How to Plot Michaelis Menten Graph in Excel (With Easy Steps)

In this article, we will learn to plot Michaelis Menten graph in Excel. We use the Michaelis Menten equation to plot the graph. Generally, it is used to analyze the kinetic data of enzymes. It explains the effect of substrate concentration on enzymes. Today, we will show step-by-step procedures to plot Michaelis Menten’s graph in Excel. We will also learn to extract the value of the Michaelis Menten constant. So, without further delay, let’s start the discussion.

What Is Michaelis Menten Graph?

In the Michaelis Menten graph, we plot the Reaction Velocity (V) on the Y-axis and the Substrate Concentration ([S]) on the X-axis. The graph follows the equation below:

V = (Vmax*[S])/([S]+Km)

It is a zero-order equation.

Here,

V = Initial velocity of reaction

Vmax = Maximum velocity of reaction

[S] = Concentration of Substrate

Km = Michaelis Menten Constant

At low substrate concentration, the equation becomes:

V = (Vmax*[S])/Km

It is a first-order equation.

How to Plot Michaelis Menten Graph in Excel: Step-by-Step Procedure

To explain the steps, we will use a dataset that contains Substrate Concentration, [S]. We will calculate the Reaction Velocity (V) with the Michaelis Menten equation. In the beginning, we will use educated values of Km and V-max. Later, we will find the value of Km and V-max using the observed and calculated Velocity. So, let’s go through the following steps to learn the way to plot Michaelis Menten’s graph.

STEP 1: Insert Michaelis Menten’s Constant and V-max Values

In the first place, you need to insert educated values of Km and V-max.
Let, the values of Km and V-max are 10.
Here, we have inserted 10 in both Cell F4 and Cell F5.

STEP 2: Calculate Value of Initial Velocity

Secondly, we need to calculate the value of the initial velocity.
To do that, we will use Michaelis Menten’s equation.
Select Cell C5 and type the formula below:

=($F$5*B5)/(B5+$F$4)

Here, Cell F5 contains Km, Cell F4 stores V-max, and Cell B5 stores the Substrate Concentration [S].

After that, press Enter and drag the Fill Handle down.

As a result, you will see the Velocity corresponding to the Concentration.

STEP 3: Plot Michaelis Menten Graph with Calculated Velocity

To plot the graph, you need to select the values of Concentration and corresponding Velocity.
Here, we have selected the range B4:C14.

After that, go to the Insert tab and click on the Insert Scatter icon. A drop-down menu will appear.
Select Scatter with Smooth Lines and Markers option from the drop-down menu.

As a result, you will see the plot on the sheet.

After changing the axis and chart titles, the graph will look like the picture below.

STEP 4: Determine Initial Velocity Along with Observed Velocity

In STEP 2, we calculated the initial velocity with a formula. In that case, we didn’t have absolute values of Km and V-max. Also, there was no observed velocity.
If you have Observed Velocity like the dataset below, you can calculate the initial velocity as well as the values of Km and V-max.

At this moment, select Cell D5 and type the formula below:

=($C$17*B5)/(B5+$C$16)

Press Enter and drag the Fill Handle down.

STEP 5: Find Difference Between Observed and Calculated Velocities

After calculating velocity with the Michaelis Menten equation, we need to find the difference between the observed and calculated velocities.
For that purpose, select Cell E5 and type the formula below:

=C5-D5

Now, press Enter and drag down the Fill Handle to see the results.

STEP 6: Find Sum of Square of Differences

To find the best values for Km and V-max, we need to determine the sum of squares of the differences.
To do so, select Cell E17 and type the formula below:

=SUMSQ(E5:E14)

Here, we have used the SUMSQ function to calculate the summation of squares of the differences.

Press Enter to see the result.
For best values of Km and V-max, the Sum of Squares of Differences must be minimum.

STEP 7: Plot Michaelis Menten Graph with Both Observed & Calculated Velocities

To plot the graph with both observed and calculated velocities, select the range B4:D14.

After that, go to the Insert tab and click on the Insert Scatter icon. A drop-down menu will appear.
Select Scatter with Smooth Lines and Markers option from the drop-down menu.

As a result, you will see the graph of both Observed and Calculated velocities.

STEP 8: Find Michaelis Menten’s Constant and V-max

To find Km and V-max for the observed values, we need to calculate the minimum value of the sum of squares of the differences.
For that purpose, we need to take the help of the Solver Add-in.
Go to the Data tab and click on the Solver option from the Analysis section.

In the Solver Parameters box, type the cell that contains the value of Sum of Squares of Differences in the Set Objective field. In our case, that is Cell E17.
Then, select Min.
After that, type the cells that contain the values of Km and V-max in the “By Changing Variable Cells” field.
Here, we have typed $C$16:$C$17.
Click Solve to proceed.

In the following step, click OK to move forward.

Finally, you will find the desired results like the picture below.

STEP 9: Insert Half V-max Value in Graph

To insert the Half V-max value, you need to create a chart like the picture below.
Here, Cell B20 stores 0. Also, Cell B21 and Cell B22 store the value of Km.
On the other hand, Cell C20 and Cell 21 contain the Half V-max value. That means, C17/2. And Cell C22 stores 0.

After creating the Half V-max table, select the graph and right–click on it. A menu will appear.
Click on the Select Data option from there.

Then, select Add from the Select Data Source box.

Then, select the Series Name, X-values, and Y-values.
Here, Cell 19 is the Series Name, range B20:B22 is the X-values, and range C20:C22 is the Y–values.
After inserting the values, click OK.

Again, click OK in the Select Data Source box.

As a result, you will see a graph like the picture below.

STEP 10: Change Series Chart Type

Finally, we need to change the chart type for the Half V-max value graph.
To do so, select the Half V-max value graph first and then, right–click on it. A menu will appear.
Select Change Series Chart Type from there.

In the Change Chart Type box, change the Chart Type of the Half V-max Value graph to Scatter with Straight Lines and Markers.
Then, click OK.

Final Output

In the end, you will get the desired point where Km is 9.115 and V-max is 7.328.

Download Practice Workbook

You can download the practice workbook from here.

Michaelies-Menten Graph.xlsx

Conclusion

In this article, we have demonstrated step-by-step procedures to Plot Michaelis Menten’s Graph in Excel. I hope this article will help you to perform your tasks efficiently. Furthermore, we have also added the practice book at the beginning of the article. To test your skills, you can download it to exercise. Lastly, if you have any suggestions or queries, feel free to ask in the comment section below.

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