Calculator
Choose a calculation route, enter known values, and submit to see the result panel above this form.
Plotly Graph
The graph updates with your selected calculation pathway and highlights the current operating point.
Example Data Table
Use this sample enzyme dataset to compare measured values and saturation behavior.
| Assay | Substrate Concentration (mM) | Velocity (µmol/min) | Saturation (%) |
|---|---|---|---|
| A | 0.25 | 14.7 | 14.7 |
| B | 0.5 | 25.3 | 25.3 |
| C | 1 | 40 | 40 |
| D | 2 | 57.1 | 57.1 |
| E | 4 | 72.7 | 72.7 |
Formula Used
Use this rearranged Michaelis–Menten form when rate, Km, and Vmax are known. It estimates assay substrate concentration. The observed rate must remain below Vmax.
Use this classic kinetics relation when substrate concentration is known. It predicts reaction velocity under simple enzyme saturation behavior.
This converts mass-based concentration into molarity. Unit conversion happens first, then the page reports M, mM, or µM output.
This dilution relation keeps solute amount constant. It calculates final substrate concentration after mixing an aliquot into a larger final volume.
How to Use This Calculator
- Select the mode that matches your lab task.
- Enter kinetic constants, concentration values, or dilution data.
- Keep units consistent across related inputs.
- Press calculate to display results above the form.
- Review the Plotly graph for saturation or dilution behavior.
- Download CSV or PDF outputs for reporting and sharing.
FAQs
1) What does this calculator actually solve?
It solves substrate concentration from enzyme rate data, predicts velocity from concentration, converts mass concentration to molarity, and adjusts concentration after dilution.
2) Why must observed rate stay below Vmax?
The rearranged kinetics equation contains Vmax minus observed rate in the denominator. If rate reaches or exceeds Vmax, the calculation becomes unstable or physically invalid.
3) When should I use Km in interpretation?
Km helps judge affinity and operating region. When substrate concentration equals Km, the enzyme runs at half of Vmax under simple Michaelis–Menten assumptions.
4) Can I account for diluted samples?
Yes. In the substrate-from-rate mode, enter the dilution factor. The page reports assay concentration and the original concentration before dilution.
5) How do mass units affect molarity?
Mass units are first converted into g/L. After that, the concentration is divided by molecular weight to obtain molarity in chemically meaningful units.
6) What happens when substrate concentration is much larger than Km?
The reaction approaches saturation. Velocity moves closer to Vmax, and extra substrate produces smaller incremental gains in reaction speed.
7) Why does the graph flatten at higher concentrations?
The flattening shows enzyme saturation. Once most active sites are occupied, velocity increases slowly because catalytic capacity becomes the main limit.
8) Are these outputs enough for formal reports?
They are useful for screening, teaching, and draft calculations. For regulated work, confirm assumptions, units, calibration, and experimental design before final reporting.