A PEGylated Photocleavable Auxiliary Mediates the Sequential Enzymatic Glycosylation and Native Chemical Ligation of Peptides

Abstract

Research aimed at understanding the specific role of glycosylation patterns in protein function would greatly benefit from additional approaches allowing direct access to homogeneous glycoproteins. Here the development and application of an efficient approach for the synthesis of complex homogenously glycosylated peptides based on a multifunctional photocleavable auxiliary is described. The presence of a PEG polymer within the auxiliary enables sequential enzymatic glycosylation and straightforward isolation in excellent yields. The auxiliary-modified peptides can be directly used in native chemical ligations with peptide thioesters easily obtained via direct hydrazinolysis of the respective glycosylated peptidyl resins and subsequent oxidation. The ligated glycopeptides can be smoothly deprotected via UV irradiation. Here we apply this approach to the preparation of variants of the epithelial tumor marker MUC1 carrying one or more Tn, T or sialyl-T antigens.

Solid‐State NMR of PEGylated Proteins

“…Research on biologics is progressing towards the targeting of protein-protein interactions,w hich requires an even tighter control over the PEGylation processes. [46,47] The possibility of structurally characterizing PEGylated proteins represents ap owerful tool for pushing the envelope of structural biology applications to biologics. ), [35] where lysine residues are highlighted in red.…”

Just a spoonful of sugar: Short glycans affect protein properties and functions

“…Recent reviews describe very well the great advances in the field, particularly in the synthesis of N‐linked glycoproteins carrying complex antennary structures . Moreover, various efficient methodologies for the preparation of homogeneous O‐linked glycopeptides and glycoproteins have been recently developed, furnishing useful tools for biological studies and for potential therapeutic applications, such as cancer vaccines . Also, short, nonconventional N‐linked glycans that can be mainly found in bacteria and archaea have attracted attention for their possible interactions in binding events related to infections.…”

All about that Amide Bond: The Sixth Chemical Protein Synthesis (CPS) Meeting

“…Christian Becker (University of Vienna, Austria) and Carlo Unverzagt (University of Bayreuth, Germany) described tackling these challenges with two different strategies that have expanded chemical access to glycosylated proteins. The Becker group recently reported a synthetic method for glycosylated protein ligation based on a PEGylated photocleavable auxiliary, and demonstrated its utility by generating a library of site‐selectively O‐glycosylated MUC1 variants with different glycosylation patterns . Unverzagt shared his group's progress toward the extremely challenging semisynthesis of biologically active glycoforms of human IL‐6 by NCL of recombinant and synthetic glycoprotein fragments.…”