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Kinetic Assay Analyzer

Upload plate reader time-series data and compute initial reaction rates. Automatic linear region detection, blank subtraction, and path length correction. Data never leaves your browser.

EnzymologyInitial RatesClient-Side

Try it out

Load example kinetic-assay data to see the full workflow

  • Compute initial reaction rates from plate reader kinetic data (absorbance, fluorescence, luminescence)
  • Automatically identify the linear region of time-course data using R² optimization
  • Apply blank subtraction and path length correction to raw plate reader data
  • Compare reaction rates across wells, conditions, or enzyme concentrations
  • Export rates table for downstream Michaelis-Menten or IC50 analysis

Don't use for

  • Michaelis-Menten curve fitting (Km/Vmax) — use the rates from this tool as inputs to a dedicated Km calculator
  • Real-time PCR amplification curves — use the qPCR ΔΔCt tool instead
  • Non-linear time-courses where the linear region cannot be identified

Measuring Initial Rates in Enzyme Kinetics

The initial rate (V₀) is measured during the linear phase of the reaction — typically the first 5-10% of substrate conversion. During this phase:

• [S] ≈\approx [S]₀ (substrate is essentially unchanged) • [P] is small (no significant product inhibition) • The enzyme is saturated at its working [S]

The slope of the time-course during this phase equals V₀. This tool automates the identification of this linear region using R2\text{R}^{2}-based sliding window detection.

Blank Subtraction and Path Length Correction

Two corrections are often needed for plate reader data:

Blank subtraction: Removes background signal from the assay buffer, substrate auto-hydrolysis, or non-enzymatic reactions. Designate wells with no enzyme (or no substrate) as blanks.
Path length correction: Microplate wells have shorter path lengths than 1 cm cuvettes. For Beer-Lambert law calculations (ε\varepsilon, specific activity), divide absorbance by the well path length. Common values: 200 µL in 96-well ≈\approx 0.55 cm; 100 µL ≈\approx 0.29 cm.

Frequently Asked Questions

Next Steps

Plate Readers

Absorbance, fluorescence, and luminescence microplate readers

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Microplates

96-well and 384-well plates for kinetic assays

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