Amylase is an enzyme that acts as a catalyst within living cells. As an enzyme, one of its potent properties is its ability to increase the rate of reaction without being consumed itself. It is able to undergo processes of converting reactants into products and is able to facilitate this reaction continuously over time. As a digestive enzyme, amylase catalyses the hydrolysis of dietary starch into disaccharide and trisaccharide molecules allowing them to be absorbed by the blood and thus be used as a source of energy by the body. This enzyme is secreted by the pancreas and the major salivary glands located in the mouth- the parotid (near upper teeth), submandibular (located under the tongue) and sublingual glands (located in the floor of the mouth). As one starts to chew food, this mechanical action activates the secretion of amylase, immediately starting the process of carbohydrate breakdown. However, amylase requires specific conditions in order to function at its optimum level and is highly sensitive to environmental changes of temperature and pH levels. The purpose of this exploration is to investigate at what pH amylase is most effective at carbohydrate breakdown and to understand potential consequences the human body may experience as these favorable conditions are altered. This exploration has real world significance because starch is a vital constituent of the human diet as it is a major storage product of economically important crops such as wheat, potatoes, maize, rice etc.1Due to its presence in many staple foods and its ability to provide the body with immediate energy, It is important for humans to understand under what conditions their bodies can effectively utilize its functional properties.
2.1 background Information
Belonging to the amylolytic enzyme group, alpha-amylase present in the oral cavity is a protein enzyme that has the ability to hydrolyse alpha bonds of polysaccharides such as starch. Starch, an organic chemical produced by all green plants is composed of long chains of individual glucose monosaccharides and exists in two forms: as amylose and amylopectin. Amylose contains over 250 glucose units in just one molecule and its structure is a straight chain with no branching points.2 On the contrary, amylopectin contains over 1000 glucose units in just one molecule and its structure consists of many branching points from the main chain of glucoses.3 In both forms of starch, the series of glucose links are held together by glycosidic bonds, a form of covalent bond. When referring to amylase as a catalyst for the starch hydrolysis reaction, one must understand that it is only efficient at that specific reaction, to the point that it cannot take part in any other reactions. For example, although amylase can break down glucose bonds in starch chains, it cannot break down glucose bonds in cellulose chains, despite the fact that in both cases the chains are composed of many glucose units.4 Amylase is only specialized to identify and hydrolyse the glucose-to-glucose linkages found in starch, not any other glucose-to-glucose bonds.5 In terms of the process of hydrolysis, it is the breakdown of a molecule due to its reaction with water. In order for this process to occur effectively, the starch molecules must have effective collisions with amylase by having a shape that is complementary to the active site on amylase. This will result in the formation of an enzyme-substrate complex. Amylase lowers the activation energy of the reaction and so increases the rate of reaction. Changes in pH cause amylase to undergo a conformational change and thus lose its ability to bind substrate (starch) molecules. As a protein enzyme, amylase is composed of many hydrogen and ionic bonds which hold the molecule together so any pH change which breaks such interactions results in a change of attraction between the side chains of amino acids that make up the protein. This is the factor that causes the misfold or the change in shape. A typical pH curve at which amylase activity is at its optimum level is shown below. Through this exploration, I aim to find the exact pH at which amylase is most effective and also the range of pH values over which the enzyme is still active, even though it may have a slow rate of reaction.