Researchers from Nina Hartrampf’s group at the University of Zürich, in collaboration with Songlin Wang at the National Magnetic Resonance Facility at Madison, NMRFAM, University of Wisconsin, have published a study in the Journal of the American Chemical Society, unveiling a novel synthesis tag, SynTag, for improving the chemical synthesis of aggregating peptides and proteins. SynTag consists of a six-arginine sequence linked to the target peptide via a cleavable MeDbz linker, offering dual benefits: mitigating sequence-dependent aggregation during solid-phase peptide synthesis, SPPS, and enhancing solubility post-cleavage.
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Addressing Key Challenges in Peptide Synthesis
SPPS enables the production of peptides and proteins with noncanonical amino acids and post-translational modifications, but synthesis efficiency is frequently hindered by peptide aggregation and poor solubility. The Hartrampf and Wang teams addressed these issues by incorporating SynTag into flow-based SPPS, demonstrating its ability to improve synthesis outcomes, reduce aggregation, and enhance solubility across multiple challenging peptide sequences.
Key findings include:
Aggregation Suppression: SynTag shifts the peptide conformation from β-sheet to α-helix, reducing inter- and intrachain interactions that contribute to aggregation.
Enhanced Solubility: The polyarginine tag increases hydrophilicity, facilitating HPLC purification and enabling direct hydrolysis to yield native peptide sequences.
Versatile Applications: SynTag was successfully employed in the synthesis of difficult peptides such as Barstar[75–90], amyloid-β Aβ[27–42], and the MYC transactivation domain, MYC[1–143].
Expanding the Chemical Toolbox
The study marks the first successful combination of automated fast-flow peptide synthesis, AFPS, with native chemical ligation, NCL, enabling the production of full-length MYC[1–143] via a single ligation step. Structural investigations using infrared spectroscopy, IR, and solid-state nuclear magnetic resonance, SSNMR, confirmed that SynTag prevents aggregation by disrupting β-sheet formation, improving peptide synthesis efficiency.
By providing a single, cleavable tag that addresses both aggregation and solubility, SynTag represents a transformative advance in peptide chemistry. Its broad applicability across SPPS and NCL platforms enhances the accessibility of complex peptides and proteins for biochemical and therapeutic applications.
