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Enzyme Activity Calculator

Compute enzyme activity in U/mL from the rate of absorbance change in a spectrophotometric assay using the Beer-Lambert law. One unit (U) is conventionally the amount of enzyme converting 1 µmol of substrate per minute.

Change in Absorbance (ΔA/min)

Path Length (cm)

Extinction Coefficient (M⁻¹cm⁻¹)

Sample Volume (ml)

Fill in the required fields to see your result.

Biology

Protein Extinction Coefficient Calculator

Estimates a protein's molar extinction coefficient at 280 nm from its tryptophan, tyrosine, and cysteine residue counts. Used to calculate protein concentration from UV absorbance measurements.

Tryptophan Count (residues)

Tyrosine Count (residues)

Cysteine Count (residues)

Fill in the required fields to see your result.

Key differences

	Enzyme Activity Calculator	Protein Extinction Coefficient Calculator
Category	Biology	Biology
Inputs required	4	3
Result	Enzyme Activity (U/ml)	Extinction Coefficient (M⁻¹cm⁻¹)
What it does	Compute enzyme activity in U/mL from the rate of absorbance change in a spectrophotometric assay using the Beer-Lambert law. One unit (U) is conventionally the amount of enzyme converting 1 µmol of substrate per minute.	Estimates a protein's molar extinction coefficient at 280 nm from its tryptophan, tyrosine, and cysteine residue counts. Used to calculate protein concentration from UV absorbance measurements.