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
In the lab, Inhibiting the Action of Catechol Oxidase we had to investigate what type of enzyme inhibition occurs when an inhibitor is added. Catechol oxidase is an enzyme in plants that creates benzoquinone.Benzoquinone is a substance that is toxic to bacteria. It is brown and is the reason fruit turns brown. Now, there are two types of inhibitors, the competitive inhibitor and non-competitive inhibitor. For an enzyme reaction to occur a substrate has to bind or fit into the active site of the enzyme. In competitive inhibition there is a substrate and an inhibitor present, both compete to bind to the active site. If the competitive inhibitor binds to the active site it stops the reaction. A noncompetitive inhibitor binds to another region
This evidence alone suggests that higher increases in substrate concentration causes smaller and smaller increases in enzyme activity. As substrate concentration increases further, some substrate molecules may have to wait for an active site to become empty as they are already occupied with a substrate molecule. So, the rate of the reaction starts to level off resulting in a plateau in the graphs. This means that the reaction is already working at its maximum rate, and will continue working at that rate until all substrates are broken down. The only way the reaction rate would increase, is if more enzyme was added to the solution. This confirms that increases in substrate concentration above the optimum does not lead to greater enzyme activity. Therefore, the rate of reaction is in proportion to the substrate
Whole carrots have a different reaction to the higher concentrations of hydrogen peroxide. There is a dramatic increase in the rate of reaction of catalase enzymes in the whole carrot, meaning that the saturations kinetics can be utilized at much higher rates of concentration.
Catecholase is an enzyme formed by catechol and oxygen used to interlock oxygen at relative settings, and it is present in plants and crustaceans (Sanyal et. al, 2014). For example, in most fruits and vegetables, the bruised or exposed area of the pant becomes brown due to the reaction of catechol becoming oxidized and oxygen becoming reduced by gaining hydrogen to form water, which then creates a chain that is is the structural backbone of dark melanoid pigments (Helms et al., 1998). However, not all fruits and plants darken at the same rate. This leads to question the enzymatic strength of catecholase and how nearby surroundings affect its activity. The catecholase enzyme has an optimal temperature of approximately 40°C (Helms et al., 1998). Anything above that level would denature the tertiary or primary structure of the protein and cause it to be inoperable. At low temperatures, enzymes have a slower catalyzing rate. Enzymes also function under optimal pH level or else they will also denature, so an average quantity of ions, not too high or low, present within a solution could determine the efficiency of an enzyme (Helms et al., 1998). Also, if more enzymes were added to the concentration, the solution would have a more active sites available for substrates and allow the reaction rate to increase if excess substrate is present (Helms et al., 1998). However, if more
Investigating Factors that Affect the Rate of Catalase Action Investigation into the factors which affect the rate of catalase action. Planning Aim: To investigate the affect of concentration of the enzyme catalase on the decomposition reaction of hydrogen peroxide. The enzyme: Catalase is an enzyme found within the cells of many different plants and animals. In this case, it is found in celery.
The nitrophenol standard curve was then constructed by the plotting of A410 of tubes S1-S6 vs. the concentration of nitrophenol. The preparation of acid phosphate from wheat germ extract was previously performed by the instructor at the beginning of the class. In the second part of the lab the velocity of commercially available purified acid phosphatase was measured. Firstly, 12 test tubes were spitted in groups of six and labeled A1-A6 and B1-B6.
In this experiment increasing amounts of Catechol and L.Dopa where used to determine the rate of enzyme catalysis of PPO. Also an inhibitor, PTU was analyzed with the substrate, Catechol and the enyme PPO. The results were then plotted using a Michaelis-Menten plot and PPO’s affinity (Km) for a particular substrate was determined. The PTU results were also plotted on a Michaelis-Menten plot to see whether or not PTU was a competitive or non-competitive inhibitor. A constant amount of PPO extract from potatoes and Phosphate buffer was used in each of the experiments with varying amounts of DI water
Enzyme peroxidase is essential in any cell metabolic reaction as it breaks down the harmful hydrogen peroxide to harmful products in the body. The report analyzed its effect on changes in temperatures by determining the optimum temperatures and the effects of its reversibility. Through the method of extracting the enzyme by blending it with potato tissue in phosphate buffer, the effects were analyzed on the effect of the dye guaiacol and the activity measured under different temperatures. The optimum temperature was obtained at 22.20C and above this temperature, the enzyme was denatured. Conclusively, increase in temperature increases
These findings follow my prediction, other than the 90% readings. According to my prediction, even with an inhibitor present the 90% concentration readings should have been higher than the 80% concentration readings. As stated above this could be because that the enzyme concentration is the limiting factor. But the figures actually drop from 80% concentration to 90%. This could be explained because there are so many substrate molecules competing for the active sites of the enzyme molecules that they actually start to block the site.
Comparing the Reaction Rates Between Potato and Hydrogen Peroxide Against Liver and Hydrogen Peroxide Through Loss in Mass
Abstract: Different compounds were tested to see their ability to inhibit polyphenol oxidase and prevent the browning from ortho quinones of fruits and vegetables. Five compounds were tested to see which compound produced more brown product and which compound showed higher inhibition. The production of benzoquinone was tested through a 420 nm spectrophotometer. Compounds A and D showed the most inhibition for the production of benzoquinone.
We were not given any instructions either to shake or not to shake the test tubes with the coloured solutions before inserting them in the spectrophotometer to read the absorbance. By shaking each test tube a certain number of times before putting it in the spectrophotometer could have improved the accuracy of the of absorbance of the solutions.
The results of this experiment showed a specific pattern. As the temperature increased, the absorbance recorded by the spectrophotometer increased indicating that the activity of peroxidase enzyme has increased.At 4C the absorbance was low indicating a low peroxidase activity or reaction rate. At 23C the absorbance increased indicating an increase in peroxidase activity. At 32C the absorbance reached its maximum indicating that peroxidase activity reached its highest value and so 32 C could be considered as the optimum temperature of peroxidase enzyme. Yet as the temperature increased up to 60C, the absorbance decreased greatly indicating that peroxidase activity has decreased. This happened because at low temperature such as 4 C the kinetic energy of both enzyme and substrate molecules was low so they moved very slowly, collided less frequently and formed less enzyme-substrate complexes and so little or no products. Yet, at 23 C, as the temperature increased, enzyme and substrate molecules
The rejected material from red beet processing plant comprises of red beet peels, crown, stalks, and beet greens (Figure ). As shown in stream of Figure, these by-products can be subjected to microwave blanching (350 W, 5 mins) to degrade peroxidases (POD), and improve the extraction yield of bioactive compounds. However, there are no evidences in the literature demonstrating the effect of microwave blanching on the red beet pomace residue.
Abstract: Enzymes are catalysts therefore we can state that they work to start a reaction or speed it up. The chemical transformed due to the enzyme (catalase) is known as the substrate. In this lab the chemical used was hydrogen peroxide because it can be broken down by catalase. The substrate in this lab would be hydrogen peroxide and the enzymes used will be catalase which is found in both potatoes and liver. This substrate will fill the active sites on the enzyme and the reaction will vary based on the concentration of both and the different factors in the experiment. Students placed either liver or potatoes in test tubes with the substrate and observed them at different temperatures as well as with different concentrations of the substrate. Upon reviewing observations, it can be concluded that liver contains the greater amount of catalase as its rates of reaction were greater than that of the potato.