Calculate the molecular weight of protein sequences including fusion tags and extinction coefficient at 280 nm.
MW (with H₂O): Σ(residue weights) + 18.02 g/mol
Residue weights (average): G=57.05, A=71.08, V=99.13, L/I=113.16, P=97.12, F=147.18, W=186.21, M=131.20, S=87.08, T=101.10, C=103.14, Y=163.18, H=137.14, D=115.09, E=129.12, N=114.10, Q=128.13, K=128.17, R=156.19
Extinction coefficient (Pace formula): ε₂₈₀ = (nW × 5500) + (nY × 1490) + (nC × 125) M⁻¹cm⁻¹
Assumes all Cys residues are in disulfide bonds (125 per Cys). For reduced Cys, use 0.
A₂₈₀ at 1 mg/mL: ε₂₈₀ / MW × 1000