Enzymes ==> Enzymes are catalysts, made of protein, that help to speed up chemical reactions in the body. Biochemical reactions would occur at a pace far too slowly to sustain life if it were not for enzymes. In reactions, the enzymes themselves are used, but are not consumed by the reaction. The enzyme reduces the activation energy to jumpstart the reaction. Activation energy is the amount of energy it takes to start a chemical reaction. One or more polypeptide chains folded together form what is called the active site of the enzyme. The active site is where the substrate, the material that is acted upon by the enzyme, binds and the actual chemical reaction takes place (Campbell & Reece, 2005). Many factors affect the rate at which enzymes work. The factors shown in this experiment are pH, temperature, enzyme and substrate concentration (Helms et al, 1998). The favorable condition for most enzymes, the point that they work best, is known as optimal pH. Different enzymes, depending on where they are present in the body have different optimal pH levels. For example, enzymes that are present in the stomach work better at higher pH levels, and those present in the intestines work best at lower pH (Marieb et al, 2005). Although, most enzymes optimal pH is around neutral, 7, on the pH scale. A pH level too high or too low will cause the breakdown of the secondary and tertiary structure of the enzyme, this is known as denaturation. Denaturation is the complete disruption of the secondary or tertiary structure of the protein. When denaturation occurs the substrate can no longer bind to the active site, and no reaction can occur. Temperature affects the rate of speed at which enzymes work. A temperature too high, like a pH too high or low, will cause denaturation of the enzyme. A temperature above 40 degrees Celsius will cause denaturation. However, a temperature too low will not have the same affect, it will only slow the movement of the enzymes and substrate. A reaction will still occur, just far more slowly. The ideal temperature for most enzymes is around 25 degrees Celsius (Helms et al, 1998). Enzyme-substrate complex is formed when the substrate fits into the active site of an enzyme. This is when the actual reaction occurs (Campbell & Reece, 2005). Enzyme concentration can be increased to further increase the rate of reaction time. As long as there are plenty of substrates present, the more enzymes added would in turn increase the amount of reactions (Helms et al, 1998). Adding substrates to the reaction, like adding enzymes, will increase rate of reactions. However, once all of the enzymes become occupied with a substrate there is nothing but left over substrate, at this point v-max is reached. At v-max, the velocity of the reaction can no longer be increased because all enzymes have formed an enzyme-substrate complex (Helms et al, 1998). The enzyme in this experiment is Catecholase. It is contained in a variety of fruit and vegetables. Potato juice, specifically, is used in this experiment and it contains the enzyme Catecholase. Peeled fruits and vegetables begin to turn brown when left out in open air, this is the reaction between catechol and oxygen becoming apparent. This reaction causes catechol to be oxidized and converted to benzoquione, and oxygen is reduced and forms water (Helms et al, 1998).
Posted on: Fri, 05 Jul 2013 23:26:32 +0000
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