The Effects of Varying Ph on Enzyme Activity

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The Effects of Varying pH on Enzyme Activity
A lab was conducted to test different pH balances on an enzyme.


Enzymes are protein catalysts that speed up a chemical reaction without being consumed in the process. Enzymes are three-dimensional structures that consist of one or more polypeptide chains. The polypeptide chains form an active site (where a substrate will fit into). Enzyme molecules are folded into a very specific shape held together by the different forces of attraction, including electrical charges. The pH of the surrounding environment can affect the charges on the enzyme molecule, causing it's shape to be changed. Even a slight change in an enzyme molecule's shape can prevent it from working properly. This change of shape is called denaturation. The lab will look at the affects of pH on enzyme activity. High pH or low pH can make the enzyme loose all activity. Most enzymes work best in a neutral pH.

Materials and Method:

Safety:Sodium hydroxide (NaOH) is a strong base and can be harmful if it get's on to the skin or in the eyes. Hydrochloric acid is a very corrosive acid and should also not get on to the skin or in the eyes. Goggles were mandatory for this experiment.

For this experiment chicken liver was used as the enzyme source. An enzyme solution was made by crushing a small piece of chicken liver and then adding 10 mL of distilled water. The pH of the enzyme solution was taken using pH paper. In 3 separate test tubes 10 drops of the enzyme solution was deposited. Test tube #1only had the enzyme solution and hydrogen peroxide. In test tube #2 one drop of 1.0M sodium hydroxide(NaOH) was added. In test tube #3 one drop of 1.0M hydrochloric acid(HCl) was added. Then 4 mL of hydrogen peroxide was added to each test tube. The pH was tested for each test tube. Both time of reaction and pH are recorded.


Table 1: Affects of pH on enzyme activity
Test tube |Amount of Acid or Base |Time of...
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