File Exchange > Data Analysis >    Enzyme Kinetics

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Enzyme Kinetics.opx
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Fit enzyme kinetics data and rank models.

Screen Shot and Video:

Download the Enzyme Kinetics.opx, and then drag-and-drop onto Origin workspace. An icon will appear in the Apps Gallery window.
NOTE: This tool requires OriginPro.

Sample OPJ File

This App ships with a sample OPJ file. In the Apps Gallery, right-click on the Enzyme Kinetics icon and select Show Samples Folder. Drag and drop Enzyme Kinetics Sample.opj  onto Origin to open the project.
Note: If you want to save the OPJ after changing it, it is best to save to a different location (e.g. save to your User Files Folder).


  1. Click on the Enzyme Kinetics icon. A dialog will be open that lets you specify the worksheet structure for input data.
    In the dialog, choose Number of Independent Variables according to your data and fitting function.
    In Independent Variable branch, specify Name, Units, Measurements and Replicates for each independent variable.
    In Dependent Variable branch, specify Name and Units for the dependent variable. 
    There can be multiple measurements for each independent variable, and multiple replicates for each measurement.
    Units, Measurements and Replicates can be customized in the combo box.
    Click OK button. A worksheet template with the specified settings will be created.
  2. Enter data in the worksheet.
    Fill first X column with data of the first independent variable. If multiple measurements for the first independent variable are defined, multiple X columns need to be filled. If there are 2 independent variables, specify the value for the second independent variable of each group of Y data in its column header Indep2 Value.  Fill each Y column with data for the dependent variable.

  3. Click the upper-left button Fit Model in the worksheet, to open the dialog for fitting.
    Choose the reaction and the study type.
    In Analysis branch,  select fitting functions in Models to Fit list, choose a method in Compare Models by drop-down list to rank models, methods include R-Square (COD), Sy.x, and AICc.
    If there are 2 independent variables, choose 1st Independent Variable for the fitting function from the drop-down list, make sure the 1st Independent variable here must be consistent with the worksheet's data settings, and 2nd Independent Variable will be updated automatically in the dialog.
    Available models for enzyme kinetics analysis:
    Reaction Study Model Independent Variables
    One Substrate Absence of Inhibitor Michaelis Menten Substrate
    Substrate Activation (Ordered) Substrate
    Substrate Activation (Random) Substrate
    Hill Substrate
    Isozyme Substrate
    Reversible Inhibition Complete Competitive inhibition Substrate, Inhibitor
    Complete Non-competitive inhibition Substrate, Inhibitor
    Complete Non-competitive mixed inhibition Substrate, Inhibitor
    Complete Un-competitive inhibition Substrate, Inhibitor
    Partial Competitive inhibition Substrate, Inhibitor
    Partial Non-competitive inhibition Substrate, Inhibitor
    Partial Non-competitive mixed inhibition Substrate, Inhibitor
    Partial Un-competitive inhibition Substrate, Inhibitor
    Tight Binding Inhibition Competitive inhibition Substrate, Inhibitor
    Noncompetitive inhibition Substrate, Inhibitor
    Uncompetitive inhibition Substrate, Inhibitor
    Mixed inhibition Substrate, Inhibitor
    Nonessential Activator Nonessential Activation Substrate, Activator
    Substrate-activator (SA) complex Specific Substrate, Activator
    Catalytic Substrate, Activator
    Mixed Substrate, Activator
    Two Substrates Two Substrates Sequential Random bi-bi Mechanism Substrate A, Substrate B
    Sequential Ordered bi-bi Mechanism Substrate A, Substrate B
    Non-sequential Ping Pong bi-bi Mechanism Substrate A, Substrate B
    Others pH Activity Profile pKa Rise pH
    pKa Fall pH
    pKa With Offset pH
    Bell Shaped pH
    Bell Shaped With Plateau pH
    Plateau Shaped pH
    First Order Rate First Order Time
    First Order with Offset Time
    Chemical Denaturation Chemical Denaturation Denaturant
    Thermal Denaturation Thermal Denaturation Temperature
    Exponential Delay Single Exponential Time
    Single Exponential + Offset Time
    Double Exponential Time
    Double Exponential + Offset Time
    Linear Regression Linear Regression X
  4. Click OK button. A report sheet and a report data sheet will be created which include fitted results and the ranking models result.


  1. If replicate data are stacked in a column, choose 1 in the Replicates combo box.
  2. The report sheet contains a Model Information table, which shows fdf file names for fitting functions in the analysis.
    If you want to modify some fitting functions, (e.g. you may think default initial values for some functions are not good enough) 
    you can change them by choosing the function from the Enzyme Kinetics category in the Fitting Function Organizer dialog or Fitting Function Builder dialog. 
    You can also choose the fitting function in the built-in Nonlinear Curve Fit tool to perform fitting manually.


v1.1 FDF files for Sequential Random bi-bi Mechanism updated.

Reviews and Comments:
09/22/2021jzubekHow to cite this App in a master thesis?

12/13/2017easwarHello MarcHoemberger,
Thank you for your comment. We have fixed the issue and uploaded version 1.1.
Please update the App to get the latest version.

08/08/2017MarcHoembergerGreat app, however the equation used for Sequential-Random-Bi-Bi reaction (2 substrate MM) is incorrect. In the app the equation only has the alpha for the first term in the denominator. The correct function has the alpha factor for all but the last ([A][B]) term (1):
The correct function that should be used:
y = Vmax*x*B/(alpha*Ka*Kb+alpha*Kb*x+alpha*Ka*B+x*B)

(1) :Segel, I.H.(1975): Enzyme Kinetics, John Wiley & Sons, Inc., New York

07/11/2017M-nagiacould you please tell me how to plot a Michaelis Menten curve and displaying the error bars (standard deviation) on it using the app of Enzyme Kinetics