Effect of pH on Enzyme’s Activity – Lab Report

Lab: Enzymes

Experiment: Effect of pHon Enzyme’s activity


Enzyme’s activities are influenced by a number of factors including pH and temperature among others. Changes in pH not only distort the enzyme’s shape but it could also alter the shape or the properties of the substrate. As a result, either the substrate will not be able to bind to the active site or it will be unable to undergo catalysis. How the pH may affect the activities of a given enzyme may be understood by conducting an experiment whereby an acid and a base (in food form) are added in a reaction mixture or one where the reaction between enzyme and food stuff is encouraged (Eswar et al., 2008).


Recognition of the impact that pH may have on the activities of an enzyme.

Material required

, fresh meat (acidic food), Fresh potato (alkaline food), scaled beaker, and a dropper

Hypothesis testing

Catalase enzyme reacts on its substrate as follows:

If the pH can affect the activities of the enzyme, then any transformation introduced in it might influence the level of oxygen too thus, the procedure related with creation of bubbles might get affected as well. The effect however depends on oxygen levels.


The experiment was performed in the following way: reaction of yeast was promoted on Hydrogen peroxide in the presence of food. Here I will include both types of foods, acidic and alkaline; the impact of pH on the enzyme’s action on both foods will then be scrutinized. Owing to the catalase that is found in yeast, oxygen gas was produced from the  and released in form of bubbles. By measuring the action of bubbles, the enzyme’s action on the food items at a given pH can be observed.

Below is the protocol that I followed:

  1. 1 cm cube of meat was added into 100 ml granulated cylinder
  2. Addition of 2of yeast (the source of catalyst) was also done into the same cylinder.
  • 2 ml. of Hydrogen peroxide was introduced into the boiling tube
  1. Cylinder and the boiling tube were both put in a water bath at 25ºC.
  2. Then I poured hydrogen peroxide from the boiling tube into the cylinder
  3. Further, I noted the initial volume of the mixture in the cylinder and recorded the same.
  • After 2 minutes, I noted the volume (final volume) again.
  • The difference between the initial and the final volumes, the foam volume, is recorded.
  1. I then repeated this experiment but this time using 1 cm cube of potato in the place for the meat.
  2. Finally, I drew a chart based on the experiment results.


Data collection

I will collect the data through the help of a granulated cylinder.

Tube Food Initial volume Final volume Bubbling (form level)
1 Potato 25 ml 28.4ml Bubbling present, volume= 3.50 ml
2 Meat (fish) 25 ml 26.2ml Bubbling present, volume= 1.40 ml


Activity of the Enzyme

Data analysis

Data analysis was based on the pH levels and the amount of form produced, data analysis.


From the data collected during the experiment, it was clear that there was a diminishing level of oxygen generation during the acidic condition due to reduced enzyme activity, but in a basic situation, enzymatic activity superior so augmentation in form’s creation may be observed. If a graph was to be drawn, the maximum enzyme activity would be seen at pH 8.

In line with this, my hypothesis is that pH affects enzyme’s activity, in this case adversely. This experiment reveals that there is a need to establish the optimum pH condition for an enzyme reaction to ensure the attainment of utmost benefit (Machida et al., 200).


The pH affects enzyme’s activity. This impact may be have been due to modification in the ionization of amino acid residues and the alteration of the non- covalent bonds in the enzyme.

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