Chemoproteomic profiling of protein electrophilic and oxidative post-translational modifications

A method for detecting an endogenous electrophilic post-translational modification (PTM) or an endogenous oxidative PTM of at least one protein in a proteomic mixture in a living organism or living cell, the method comprising:

• (i) contacting the proteomic mixture in the living organism or living cell with a probe comprising a hydrazine moiety and an alkyne moiety to form a covalent linkage between the hydrazine moiety of the probe and the endogenous electrophilic PTM or the endogenous oxidative PTM of the at least one protein, thereby forming a mixture comprising at least one alkyne-derivatized protein, wherein the probe having the structure of formula (1) or (2)
• wherein Z=NH and X is a linker selected from the group consisting of alkyl, aryl, and arylamines, wherein the endogenous electrophilic PTM or the endogenous oxidative PTM is a functional modification that affects a biological activity of the at least one protein and is installed onto the at least one protein by dedicated enzyme machinery or by high affinity binding of metabolite-derived small molecules;
• (ii) labelling the at least one alkyne-derivatized protein with an azide-modified tag, optionally in the presence of a copper catalyst, to obtain at least one labelled protein;
• and
• (iii) analyzing the at least one labelled protein to thereby detect the endogenous electrophilic PTM or the endogenous oxidative PTM of the at least one protein.