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Converts product-amount or ΔA/min assay data into enzyme units: 1 U = 1 µmol/min = 16.67 nkat, with Beer–Lambert absorbance conversion and linear-window checks. Educational use only.
Execution
Fill in the form, run the tool, and review the result in one place.
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Tool usage guide
The Enzyme Activity Unit Calculator converts enzyme assay data into U (µmol/min) and nkat. Choose product amount plus assay time, or use an absorbance slope with the extinction coefficient, path length, and reaction volume. Educational use only.
Background
A fixed-time enzyme assay produces 6 µmol of product during a 3-minute measurement.
Problem
Find the enzyme activity in U and express the same result in nkat.
How to use
Select Product amount + time, enter 6 for Product Formed and 3 for Assay Time, then set Decimal Places to 2.
mode: amount; productUmol: 6; timeMin: 3; decimalPlaces: 2Outcome
The activity is approximately 2 U (2 µmol/min), equal to 33.33 nkat.
Background
A continuous NADH-coupled assay uses a 1 cm path length and 1 mL reaction volume. The initial absorbance slope is 0.622 ΔA/min, with ε = 6.22 mM⁻¹cm⁻¹.
Problem
Convert the measured absorbance rate into enzyme activity.
How to use
Select Absorbance rate (ΔA/min), enter 0.622 for Absorbance Change, 6.22 for the extinction coefficient, 1 cm for path length, and 1 mL for reaction volume.
One unit is 1 µmol of product formed per minute under the stated assay conditions.
The calculator uses 1 U = 16.67 nkat.
Enter the product formed in µmol and the assay time in minutes.
Enter ΔA/min, the extinction coefficient, path length in cm, and reaction volume in mL.
No. It is intended for education and assay planning, and results depend on valid measurements and assay conditions.
mode: absorbance; deltaAPerMin: 0.622; extinctionCoeff: 6.22; pathLength: 1; volumeMl: 1; decimalPlaces: 2Outcome
The calculator returns approximately 0.1 U (0.1 µmol/min), equal to 1.67 nkat.