Angie Phan
The Effects of pH and Temperature on Phosphorylase Assay
Introduction
An enzyme is a protein that acts as a catalyst which reduces the activation energy needed for a chemical reaction. Without the presence of enzyme, cell reactions would take so long that they would detectable. During a reaction, in the presence of an enzyme, the substrate first creates a complex with the enzyme. While the substrate is a part of the complex, it’s converted into the product. Then, finally, the complex dissociates from the molecule which allows the release of the enzyme and formed product. An enzyme’s activity depends on a variety of conditions which includes the pH level and temperatures. Phosphorylase is an enzyme that catalyze the addition of a
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For this experiment, we have to prepare our phosphorylase which extracted from a potato. We prepared by weighed about 250 grams of peeled potato and cut it into cubes. The extracts then blended with 100mL of 0.1M NaF. After filtered the contents into a clean 250mL centrifuge bottle, we centrifuged it for 3 minutes. Then, separated the supernatant into a centrifuge bottle, which is our phosphorylase preparation. The enzyme assay used in this experiment today is the iodine test. As the iodine reacts with starch, it will form a brown, blue or black precipitate due to the iodine ions forcing into a linear arrangement. The endpoint of the enzyme reaction indicates the presence of starch by using the iodine test to determine. The faster the endpoint is reached, the less active the phosphorylase is.
Discussion
Based on the class data of the pH of phosphorylase reaction, the potato phosphorylase is reached the endpoint which the phosphorylase active at pH 6, it started active within 6 minutes. The optimal pH of phosphorylase is at pH 7 which active just within 4 minutes. At pH 6, it started to breaking down the starch primer +glucose-1-phosphase into starch + phosphate which reacted with the iodine test to formed the blue precipitate. At the optimal pH 7, it shows that it maximized its activity. Comparing the data of the pH of the potato phosphorylase reaction with the study published by Russell Pressey from Plant
Five cuvettes provided by the instructor were used during the experiment. The transmittance on the spectrophotometer was zeroed on an empty chamber and it was set at a wavelength of 486 nm. There was only one blank containing 0.5 mL of enzyme solution (catechol oxidase) and 4.5 mL of pH 6 buffer. The blank was prepared at the beginning of the experiment and used throughout the experiment. The blank was used to zero the absorbance on the spectrophotometer before each experimental trial. The experimental cuvettes contained 0.5 mL of catechol oxidase (enzyme), 0.5 mL of 5mM catechol (substrate), and 4.0 mL of pH 6 buffer for a total of 5.0 mL of solution. The results for the experimental trials were obtained after 0 seconds, 30 seconds, 1minute and 30 seconds, 3 minutes, and 5 minutes in five different reactions. The enzyme and substrate were obtained using a micropipette, and the pH was measured using a 10mL pipet. Each experimental trial was carried out twice for a total of ten experimental
The use of multiple test tubes and Parafilm was used for each experiment. Catechol, potato juice, pH 7 phosphate buffer, and stock potato extract 1:1 will be used to conduct the following experiments: temperature effect on enzyme activity, the effect of pH on enzyme action, the effect of enzyme concentration, and the effect of substrate concentration on enzyme activity. For the temperature effect on enzyme activity, three test tube were filled with three ml of pH 7 phosphate buffer and each test tube was labels 1.5 degrees Celsius, 20 °C, and 60 °C. The first test tube was placed in an ice-water bath, the second test tube was left at room temperature, and the third test tube was placed in approximately 60°C of warm water. After filling the test tubes with three ml of the
Amylase experiment # 2 was done to see how the pH affected the efficacy of the enzyme. First we collected all of the materials that were necessary to make this experiment. We needed five clean test tubes, the following standard solutions, 1% Starch Solution pH 3,1% Starch Solution pH 5,1% Starch Solution pH 7,1% Starch Solution pH 9,1% Starch Solution pH 11
Enzymes are types of proteins that work as a substance to help speed up a chemical reaction (Madar & Windelspecht, 104). There are three factors that help enzyme activity increase in speed. The three factors that speed up the activity of enzymes are concentration, an increase in temperature, and a preferred pH environment. Whether or not the reaction continues to move forward is not up to the enzyme, instead the reaction is dependent on a reaction’s free energy. These enzymatic reactions have reactants referred to as substrates. Enzymes do much more than create substrates; enzymes actually work with the substrate in a reaction (Madar &Windelspecht, 106). For reactions in a cell it is
Lab six requires students to observe the effects of pH and enzyme concentration on catecholase activity. Enzymes are organic catalysts that can affect the rate of a chemical reaction depending on the pH level and the concentration of the enzyme. As pH comes closer to a neutral pH the enzyme is at its greatest effectiveness. Also at the absorbance of a slope of 0.0122 the enzyme is affected greatly. The pH effect on enzymes can be tested by trying each pH level with a pH buffer of the same pH as labeled as the test tube and 1mL of potato juice, water, and catechol. This is all mixed together and put in the spectrophotometer to test how much is being absorbed at 420nm. As the effect on enzyme concentration can be tested almost the same way. This part of the exercise uses different amounts of pH 7-phosphate buffer and potato juice, and 1mL of catechol mixed together in a test tube. Each substance is put in the spectrophotometer at a wavelength set tot 420nm. The results are put down for every minute up to six minutes to see how enzyme concentration affects reaction rate. The results show that the pH 8 (0.494) affects the enzyme more than a pH of 4 (0.249), 6 (0.371), 7 (0.456), and 10 (0.126). Also the absorbance is greatest at a slope of 0.0122 with test tube C that has more effect on the reaction rate, than test tube A, B, and D.
The purpose of this experiment was to determine (1) the reaction rate of an amylase enzyme in starch and (2) the environmental factors that can affect the enzymatic activity. The hypothesis, in relation to the enzymatic activity by variables such as the substrate concentrations, temperature, PH and chemical interactions on the rate of reaction, stated
This lab was performed in order to discover the activity of the enzyme catecholase in different pH levels as well as its absorbance in differently concentrated solutions. A spetrophotometer was used to measure the absorbance of the enzyme catecholase in different pH solutions as well as to measure the absorbance of catecholase in solutions with different concentrations of potato juice and phosphate buffers. Absorbance of the enzyme catecholase was at an optimum level when pH was close to neutral. When pH was acidic or basic, the catecholase was less effective. Also, when there was a higher concentration of potato juice and a lower concentration of phosphate buffer, absorbance of the enzyme increased.
This experiment consisted of setting up a control group of starch in various temperature and then placing both fungal amylases and bacterial amylases in a mixture of starch and placing the solution of amylase and starch in various temperatures of water. After a certain amount of time- different amount of time needs to be used in order to have reliable results- iodine is added in a well on spot plates, then two drops of the mixture of amylase-starch is added from each temperature used, by adding iodine into the plates the mixture will show how much starch was hydrolyzed, this is used to calculate the amount of
The experiments involved PH buffers of different pH were added to potato juice, water, and the enzyme catecholase. The mixture was then subjected to spectrophotometer at a wavelength of 420nm taking the absorbance readings. In the second experiment, a phosphate buffer of PH 7.0 was used in different measures together with different measurement of potato juice and the enzyme catecholase then subjected to the spectrophotometer at a wavelength of 420nm. The data collected inform of table and analyzed using descriptive statistics such as line graph and later interpreted, showing that PH and enzyme concentration do affect the rate of enzyme reaction
Organisms cannot depend solely on spontaneous reactions for the production of materials because they occur slowly and are not responsive to the organism's needs (Martineau, Dean, et al, Laboratory Manual, 43). In order to speed up the reaction process, cells use enzymes as biological catalysts. Enzymes are able to speed up the reaction through lowering activation energy. Additionally, enzymes facilitate reactions without being consumed (manual,43). Each enzyme acts on a specific molecule or set of molecules referred to as the enzyme's substrate and the results of this reaction are called products (manual 43). As a result, enzymes promote a reaction so that substrates are converted into products on a faster pace (manual 43). Most enzymes are proteins whose structure is determined by its sequence of its amino acids. Enzymes are designed to function the best under physiological conditions of PH and temperature. Any change of these variables that change the conformation of the enzyme will destroy or enhance enzyme activity(manual, 43).
In the exercise # 2 we observed the effect of substrate concentration, enzyme concentration, pH and temperature on enzyme activity. All the data showed that once potato extract was added to catechol and water the reaction varied dependent on the level of catechol. As in
However one beaker received 100 mL of Deionized water with a molarity of 0.0. Afterwards a cork borer was pushed through the potato and was twisted back and forth. Once the borer was filled it was removed from the potato. Pushing the potato cylinder out of the borer, this this step was repeated six more times in order to get seven undamaged potato cylinders. Using a sharp razor blade, the potato cylinders were both cut to a uniform length of about 5cm, and were removed of their potato skins. The potato pieces were also cut in half to give the cells a greater surface area in which it was easier to absorb the solution. After the cylinders were weighed on a balance and the data was recorded in Table 4. Using the razor blade each potato was cut lengthwise into two long halves. Then the potato pieces were transferred to the water beaker and the time they were submerged was recorded. This step was repeated for all potato cylinders in which the pieces were placed in solutions 0.1 to 0.6 M. The potatoes were incubated for ninety minutes. At the end of the incubation period the time was recorded. Then the potato piece was removed form the first sample. Next potato pieces were weighed the and the final weight was recorded in Table 4. This procedure was repeated until all samples had been weighed and recorded in the chronological order they were initially placed in the test solution. Afterwards the table was completed by recording the
The materials needed for the experiment is a vial of the blood serum containing the enzyme alkaline phosphatase, a stock solution of 10mM of p-nitrophenyl phosphate in water (substrate). 5mM of phenyl phosphate in pH10 buffer solution, 0.1NaOH solution to stop enzyme activity, buffer solution at pH10 and a vortex mixer to mix the solution.
The purpose of this experiment was to determine the concentration of the cytosol of potato cells. The solutions of varying sucrose concentrations contained 0 M, 0.1 M, 0.2 M, 0.3 M, 0.4 M, 0.5 M, and 0.6 M sucrose. The potato was cut into small samples using the cork borer until there were seven cylinders of potato. Once the seven samples were made they were then all cut to equal sizes. After they were cut to the same size, the samples were placed in a plastic weigh boat onto a digital scale where the weight was measured in grams. The potato samples were then cut in half using a razor blade. Once the samples were cut in half, two pieces of potato were dropped into each beaker containing varying solutions of sucrose concentrations. After two
Enzymes are proteins that act as catalysts and help reactions take place. In short, enzymes reduce the energy needed for a reaction to take place, permitting a reaction to take place more easily. Some enzymes are shape specific and reduce the energy for certain reactions. Enzymes have unique folds of the amino acid chain which result in specifically shaped active sites (Frankova Fry 2013). When substrates fit in the active site of an enzyme, then it is able to catalyze the reaction. Enzyme activity is affected by the concentrations of the enzymes and substrate present (Worthington 2010). As the incidence of enzyme increases, the rate of reaction increases. Additionally, as the incidence of substrate increases so does the rate of reaction.