Disulfide linkage assignment based on reducing electrochemistry and mass spectrometry using a lead electrode

Tyrosine-Reactive Cross-Linker for Probing Protein Three-Dimensional Structures

“…In order to develop a cleavable, selective cross-linker targeting tyrosine residues, the search for suitable reagents began with the urazol compound because of its ability to label tyrosine in proteins as reported previously . Besides, it is well documented that disulfide bond-containing peptide parent ions generate a series of predictable fragmental ions after EC reduction due to the fracture of the disulfide bond . To facilitate the identification of the cross-linked products, a disulfide bond was designed inserting into the novel cross-linker.…”

“…28 Besides, it is well documented that disulfide bond-containing peptide parent ions generate a series of predictable fragmental ions after EC reduction due to the fracture of the disulfide bond. 29 To facilitate the identification of the cross-linked products, a disulfide bond was designed inserting into the novel crosslinker. Therefore, an EC-cleavable cross-linker was designed and synthesized, namely, DBB, which contains two urazol functional groups targeting tyrosine residues in protein and one EC-labile S−S bond (Figure 1).…”

“…Given the feasibility of click-electrochemistry to label tyrosine and the capability of electrochemistry to reduce disulfide bonds, a novel and simple disulfide-containing EC-cleavable cross-linker, namely, [4,4′-( d isulfanediyl b is­(ethane-2,1-diyl)) b is­(1,2,4-triazolidine-3,5-dione)] (DBB), has been designed, synthesized, and characterized to facilitate the identification of tyrosine cross-linked peptides in this study. To the best of our knowledge, DBB represents the first tyrosine-specific cross-linker without using photoirradiation or a metal catalyst, which undoubtedly enhances the capability of XL-MS for probing the 3D structures of proteins and protein complexes, along with mapping PPIs in the future.…”

Electrochemistry for the Chemoselective Modification of Peptides and Proteins

“…However, the variety of redox-active amino acids and similarities in their redox potentials complicate the task of achieving chemo­selective modification (see Figure D), particularly in the context of proteins. There has been, and continues to be, considerable effort devoted to the direct modification of native polypeptide functionality on an analytical scale (e.g., for online mass spectrometry and electrochemical sensors). − With a goal of accelerating the development of targeted and selective functionalization on a preparative scale, the remainder of this Perspective will focus on the few existing methods that strive to meet these criteria, together with key strategies that provide promise for the future development of direct electrochemical functionalization methods.…”

“…This Perspective seeks to identify and highlight the emerging potential of electrochemistry as a modality to further accelerate reaction discovery. Electrochemistry is gaining considerable momentum for small-molecule funtionalization. − However, it remains underexplored as a tool for peptide and protein modification, having, until recently, been primarily employed in an analytical capacity. − This Perspective will outline contemporary advances in electrochemical methods (primarily reported in the past three years) that have been applied to the modification of peptides and proteins on a preparative scale. The review will be organized into three sections based on the manner in which electrochemistry is used to install a given modification: (1) indirect electrochemical approaches to peptide and protein modification, (2) the use of peptide electroauxiliaries, and (3) direct, residue-specific electrochemical modification of peptides and proteins.…”