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The Kinetics of Lactose Conversion by Enzymes

Purpose/Overview of Experiment

The experiment purpose is to understand and calculate the impacts of temperature on activity of enzyme and alterations in the concentration of enzyme reaction of an enzyme-catalyzed, to explain the connection among level of substrate plus the maximum enzyme velocity, Michaelis Menten parameters can be appraised by the effect of pH also enzyme temperature activity and inhibition kinetics.

The experiment first part is about the enzyme in which the substrate is mixed with a solution of a buffer at values that are varying. The pH 9 is recorded as the highest absorbance in this experiment and the optical density value is 8.10. The analysis second part is about the substrate and enzyme is focused on many values of temperature ranging from 30 °C to 70 °C. Here the absorbance value is 7.01, and the temperature that is recorded as highest is 70 °C. The experiments third part is about the concentration of substrate that is not constant. By fixing the substrate concentration the highest recorded value of absorbance is 5.36 at a substrate concentration of 1.5 g/mL. Absorbance is taken at the wavelength at 540nm for all three parts.

Literature Review

Starch, otherwise called glucose polymers can be corrupted into littler maltose or disaccharides by utilizing a group of Enzyme called as amylase. This procedure additionally makes a particle of water divides among this response and the OH-plus H+ particles tie to the uncovered closures of the broken polymer of starch. The method of being part of water is known as hydrolysis. Hydrolysis is likewise a typical instrument use by catalysts to cut down concoction connection or bond.

By utilizing a catalyst test or analysis, the hydrolysis of skim milk must be estimated. The purpose of a Enzyme measure is to analyze for the basic nearness of compound movement. It can likewise be utilized to gauge the response value of a Enzyme catalyzed-response. The chemical test or examine makes it conceivable to quantify the presence of an item or the vanishing of one of the substrates after some period.

To gauge test action in the analysis completed to explore on catalyst movement and energy, we are told to screen the vanishing of substrate amylase’s, starch. The response of skim milk framing a compound that is blue when responded in yellow color with iodine was utilized as a premise of a measure that is colorimetric for amylase action. The amylase, juices culture supernatant containing that is discharged was then hatched with the skim milk. After the hatching has finished, a bit of the blend of skim milk and supernatant remained joined with iodine that is acidic. to stop the enzymatic response this is done while the iodine responds with the skim milk to turn the substance in blue color. The force of the shading blue decides the measure of skim milk that was not hydrolyzed by the amylase. The power of the blue shading can be additionally evaluated at an absorbance estimation of 620nm using a spectrophotometer. The higher the evaluation of absorbance between the example containing the underlying measure of skim milk and the hydrolyzed blend consisting the catalyst, the higher the ratio of skim milk corrupted by the chemical, thus the more noteworthy the action of the compound being estimated.

Catalyst action is likewise influenced by the atmosphere circumstances, either in a lab or the nature. Cases of components that impact on catalyst movement are the pH esteem and temperature. These circumstances are equipped with modifying connection of the amino side in an Enzyme, causing the Enzyme structure, collapsing and in some cases the compound’s dynamic site to alter. Enzyme energy takes after the Model of Michaelis-Menten in which:

Where: Km = constant of Michaelis

[s] = concentration of substrate

Experimental Plan

To decide catalyst action, we can gauge the measure of item framed as the outcome from the response among the substrate of Enzyme. The issue framed by the Amylase catalyst happens through a procedure called as hydrolysis. The chemical makes the polymer of the skim milk debase into littler disaccharides called maltose. The water atoms will then part to shape an OH-and H+ particle that in swings ties to the uncovered closures of the broken polymer of starch.

Various components influence enzyme action. Some of these variables are the substrate fixation, temperature, and pH. The additional factor that backs off or subdues catalyst action is the nearness of inhibitors. Enzymes must have a particular site called the dynamic location in which a response will occur; it is a similar place where items are framed. Dynamic destinations are individual, implying that exclusive a particular substrate can best fit into a specific active site, as it are, a bolt and system of a key.

Line Sketch of Equipment

  • 4g of solvent skim milk blended in fifty ml of water that is fresh.
  • The slurry is included in hundred ml of delicately bubbling in a substantial receptacle and blending is being finished.
  • Another two-hundred ml of water was included, and the last arrangement was blended well.


Five test tubes are named with pH five, six, seven, eight and nine separately. 1 ml of 2 percent skim milk was set inside each test tube, and 1 milliliter of cradle was then fixed to every machine.

2 milliliter of amylase arrangement was put inside another five test tubes.

Each of the ten test tubes was put inside a fresh water shower at a temperature of 37 degree Centigrade for five minutes.

The substance of every amylase test tube was filled each skim milk test tube and blended utilizing a vortex blender.

The tubes are then put again into the water shower at 37 degree centigrade

The test tubes are left for ten minutes to enable hydrolysis to happen.

The movement of amylase was resolved to utilize the strategy.

A diagram of pH against chemical movement was then plotted.

Materials and Equipment Required

  • pH buffer solution
  • Measuring cylinder
  • Micropipette and tips
  • Alpha Amylase enzyme
  • DNSA reagent
  • Water bath
  • Spectrophotometer
  • Starch
  • Beaker

Falcon tube rack

  • Hotplate

Vortex mixer

  • Cuvette

Label sticker

Safety Precautions

When dealing with chemical arrangements or Enzyme sullied gear, keep away from coordinate skin contact. Wear proper gloves when there is a potential for skin contact with chemicals. Wash Enzyme polluted surfaces altogether before taking care of. Under most working conditions including compounds, respiratory insurance isn’t ordinarily fundamental. There are a few activities, for example, spill cleanup, gear cleaning, and hardware repairing, that may produce mist concentrates. In these occurrences, respiratory insurance might be essential. The utilization of respiratory protection is typically crucial when working with powdered compounds. Respiratory assurance ought to likewise be utilized when shown by your manager, security expert or the medicinal workforce.

Data and Results Sheets

Concentration of Glucose (g/mL) Optical Density Real Optical Density
0.2 0.107 0.107
0.4 0.134 0.134
0.6 0.596 0.596
0.8 0.600 0.600
1.0 0.790 0.790
pH Optical Density Real Optical Density
5 0.205 4.10
6 0.216 4.32
7 0.259 5.18
8 0.393 7.86
9 0.405 8.10
Temperature (°C) Amylase Activity Real Optical Density
30°C 0.096 0.096
40°C 0.219 2.190
50°C 0.409 4.090
60°C 0.512 5.120
70°C 0.701 7.010
Substrate Concentration (g/mL) Real Optical Density
0.5 0.378
1.5 5.36
2.0 5.10
2.5 4.21
3.0 1.66

Methodology of Analysis/ Discussion of Results/ Limitations of Results

After the investigation is finished, a chemical action was estimated by the method for estimating the centralization of item framed. Before estimating the fixations, we began by making a standard of glucose bend. To make the glucose standard bend, grouping of glucose is differed at estimations of 0.2 g/mL, 0.4 g/mL, 0.6 g/mL, 0.8 g/mL and 1.0 g/mL. The each absorbance example was then taken at a wavelength of 540nm following 10 minutes. For making the diagram of optical thickness contradictory pH esteem, Against temperature chart of amylase movement and diagram of optical thickness against substrate focus, every one of the responses was ceased by including four milliliter of DNS reagent following ten minutes.

For the initial segment of the test which is making a diagram of optical thickness in opposition to pH esteem, it can be seen that the most noteworthy absorbance recorded was 8.10 at a pH of 9. In any case, this esteem may not be right is hypothetical, the ideal pH for amylase ought to be within the scope of 5.5 to 6.5. This might have happened because of the nearness of OH-particles being in wealth.

For the next piece of the examination where the impact action of amylase in changing temperatures was investigated, the information recorded demonstrates that the greatest absorbance esteem was at a temperature of seventy degree centigrade with an absorbance estimation of 7.01. The expansion in heat would at first causes the response rate to increment marginally as the ongoing vitality of the protein increments. This impact will then begin to demonstrate a side that is negative once the temperature achieved a point where chemical movement somewhat backs off because of the catalyst getting to be denatured.

For the 3rd piece of the trial, we directed an examination to check or examine the impact of substrate fixation on protein action. This was clarified by making a chart of optical thickness against substrate focus. From the information classified, it can be checked that the most remarkable optical depth is at an estimation of 5.10 at a substrate convergence of 2.0 g/mL. By expanding the focus of substrate, it builds the odds for the dynamic site to respond as there are more substrates. From the information, it can be examined that the esteem absorbance begins to diminish after a focus on respect higher than 2.0 g/mL was utilized. This ought not to happen as it ought to whether increment or demonstrate a steady an incentive to decide the legitimacy of this hypothesis.


Toward the finish of this analysis, it can be inferred that catalysts, for example, Amylase are exceedingly influenced by variables, for example, pH, substrate focus and temperature. The outcomes got to demonstrate that the ideal pH is at nine as it proves the most astounding absorbance estimation. The perfect temperature for protein amylase is at 70 °C which has an absorbance estimation of 7.01. While the most extreme centralization of a substrate for ideal catalyst movement is at 1.5 g/milliliter which has an absorbance estimation of 1.5. Expanding the fixation absorbance causes incentive to diminish exponentially as found in focus substrate at an opinion of 3.0 g/milliliter.


A few components ought to be considered exactly when doing this analysis to ensure it is fruitful. The primary element is fixation of substrate. By keeping the measure of the chemical a consistent while expanding the substrate focus, the response speed will then increment until the point that it achieves it’s most excellent. In doing as such, we ensure that every one of the catalysts will be changed over into chemical complex substrate. The second factor is to check for inhibitors. Inhibitors contend with the substrate for when attempting to respond with the catalyst. Some of the time, inhibitors win and access the chemical despite the fact that no response will happen. This makes the reaction back off because of rivalry among the substrates and the inhibitors. The 3rd element will be temperature. Ensure the surroundings temperature is at an ideal; this enables the response to happen at a most extreme rate. Ensure the heat isn’t too high or too low, this is to guarantee the catalyst does not denature and quits responding or responds at a much slower rate. The 4th element is the pH esteem. Make a point to put the compound in ideal pH esteem with the goal that the chemical is at its dynamic. Putting it in an answer that is excessively acidic or fundamental will make it denature and quit responding entirely.


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Pfeiffer, J.: Enzymes, the Physics and Chemistry of Life, pg 171-173, Simon and Schuster, NY (1954)

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