enzyme experiments at home

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Video: Enzyme science experiment you can do at home

• Published June 12, 2015

In this al.com video, HudsonAlpha Education Specialist Dasi Price conducts a science experiment, using applesauce, to illustrate the role of enzymes.

Enzymes are protein catalysts that change or alter the speed of chemical reactions by lowering the energy needed to start the reaction.

“Enzymes are what we call in the biotechnology community, the workhorses,” said Price.“The research that goes on here at HudsonAlpha often uses enzymes in the laboratory.”

This experiment uses a variety of enzymes ─ made from everyday, household and grocery store items ─ to produce apple juice from applesauce. The goal is to see which enzymes produce the most apple juice. The following enzymes are readily available in the laboratories at HudsonAlpha but can also be found in your home or grocery store:

• Protease – found in meat tenderizer
• Pectinase – found at your local wine making store
• Cellulase – found at your local health food store or places like Earth Fare

After about 20 minutes, if the enzymes did their job, you should have a liquid product, or apple juice, from the filtered applesauce.

“This is really quick, really easy and it’s fun!” said Price. “You’re doing the same type of science that goes on in the laboratory here at HudsonAlpha.”

And remember, don’t eat the science!

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November 10, 2016

Exploring Enzymes

A catalyzing science project

By Science Buddies & Svenja Lohner

Ready, set, react! Learn how enzymes power everything from our digestion to protecting our cells from damage--and watch them in action in this activity!

George Retseck

Key concepts Biology Biochemistry Enzymes Physiology Chemistry

Introduction Have you ever wondered how all the food that you eat gets digested? It is not only the acid in your stomach that breaks down your food—many little molecules in your body, called enzymes, help with that too. Enzymes are special types of proteins that speed up chemical reactions, such as the digestion of food in your stomach. In fact, there are thousands of different enzymes in your body that work around-the-clock to keep you healthy and active. In this science activity you will investigate one of these enzymes, called catalase, to find out how it helps to protect your body from damage.

Background Enzymes are essential for our survival. These proteins, made by our cells, help transform chemicals in our body, functioning as a catalyst. A catalyst gets reactions started and makes them happen faster, by increasing the rate of a reaction that otherwise might not happen at all, or would take too long to sustain life. However, a catalyst does not take part in the reaction itself—so how does this work? Each chemical reaction needs a minimum amount of energy to make it happen. This energy is called the activation energy. The lower the activation energy of a reaction, the faster it takes place. If the activation energy is too high, the reaction does not occur.

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Enzymes have the ability to lower the activation energy of a chemical reaction by interacting with its reactants (the chemicals doing the reacting). Each enzyme has an active site, which is where the reaction takes place. These sites are like special pockets that are able to bind a chemical molecule. The compounds or molecules the enzyme reacts with are called their substrates. The enzyme pocket has a special shape so that only one specific substrate is able to bind to it, just like only one key fits into a specific lock. Once the molecule is bound to the enzyme, the chemical reaction takes place. Then, the reaction products are released from the pocket, and the enzyme is ready to start all over again with another substrate molecule.

Catalase is a very common enzyme that is present in almost all organisms that are exposed to oxygen. The purpose of catalase in living cells is to protect them from oxidative damage, which can occur when cells or other molecules in the body come into contact with oxidative compounds. This damage is a natural result of reactions happening inside your cells. The reactions can include by-products such as hydrogen peroxide, which can be harmful to the body, just as how a by-product of a nice bonfire can be unwanted smoke that makes you cough or stings your eyes. To prevent such damage, the catalase enzyme helps getting rid of these compounds by breaking up hydrogen peroxide (H 2 O 2 ) into harmless water and oxygen. Do you want to see the catalyze enzyme in action? In this activity you will disarm hydrogen peroxide with the help of catalase from yeast.

Safety goggles or protective glasses

Five teaspoons of dish soap

One package of dry yeast

Hydrogen peroxide, 3 percent (at least 100 mL)

Three tablespoons

One teaspoon

Five 16-ounce disposable plastic cups

Measuring cup

Permanent marker

Paper towel

Workspace that can get wet (and won't be damaged by any spilled hydrogen peroxide or food-colored water)

Food coloring (optional)

Preparation

Take one cup and dissolve the dry yeast in about one-half cup of warm tap water. The water shouldn't be too hot but close to body temperature (37 Celsius). Let the dissolved yeast rest for at least five minutes.

Use the permanent marker to label the remaining four cups from one to four.

To all the labeled cups, add one teaspoon of dish soap.

To cup one no further additions are made at this point.

Before using the hydrogen peroxide, put on your safety goggles to protect your eyes. In case you spill hydrogen peroxide, clean it up with a wet paper towel. If you get it on your skin, make sure to rinse the affected area with plenty of water.

To cup two, add one tablespoon of 3 percent hydrogen peroxide solution. Use a fresh spoon for the hydrogen peroxide.

To cup three, add two tablespoons of  the hydrogen peroxide.

To cup four, add three tablespoons of the hydrogen peroxide.

Optionally, you can add a drop of food color to each of the labeled cups. (You can choose a different color for each one for easy identification)

Take cup number one and place it in front of you on the work area. With a fresh tablespoon, add one tablespoon of the dissolved yeast solution to the cup and swirl it slightly. What happens after you add the yeast? Do you see a reaction happening?

Place cup number two in front of you and again add one tablespoon of yeast solution to the cup. Once you add the enzyme, does the catalase react with the hydrogen peroxide? Can you see the reaction products being formed?

Add one tablespoon of yeast solution to cup number three. Do you see the same reaction taking place? Is the result different or the same compared to cup number two?

Finally, add one tablespoon of yeast solution to cup number four. Do you see more or less reaction products compared to your previous results? Can you explain the difference?

Place all four cups next to each other in front of you and observe your results. Did the enzymatic reaction take place in all of the cups or was there an exception? How do the results in each cup look different? Why do you think this is the case?

Now, take cup number one and add one additional tablespoon of 3 percent hydrogen peroxide to the cup. Swirl the cup slightly to mix the solution. What happens now? Looking at all your results, what do you think is the limiting factor for the catalase reaction in your cups?

Extra: Repeat this activity, but this time do not add dish soap to all of the reactions. What is different once you remove the dish soap? Do you still see foam formation?

Extra: So far you have observed the effect of substrate (H 2 O 2 ) concentration on the catalase reaction. What happens if you keep the substrate concentration constant but change the concentration of the enzyme? Try adding different amounts of yeast solution to three tablespoons of hydrogen peroxide, starting with one teaspoon. Do you observe any differences, or does the concentration of catalase not matter in your reaction?

Extra: What happens if the environmental conditions for the enzyme are changed? Repeat the catalase reaction but this time vary conditions such as the pH by adding vinegar (an acid) or baking soda (a base), or change the reaction temperature by heating the solution in the microwave. Can you identify which conditions are optimal for the catalase reaction? Are there any conditions that eliminate the catalase activity?

Extra: Can you find other sources of catalase enzyme that you could use in this activity? Research what other organisms, plants or cells contain catalase and try using these for your reaction. Do they work as well as yeast?

Observations and results You probably saw lots of bubbles and foam in this activity. What made the foam appear? When the enzyme catalase comes into contact with its substrate, hydrogen peroxide, it starts breaking it down into water and oxygen. Oxygen is a gas and therefore wants to escape the liquid. However, the dish soap that you added to all your solutions is able to trap the gas bubbles, which results in the formation of a stable foam. As long as there is enzyme and hydrogen peroxide present in the solution, the reaction continues and foam is produced. Once one of both compounds is depleted, the product formation stops. If you do not add dish soap to the reaction, you will see bubbles generated but no stable foam formation.

If there is no hydrogen peroxide present, the catalase cannot function, which is why in cup one you shouldn't have seen any bubble or foam production. Only when hydrogen peroxide is available, the catalase reaction can take place as you probably observed in the other cups. In fact, the catalase reaction is dependent on the substrate concentration. If you have an excess of enzyme but not enough substrate, the reaction will be limited by the substrate availability. Once you add more hydrogen peroxide to the solution, the reaction rate will increase as more substrate molecules can collide with the enzyme, forming more product. The result is an increasing amount of foam produced in your cup as you increase the amount of H 2 O 2 in your reaction. You should have seen more foam being produced once you added another tablespoon of hydrogen peroxide to cup one, which should have resulted in a similar amount of foam as in cup two. However, at some point you will reach a substrate concentration at which the enzyme gets saturated and becomes the limiting factor. In this case you have to add more enzyme to speed up the reaction again.

Many other factors affect the activity of enzymes as well. Most enzymes only function under optimal environmental conditions. If the pH or temperature deviates from these conditions too much, the enzyme reaction slows down significantly or does not work at all. You might have noticed that when doing the extra steps in the procedure.

Cleanup Pour all the solutions into the sink and clean all the spoons with warm water and dish soap. Wipe your work area with a wet paper towel and wash your hands with water and soap.

More to explore Biology for Kids; Enzymes , from Ducksters Enzymes: The Little Molecules That Bake Bread , from Scientific American Catalase , from PDB-101 Enzyme-Catalyzed Reactions—What Affects Their Rates? , from Science Buddies The Liver: Helping Enzymes Help You! , from Scientific American Science Activity for All Ages!, from Science Buddies

This activity brought to you in partnership with Science Buddies

Catalase Enzyme Lab

A common enzyme lab for students to measure the impact of temperature and pH on the efficiency of catalase. Catalase is an enzyme is found in almost all living organisms that breaks down hydrogen peroxide (H 2 O 2 ) into oxygen and water. Many teachers use raw chicken liver or potato as the source of the catalase. I’ve done both and frankly potato is less stinky and is easier to clean up after. Here is the gist of the lab:

• Students will need: potato puree, tweezers, a beaker full of hydrogen peroxide, and a stopwatch.
• Peel a raw potato and cut it into pieces. Place the potato in the blender and add a small amount of water. Puree until smooth. (One large potato should be enough for 1 class period).
• Note: The potato will turn brown relatively quickly as it comes in contact with the air. Don’t worry! This does not impact the results of the experiment.
• Collect the paper discs out of your hole puncher (or hit up the copy center at your school).
• Using tweezers, have students dip a paper disc in the potato puree. Place the paper in the bottom of the beaker of peroxide and start the stopwatch. As the catalase on the paper disc breaks peroxide into oxygen and water, the disc will float. Have students time how long it takes for the paper to rise.
• pH: To show students the impact of pH on enzyme efficiency, have them add a few drops of an acid and a base to the potato purees on a spot plate. Vinegar and bleach are great options. Repeat the experiment and have students determine at which pH catalase works best.
• Option 1: Change the temperature of the peroxide. Place a beaker of peroxide in an ice bath, and another in a warm water bath. This option tends to yield the best results.
• Option 2: Change the temperature of the potato puree. This can be done easily by putting some of the puree in the fridge and some in the microwave (or boil it at home ahead of time). This does not always give the best results because the cold potato can warm up pretty quickly, but still works if you don’t have water baths available.

• Have students do multiple trials (at least 3) and take the average. Sometimes they get weird data, so this helps with accuracy.
• If you are testing multiple variables, have students get fresh peroxide before starting the new variable. For example, have students collect all the temperature data, get fresh peroxide, and then collect pH data.
• If the paper disc takes more than 1 minute to rise, tell students that the enzyme is denatured and they can stop timing and move on to the next trial.
• When I first started doing this lab I used petri dishes for all the potato purees and it was a lot of clean up. I recently switched to chemistry spot plates (pictured above) and it made clean up so much easier!

If you have any additional questions, leave me a comment! ​Rock on,

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Friday, November 9, 2012

Easy enzyme experiments anyone can do.

Antioxidant enzymes are capable of stabilizing, or deactivating free radicals before they attack cellular components. antioxidant enzymes

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Everything About Enzymes!! (and a free lab!)

• Enzymes are biological catalysts that speed up the chemical reactions of the cell.
• Enzymes are proteins.
• Enzymatic reactions occur faster and at lower temperatures because enzymes lower the activation energy for that chemical reaction.
• Enzymes are never consumed or used up during the reaction. They can do their job over and over again.

• Enzymes are highly specific for just one substrate.  The enzyme has an active site with a unique 3-D shape into which this substrate must fit.  
• Enzymes catalyze both the forward and the reverse of the same reaction.
• Enzymes can be denatured by temperatures and pH levels outside the optimal range for that particular enzyme.

I teach 2nd grade during the year, but do high school science camps in the summer. Can't wait to check these out and see if they work for us when we're studying enzymes! Thanks! Jenny Luckeyfrog's Lilypad

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At GCSE, students should appreciate that enzymes are important proteins, essential for reactions to take place. They need to be able to explain the mechanism of enzyme action, including the active site, enzyme specificity and factors affecting the rate of enzymatic reactions.

Misconceptions about enzymes include the idea that enzymes work best at 37 0 C. It is important to make  students aware early on in the delivery of this topic that enzymes are found in a variety of organisms which exist in extremes of temperature and do not have a constant body temperature. To ensure that students do not refer to enzymes as "being killed" it is essential that they have an understanding of the structure and concept of an enzyme as a component within a cell so that they are comfortable referring to enzymes being denatured.

Whilst this list provides a source of information and ideas for experimental work, it is important to note that recommendations can date very quickly. Do NOT follow suggestions which conflict with current advice from CLEAPSS, SSERC or recent safety guides. eLibrary users are responsible for ensuring that any activity, including practical work, which they carry out is consistent with current regulations related to Health and Safety and that they carry an appropriate risk assessment. Further information is provided in our  Health and Safety  guidance.

Using enzymes to make creme eggs

This video demonstrates how to make soft-centred chocolates, using enzymes. Students could carry out this practical and if undertaken in a food safe environment, using food materials and following a scrupulous hygiene regime, produce chocolates that could be eaten.

This practical/demonstration provides a "real-world" application of the use of enzymes, which will be of interest to many students (chocolate!). It would be a good practical to complete at the start of this topic or as a reward at the end of the topic if students can demonstrate appropriate knowledge and understanding of enzyme action.

Upgrading Whey

Quality Assured Category: Science Publisher: Science & Plants for Schools (SAPS)

This practical activity is a good demonstration of the use of immobilised enzymes in biotechnology. The materials give a method for producing whey from milk. Students then use immobilised enzymes to produce glucose from the ‘waste’ whey. Students use a glucose test strip to measure the amount of glucose produced. They can be challenged to optimise the process to see how to get the greatest yield of glucose.

Microscale investigations of catalase activity in plant extract

This is a relatively straightforward practical activity that allows students to compare catalase activity across a range of different fruits and vegetables. The protocol uses a deceptively simple, yet very accurate, method to measure the rate of reaction by collecting the oxygen evolved as a product of the reaction.

The whole reaction can be carried out on a very small scale, in a centrifuge tube.

An enzyme extract is adsorbed to filter paper discs. These discs initially sink in a hydrogen peroxide solution, but then float to the surface as the oxygen produced gets trapped in the paper fibres. The time taken for the discs to rise is measured.

As the protocol uses small samples of tissue it is also possible for students to take a series of samples across one particular plant organ (for example a diseased vegetable) and investigate the difference in catalase activity in different areas.

Investigating the effect of pH on amylase activity

This is a standard protocol for this investigation, which is a required practical activity for GCSE Biology students. The Nuffield Foundation link here provides a student sheet with questions and answers (remember to remove the answer sheet before handing out to students).

Having completed the practical in class, the questions would provide a useful homework for students. 

Jelly Liquidiser

Quality Assured Category: Science Publisher: National STEM Learning Centre and Network

This video shows how pineapple is able to liquify a bowl of jelly due to enzyme action.

Using the video (without the commentary), a teacher led demonstration or getting students to complete this practical would then lead to a set of useful questions:

What is causing the jelly to liquify?

Why would pineapple have this ability? What possible use could it be?

Would it work with tinned pineapple-why would using this make a difference?

One half of the class could try the experiment with fresh pineapple and one half with tinned.

Converting Milk Products Using Lactase

In this practical students investigate the treatment of milk with lactase. Following treatment of the milk students then test the glucose content of the converted milk products, and compare products of frozen converted and non-converted milk samples.

Different groups (pairs) of students could also be given different types of milk to use (Full fat, semi skimmed, skimmed), so that class results could be compared. The equipment is a little tricky to set up, but should provide some worthwhile results for effective evaluation.

Students are given useful guidance about what to include in their evaluation and there are some challenging questions for them to answer.

RADAAR framework - How I teach enzymes

Quality Assured Category: Science Publisher: Education Endowment Foundation

This infographic gives ideas on how to teach enzymes to 14-16 year olds using the RADAAR (research, anticipate, diagnose, address, assess, review) framework developed by the Best Evidence Science Teaching (BEST) project based at the University of York. 

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Enzyme activity - distance learning lab.

Investigate the catalyzed decomposition of hydrogen peroxide by catalase with measurements from an oxygen gas sensor.

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Easy Enzyme Experiments Anyone Can Do

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13 Enzymes Lab Report Activities 

January 4, 2023 //  by  Alison Vrana

Learning about enzymes is important to build basic skills and an understanding of biological processes. An enzyme is a protein that helps chemical reactions to occur in the body. Digestion, for example, wouldn’t be possible without enzymes. In order to help students better understand the ability of enzymes, teachers often assign labs and lab reports. The experiment activities below explore how enzymes react under different experimental conditions such as temperature, pH, and time. Each enzymatic activity is engaging and can be adapted for any level of science class. Here are 13 enzyme lab report activities for you to enjoy. 

1. Plant and Animal Enzyme Lab

This lab explores an enzyme that is common to both plants and animals. Firstly, students will explore important concepts about enzymes; including what enzymes are, how they help cells, and how they create reactions. During the lab, students will look at plants and animals and discover enzymes that are common to both.

Learn More: Amy Brown Science

2. Enzymes and Toothpicks

This lab explores enzymes using toothpicks. Students will practice different simulations with toothpicks to see how enzyme reactions can change with different variables. Students will look at enzyme reaction rates, how enzymes react with substrate concentration and the effect of temperature on enzyme reactions.

Learn More: Science Buddies

3. Hydrogen Peroxide Lab

In this lab, students explore how enzymes break down hydrogen peroxide using different catalysts. Students will use liver, manganese, and potato as catalysts. Each catalyst produces a unique reaction with hydrogen peroxide.

Learn More: Royal Society of Chemistry

4. Critical Thinking With Enzymes

This is an easy assignment that encourages students to think about what they know about enzymes and apply their knowledge to real-world scenarios. Students will think about how enzymes impact bananas, bread, and body temperature.

Learn More: The Science Teacher

5. Enzymes and Digestion

This fun lab explores how catalase, an important enzyme, protects the body from cell damage. Kids will use food coloring, yeast, dish soap, and hydrogen peroxide to simulate how enzymes react in the body. Once students complete the lab, there are also several activities for extension learning.

6. Enzymes in Laundry and Digestion

In this activity, students will take a look at how enzymes to aid digestion and laundry. Students will read A Journey Through the Digestive System and  Amazing Body Systems: Digestive System, along with watching several videos in order to prepare to discuss how enzymes aid in digestion and the cleaning of clothes.

Learn More: Teach Engineering

7. Lactase Lab

Students investigate the enzyme lactase in rice milk, soy milk, and cow’s milk. During the lab, students will be able to identify the sugars in each type of milk. They will run the experiment with and without lactase to assess the glucose levels in each sample.

Learn More: Learning Undefeated

8. Catalase Enzyme Lab

In this lab, students assess how temperature and pH affect catalase efficiency. This lab uses potatoes to measure how pH affects catalase. Then, students repeat the experiment by changing the temperature of either the potato puree or the hydrogen peroxide to measure the effect of temperature on catalase.

Learn More: Science Lessons that Rock

9. How Heat Affects Enzymes

In this hands-on experiment, your pupils will learn how heat affects the activity of enzymes. Start by going through these informative examples and explanations with your class before encouraging them to use objects like pineapples and marshmallows to transform theory into reality.

Learn More: Expii

10. Enzymatic Virtual Lab

This website offers games that teach students about biology concepts such as enzymes. This virtual lab covers enzymes, substrates, enzyme shapes, and variables that affect enzyme reactions. Kids complete the lab online via a virtual portal.

Learn More: Bioman Biology

11. Enzyme Simulation

This website shows students how enzymes react in real-time via an online simulation. This simulation helps students make cognitive connections from physical labs. This simulation shows how starch breaks down with different enzymatic reactions.

Learn More: Biology Simulations

12. Enzyme Function: Penny Matching

This is another online activity that challenges students to see the similarities between using a penny machine and the enzymatic process. Students will view the penny machine in action and then compare this process to an enzyme-catalyzed reaction. Then, students can answer challenging questions. 

Learn More: CK-12

13. Apples and Vitamin C

For this experiment, students will test how vitamin C affects apples. Students will observe an apple sprinkled with powdered vitamin C and an apple without any powder over a period of time. Students see how vitamin C slows the browning process.

Learn More: The Homeschool Scientist

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Experiments on Enzyme Activity | Biochemistry

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The below mentioned article includes a collection of seven experiments on enzyme activity.

1. Experiment to demonstrate the activity of enzymes:

Requirements:

Benzidine solution, razor, thin sections of actively growing root (or germinating seeds or germinating pollen grains), phosphate buffer, hydrogen peroxide (1%), ammonium chloride (5%), starch paste.

Method, observations and results:

1. Cut thin sections of fast-growing roots or germinating seeds or take some pollen grains and put the material in phosphate buffer at pH 7.0. Now transfer the material in the incubation mixture [made of 5% benzidine saturated solution + 5 ml hydrogen peroxide (1%) and 1 ml ammonium chloride (5%)]. Incubate the entire mixture at room temperature for 5 minutes and observe. Dark-blue colour appears. This is due to the presence of the enzyme peroxidase.

2. Make a paste of starch, immerse in it the provided material like actively growing roots or germinating pollen grains and test for sugar. Positive test of sugar indicates that starch has transformed into sugars, and this further confirms the presence of enzyme amylase in the studied plant material.

2. Experiment to demonstrate that heat destroys activity of enzyme but not that of a catalyst:

Four test tubes, manganese dioxide (MnO 2 ), water, beaker, spirit lamp, piece of fresh liver or potato, hydrogen peroxide, boiled and cooled piece of liver or potato, boiled and cooled manganese dioxide solution.

Pour 2 ml of H 2 O 2 solution is each of the four test tubes. Add a pinch of manga­nesedioxde in the first test tube, pre-boiled and cooled 1 ml of manganese dioxide solution in the second, small piece of fresh liver or potato in third and pre-boiled and cooled piece of liver or potato in the fourth.

All the test tubes are kept at room temperature if it is summer and warm water (kept at about 38°C) if it is winter. Oxygen bubbles are found to come out of solution in the first three test tubes but not in the fourth one.

Manganese dioxide is a catalyst that helps to break hydrogen peroxide into water and oxygen. The catalyst is not affected by heat as it is clear from evolution of oxygen in the second test tube.

Fresh liver or potato contains enzymes peroxidase and catalase that help in evolving oxygen from hydrogen peroxide. The enzymes are functional at room temperature (test tube three) but heating destroys their activity (test tube four). Therefore, heat kills enzyme activity but has little effect on the activity of a catalyst.

Precautions:

(i) Test tubes must be thoroughly washed with water before use.

(ii) Do not perform the experiment without warm water if it is cold outside,

(iii) Keep the temperature of warm water to about 38″C. Do not allow it to go beyond 50°C.

(iv) Use fresh potato slice or liver piece.

3. Experiment to prove that enzymes are specific in their activity:

Four test tubes, one percent starch solution, one percent sucrose solution, saliva, Bennedict’s or Fehling’s solution, spirit lamp.

Take four test tubes. Pour 1 ml of 1% starch solution in the first, 1 ml of 1% sucrose solution in the second, 1 ml each of 1% starch solution and saliva in the third, and 1 ml each of 1% sucrose solution and saliva in the fourth. Keep all the test tubes undisturbed for one hour at room temperature if it is summer and in warm water (about 38°C) if winter.

Afterwards pour 3 ml of Bennedict’s or Fehling’s solution (having cupric ions) in each of the test tube. Heat the test tube to boiling for about 2 minutes and observe. There is no change of colour in first and second test tubes. The fourth test tube also does not show any change in colour. However, in the third test tube, the blue colour of Bennedict’s or Fehling’s solution gets changed to yellowish or reddish precipitate.

The change of colour from blue to yellowish or reddish precipitate is caused by conversion of cupric ions of Bennedict’s or Fehling’s solution into cuprous oxide.

This occurs in the presence of reducing sugars. Both sucrose and starch are non-reducing in nature as is found by the absence of colour change in test tube one and two. In test tube four having sucrose and saliva there is no enzyme activity since colour change is absent.

However, test tube three having starch and saliva (containing enzyme salivary amylase) reducing sugars are produced as is clear from change of colour. Therefore, the enzyme, salivary amylase, present in saliva catalyses hydrolysis of starch but not sucrose which is a common disaccha­ride.

(i) Test tubes must be thoroughly washed and dried;

(ii) The water in which the solutions are to be kept must not be very hot.

(iii) In winter warm water must be taken,

(iv) Before the collection of saliva, mouth must be washed thoroughly with distilled water,

(v) Swill the rinsed mouth with 7-10 cc of distilled water for 1 minute and then collect the same, as water containing saliva,

(vi) While heating the solution should not be allowed to bump violently.

4. Experiment to demonstrate the activity of the enzyme amylase extracted from the germinating barley or pea seeds:

Starch powder, iodine solution, germinating barley or pea seeds, distilled water, test tubes, mortar, pestle, filter paper, and funnel.

1. Take a little amount of ordinary starch and make a thin paste of it in about 50 ml boiling water. Allow it to cool down.

2. Take about 5 gm. of germinating seeds of barely or pea. In case of pea seedlings, remove their cotyledons. Ground the cotyledons along with distilled water in the mortar, and filter the contents through a funnel.

3. Pour the starch solution in two test tubes and mark them as ‘A’ and ‘B’.

4. Add a few drops of iodine solution in tube ‘A’ and observe the colour change.

5. Add the filterate of the crushed cotyledons or endosperm of barely in tube ‘B’.

6. Keep both the tubes at a warm place (about 35°- 40°C) for about 30 minutes.

Observations:

In test tube ‘A’, the contents turn blue in colour. In test tube ‘B’, the contents show reddish- brown colour. After about 15 minutes, if iodine solution is added, it shows no positive test for starch in tube ‘B’. However, if a few drops of Fehling’s solution are added in tube ‘B’, a brick-red precipitate appears.

Formation of blue colour in tube ‘A’ confirms the test of starch. In tube ‘B’, formation of reddish-brown colour is due to the fact that addition of seed extract supplied the enzyme amylase which partially hydrolysed the starch into maltose (a 12-carbon sugar). After about 30 minutes, the entire starch in tube ‘B’ gets completely hydrolysed into hexose sugar.

Due to this the iodine solution gives negative test for starch. Formation of reddish-brown colour after the addition of Fehling’s solution confirms the presence of hexose sugar. It is a reducing sugar, and a product of hydrolysis of starch made of amylase and amylopectin.

The enzyme amylase is present in the germinating barley or pea seeds. It is released during the crushing process. Amylase is actually an enzyme which catalyzes the breakdown of starch into monosaccharide units.

5. Experiment to study the enzyme activity of diastase in germinating seeds of barley and to study the influence of pH and temperature:

The enzyme diastase acts on starch and converts it to hexose sugar.

Germinating barley seeds, mortar, water, muslin cloth, centrifuge, measuring flask, iodine solution prepared in potassium iodide), starch solution, test tubes, beaker, enzyme extract, pipette, Benedict’s solution, buffer solutions of known pH, diastase solution, water baths (7), stop watch.

Preparation of Required Solutions:

(a) Starch solution:

It is prepared by adding 2 gm. of soluble starch in 50 ml of boiling water.

(b) Buffer solution A:

Add 6.95 gm. of monobasic sodium phosphate (0.2 M) in 250 ml of distilled water and use it as buffer solution A.

(c) Buffer solution B:

Dissolve 17.92 mg of dibasic sodium phosphate (Na 2 HPO 4 .12H 2 O) in 250 ml of water to get 0.2 M buffer solution B.

(d) Iodine solution (1 %):

Mix 1 gm. iodine and 2 gm. KI in 300 ml water and use it as iodine solution.

Method and observations:

1. Take 10 gm. of germinating barley seeds and 20 ml of water and grind them in mortar.

2. Filter the above mixture through muslin cloth, centrifuge the filtrate at low speed, take the supernatant liquid in a measuring flask and make up the volume of the enzyme extract upto 100 ml.

3. Take six test tubes and put 1 ml iodine solution (1 %) in each of them. Also add 20 ml water in each of them.

4. In a separate test tube take 1 ml of 1% iodine solution and 20 ml water and add 1 ml starch solution. This will work as a control.

5. Take 10 ml of starch solution in a beaker, add 1ml enzyme extract and shake it well.

6. This starch diastase mixture is now called digestion mixture. Pipette out 1ml of this digestion mixture and add it in each of the six test tubes containing iodine solution and observe. Colour starts disappearing. Note the time of disappearance of colour.

7. After about 10 minutes of digestion, take out 1ml of digestion mixture into a test tube, and now test for sugar by Benedict’s reagent. Sugar test is positive.

This shows that activity of the enzyme diastase has transformed the starch into sugar. This further confirms the enzyme activity of diastase in germinating seeds of barley.

Effect of pH:

Take 9 test tubes and in each of them take 5ml of buffer solution of known pH like 5.0,5.5, 6.0,6.5,7.0,7.5,8.0,8.5,9.0. In each test tube, add 5 ml of starch solution (1%). Now add 1 ml of diastase solution in each of the test tubes and note the time of addition. Shake the contents thoroughly and mix them well.

Now pipette 1 ml of the reaction mixture every 5 minutes into separate test tubes containing 1ml of iodine solution and 20 ml of water. Take a graph paper and plot the time taken in minutes for complete hydrolysis (as shown by complete disappearance of colour of iodine) against the pH. Time of disappearance of colour is different in different pH, and this shows the influence of pH on enzyme activity.

Effect of temperature:

Take seven water baths and maintain them at seven different temperatures like 100°C, 80°C, 60°C, 40°C, 20°C, 10°C and 0°C. Take seven test tubes and in each of them add 5 ml of soluble starch (1 %) maintained at pH 7 and put them in seven different water baths maintained at different temperatures.

Note the time when contents in different test tubes attain the temperature of their respective water baths and now add 1 ml of diastase solution in each test tube. Shake the test tubes well, wait for 5 minutes and add in each test tube 1 ml mixture of 1 ml iodine solution and 20 ml water. Wait for some time, note the time taken for disappearance of iodine colour against each temperature and plot the time on graph paper.

6. Experiment to demonstrate the activity of peroxidase in plant material:

Potato tuber, test tube, muslin cloth, hydrogen peroxide (3%), pyrogallol solution (1%).

1. Macerate 5 gm. of potato tuber, squeeze it through a muslin cloth, and take 3 ml of the potato extract in a test tube.

2. Put 1% solution of pyrogallol (a phenolic compound) in the test tube containing potato extracts and add 3 drops of hydrogen peroxide (3%) and observe.

Observation:

Change in colour takes place.

This change in colour shows the presence of peroxidase activity in the extract of potato tuber.

7. Experiment to demonstrate the pH change inhibits in enzyme activity:

Two test tubes. 1% starch solution, saliva, dilute HCI, beaker, water, spirit lamp, iodine solution (I + KI).

Pour 2 ml of starch solution in each of the two test tubes. Add 1 ml of fresh saliva in each. A few drops of dilute hydrochloric acid are added to one of the test tubes to make its solution acidic. Both the test tubes are kept for one hour at room temperature if it is summer or in warm water (about 38°C) if it is winter.

After one hour both the test tubes are tested for starch by pouring 1 to 2 drops of iodine solution. Test tube one shows negative starch test while test tube two (acidified) develops blue colour showing the presence of starch.

In test tube one, pH is nearly that of saliva. The salivary amylase contained in saliva is functional and causes hydrolysis of starch because starch test is negative.

In test tube two appearance of blue colour indicates that the starch has not been hydrolysed by enzyme present in saliva. The only difference in two test tubes is that the solution of the second test tube has been acidified. Therefore, change in pH inhibits enzyme activity.

(i) Test tubes must be thoroughly washed and dried,

(ii) Before the collection of saliva mouth must be washed and any acidic or alkaline food must not be taken,

(iii) Warm water must be used in winter,

(iv) Care must be taken that there is no contamination of first test tube by the HCI which is being used for second test tube.

Related Articles:

• Detection of Enzymatic Activity | Plant Tissue
• Estimation of Amylase | Enzyme Activity

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Shop Experiment Enzyme Action: Testing Catalase Activity Experiments​

Enzyme action: testing catalase activity.

Experiment #2B from Advanced Biology with Vernier

Introduction

Many organisms can decompose hydrogen peroxide (H 2 O 2 ) enzymatically. Enzymes are globular proteins, responsible for most of the chemical activities of living organisms. They act as catalysts, substances that speed up chemical reactions without being destroyed or altered during the process. Enzymes are extremely efficient and may be used over and over again. One enzyme may catalyze thousands of reactions every second. Both the temperature and the pH at which enzymes function are extremely important. Most organisms have a preferred temperature range in which they survive, and their enzymes most likely function best within that temperature range. If the environment of the enzyme is too acidic or too basic, the enzyme may irreversibly denature , or unravel, until it no longer has the shape necessary for proper functioning.

H 2 O 2 is toxic to most living organisms. Many organisms are capable of enzymatically destroying the H 2 O 2 before it can do much damage. H 2 O 2 can be converted to oxygen and water, as follows:

Although this reaction occurs spontaneously, enzymes increase the rate considerably. At least two different enzymes are known to catalyze this reaction: catalase, found in animals and protists, and peroxidase , found in plants. A great deal can be learned about enzymes by studying the rates of enzyme-catalyzed reactions.

In this experiment, you will

• Use a Gas Pressure Sensor to measure the production of oxygen gas as hydrogen peroxide is destroyed by the enzyme catalase or peroxidase at various enzyme concentrations.
• Measure and compare the initial rates of reaction for this enzyme when different concentrations of enzyme react with H 2 O 2 .
• Measure the production of oxygen gas as hydrogen peroxide is destroyed by the enzyme catalase or peroxidase at various temperatures.
• Measure and compare the initial rates of reaction for the enzyme at each temperature.
• Measure the production of oxygen gas as hydrogen peroxide is destroyed by the enzyme catalase or peroxidase at various pH values.
• Measure and compare the initial rates of reaction for the enzyme at each pH value.

Sensors and Equipment

This experiment features the following sensors and equipment. Additional equipment may be required.

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This experiment is #2B of Advanced Biology with Vernier . The experiment in the book includes student instructions as well as instructor information for set up, helpful hints, and sample graphs and data.