Enzyme Activity Calculator
Calculate enzyme activity (U), determine how much enzyme is needed, and convert between enzyme units and katal.
Select the type of calculation
Target enzyme activity in Units
Enzyme specific activity in Units per mg protein
Amount of enzyme protein in milligrams
Volume of enzyme solution in mL
Protein concentration in mg/mL
What is enzyme activity?
Enzyme activity (U) is the amount of enzyme that catalyzes 1 micromole of substrate per minute under defined conditions. One unit (U) = 1 μmol/min. Specific activity = activity per mg protein (U/mg), measuring enzyme purity. Higher specific activity = purer enzyme.
How do you calculate enzyme activity?
Activity (U) = Specific Activity (U/mg) × Protein (mg). For 10 mg protein at 50 U/mg: Activity = 50 × 10 = 500 U. The volume needed: Volume (mL) = Activity / (Concentration × Specific Activity).
What is katal?
Katal (kat) is the SI unit: 1 kat = 1 mol/s = 60,000,000 U. More common: 1 nkat = 1 nmol/s = 0.06 U. 1 U = 16.67 nkat. Most commercial enzymes still use Units (U).
How do you dilute enzyme solutions?
C1V1 = C2V2 for activity. If you have 1000 U/mL and need 100 U in 10 mL: dilute 1 mL stock to 10 mL. For concentrated enzyme: Volume needed = Desired Activity / (Starting Activity concentration).