Polyphenol Oxidase Lab Report

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Effects of Sodium Chloride on the activity of Polyphenol Oxidase located on potato extract.

Abstract
Polyphenol Oxidase (PPO) is an enzyme that catalyze the oxidation of phenols. This particular enzyme is located in a lot of fruits and vegetables such as potato. This enzyme when exposed to oxygen, oxidizes and it is the reason why fruits gets brown after they are peeled. In this experiment we will used potato extract that contain PPO and will look for the affect of Sodium Chloride in the activity of this particular enzyme.

Introduction

Polyphenol Oxidase (PPO) is a major enzyme present in fruits and vegetables. It is responsible for the browning of vegetables and fruits that contains this particular enzyme. When exposed to air, PPO …show more content…

It shows that absorbance increases as time passes but also it shows that the more substrate present the more absorbance. We can clearly see that the line of the 6th test-tubes (more concentrated one) is way higher than the one with no substrate. All of the test-tubes data have each a linear-correlation (R2 >95%) with a slope more and more positive as the concentration of substrate increase. The only data that can be a little less precise is the data of the first test tube (trend line with 0mL substrate). Some issue with the spectrophotometer may have altered the results and thus this particular trend-line may be not correct (all the data from test tube 1 should be the same for all 15 minutes as no substrate as been added). This particular graph shows us that substrate concentration plays a role in enzyme activity as we already know and that the absorbance continued to increases after 15 minutes. With this particular data we were able to construct a graph of Substrate concentration versus Enzyme activity (slope) and we compared our graph with the data of a control group that did not added any NaCl in the solutions. This graph (figure 2) is one of the key to answer our hypothesis. In fact, with this particular graph we can definitely see that Sodium Chloride is an inhibitor of the enzyme PPO. The curve of the experimental data (green) is clearly below the control group curve, which means that the enzymatic activity slows down in presence of NaCl. But, we also want to know if this particular inhibitor is a non-competitive or competitive one. The third graph (figure 3) is a lineweaver-burk plot and will represent the inverse graph of the figure 2 curves. This particular graph will convert the original data that was curves into linear correlation so that we are able to made some assumption on the characteristics of the

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