Polyphenol Oxidase Lab Report

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In this experiment, we will explore the properties of fresh potato extract in Phosphate buffer pH6 containing the enzyme polyphenol-oxidase and measure the different concentration of this enzyme activity by observing the production of pink/gold melanin, when 0.1% catechol and phosphate buffer pH6 is mixed into the solution. At this stage of the experiment, we are assuming that all other variables that can act as inhibitors of the enzymatic activity such as temperature or pH levels are under control. Fruits and vegetables are known to have small amounts of catechol and polyphenol-oxidase (enzyme), which are the cause of the production of browning effect in the out-layer skin or liquid of the fruit or vegetable when it is damaged. Polyphenol-oxidase …show more content…

In this situation we were able to observe the production of pink/ gold melanin; however it is the amount of polyphenol-oxidase found in each cell and time that reflects the production and color change of melanin. The production and color change of melanin would guide us to determine the rate of the enzymatic activity. The higher amount of melanin being produce will result darker colors, which will lead to higher absorbance, which shows faster enzymatic rate. In addition, polyphenol-oxidase acts as an oxidase that can catalyze the oxidation by binding with molecular oxygen to form OH group. (Samisch 1935) When polyphenol-oxidase is exposed to oxygen, it will immediately catalyze the oxygen to speed up reactions with substrate to produce melanin. In this procedure we also assumed that the substrate in our solution is in excess. Since there is an excess substrate concentration, all the active sites of the enzyme will become occupied with substrate, resulting for the enzyme to become saturated with substrate and the velocity of the chemical reaction has reach its maximal rate, also known as

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