Catechol Oxidase Experiment

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Biology 190A-Section B10 Jeevan Minhas
Jill Lemmen Student Number: V00827823

The effect of different pH and temperature levels on the activity and action of catechol oxidase used from a solanum tuberosum specimen

Abstract The various effects of temperature and pH on the enzyme activity and action of catechol oxidase, an enzyme containing copper which oxidizes phenols such as catechol with the use of dioxygen, were examined throughout several trial procedures. The experiment was conducted to determine the optimal pH for an enzyme to carry out its action, as well as to determine
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The formed benzoquinone molecules link together, forming a chain which act as backbone for melanoid pigments, which cause brown and red darkening in various specimens. The colour intensity is dependent on the amount of product formed. To measure, a spectrophotometer monitors the colour intensity, which allows the determination of reaction rate. As the temperature increased, the average absorbance reading at 420 nm decreased, which is clearly depicted in Figure 1 below. The enzyme reached a maximum at its greatest absorbance point of 0.526 at 10°C, the lowest temperature tested. Enzymes are most active at their ideal temperature, allowing us to confirm that 10°C is the optimal temperature for catechol oxidase. Temperatures that are too high or too low can denature enzyme shape and function. A test was conducted, monitoring a phosphate buffer at several levels of pH. As seen in Figure 2, the phosphate buffer with a neutral pH of 7, had the highest average absorbance level of 0.513. Thus, catechol oxidase has an optimal pH of …show more content…
The reaction rate should then reach a maximum point, where the absorbance of the enzyme is at its highest. The absorbance of the enzyme should then begin to decrease as the temperature continues to decrease. This was not supported during the experiment, as the absorbance values continuously decreased from 0.526 to 0.119 as the temperature increased 10° C to 80°C. Catechol oxidase, also known as tyrosinase, is an enzyme that assists in the reaction where catechol is exposed to oxygen. In a study examining polyphenol oxidase, researchers discovered that the enzyme has an optimal pH from 5-6 when incubated for 24 hours. Also, an optimal temperature of 20°C was discovered as the polyphenol oxidase was able to retain 70% of its original activities at this temperature (Öz et al. 2011). This is fairly close to the data obtained during the experiment using catechol oxidase, which had an optimal pH level of 7 and an ideal temperature of

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