Calculadora de Beer-Lambert para Proteínas — Fórmula

Protein Concentration from A280

UV absorbance at 280 nm is widely used to measure protein concentration. Aromatic residues (Trp, Tyr) and disulfide bonds absorb at this wavelength.

Formula

c (M) = A280 / (epsilon × l)

c (mg/mL) = c (M) × MW / 1000

The extinction coefficient epsilon can be calculated from the amino acid sequence using tools like ProtParam. Typical values range from 10,000 to 100,000 M⁻¹cm⁻¹.

Ejemplo Resuelto

A protein with epsilon = 43,000 M⁻¹cm⁻¹ and MW = 45 kDa, measured A280 = 1.0 in a 1 cm cuvette.

  1. c = 1.0 / (43000 × 1) = 2.326 × 10⁻⁵ M = 23.26 uM
  2. c = 23.26 × 10⁻⁶ × 45000 / 1000 = 1.047 mg/mL