Enzyme Activity Calculator
Calculate Enzyme Activity
Calculate enzyme activity (U) from amount of product formed per time
Specific Activity & Turnover Number
Calculate specific activity and kcat from enzyme and activity data
Formula
Activity (U) = µmol product / min. Specific activity = U / mg protein. kcat = (Specific activity × MW) / (1000 × 60) in s⁻¹. 1 U = 16.67 nkat.
Frequently Asked Questions
What is an enzyme unit (U)?
One enzyme unit (U) is defined as the amount of enzyme that catalyzes the conversion of 1 µmol of substrate per minute under specified conditions. The SI unit is the katal: 1 U = 16.67 nkat.
What is specific activity?
Specific activity is the enzyme activity per mg of total protein (U/mg). It measures enzyme purity — higher specific activity indicates a purer enzyme preparation.
What is turnover number (kcat)?
Turnover number (kcat) is the number of substrate molecules converted to product per enzyme molecule per second. It reflects the intrinsic catalytic efficiency of the enzyme.
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