Effect of Temperature on Rennin Enzyme Activity

Categories: Biology

Abstract

The aim of this experiment was to investigate the impact of temperature on the activity of the enzyme rennin. Enzymes are biological catalysts that speed up chemical reactions, and their activity is highly dependent on temperature. The hypothesis suggested that the rate of the enzyme's reaction would increase with rising temperature until it reached approximately 37°C, the body temperature, after which it would slow down and cease to function effectively due to denaturation.

Introduction

Enzymes are specialized proteins produced within living cells that act as catalysts, facilitating and speeding up various chemical reactions.

They consist of long chains of amino acids containing carbon, hydrogen, oxygen, and nitrogen. Enzymes are highly specific to their substrates, which are the molecules they act upon. Each enzyme has an active site that is uniquely shaped to accommodate a specific substrate. When the substrate and enzyme bind at the active site, they form an enzyme-substrate complex, leading to the breakdown of the substrate into products without any change in the enzyme itself.

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For most biological organisms, survival is possible only within specific temperature ranges. Chemical reactions require molecules to collide with sufficient energy and the correct orientation to overcome the activation energy barrier. Enzymes play a crucial role in biological systems by lowering the activation energy, enabling reactions to occur at lower temperatures and accelerating their rates. Each enzyme has an optimal temperature range at which it functions most efficiently, with the average optimal temperature being around 37.5°C for many enzymes in the human body.

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When the temperature exceeds this optimal range, enzymes begin to denature as intermolecular and intramolecular bonds break due to increased kinetic energy. Once denatured, enzymes lose their functionality irreversibly.

Rennin is a digestive enzyme found in the stomachs of mammals, such as cows. Its primary function in the cow's fourth stomach is to thicken milk and prolong its retention in the stomach. Rennin catalyzes the conversion of the milk protein caseinogen into casein, causing the milk to curdle and become lumpy. In this experiment, rennin was used as the enzyme of interest to observe how different temperatures affect enzyme activity.

Materials

  • 6 Test tubes
  • Full cream milk
  • Stopwatch
  • Junket powder
  • Saucepan
  • Water
  • Thermometer
  • 100ml Measuring cup
  • 2 x 10ml Measuring cups
  • Teaspoon
  • Ice cubes

Method

  1. Set up the apparatus by placing water in a saucepan on a stove top.
  2. Pour 5 ml of milk into six test tubes and store them in the refrigerator.
  3. Prepare the enzyme mixture by measuring 25ml of water with the 100ml measuring cup and mixing in 1 level teaspoon of junket powder. Set the mixture aside.
  4. Heat the water in the saucepan to 30°C using a thermometer, then turn off the stove.
  5. Take two test tubes with milk and place them in the saucepan, ensuring that no water enters the test tubes. Wait for the milk to reach 30°C, as indicated by the thermometer.
  6. Stir the milk and pour 2.5ml of the enzyme mixture into one of the test tubes, taking care not to allow any water from the saucepan to enter the test tube. The test tube without the enzyme mixture will serve as the control.
  7. Start the stopwatch and record the time it takes for the milk to clot.
  8. Monitor the temperature throughout the experiment and adjust the heat if the temperature drops.
  9. Record the clotting time in a table.
  10. Repeat steps 4-7 two more times, changing the temperature to 40°C and 50°C.
  11. Fill the saucepan with water and ice cubes until it reaches 10°C, as measured by a thermometer.
  12. Once the water in the saucepan reaches 10°C, take two test tubes with milk and place them in the saucepan, ensuring that the milk reaches 10°C.
  13. Stir the milk and pour 2.5ml of the enzyme mixture into one of the test tubes without allowing any water from the saucepan to enter.
  14. Start the stopwatch and record the time it takes for the milk to clot.
  15. Record the clotting time in a table.
  16. Repeat steps 11-14, changing the temperature to 20°C.
  17. Repeat the entire experiment one more time (or more if time allows).

Note: Clotting is determined by tilting the test tube, and if the milk retains its shape, it is considered clotted.

Results

The results of the experiment demonstrated the effect of temperature on rennin enzyme activity. The data showed that the rate of milk clotting increased with rising temperature, reaching its peak around 40°C, after which the rate began to slow down. This pattern supported the hypothesis that enzyme activity would accelerate with increasing temperature until reaching the optimal temperature range and then decline due to denaturation.

Discussion

Temperature controls the speed the enzymes work at. Higher temperatures increase the kinetic energy which increases the chance of collision therefore speeding up the rate of the milk solidifying. Once the temperature reached about 40oC the speed of the reaction began to slow down. This because once the heat rises above the enzymes temperature range the shape of the enzyme will change consequently making it ineffective because its shape will not fit with the substrate.

The results from the experiment support the hypothesis that the rate for the milk to solidify would speed up as the temperature got closer to 37oC and would slow down and stop once it passed that temperature.

In conducting the experiment I came across a few difficulties. One was keeping the temperature consistent. When heating the water it would still continue to rise about one or two degrees once I had turned the stove off then after a few minutes if would begin to drop so I would have to turn the stove back on again. It was also difficult keeping the cooler temperatures consistent as well. I had to keep restocking with ice cubes but if I put too many in it would drop below the desired temperature. Another difficulty was measuring the exact amount of milk and enzyme mixture. Parallax error could have made the measurements inaccurate because the view at which I looked upon the measuring cups could have varied each time.

The role of the test tube without the enzyme mixture was to insure that when the milk reached certain temperatures it did not clot without the enzyme. This was to rule out the possibility of temperature making the milk clot.

An area to improve the reliability of the experiment would be to repeat the experiment more times. This would make the averaged result more accurate and by repeating the experiment any results that are very different to the rest of the results could be easily noticed and disregarded as they do not follow the same trends. The accuracy could be improved by having more accurate measuring equipment. For measuring the amount of liquids a pipette could be used to have more precise measurements of the enzyme mixture and milk. The thermometer has a margin of error of ±0.5 degrees therefore more exact equipment would make the results more reliable. The results from the experiment are valid as they are similar to the excepted value that the rennin enzymes optimal temperature is 37oC and follows the trend that the rate of reaction will speed up until it reaches that temperature then start to slow down once it has passed it. To further show enzymes being denatured higher temperatures could be used in the experiment.

The optimal temperature at which an enzyme works within the body is 37oC. This is the temperature the enzymes work most efficiently at. If the temperature rises above 37oC the activity level decrease because the enzyme will become less efficient as the heat will begin to start changing the shape of the enzyme and as the temperature increases the enzyme will by destroyed by the heat. As the temperature rises the intermolecular and intramolecular bonds begin to break causing the active site to change shape and therefore the active site is no longer the correct shape for the caseinogen substrate. This is a denatured substrate and once denatured it cannot be reversed.

The active site on an enzyme is where the enzyme combines with a substrate. The characteristics of the amino acids at the active site play a large role in whether the substrate molecule with fit or by attracted to the enzyme. Amino acids at the active site break the bonds of the substrate molecule to form the products. Other amino acids at the active site work by attracting specific areas of the substrate molecule so that it is held in the correct position so the reaction at the active site can carry on.

Enzyme specificity refers to enzymes limitations to only react with on type of substrate. This can be demonstrated through the lock and key model which illustrates the substrate acting upon the enzyme. Once they combine they form an enzyme-substrate complex. This is where the amino acids of the enzyme break bonds in the substrate to form products. The enzyme is then freed and is not changed during the reaction.

The controls of this experiment were the amount and concentration of the enzyme mixture and the amount of milk used. Keeping these the same throughout the experiment was important because my research showed that the concentration of the enzyme would affect the results of my experiment. In order to eliminate the possibility of my results being affected by something other than temperature I had to keep the concentration the same.

Pepsin is an enzyme in the human body which is found in the stomach. Its role in the body is to break down proteins from meat, dairy products, seeds and eggs, into shorter chains of amino acids. These are then absorbed into the blood stream or broken down further. Within the lining of the stomach, glands produce and store an inactive protein called pepsinogen. When it is combined with hydrochloric acid it converts to an active enzyme, pepsin. The pepsin is most effective in pH levels of 1.5-2.5 though can still work up to about pH 6 and is ineffective when gastric acids have been neutralised. The temperature at which it is efficient ranges between 30 oC end 40 oC but can work at temperature between 15 oC and 48 oC.

Conclusion

This experiment investigated the impact of temperature on rennin enzyme activity, with the results demonstrating the enzyme's sensitivity to temperature changes. Rennin displayed its highest level of activity at approximately 40°C, which aligns with its expected optimal temperature range. Temperatures below and above this range led to reduced enzyme activity due to lower kinetic energy and denaturation, respectively. Enzymes play a crucial role in biological processes, and understanding their temperature-dependent activity is essential for various applications in science and industry.

Updated: Dec 29, 2023
Cite this page

Effect of Temperature on Rennin Enzyme Activity. (2016, Jul 25). Retrieved from https://studymoose.com/document/biology-experiment

Effect of Temperature on Rennin Enzyme Activity essay
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