Enter Experimental Data
Use positive substrate concentrations and initial rates only.
Example Data Table
| Point | Substrate [S] (mM) | Velocity V (µmol/min) | 1/[S] | 1/V |
|---|---|---|---|---|
| 1 | 0.50 | 10.00 | 2.0000 | 0.1000 |
| 2 | 1.00 | 16.67 | 1.0000 | 0.0600 |
| 3 | 2.00 | 25.00 | 0.5000 | 0.0400 |
| 4 | 4.00 | 33.33 | 0.2500 | 0.0300 |
| 5 | 6.00 | 37.50 | 0.1667 | 0.0267 |
| 6 | 8.00 | 40.00 | 0.1250 | 0.0250 |
Formula Used
Michaelis Menten form: V = (Vmax × [S]) / (Km + [S])
Lineweaver Burk form: 1/V = (Km/Vmax)(1/[S]) + 1/Vmax
Linear regression: y = mx + b, where x = 1/[S] and y = 1/V.
Slope: m = Km/Vmax
Y-intercept: b = 1/Vmax
Vmax: Vmax = 1/b
Km: Km = m/b
X-intercept: x = -b/m = -1/Km
How to Use This Calculator
- Enter a name for the experiment and optional units.
- Add at least two positive substrate and velocity pairs.
- Choose the number of decimal places for results.
- Click Calculate Plot Parameters to fit the reciprocal line.
- Review the slope, intercepts, Km, Vmax, and R² values.
- Check the transformed data table and fitted chart for consistency.
- Use the export buttons to save the current analysis as CSV or PDF.
Frequently Asked Questions
1. What does a Lineweaver Burk plot show?
It converts Michaelis Menten data into a straight-line form using reciprocal axes. That lets you estimate Km, Vmax, slope, and intercepts from linear regression more easily.
2. Why must substrate and velocity both be positive?
The method uses 1/[S] and 1/V. Zero or negative inputs create invalid reciprocals and make the transformed plot mathematically unsuitable.
3. What does the slope represent?
The slope equals Km divided by Vmax. A steeper slope generally indicates a larger Km, a smaller Vmax, or both.
4. How is Vmax obtained from the plot?
The y-intercept equals 1/Vmax. Taking its reciprocal gives the fitted maximum reaction velocity for the entered dataset.
5. How is Km obtained from the plot?
Km is calculated from slope divided by y-intercept. You can also infer it from the x-intercept because that value equals negative one over Km.
6. What does R squared mean here?
R² measures how well the fitted line explains the transformed reciprocal data. Values nearer one indicate a stronger linear fit.
7. Can reciprocal plotting distort experimental error?
Yes. The transformation can overweight low substrate measurements and amplify noise. Use the plot for interpretation, but review raw kinetic data too.
8. When should I use example data?
Use it to test the calculator layout, verify exports, and understand how transformed points relate to the fitted kinetic constants.