383 Chemoenzymatic Synthesis of Glycosylphosphatidylinositol (GPI)-Anchored Peptides/Glycopeptides and Proteins/Glycoproteins

Friday, November 6, 2009: 2:30 PM
Angus (Camino Real Hotel)
Zhimeng Wu , Department of Chemistry, Wayne State University, Detroit, MI
Xueqing Guo , Department of Chemistry, Wayne State University, Detroit, MI
Zhongwu Guo , Department of Chemistry, Wayne State University, Detroit, MI

Glycosylphosphatidylinositol (GPI)-anchoring of cell surface proteins and glycoproteins onto cell membranes is ubiquitous in eukaryotic species, and GPI-anchored proteins and glycoproteins play a vital role in various biological processes.  To study the functions of GPI-anchored proteins and glycoproteins at the molecular level, it is necessary to have access to these structures and their derivatives in homogeneous forms and in sufficient quantity, which is currently difficult to achieve by either biological or chemical means. This programs aims to develop a feasible method for the preparation of GPI-anchored proteins and glycoproteins based on chemoenzymatic methodologies. For this purpose, sortase A (SrtA) of Staphylococcus aureus origin, which can recognize a pentapeptide LPXTG sequence near the C-terminus of proteins (Scheme), break the peptide bond between T and G and finally link the newly formed C-terminus of target proteins to an amino group as nucleophile, was explored for the potential applications to coupling peptides and glycopeptides or proteins and glycoproteins to GPI anchors.  It has been demonstrated that SrtA could efficiently conjugate peptides and glycopeptides to GPI derivatives with a glycine residue attached to the phosphoethanolamine group at the GPI carbohydrate chain nonreducing end.