Enzyme Activity

Part II:

    The research question for part II of this enzyme activity lab was how differing levels of pH would affect the rate of an enzymatic reaction: How will pH have an effect on Enzymatic Activity? My claim was that the enzyme would have a set range of pH levels that would be optimal for enzymatic activity to occur. pH solutions of 3, 5, 7, 8, and 10 were tested. Each substrate solution contained 7mL of the pH solution, .3mL hydrogen peroxide, and .2mL guiacol. Each enzyme solution contained 6mL distilled water, and 1.5 mL peroxidase. The control group from part I contained water in place of the different pH solutions.These solutions were mixed together and the colors of each pH solution were observed and categorized on a scale from 1-10 in order of increasing darkness over a 4 minute period every 30 seconds. The following data table reveals the yields of this experiment:

Color Change of Solutions Over Time

Mins	0	.5	1	1.5	2	2.5	3	3.5	4
pH 7	1	2	4	5	6	7	7	8	9
pH 3	1	1	1	1	1	1	1	1	2
pH 5	2	4	6	8	9	10	10	10	10
pH 8	1	2	3	4	6	7	8	8	8
pH 10	1	1	1	1	1	1	1	1	1

    This data table supports the hypothesis that there is a specific range of pH is better for enzymatic activity. It is clearly shown in the data table that extremes in ph (pH 10 and pH 3) almost completely shut down the activity of the enzyme and result in denaturing it. These solutions did not change color showing that the enzyme’s activity was negatively affected by the change in its environment. In contrast the pH solutions that were in the range of the enzyme excelled and changed color at fairly similar fast rates. (pH solutions 5, 7, and 8). These results also support the hypothesis as it shows a range of pH that would be optimal for the enzyme’s activity. Outside of this range it can be seen that the enzyme will cease to function because of the denaturation that occurs.

Part III:

    In this part of the experiment the effect of heat on enzymatic reactions was tested. How does heat affect the rate at which enzymes are able to function? My claim for this section of the experiment was that water that was too hot would denature the enzyme and cause it to stop functioning. For this experiment the same enzyme solution was made up of 6mL heated distilled water, and 1.5 mL peroxidase.  Each substrate solution contained 7mL of heated distilled water, .3mL hydrogen peroxide, and .2mL guiacol. The heats of the separate test tubes were 20, 40, 60, and 80 degrees celsius. The solutions were mixed together and their colors were categorized from 1-10 every minute for four minutes. The following was the results:

Color Change of Solutions Over Time

Mins	0	1	2	3	4
20 C	1	2	4	6	7
40 C	1	3	5	7	8
60 C	1	5	6	8.5	8.5
80 C	1	3	5	7	8

These results do not support the proposed hypothesis. The rate at which the enzyme was able to work increased as the temperature increased as seen on the graph above. This could be explained as the increased water temperature would have sped up the molecules in the solution, allowing the enzyme to work at a faster rate, while the temperature was not yet hot enough to denature the enzymes. Signs that the enzyme may have began to denature are shown by the fact that the rate of reaction of 60 degrees celsius was slightly faster than that of the reaction at 80 degrees celsius. If the experiment was continued to higher temperatures results may have differed.