Enzymes Lab Report_BIO1511_Win2023

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Wayne State University *

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1511

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Biology

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Dec 6, 2023

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pdf

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1 Dependence of Enzyme Activity on pH, Temperature, Denaturation, and Substrate Concentration Wayne State University Basic Life Mechanisms Laboratory (BIO1511)
2 Introduction Enzymes are proteins that catalyze chemical reactions by lowering the action potential of a certain reaction. This generally means reducing the amount of energy needed for that reaction and allowing for more substrate to get converted into a product. The enzyme’s makeup does not get altered in this process, allowing it to be reusable for multiple reactions. However, enzymes have specificity, only binding to a certain substrate in a “lock and key” manner. Enzymes also function at their highest rate under certain conditions, such as temperature and pH level, any deviations from these conditions can decrease enzyme function. Significant deviations from the enzyme's optimal state can cause denaturation, in which the enzyme's active site degrades and can no longer bond with the substrate, losing its function. Depending on the severity of the deviation, the enzyme can renature and regain function when taken out of the condition, however, in severe cases, the enzyme can remain denatured. Substrate concentration can also impact enzyme function, generally, the higher the substrate concentration, the higher the rate of reaction (enzyme function). However, this only occurs up to a certain limit, known as the saturation point, in which all of the enzymes are bonded to a substrate, and adding more substrates doesn’t increase the reaction rate. At this point, the enzymes reach their maximum velocity, their highest rate of reaction (Tucker & Van Thiel, 2022). This lab will focus on how these conditions, temperature ( °C) , pH, denaturation, and substrate concentration affect sucrase function. Sucrase is an enzyme that breaks down sucrose into fructose and glucose (Groves, 2022). These can be tested by running a variety of experiments all based on the Benedict’s Test. The Benedict's Test measures the amount of reducing sugars in a sample, sucrose is not a reducing sugar, however both fructose and glucose are. Because of this, the rate of reaction for sucrase can be measured, a high amount of reducing
3 sugars means that the enzyme is working at a high rate to break down sucrose. A low amount of reducing sugars means that the enzyme is working at a lower rate to break down sucrose, and a negative Benedict’s test means that the enzyme is denatured and isn’t breaking down sucrose. This lab will use Benedict's test to determine how different conditions affect sucrase function. The objective of this lab is to be able to use and interpret the Benedict's test to determine how certain factors, such as temperature, pH, denaturation, and substrate concentration affect the function of sucrase. Be able to determine at what conditions the enzyme functions at its minimum, optimum, and maximum in terms of pH and temperature. Along with determining how denaturation of the enzyme and/or the substrate affects the rate of reaction and how substrate concentration affects the enzyme's function. I predict that sucrase will function at its highest rate at a pH of 7, any pH slightly above or below (pH 6 or 8) may cause a slight decrease in the enzyme's function but any pH that is too basic or acidic may cause enzyme denaturation. I predict that sucrase will function at its highest rate at a temperature of 37 °C , any temperature slightly above or below may decrease the enzyme's function, and temperatures significantly higher or lower may cause enzyme denaturation. I predict that denaturation of the enzyme will completely stop enzyme function and that substrate concentration and enzyme function have a linear relationship, as substrate concentration increases, so does enzyme function and vice versa.
4 Methods This lab involved 4 experiments to test each condition, each experiment had its own set of materials and methods. Results from every experiment were observed and recorded based on a color scale (blue = 0, green = 1, yellow = 2, orange = 3, red = 4). There were no deviations or errors in the protocol. PH Ten test tubes were labeled 1A - 5A and 1B - 5B. 2ml of buffers of varying pH was added to each A tube based on their number (1A = pH 3, 2A = pH 5, 3A = pH 7, 4A = pH 9, 5A = pH 11). Each A test tube received 3ml of sucrase and then 3ml of sucrose and was left at room temperature for ten minutes. Then 1 ml of the contents from each A test tube was transferred to its corresponding B tubes. Each B test tube received 1ml of Benedict's reagent and was gently mixed. Then each B test tube was placed in a boiling water bath for three minutes. Color changes were observed and recorded based on the color scale. Temperature Ten test tubes were labeled 1A - 5A and 1B - 5B. 2ml of pH 5 buffer was added to each A tube and then 3ml of sucrase. 3 ml of sucrose was added to each B test tube. Then all the test tubes were placed in conditions of varying temperature based on their letter and number (1A and 1B = 0 °C , 2A and 2B = 24 °C , 3A and 3B = 37 °C , 4A and 4B = 55 °C , 5A and 5B = 100 °C ). After five minutes, all the test tubes were taken out of the conditions. Then each A test tube received 1ml of sucrose from each B test tube depending on its corresponding number. B tubes were then washed and 1ml of Benedict's solution was added and gently mixed. All test tubes were then placed in a boiling water bath for three minutes. Color changes were observed and recorded based on the color scale.
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