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The effect of pH on the activity of the enzyme Amylase

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The effect of pH on the activity of the enzyme Amylase Aim :- To find the effect of pH on the activity of the enzyme amylase. An enzyme is a type of protein found in all living cells. Enzymes act as biological catalysts, breaking down substrates without needing a high temperature, allowing all the chemical reactions of metabolism to take place, regulating the speed at which they progress, lowering the activation energy and providing a means of controlling individual biochemical pathways. Enzymes owe their activity to the precise three-dimensional shape of their molecules. According to the 'lock-and-key' hypothesis, the substrates upon which an enzyme fit into a special slot in the enzyme molecule: the active site. A chemical reaction takes place at this site (hydrolysis - the addition of water in order to break a peptide bond between two amino acids) and the products are released, leaving the enzyme unchanged and ready for re-use. Enzymes are very specific in relation to the substrates with which they work, and are normally only effective for one reaction or a group of closely related reactions. They function best in particular conditions of temperature and acidity (pH), and their action can be slowed or stopped by inhibitors. Extracted from 'Oxford interactive Encyclopedia' by TLC The graph shows that when the pH is changed the reaction rate of the enzyme changes too. ...read more.


At some point all the enzymes are denatured and the reaction rate falls to zero. Prediction More specifically to our experiment we are using the enzyme Amylase, this is a enzyme found in the salivary glands, pancreas and small intestine. Amylases, act on starch, breaking down (hydrolysis) to produce glucose and other sugars, other uses are in textile manufacture, in some biological detergents, and baking, to produce lighter loaves. In our experiment we will be measuring how quickly the enzyme Amylase catalyses (breaks down) the substrate starch (a polysaccharide) into the product Maltose (a disaccharide). The Maltose produced will be a reducing sugar and to test this with our final product we will be using Benedict's solution. With this information I can predict that the optimum pH of Amylase will be of pH 7. I predict this because generally most enzymes work at a neutral pH, where there are least Hydrogen ions for less interference. If amylase was of a high deviation from a neutral pH it would be unlikely that it would be found in the small intestine, the small intestine contains fine glandular tissue (Villi) used for absorbing nutrients from broken down food and any high pH would be likely to destroy the fine tissue. ...read more.


Specifically to this experiment we must keep the Starch suspension, buffers and amylase suspension at a constant of 37�C. Doing so will keep my results constant and accurate. Substrate concentration:- Must remain constant because as the concentration increases the reaction rate does also. This is because as the substrate concentration increases the enzymes can bind with the substrate more frequently. I shall keep the volume of substrate the same each time this should produce accurate results. Variables that I will be altering:- I will be altering the pH in order to see how it affects the reaction rate of enzymes. Observations and Measurements I will use a stop watch to measure the time the enzyme takes to convert starch (a polysaccharide chain) to maltose (a disaccharide) I will test the end solution with Benedict's solution to see if maltose is definitely produced. Repeats I shall repeat the experiment 3 times this shall produce an accurate set of results. This will insure that any anomalous results obtained will be more spread out. Accuracy In order to achieve a high level of accuracy I have made the following choices:- * All glass wear used for measuring e.g. measuring cylinder will be of a grade B or higher. * Safety The usual safety precautions must be enforced for example safety goggles and clear walkways. Specific care must be taken when handling the acidic pH as they may burn the skin. ...read more.

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