Investigating the Effect of Ph on the Activity of the Enzyme Catalase.

4164 Words Dec 26th, 2010 17 Pages
Investigating the effect of pH on the activity of the enzyme catalase.


Hydrogen peroxide (H2O2) is a very pale blue liquid which appears colourless in a dilute solution, slightly more viscous than water. It is a weak acid. It has strong oxidizing properties and is therefore a powerful bleaching agent that is mostly used for bleaching paper.

Catalase is a common enzyme found in all living organisms. Its functions include the conversion of Hydrogen Peroxide, a powerful and potentially harmful oxidizing agent, to water and oxygen. One molecule of catalase can convert millions of molecules of hydrogen peroxide to water and oxygen per second.
Liver and other living tissues contain the enzyme catalase. Hydrogen peroxide,
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* PH

Each enzyme has an optimal pH that helps maintain its three-dimensional shape. Changes in pH may denature enzymes by altering the enzyme's charge. This alters the ionic bonds of the enzyme that contribute to its functional shape.
Most human enzymes work at an optimum pH of around 7.3 or 7.4. The majority of these are intra-cellular enzymes. Extra-cellular enzymes e.g. digestive enzymes work at more extreme pH’s e.g. protease at pH2 and arginase at pH 11.
Rate of reaction is affected by changes in pH. The charges on R groups maintaining a structure of the active site are essential for the formation of E-S complex. If the properties of the active site change, the substrate can no longer combine (I.e. increase in protons of hydroxyl ions will repel the substrate) pH can also effect individual amino acids as formation of zwitter ions are common.

* Enzyme Concentration

Assuming a sufficient concentration of substrate is available, increasing enzyme

concentration will increase the enzyme reaction rate.
If you increase the enzyme concentration there is more chance of a collision and an increase in the rate of reaction. When there’s more substrate than enzymes (substrate becomes the limiting factor) it will stay at one level.

* Substrate Concentration

Rate of reaction will increase proportional to the sub concentration until