A General Method for Synthesis of GPI Anchors Illustrated by the Total Synthesis of the Low-Molecular-Weight Antigen from Toxoplasma gondii

摘要

Glycosylphosphatidylinositol (GPI) anchors are a class of naturally occurring glycolipids with a conserved core structure : H2N(CH2)2OPO3H-6Manα1→2Manα1→6Manα1→ 4GlcNH2α1→6myo-Ino1-OPO3H-Lipid (Man = mannose; GlcNH2 = glucosamine; Ino = inositol; Scheme 1). GPI anchors are present in all eukaryotic cells and their structures vary in a species dependent manner. Possible modifications of the core structure include: an extra mannose at the non-reducing end of the linear pseudopentasaccharide, branching at the 3 or 4 position of the mannose I, and additional phosphorylations. There are many known variations of the phospholipid moiety of GPI anchors. Additionally, a fatty acid ester may be present at the 2-position of myoinositol.