The picture on the next page will carefully show how the active site works. I got this picture from Microsoft Encarta 2001 World Encyclopedia
This experiment is also about determining the Vmax and Km for the reaction. Vmax is also known as the maximum velocity of the reaction. This can be determined by plotting a graph for rate of reaction with the enzyme. To determine the Vmax all I have to do is look at the slope of the line. Where the slope of the line is the steepest there I will know is the Vmax. There is also a mathematical method to determine the rate of a reaction, this is given by the following formula:
Rate of reaction =
For any reaction we are able to calculate the instantaneous rate or average rate of reaction. The instantaneous rate is given by the equation above. The average reaction can be given by using the following equation:
Average rate of reaction =
Apparatus Used:
Stop Watch
Suction Tube
Enzyme
Pipette
Cuvette
Colorimeter
Water
Hydrogen Peroxide
Guiacol
Method Used:
- Set up a Vernier Lab Pro with TI 83 calculator.
- Set Up an colorimeter
- Design different configurations of substance with the total volume making up 2.1 ml
- Calibrate the colorimeter by placing a blank cuvette in and taking readings.
- Set the Colorimeter to a blue wavelength as it is the most appropriate for this experiment.
- Make the solution with the desired configuration but leaving out one reactant thus either the Guiacol the enzyme or the hydrogen peroxide.
- Add the reactant left out when you are ready to insert the cuvette into the colorimeter right after you have inserted the reactant.
- Record how much time went by between inserting the reactant and the colorimeter giving it’s first reading.
- Record data for approximately 30 seconds with intervals of 5 sec each. Meaning you will have 6 results.
For the experiment with HCL follow the same steps and just add HCL adjust the volume of water added to compensate for the adding of HCL.
Results:
The following table will show our different configurations that we used of the substances.
The next tables will illustrate our results.
Table 2: Experiment 1
Experiment 2
Experiment 3
Experiment 4
Experiment 5
Experiment 6
Experiment: with following configurations..
- mL of 0.1 M HCl
0.1 mL H2O2
- mL guaicol
- mL Enzyme
1.2 mL water
The following section will include graphs plotted according to the data above.
Experiment 1
Experiment 2:
Experiment 3:
Experiment 4:
Experiment 5:
Experiment 6:
Experiment with HCL:
Conclusion:
When I look at the different graphs I can notice a general trend which is taking place between the graphs. This trend is that the slope of the curve is decreasing gradually. However in graph of experiment 3 I can see that it does decrease gradually. This lets me to conclude that there might have been certain factors, which could have influenced the rate of the reaction. Such factors could include a temperature change within the solution. A sudden decrease in the temp of solution will cause rapid quick changes.
When I look at the results we obtained from the experiment with HCL then I notice that rate of change is not smooth at all. This let me to conclude that the acid might have influenced the enzyme. The only two possible influences there can be is that there could be competitive and non-competitive inhibitors present. This will affect the performance of the enzyme dearly and will cause it to catalyze the reaction less.
Evaluation:
I feel that the process which we undergone in this lab is excellent. We were really prepared for what was coming because we practiced how to use the colorimeter and how to use the suction tubes. This made the experiment a huge success. I feel that my contribution to the experiment has also led to the success of our group. I made in my goal to keep the team motivated and to double-check all the configurations of reactant so that we could eliminate as much error as possible.
For further study I would definitely recommend that more acids should be used and that bases could also be used to see what there affect might be.
I would also recommend to experiment with the differences in a reaction with a competitive inhibitor and in the other a non competitive inhibitor