Investigating Enzyme Activity Essay

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Investigating Enzyme Activity


To investigate how the concentration of hydrogen peroxide effects the rate of reaction of an enzyme (catalase)


These factors could effect the rate of reaction on an enzyme:

· pH

· Concentration

· Temperature

· Surface Area

pH - Enzymes function at different pH values. In neutral conditions the amount of oxygen gas given of in an enzyme-catalysed reaction will increase.

An enzyme is affected by how much acid or alkali is present. Many enzymes work best in neutral conditions but some prefer acids and some prefer alkalis.

This graph shows that the enzyme activity reacts best at pH7 (neutral)

Concentration -
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For this variable I will use three different concentrations of hydrogen peroxide with catalase (enzyme). I will change the concentration whilst keeping the time, concentration of catalase and the volume of hydrogen peroxide constant.

I will begin all my tests at a constant temperature (room temperature) and I will repeat each test three times so I can obtain an average result.

Background Knowledge:

Lock and Key Model

A catalyst is a substance which alters the rate of reaction without being used up. Enzymes are the catalysts in biological processes. They are large proteins that speed up chemical reactions. The enzyme forms the active site from small numbers of amino acids.

The active site is the location on the enzyme where the substrate collides and the reaction takes place. If the shape of and the substrate do not match exactly then they do not bind. This makes sure that the enzyme does not work with the wrong reaction.

Enzymes are not affected by the reaction, so when the products have been released, the enzyme is ready to bind with a new substrate.

In my experiment the substrate was the hydrogen peroxide, the enzyme that we used was hydrogen peroxide and the product that was formed was oxygen and water.

This can be explained by an equation:

Enzyme + Substrate ÞProduct

In my experiment this is shown as:

Catalase + H202 ÞH202 + 02