogen peroxide. The enzyme used (contained in the yeast) would have most likely been catalase.

2) Yes, the rate of gas production increased as more yeast was added, since more enzyme was able to convert hydrogen peroxide more quickly.

3) Adding less enzyme caused the reaction to proceed more slowly than when more enzyme was utilized.

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).

5) Hydrogen peroxide can be safely broken down into water and oxygen gas by removing oxygen from H2O2. Catalase will speed up this reaction in the body.

Procedure 2
1) As in the last procedure, catalase is the enzyme, and hydrogen peroxide is the substrate.

2) According to the data, temperature had little effect on the rate of reaction, until near-boiling, where higher temperatures caused a significant decrease in enzyme activity.

3) Yes, plants and animals also contain catalase. The way to test this would be to collect homogenates of plant tissue or animal blood to run the same experiments as on yeast, testing rate of hydrogen peroxide catalysis.

4) Enzyme activity can generally be increased by several factors. 1) Running the reaction at optimal pH. 2) Increasing temperature (though going too high will destroy the enzyme). 3) Increasing substrate or enzyme concentration

5) In order to determine the optimal temperature for catalase, I would grow yeast in a broth and harvest the protein using ion-exchange chromatography so that I can test the purified enzyme activity. I would test the purity of this enzyme by gel electrophoresis, and then I would set up a series of enzyme reactions where I attach a balloon to a flask to catch oxygen gas that is released through the...
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