How do you calculate the protein extinction coefficient for a given protein sample?

To calculate the protein extinction coefficient for a given protein sample, you can use the formula: Extinction coefficient (Absorbance at 280 nm) / (Concentration of protein in mg/ml). The absorbance at 280 nm can be measured using a spectrophotometer, and the concentration of the protein can be determined using methods such as the Bradford assay or the bicinchoninic acid (BCA) assay.