Michaelis-Menten Equation Calculator
Combine substrate concentration, Km, and Vmax to predict reaction velocities and turnover numbers for enzymes.
Units could be micromoles per minute, absorbance per minute, etc.
Provides turnover number kcat when supplied.
Reaction velocity v
0.714
How to Use This Calculator
Collect kinetic parameters
Obtain Km and Vmax from Lineweaver-Burk plots, nonlinear fits, or literature data.
Supply substrate concentration
Enter the substrate level used in the experiment in consistent concentration units.
Optionally include enzyme concentration
Provide total enzyme concentration to calculate turnover number kcat.
Interpret velocity
The calculator applies v = Vmax * [S] / (Km + [S]). Compare across conditions or inhibitors.
Formula
v = Vmax [S] / (Km + [S])
kcat = Vmax / [E] when enzyme concentration is known. Ensure all concentrations use the same units.
Example
With Vmax = 1.0 AU/min, Km = 0.2 mM, [S] = 0.5 mM: v = 1.0 * 0.5 / (0.2 + 0.5) about 0.71 AU/min.
Full Description
Michaelis-Menten kinetics describe how enzyme velocity depends on substrate concentration, assuming steady-state conditions and a single substrate mechanism.
The relationship helps predict reaction rates, compare mutant enzymes, and design inhibitor experiments in biochemical research.
Frequently Asked Questions
Can I use different units?
Yes. Keep units consistent across Vmax, substrate concentration, and Km. The output velocity will match the Vmax units.
What if [S] equals Km?
Velocity equals half of Vmax when substrate concentration equals Km.
Does this account for inhibition?
No. Use modified Michaelis-Menten expressions for competitive or noncompetitive inhibitors.
How do I get Vmax?
Fit initial velocity data over a range of substrate concentrations using nonlinear least squares or Eadie-Hofstee plots.
Can I plot the curve?
This tool focuses on single calculations. Export parameters to plotting software for full curves.