Calculator Inputs
Use the fields below to model enzyme behavior across substrate and inhibitor conditions.
Example Data Table
| Substrate (mM) | Vmax (µmol/min) | Km (mM) | Inhibition | Velocity (µmol/min) |
|---|---|---|---|---|
| 0.5 | 120 | 3.5 | None | 15.0000 |
| 1.0 | 120 | 3.5 | None | 26.6667 |
| 2.0 | 120 | 3.5 | None | 43.6364 |
| 5.0 | 120 | 3.5 | None | 70.5882 |
| 8.0 | 120 | 3.5 | None | 83.4783 |
These sample values illustrate standard Michaelis-Menten behavior without inhibition.
Formula Used
Outputs follow the units you enter. Pure noncompetitive inhibition is assumed for that selected mode.
How to Use This Calculator
- Enter a current substrate concentration for the main velocity estimate.
- Provide Vmax, Km, and total enzyme concentration using consistent units.
- Choose an inhibition type, then enter inhibitor concentration and Ki when needed.
- Use a Hill coefficient above one to model cooperative behavior.
- Add a comma-separated substrate series to generate a comparison table.
- Submit the form to view the result panel directly below the header.
- Use the CSV and PDF buttons to save the current results.
FAQs
1. What does Vmax represent?
Vmax is the theoretical maximum reaction rate reached when the enzyme is saturated with substrate. It reflects the upper speed limit under the chosen conditions.
2. What does Km tell me?
Km is the substrate concentration that gives half of Vmax in the basic model. Lower Km usually suggests stronger apparent substrate affinity.
3. Why include a Hill coefficient?
The Hill coefficient helps model cooperative binding. Values above one indicate positive cooperativity, while values near one approximate standard Michaelis-Menten behavior.
4. How does competitive inhibition affect results?
Competitive inhibition raises the apparent Km, so more substrate is needed to reach the same rate. In this model, Vmax remains unchanged.
5. What changes under noncompetitive inhibition?
Pure noncompetitive inhibition lowers apparent Vmax without changing Km. The enzyme becomes less productive even if substrate concentration increases.
6. Why is enzyme concentration required?
Total enzyme concentration is needed to estimate kcat. That turnover value shows how many substrate molecules one enzyme site processes per time unit.
7. What if I leave the substrate series empty?
The calculator automatically builds a small substrate range from Km. That keeps the comparison table useful even when no custom series is entered.
8. Are unit conversions automatic?
No. The calculator assumes your entered values already use compatible units. The unit labels are displayed with outputs for clarity only.