Effects of Temperature, PH, boiling and concentration on Horseradish Peroxidase
ABSTRACT
The purpose of this report is to find out the effect of change in the Temperature, PH, boiling, concentration in peroxidase activity. Peroxidase is an enzyme that converts toxic hydrogen peroxide (H2O2) into water and another harmless compound. In this experiment we use, turnips and horseradish roots which are rich in the peroxidase to study the activity of this enzyme. The activity of peroxidase with change in temperature was highest at 320 Celsius and lowest at 40C. The activity of peroxidase was highest at a pH of 7, while it was lowest at pH of 9.Peroxidase activity was very low and constant with boiled extract, while the activity was moderate
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Turnips and horse radish roots are rich source of this enzyme. In this experiment, we would carry out a reaction between hydrogen peroxide and guaiacol which is colorless dye, using peroxidase as a catalyst, to produce water and an oxidized form of guaiacol which is brown. The formation of brown color would serve as an indicator that the breakdown of Hydrogen Peroxide took place. The enzyme activity would be directly proportional to the brown color intensity. The color intensity would be measured using a spectrophotometer and standardized to find the corresponding concentration for each absorbance unit.
MATERIALS
Blender or mortar and pestle
Fresh turnip or horseradish root
Spectrophotometer curvettes
10 ml test tubes and rack
50ml beakers
5ml pipettes graduated in 0.1 ml units with suction devices or automatic pipetters and tips
Thermometer
METHOD
As directed in the lab text book “BIOLOGICAL INVESTIGATIONS”
RESULTS Time (sec) | Tube 2 and 340C | Tube 4 and 5 250C | Tube 6 and 7320C | Tube 8 and 9480C | 20 | 0.100 | 0.418 | 0.535 | 0.331 | 40 | 0.107 | 0.575 | 0.708 | 0.412 | 60 | 0.109 | 0.775 | 0.904 | 0.404 | 80 | 0.109 | 0.897 | 1.123 | 0.578 | 100 | 0.106 | 1.066 | 1.296 | 0.681 | 120 | 0.099 | 1.229 | 1.436 | 0.787 |
Table 1: Temperature effects on Peroxidase Activity (absorbance at 500nm)
Figure 1
From Figure 1 above, the optimal temperature for peroxidase activity
In this experiment, the change of pH was also a key step of the reaction because the pH factors in the stability of an enzyme. Since we used an enzyme in this reaction, the pH levels of the solution needed to change first before adding the Horseradish peroxidase Type 1. The reason for changing the pH levels is to ensure that the enzyme will work during the reaction and having a high or extreme pH causes the denature an enzyme. After 0.50 grams of Vanillin were dissolved in Deionized water, we added 0.1 M acetic acid for the pH levels to drop until the pH was 4 which was the desired pH level.
In this experiment, the naturally occurring peroxidase is extracted from homogenized turnip (Brassica rapa) pulp (Coleman 2016). Its role in the environment is to remove toxic hydrogen peroxide during metabolic processes where oxygen is used (Coleman 2016). The goal of this experiment is to evaluate the change of absorbency of turnip peroxidase within a metabolic reaction utilizing oxygen. Any change noted is indicative of the peroxidase removing hydrogen peroxide. Within this experiment, the extract will be prepared, the amount of enzyme will be standardized, and the effect of changing the optimal conditions will be observed. If the enzyme concentration is increased then the rate of the reaction decrease. If the pH of solutions used is increased
The data in proves that our hypothesis was correct. When we increased the temperature to 35°C, the the enzyme activity increased because kinetic energy increased, increasing the collisions between the substrate and the enzyme, and thus creating a higher chance of reaction. When we increased the temperature to 45°C, the enzyme activity decreased as the enzyme became denatured,because the atoms in the enzyme had enough energy to overcome the hydrogen bonds between the R groups that give the enzyme its shape From our data, we could conclude that the optimal temperature of turnip peroxidase is around 35°C and around 45°C, it will start to denature.
In the blank cuvettes, the 2 mL of pH levels 2,5,7, and 10 were added first, followed by the 1mL of peroxidase. However our experimental cuvettes contained both hydrogen peroxide and guaiacol. Before the cuvettes were placed in the spectrophotometer we added 0.1 mL of H202, followed by 0.02 mL of guaiacol these two substances were added last immediately before they were placed in the spectrophotometer. Para film was placed over the cuvette opening, and the assay solution was shaken and placed into the spectrophotometer where its saturation level was then tested. We recorded the saturation level of the solution every 15 seconds for 3 minutes. This process was repeated two times for each pH level for a total of two trials.
The type of peroxidase is used is called turnip peroxidase. Turnip peroxidase is made up of Guaiacol and hydrogen peroxide. The reactants to the product are turnip peroxidase or called tertraguaiacol and water. The color of the react is brown. In the experiment was conducted there were baseline experiment, temperature, pH, 10X substrate, Inhibitor, and half the amount of enzyme.
The preparation for the experiment started by gathering the solutions of enzyme Peroxidase, substrate hydrogen peroxide, the indicator guaiacol and distilled water. Two small spectrometer tubes and three large test tubes with numbered labels. In addition, one test tube rack, one pipet pump and a box of kimwipes were also gathered. Before the experiment, the spectrometer must be set up to use by flipping the power switch to on. Following, the machine was warmed up for 10 minutes and the filter lever was moved to the left. In addition, I set the wavelength to 500 nm with the wavelength control knob. Before the experiment, I had to create the blank solution by pipetting 0.1 ml of guaiacol, 1.0 ml of turnip extract and 8.9 ml water into tube #1. Following the creation of the blank, a control 2% solution was created.
Peroxidase is an enzyme found in potatoes that catalyzes the breakdown of hydrogen peroxide, H2O2, into O2 gas and water. We examined the different pH environments that can affect the enzyme activity during the breakdown of H2O2. In order to do this, we added different levels of pH, low, medium, and high, into different test tubes with the enzyme and H2O2, and we then inverted the tube. The amount of O2 gas produced was then measured and recorded. The result was that the higher pH produced more gas, followed by medium pH, then low pH. The enzymes were more active in the pH of about 10. It increased
Catechol, in the presence of oxygen is oxidized by catechol oxidase to form benzoquinone (Harel et al., 1964). Bananas and potatoes contain catechol oxidase that acts on catechol which is initially colorless and converts it to brown (Harel et al., 1964). In this experiment, the effect of pH on the activity of catechol oxidase was conducted using buffers ranging from pH2 to pH10. Two trials were conducted due to the first trial results being altered by an external factor. The results were acquired by taking readings every 2 minutes for 20 minutes from a spectrophotometer and then recorded on to the table. The data collected in the table were then made into graphs to illustrate the influence of pH on the catechol oxidase catalyzed reaction. After analysis, the data revealed that pH did have a significant influence on the enzyme as recorded by absorbance per minute. However, the data was collected was not accurate due to external factors, thus the results are debatable and should be experimented again for validation.
The purpose of this experiment is to learn the effects of a certain enzyme (Peroxidase) concentration, to figure out the temperature and pH effects on Peroxidase activity and the effect of an inhibitor. The procedure includes using pH5, H202, Enzyme Extract, and Guaiacol and calibrating a spectrophotometer to determine the effect of enzyme concentration. As the experiment continues, the same reagents are used with the spectrophotometer to determine the temperature and pH effects on Peroxidase activity. Lastly, to determine the effect of an inhibitor on Peroxidase, an inhibitor is added to the extract. It was found that an increase in enzyme concentration also caused an increase in the reaction rate. The reaction rate of peroxidase increases at 40oC. Peroxidase performed the best under pH5 and declined as it became more basic. The inhibitor (Hydroxy-lamine) caused a decline in the reaction rate. The significance of this experiment is to find the optimal living conditions for Peroxidase. This enzyme is vital because it gets rid of hydrogen peroxide, which is toxic to living environments.
Within the experiment, pure catechol was mixed with different concentrations of catechol oxidase and the rate at which each solution produced benzoquinone was measured. The amount of benzoquinone made throughout the trials was measured by using a colorimeter to measure the level of “brownness” of the liquid. The colorimeter worked by shining a light through the liquid and then measuring that light on the other side to see how much of it was absorbed. In this experiment, absorbance of blue light was measured because blue light is absorbed by the color brown. The amount of blue light absorbance was measured every 15 seconds for five minutes. Because enzymes speed up reactions, more enzymes would cause the reaction to be even faster.1
This experiment looked at how substrate concentration can affect enzyme activity. In this case the substrate was hydrogen peroxide and the enzyme was catalase. Pieces of meat providing the catalase were added to increasing concentrations of hydrogen peroxide in order to measure the effect of hydrogen peroxide concentrations on the enzyme’s activity. The variable measured was oxygen produced, as water would be too difficult to measure with basic equipment.
The role of an enzyme is to catalyse reactions within a cell. The enzyme present in a potato (Solanum Tuberosum) is catechol oxidase. In this experiment, the enzyme activity was tested under different temperature and pH conditions. The objective of this experiment was to determine the ideal conditions under which catechol oxidase catalyses reactions. In order to do this, catechol was catalyzed by catechol oxidase into benzoquinone at diverse temperatures and pH values. The enzyme was exposed to its new environment for 5 minutes before the absorbance of the catechol oxidase was measured at 420 nm using a spectrophotometer. The use of a spectrophotometer was crucial for the collection of data in this experiment. When exposed to hot and cold temperatures, some enzymes were found to denature causing the activity to decrease. Similarly, when the pH was too high or low, then the catechol oxidase enzyme experienced a significant decrease in activity. It can be concluded after completing this experiment that the optimal pH for catechol oxidase is 7 and that the prime temperature is 20º C. Due to the fact that the catechol oxidase was only tested under several different temperatures and pH values, it is always possible to get a more precise result by decreasing the increments between the test values. However, our experiment was able to produce accurate results as to the
Hydrogen peroxide is a toxic byproduct of cellular functions. To maintain hydrogen peroxide levels the catalase enzyme deconstructs hydrogen peroxide and reconstructs the reactants into oxygen gas and water. The catalase enzyme is found inside cells of most plants and animals. Regulating the levels of hydrogen peroxide is crucial in homeostasis and analyzing it’s optimal conditions for performance is just as important. To understand the optimal environment for this enzyme, they are put into different environments based off protein activity (enzymes are proteins). Catalase samples will be put into different hydrogen peroxide environments based off pH and temperature. The more active the enzyme, the more oxygen and water it will produce. Enzyme activity can be seen through the release of oxygen in the hydrogen peroxide. Since oxygen cannot be accurately measured, the data will consist of the longevity of the reaction in different environments. If the pH is higher than 7, then the reaction rate will increase due to the ample amount of hydrogen ions in the hydrogen peroxide. However the pH level cannot be higher than 10 or else there will be too many hydrogen atoms in the peroxide for the enzyme to be able to deconstruct them. If the temperature is increased, then the reaction rate will increase due to the ample amount of energy and movement in the hydrogen peroxide and enzyme.
The aim of my investigation is to see how pH affects the activity of potato tissue catalase, during the decomposition of hydrogen peroxide to produce water and oxygen.
Enzymes catalyze biological systems by speeding up the chemical reactions included. Enzymes developed from the peroxidase that is obtained from the different roots reacts with the hydrogen peroxide, which releases H2 and water. The extra hydrogen is indicated by the color change of the solution that is used to measure the rate of enzyme activity. When the rate of enzyme activity was high, the activity always occurred in the roots in the beginning stages of their development. However, when the rate of enzyme activity was low during the roots’ development, sucrose was present. Sucrose was not present in roots when the tissues consisted of high activities of acid invertase.