Determining the Optimal Temperature and Ph of Barley Amylase Essay

1419 Words Oct 5th, 2008 6 Pages
Determining the Optimal Temperature and PH of Barley Amylase

The purpose of this experiment was to find the optimal temperature and pH of barley alpha-amylase. I hypothesize that the optimal temperature would be 55 degrees Celsius and the optimal pH would be 5.5. In this experiment, the starch is used as a substrate to examine the optimum temperature and pH for the reaction of alpha amylase. It is known that the measuring of disappearance (absorbance) of the substrate starch with iodine using spectrophotometer will show the concentration of the substrate which will also reflect on the reaction rate. Once the reaction rates are figured out, the optimal temperature and pH can be determined. The result concluded that the
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After that, I made the blank by putting 5 mls of water (5 ml glass pipette) into one of these cuvettes. Then, I took the initial reading pipette 5 mls from Erlenmeyer (5 ml glass pipette) into a cuvette. Then took an absorbance reading and recorded it on the data sheet. For the temperature experiment, five different water baths were prepared at five different temperatures, 15, 30,45,55,60, and 70 degrees Celsius. In each water bath, there are 35 ml of distilled water and 35ml of starch in separate flasks. When these reactions reached the appropriate temperature, a T=0 reading was taken and I added enzyme. Then I followed the basic step.
For the pH experiment, six different starch solutions were prepared by mixing 35ml of stock starch solution with 35ml of water buffered at the pHs of 4.0, 4.5, 5.0, 5.5, 6.0 and 6.5. All these starch solutions are in the separate reaction flask. Then the basic procedure was followed.
After obtaining all the data, the reaction rate was found using the following formula: Reaction rate = (1/2 delta Absorbance)/ (Time that Ai -1/2delta Absorbance Took) (Vliet,2008)

The results for the absorbance readings over time of reactions at different temperature turned out to be a negative slope, bowed-in graphs. Couple of the points from different temperatures overlapped but generally the graph showed consistence. From initial point to around 2-5 minutes, most of

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