Solid-phase synthesis of phosphopeptides.

Phosphopeptides are generally prepared by incorporation of suitable, protected phosphoamino acid derivatives during peptide synthesis using routine coupling protocols. The feasibility of chemical synthesis of phosphorylated peptides by Fmoc-SPPS was greatly enhanced by the introduction of the monobenzyl protecting group for the phosphate group. This minimized β-elimination of the phosphate group and made Fmoc-based synthesis of phosphopeptides the preferred synthesis strategy. Described here is our strategy for the synthesis of phosphopeptides attached to the solid support PEGA via a backbone amide linker type. This linker allows removal of side-chain protection groups without releasing the phosphopeptide from the solid support, thus enabling solid-phase-based pull-down reactions and peptide-protein interaction studies.