Observations
Effect of different concentrations of the substrate on activities of the enzyme catalase
In this experiment, we tested the decomposition actions of a catalase on hydrogen peroxide using different concentrations of the substrate. We used paper discs soaked in potato extracts and placed each of them into a test tube containing different concentrations of the substrate. No reaction was recorded as the soaked paper disc was placed into the test tube with 0% substrate as catalase only acts on Hydrogen peroxide, and not any other solution, which in this case, is water. When the soaked disc was placed into the 0.1% substrate, air bubbles which were oxygen produced during the reaction, slowly formed on the surface of the paper disk. The oxygen which were trapped in the fibres of the paper disc caused the paper disk to slowly rise to the surface. More bubbles were formed on the paper discs as it was placed into the test tube with 0.5% substrate concentration. The rate of reaction increased much faster with the 1% concentration of the substrate as more bubbles were formed on the surface of the paper disc wwhich then rose to the surface much faster than the previous ones. The highest reaction was recorded when the soaked paper disc was placed into 3% substrate as the oxygen produced and trapped in the paper fibre quickly brought the paper disc to the surface.The results showed that the activities increased as the concentration of the substrate increased.
Chart: concentration of hydrogen peroxide versus time
| Conc. H2O2 | Avg. time (s) | Rate of reaction (mm/s) |
|---|---|---|
| 0% | No reaction | 0 |
| 0.1% | 129.52 | 0.31 |
| 0.5% | 29.51 | 1.36 |
| 1% | 20.02 | 2.00 |
| 3% | 10.87 | 3.68 |
| 6% | 16.91 | 2.04 |
Effect of different concentrations of enzyme on activities of the enzyme catalase
In this experiment, we tested on the decomposition action of catalases with different concentrations of the enzyme. Catalases drastically increased the rate of hydrogent peroxide decomposition even if it existed in very small quantity. As soon as the paper disc soaked with the enzyme was placed into the test tube of hydrogen peroxide, bubbles which presented oxygen, formed on the surface of the paper circle and that oxygen trapped in the paper fibres brought the paper circle to the surface. The rate of decomposition was slowest in the 4.8% concentration as the paper disc soaked with this enzyme solution rose to the surface of the substrate in about four seconds. The reactions happened faster with the 9.1% enzyme concentration and it took about 2 seconds for the paper disc to rise to the surface. The reactions continued to accelerate with the 16.7% enzyme concentration which took less than 2 seconds to float to the top. The highest rate of reaction occurred in the l00% enzyme concentration as a thick layer of air bubbles instantly formed on the surface of the paper disc and it took less than one second for the paper disc to surface. We noticed that enzyme activities increases as concentration of the enzyme increases and that the increase was proportional to the increase in enzyme concentration.
Chart: enzyme concentration versus time
| Enzyme conc. | Time (s) | Rate of reaction (mm/s) |
|---|---|---|
| 100 | 0.94 | 7.62 |
| 16.7 | 1.52 | 2.99 |
| 9.1 | 2.10 | 2.56 |
| 4.8 | 3.84 | 2.11 |
Effect of different pH on activities of the enzyme catalase
In this experiment, we examine the effect of pH on the rate of activity of Catalases. We tested the reactions with vinegar solutions (pH 2 and 4 respectively) and no activity was noted. The test with detergent (pH l1) also showed no reaction. Maximum activities were recorded within the range of pH 7 to 9 as few enzymes can withstand extremes of pH. As shown in the results, Catalase works best in neutral pH of 7 and shows no reaction in low pH values of 2 to 4 and for pH values above l0, as the enzyme is denatured.
Chart: pH of system versus time
| pH. | Time (s) | Rate of reaction (mm/s) |
|---|---|---|
| 2 | No reaction | 0 |
| 4 | No reaction | 0 |
| 5 | 51.31 | 0.78 |
| 7 | 40.34 | 0.99 |
| 9 | 75 | 0.53 |
| 10 | No reaction | 0 |
| 12 | No reaction | 0 |
Effect of different temperatures on activities of the enzyme catalase
In this experiment, we tested on the effect of temperature on the actions of catalases on Hydrogen peroxide and water baths were prepared for warming the enzymes and the test tubes in temperatures of 0° C, 5 ºC, 25 ºC, 30º C, 35 ºC, 40° C,50 ºC, 60ºC, 70° C, 80º C, 90°C and l00ºC with the highest rate of reaction at the temperature 25 ºC. No activity was shown in the temperature group 50 ºC – 100ºC.
Chart: Temperature of system versus time
| Temperature (ºC) | Time (s) | Rate of reaction (mm/s) |
|---|---|---|
| 0 | No reaction | 0 |
| 5 | 12.81 | 3.12 |
| 25 | 8.25 | 4.85 |
| 30 | 18.77 | 2.13 |
| 35 | 25.63 | 1.56 |
| 40 | 35.66 | 1.12 |
| 50 | No reaction | 0 |
| 60 | No reaction | 0 |
| 70 | No reaction | 0 |
| 80 | No reaction | 0 |
| 90 | No reaction | 0 |
| 100 | No reaction | 0 |