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Title: Examining Some Properties of the Enzyme -amylase In this experiment a deeper meaning in the catalysts of reactions is studied. Catalysts accelerate chemical reactions without permanently changing the reaction. Enzymes, catalysts in biochemical reactions, are globular proteins which lower the activation energy needed to begin a reaction and therefore increase the rate at which efficient reactions can occur. Proteins (henceforth enzymes) are complex molecules made of amino acids in polypeptide chains held together by peptide bonds.
The structure of proteins is broken up into primary, secondary, tertiary, and quaternary structures which create complex structures which can be separated and identified by paper chromatography, or more importantly spectrophotometry can determine the concentration of proteins in an aqueous solution. Spectrophotometry is a quantitative analysis used to determine the amount or concentration of a substance (-amylase) from its ability to absorb radiant energy. The substance is usually colored and radiant energy used is visible light, which passes through the solution and is either absorbed or transmitted. The spectrophotometer measures is an instrument (used here in our experiment) which electronically measures the amount of transmitted and absorbed light, and can determine concentration and wavelength. The concentration of a solution can be determined because the amount of light absorbed by a solution is dependent on its concentration. A relationship between absorbance and concentration can be made by the Beer-Lambert Law which states absorbance is equal to a molar extinction coefficient times the concentration of the solution times the length of the light path through the solution.
The absorbance's over a range of known concentrations of the substance are measured at lambda max, the wavelength which shows maximal absorbency. For the purpose of our lab, wavelength will not need to be found, but merely the spectrophotometer must be set to 560 nm. The reacting molecule in an enzymatic reaction is called a substrate. The purpose of this lab is to determine the maximum velocity and substrate concentration for the reaction of -amylase and starch.
The substrate (starch) and the enzyme (- amylase) come together for a short time and then break down to yield the products and enzyme. Once the enzyme configuration is altered in the reaction it is useless and becomes decomposed in the normal course of cellular metabolism. The rate of the enzymatic reaction, needed for figures three and four, is set by the rate at which the enzyme-substrate complex forms and then decomposes to form the product. The amount of time it takes the enzyme to effect the substrate and the frequency at which the complex (enzyme-substrate) forms. The frequency depends greatly on the concentration of the substrate. As the reaction proceeds, and starch is turned into the product by the enzyme the chances of the enzyme encountering a starch molecule becomes less and so the reaction rate decreases.
Most starch is converted at the initial stage of the reaction and therefore the maximum reaction rate is highest at this stage in the reaction. From a resulting curve from of the enzymatic reaction, showing disappearance of substrate over time, the maximum velocity at which that particular reaction occurs and the concentration of the substrate at which Vmax/ 2 occurs can be determined. Although substrate concentration is important in determining the rate of the reaction, it is not the only factor. Certain physical environment factors of the enzyme such as temperature and pH can affect the reacting molecules and catalytic activity of the enzyme. We intend to use these factors in determining the optimal efficiency for -amylase, as an enzyme works optimally at a particular temperature and pH. We can find these optimal levels more easily by graphing the reaction rate verse temperature, and verses pH (figures three and four).
We can also check the absorbance over time for difference temperatures and pH's in order to help us procure the reaction rates (figures one and two). Heat in any system (def. ) tends to increase molecular motion, and therefore increases the chances of the enzyme encountering a substrate. Therefore, the reaction rate is clearly increasing as enzyme activity increases, and vice versa. However great high temperatures may seem, there is a limit.
At really high temperatures the shape of tertiary structure of the protein can be changed, and thus the enzyme is not nearly as effective, and the reaction rate shall slow down. The efficiency of enzymes can be graphed in a bell or spike shape. The optimal level of enzyme efficiency is important in not only simple experiments such as this, but in animal / human body upkeep and simple internal systems such as digestion. So, thermo regulation of temperature in a system or body is important in function of life. pH is the logarithm of the reciprocal of the hydrogen ion concentration of an environment. The pH of the system can affect the structure of some enzymes.
A pH of 7. 0 is neutral, anything greater is base, anything less is acid. A pH differentiating from optimum the hydrogen bonds in the tertiary structure of the protein (enzyme) are altered, and again the enzyme can not function as well as before and the velocity of the reaction is decreased. Bibliography:
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