Practice question

Molar extinction at 280 nm for individual aromatic amino acids determined from free amino acid spectra in neutral pH water. Published values approximate phenylalanine 200, tyrosine 1490, tryptophan 5500-5600 M-1 cm-1, making tryptophan strongest contributor to protein A280. Variations arise from solvent polarity, pH and nearest neighbor effects in polypeptide chain. Among provided choices 3000 represents order magnitude closest to true value, emphasizing tryptophan dominance compared with others near 1000-2000. Knowledge of these coefficients enables calculation of protein extinction from sequence using Edelhoch method, essential for concentration determination without standard curve.