<prompt> Substitution of which one of the following amino acids in place of alanine would increase the absorbance of proteins at 280 mm:LeucineArginineTryptophanProtein  <response>: The only amino acids that may absorb light are Aromatic amino acids i.e. Tryptophan, Tyrosine, Phenylalanine Histidine- Most a.a do not absorb visible light are thus colourless- Aromatic aminoacids absorb ultraviolet light 250- 290 nm.- Tryptophan makes major contribution to ability of most proteins to absorb light in the region of 280 nm. 