Essay on Enzymes
Enzymes are catalytic proteins that accelerate the rate of biological reactions while experiencing no permanent chemical modification as a result of their participation in a reaction. In order to initiate a reaction from a reactant (called a substrate) to a product, a certain amount of energy, otherwise known as the activation energy (EA), is required. An enzyme functions by lowering the required activation energy (which is usually provided by heat), thus, expediting the reaction. Enzymes may function in lowering the activation energy by bending and weakening the bonds between the reactants. Since the bonds become weakened by the enzymes, the amount of heat that is required to agitate and break the bonds is reduced. Moreover, an enzyme can provide an optimal environment for a reaction to occur by maintaining a certain pH within the enzyme-substrate complex. These are a few enzyme functions that allow reactions to occur more rapidly so that the catabolic processes within the body will not become congested. Also, since enzymes are proteins, they may be denatured by factors such as temperature and pH and alter its function. Other factors such as inhibitors may block the sites in which the substrates bind to the enzymes, therefore, decreasing the rate at which products are produced.
Polyphenoloxidase (also known as Tyrosinase) is an enzyme that is found in various plants and animals. It reacts with a colorless phenolic compound found in plant cells called catechol by oxidizing it and eventually producing a strongly pigmented product (ortho-quinone) and water. The rate at which ortho-quinone is produced is directly related to the catabolic rate of the enzyme, Tyrosinase; therefore, by use of a spectrophotometer, it is possible to experiment with and measure the rates at which the Tyrosinase enzyme catalyzes catechol.
The following experiments will test and measure the rate at which Tyrosinase oxidizes catechol into ortho-quinone and water. The rate of enzyme activity will be measured by units of optical density given by the spectrophotometer. The results should yield a higher optical density as a result of the following: a higher concentration of the Tyrosinase enzyme, a favorable environment (related to temperature or pH) that permit the enzyme to react with the substrate, the availability of active sites for substrates to bind, or any combination of the three.
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