Site Selective Modification of Peptides and Proteins

Abstract

The diazo-coupling reactions of arenediazonium salts with Tyrosine containing peptides have shown a good selectivity to the Tyrosine residues over other competitive amino acids. In addition to that arenediazonium salts are highly reactive, which allows diazo-coupling reaction to happen even at very mild conditions. So, to develop a spectrophotometric detection of the Tyrosine containing peptides, we have synthesized a series of azo-dyes with Tyrosine and calculated their molar absorptivity coefficients. We observed Tyrosine and other aromatic amino acids containing peptides shows higher selectivity of diazocoupling reaction on Tyrosine residue giving yield of 70-80%. We also studied the relative reactivity of different arenediazonium salts with Tyrosine by monitoring the reaction kinetics by using a UV-Vis spectrophotometer.