Effect of an Increasing Substrate Concentration on Enzyme Activity Rate

1006 Words Oct 26th, 2007 5 Pages
Hui Tzu(Erin) Wang ID:0720052
Effect of an Increasing Substrate Concentration on Enzyme Activity Rate
Abstract
The reaction rate of an enzyme can be affected by many factors, and the purpose of this experiment was to find out how an increasing substrate concentration influences the rate of an enzyme activity; we obtained data from recording the absorbance of the samples which contain the same amount of potato juice (enzyme oxidase) and different amount of catechol (substrate) while holding pH and temperature constant. Our findings illustrate that the rate of enzyme activity is only influenced by substrate concentration at low level of substrate concentration, and as substrate
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The data obtained would be able to tell us how enzyme reacts to different substrate concentration during a period of time.

Methods
Prior to the experiment , the following materials were prepared: 1)the extract of Solanum tuberosum(potato juice) which contains the enzyme catechol oxidase is prepared by blending potato and distilled water at high speed filtering the resulting liquid through several layers of cheese cloth. 2) A pH 7 phosphate buffer, 3) substrate catechol. First we obtained and labeled five test tubes with numbers 1 to 4 and a B (which indicates blank), and add phosphate buffer and catechol as indicated in Table 1 below. We add 1.5 mL of Potato juice to tube B, cover the tube and invert it several times to mix the contents well. The tube B will be used as blank to adjust the spectrophotometer to absorbance every time before placing the tubes into the spectrophotometer. Then we add 1.5mL catechol into tube 1 and mixed the contents; the absorbance is immediately measured by the spectrophotometer (at 420nm) and recorded and we made a measurement of the absorbance and recorded the numbers every 2 minutes for 10 minutes. For test tubes 2 to 4 we repeated the same steps we performed on test tube 1.
Table1. Protocol for preparing test tubes.
Tube/Trial pH Phosphate buffer Catechol
Blank 6.9mL None
1 6.8mL 0.1mL
2 6.5mL 0.4mL
3 5.7mL 1.2mL
4 5.3mL 1.6mL

Results
The obtained results are showed by

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