The *Enzyme Kinetics App* is designed for performing enzyme kinetics analysis in two steps:

- Properly organize the data.
- Fit the data with proper models.

Prior to performing the fitting process using the *Enzyme Kinetics App*, the data should be well-organized. When you click on the *Enzyme Kinetics* icon in *Apps Gallery*, a dialog opens with settings for your input data.

The *Enzyme Kinetics Sample.opj* shipped along with this app is located in `%LocalAppData%\OriginLab\Apps\Enzyme Kinetics\Samples`

folder. You can find it by right-clicking on the App icon in the *Apps Gallery* and selecting the *Show Samples Folder* from the context menu. The data in *[Book1]Sheet1* is for a reversible inhibition study:

The data include 2 measurements of substrate and 3 measurements of inhibitor, with 2 replicates for each inhibitor measurement. It should be organized as in the following:

There are two independent variables in the above example. The values of the first independent variable should be stored in the X column, while the second are in the corresponding row labels named *Indep2 Value.*

In the above example, for the 1st measurement of substrate, the independent variables are:

substrate = {5, 10, 20, 30, 50, 100, 200}

inhibitor = {10, 50, 100}

for the 2nd measure of substrate, the independent variables are:

substrate = {10, 15, 25, 35, 55, 105, 205}

inhibitor = {10, 50, 100}

Once the input data are ready, you can click the *Fit Model* button on the *Input Sheet*, bringing up the dialog for fitting. The following picture shows the settings used in this example:

The fitting process created 2 sheets: *EK Fitted Report*, and *EK Fitted Curves*. The sheet *EK Fitted Curves *stores the data for graphs in *EK Fitted Report*.

In the reportsheet *EK Fitted Report*:

**Model Information**: this branch reveals the fitting functions used in particular models. You can find them in the*Enzyme Kinetics*category when fitting using the built-in tool*Nonlinear Curve Fit*tool (**Analysis: Fitting: Nonlinear Curve Fit**).

**Parameters**: this branch shows the fitted parameters of each model, including the*Value*,*Standard Error*,*95% LCL*, and*95% UCL*of each parameter.

**Statistics**: this branch stores the*Number of Points*,*Degrees of Freedom*,*Reduced Chi-Sqr*,*R-Square(COD)*,*Adj. R-Square*, and*Fit Status*of each model.

**Model Comparison**: this branch sorts the*AICc*values of models, by default . The smaller the AICc, the better the model.*R-Square(COD)*and*Sy.x*are also listed in this branch.

**Fitted Curves Plot**: this branch displays the scatter plot of the original data and the line plot of the fitted curve for each model. One graph for each model.

**Residual Plots**: this branch compares the residuals of each model. For each measurement of a model, a scatter plot with a line at`y = 0`

will be created.

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