Ultraviolet spectroscopy of often used to monitor the amount of a protein in a sample, the amount of protein is correlated with the absorbance at 280nm. Explain which of the following amino acids you expect to have an absorption at 280nm, (the carbonyl groups of the peptide [amide] bond of the protein do not absorb at thiswavelength).

NH, NH NH, CH3 CH CHCO,H CH,CHCH,CHCO,H CO,H Leucine Proline Phenylalanine NH2 CH,CHCO,H NH, -HCO,H Serine H. Tryptophan