What this is for: Km and Vmax from initial-rate data via a Lineweaver–Burk fit, with kcat and a predicted rate at any substrate concentration.
The formula: 1/v = (Km/Vmax) × (1/[S]) + 1/Vmax; kcat = Vmax ÷ [E]
How to use:
- Enter the rate data in the first section, one [S],v pair per line, with [S] in mM and v in µM/min.
- Read slope, intercept, Vmax, Km and the R-squared of the Lineweaver–Burk fit, and check both charts — the double-reciprocal plot and your points against the fitted curve.
- Enter the enzyme concentration [E] in µM to get kcat per minute, kcat per second and catalytic efficiency.
- Enter an [S] to predict, in mM, and read the predicted rate v.
Enzyme Kinetics — Michaelis–Menten via Lineweaver–Burk
Enter initial rates v at substrate concentrations [S] — one [S],v pair per line. The sheet fits the double-reciprocal (Lineweaver–Burk) line: slope = Km/Vmax, intercept = 1/Vmax.
Slope = Km/Vmax
Intercept = 1/Vmax
Vmax (µM/min)
Km (mM)
R-squared of the LB fit
Turnover number kcat & rate prediction
µM
mM
kcat = Vmax/[E] (per min)
kcat (per sec)
Catalytic efficiency kcat/Km (per µM per sec)
Predicted v = Vmax[S]/(Km+[S]) (µM/min)
Prefer to work offline or keep a copy? The download link is right below.
Download the Enzyme Kinetics (Michaelis–Menten) workbook (.xlsx)
Download the Enzyme Kinetics (Michaelis–Menten) workbook (.xlsx)
Notes & limits (from the workbook): Lineweaver–Burk weights low-rate points heavily and distorts experimental error — fine for teaching and quick estimates; for publication, fit the Michaelis–Menten equation by nonlinear regression (GraphPad Prism etc.) and report both. Substrate-inhibition or sigmoidal (allosteric) kinetics will show up as a curved LB plot — do not force it. Formulas, exactly as the sheet: slope = SLOPE(1/v, 1/[S]), intercept = INTERCEPT(1/v, 1/[S]), Vmax = 1/intercept, Km = slope/intercept, kcat = Vmax/[E], catalytic efficiency = kcat/(Km in µM), predicted v = Vmax·[S]/(Km+[S]).