Solid-phase synthesis of O-mannosylated peptides: two strategies compared

Area of Science:

• * Peptide chemistry and glycobiology.

Background:

• * O-glycosylation is a crucial post-translational modification impacting protein function.
• * Synthesizing homogeneous glycopeptides remains challenging for biochemical and biomedical applications.

Purpose of the Study:

• * To compare two distinct strategies for O-glycosylated peptide synthesis: direct glycosylation of resin-bound peptides versus incorporating pre-glycosylated amino acids.
• * To evaluate the efficiency and applicability of established chemical methods for both approaches.

Main Methods:

• * Employed Fmoc/tert-butyl based protecting groups for peptide synthesis.
• * Utilized Koenigs-Knorr glycosylations with protected bromomannose derivatives.
• * Investigated glycosylation of threonine and serine residues, both in solution and on solid-phase resin.
• * Characterized resulting glycopeptides using glycosidases and mass spectrometry.

Main Results:

• * Demonstrated the feasibility of both direct O-glycosylation of resin-bound peptides and the use of glycosylated amino acids.
• * Optimized conditions for Koenigs-Knorr glycosylation on solid-phase supports.
• * Successfully characterized microgram quantities of synthesized glycopeptides.

Conclusions:

• * Both investigated methods are effective for synthesizing O-glycosylated peptides.
• * The incorporation of glycosylated amino acids provides a robust alternative for glycopeptide synthesis.
• * Established chemical methodologies are suitable for producing glycopeptides for further characterization and application.