Extinction Coefficient Calculator
Calculate protein extinction coefficient at 280nm for UV absorbance measurements
Input Parameters
Chromophore Contributions
Tryptophan (W)5,500 M⁻¹cm⁻¹
Tyrosine (Y)1,490 M⁻¹cm⁻¹
Cystine (C-C)125 M⁻¹cm⁻¹
Extinction Coefficient (ε₂₈₀)
8,480 M⁻¹cm⁻¹
Results Summary
Sequence Length51 aa
Molecular Weight5.63 kDa
Abs 0.1% (1 mg/mL)1.507
Chromophore Counts
1
Trp (W)
2
Tyr (Y)
0
Cys (C)
About Extinction Coefficient
The extinction coefficient (ε) at 280nm is used to calculate protein concentration using Beer-Lambert law:
A = ε × c × l
Where A is absorbance, c is concentration (M), and l is path length (cm).
The coefficient is calculated from the number of Trp, Tyr, and Cys residues using the Pace method.