Protein Molecular Weight, pI & Extinction Coefficient
Calculate the molecular weight, isoelectric point, net charge, extinction coefficient and amino acid composition of a protein sequence.
How to use the Protein Molecular Weight, pI & Extinction Coefficient
- Enter or select: Protein sequence (one-letter codes), pH for net charge.
- The results (Length, Molecular weight, Isoelectric point pI, Net charge at pH, Extinction coeff. (280 nm, reduced), Abs 0.1% (1 g/L), Composition) are calculated instantly as you type.
- Use “Copy link” to share the calculation with the same input values.
Formula
- MW = Σ residue masses + H₂O
- ε₂₈₀ = 5500·n(W) + 1490·n(Y)
- pI: pH where net charge = 0 (EMBOSS pKa values)