Amylase is an enzyme that is present in both saliva and pancreatic juices. Its function is to speed and aide the hydrolysis of amylose and another chemical, amylopectin into a mixture of products including dextrin and maltose.
Because of my knowledge on enzymes and what they do and how they do it, I can suggest that the higher the concentration, the quicker the speed of the break down of starch will take place: If there are more enzymes (amylase molecules) than substrate (starch) molecules and then more substrate is added the rate of reaction will increase because there will now be more active sites available for the starch to be broken up in but if there is enough substrate to occupy all the active sites on the enzymes then the rate of reaction will not change.
Plan
To test the presence of starch I will use iodine. Iodine turns a blue/black colour when exposed to starch, therefore after each concentration I will test the presence of starch by putting a small amount of iodine in the end solution.
However, enzymes are very sensitive substances and any change in a number of variants can make the test unfair or can impede the performance of the enzyme:
Temperature: It is vital that the temperature remains the same in all the experiments as this will have a great impact on the results if not. This is because if the temperature increase the amylase and starch molecules will begin to move faster due to the kinetic theory. Because of this amylase molecules will “bump into” and come into contact with the starch molecules more often causing the starch to be taken up by the active sites of the amylase, broken down quicker and the product dextrin released. This will lead to an increase in rate of reaction.
If however the temperature rises too much (above about 60 degrees) the ionic and hydrogen bonds holding the amylase together will break causing the active sites on the enzyme to become denatured, this will completely stop the enzymes working and therefore the breakdown of starch will stop thus causing the rate of reaction to stop.
pH Level: This is again like temperature in the way that every enzyme has an optimum temperature the same as they have an optimum pH. Optimum means the “best” or in this case the best conditions for the enzyme to break down the starch the quickest. If the pH level is at an extreme (in this case strong alkali) the enzyme will be denatured and work at a slower rate or even stop. For this reason the pH will remain the same throughout the experiments so as not to change the rate of reaction. In a more complicated experiment a pH buffer may be used to be certain the pH level would remain constant.
While I must attempt to keep these factors constant, because of the conditions and equipment available to me, I can guarantee neither complete accuracy nor a completely fair test.
Therefore, to make a test that involves all the predefined factors – amylase, starch and water (for varying the concentration of the amylase) I will use set amounts of starch and vary the concentration of starch as follows – 2cm of 2% amylase and 8cm of water, 2.6cm of 2% amylase and 7.4cm of water, 3cm of 2% amylase and 7cm of water, 3.4cm of 2% amylase and 6.6cm of water and finally 4cm of 2% amylase and 6cm of water.