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To determine the optimum pH for two different proteolytic enzymes.

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To determine the optimum pH for two different proteolytic enzymes Introduction In this experiment, the substrate is the gelatin coating the strip of photographic film. Apparatus and Materials Test tube x 15 Thermometer x 1 Fifteen strips of photographic film Water bath Buffer solutions at various pH values(1, 3, 4, 7, 9) Hypothesis Enzymes are protein molecules that act as catalysts in biochemical reactions. They are denatured. Enzyme is reusable, they are not consumed in a reaction. The functioning of the enzyme is determined by the shape of the protein. The arrangement of molecules on the enzyme produces an area known as the active site within which the specific substrate(s) will "fit". It recognizes, confines and orients the substrate in a particular direction. The use of enzymes can lower the activation energy of a reaction. Changes in pH will also denature the enzyme by changing the shape of the enzyme. Enzymes are also adapted to operate at a specific pH or pH range. Rate of enzymatic reaction = Each enzyme has a range of pH at which it is active as well as an optimum pH at which it is most active. The optimum pH of each enzyme is represented by the crest of the graph of enzymatic reaction against pH of buffer solution. ...read more.


3 ml each of buffer solution of pH 1.0 was pipetted in to three labeled test tubes. This step was repeated for other buffer solutions. Thus, a total of fifteen test tubes (A1, A2, A3 / B1, B2, B3 / C1, C2, C3 / D1, D2, D3 / E1, E2 ,E3) of buffer solutions were prepared. 3. The tubes were divided into three groups (Group1: A1, B1, C1, D1, E1 / Group2: A2, B2, C2, D2, E2 / Group3: A3, B3, C3, D3, E3) and a strip of photographic film was added to each tube. All the tubes were left in the prepared water bath for 10 minutes to reach working temperature. 4. 3 ml each of pepsin was pipetted to the first group (Group1) of test tubes, 3 ml each of trypsin was pipetted to the second group (Group2) and 3 ml each of distilled water was pipetted to the remaining group(Group3). 5. The time taken for the complete disappearance of gelatin on each film was recorded. The tubes were swirled from time to time. 6. The results were tabulated. If the gelatin coats were still remained in the file for over one and a half hours, the time might be considered to be infinity. 7. The experiment was repeated with other buffer solutions of different pH values. ...read more.


Enzymes can act rapidly, as in the case of carbonic anhydrase (enzymes typically end in the -ase suffix), which causes the chemicals to react 107 times faster than without the enzyme present. Carbonic anhydrase speeds up the transfer of carbon dioxide from cells to the blood. There are over 2000 known enzymes, each of which is involved with one specific chemical reaction. Enzymes are substrate specific. The enzyme peptidase (which breaks peptide bonds in proteins) will not work on starch (which is broken down by human-produced amylase in the mouth). Enzymatic pathways form as a result of the common occurrence of a series of dependent chemical reactions. In one example, the end product depends on the successful completion of five reactions, each mediated by a specific enzyme. The enzymes in a series can be located adjacent to each other (in an organelle or in the membrane of an organelle), thus speeding the reaction process. Also, intermediate products tend not to accumulate, making the process more efficient. By removing intermediates (and by inference end products) from the reactive pathway, equilibrium (the tendency of reactions to reverse when concentrations of the products build up to a certain level) effects are minimized, since equilibrium is not attained, and so the reactions will proceed in the "preferred" direction. ?? ?? ?? ?? Biology Laboratory Report 3 6S LUK KA CHEONG (28) 7/11/2003 - 1 - ...read more.

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Here's what a teacher thought of this essay

4 star(s)

A very good experimental plan. The author has a clear understanding of enzyme theory, but more complete and detailed explanations in places would reinforce this.

Marked by teacher Adam Roberts 05/09/2013

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