All of the following Aminoacids absorb light at 280 nm, except:
Phenylalanine, tyrosine and tryptophan are the only protein aminoacids that absorb light at 280 nm. Protein aminoacids that absorb light at 280nm: Tryptophan (single major contributor) Tyrosine Phenylalanine Aromatic amino acids: Absorption of light in the near UV range (Near 280 nm) Three Amino acids, Phenylalanine, tyrosine and tryptophan carry aromatic side chains. Because of the conjugated double-bond system of their aromatic rings, tyrosine, tryptophan and phenylalanine have the unique ability to absorb light in the ultraviolet Range. Only three aminoacids, Phenylalanine, tyrosine and tryptophan, absorb light in the near UV range (Near 280 nm) Tryptophan makes the major contribution to the ability of most proteins to absorb light in the region of 280 nm. Proteins containing these aminoacids will absorb light in UV range. This characteristic ids frequently used for the analytical detection of proteins by measuring absorption at 280 nm. Ref: Harper
Phenylalanine
Tyrosine
Tryptophan
Methionine
Metabolism of protein and amino acid