O-linked glycopeptide epitope containing carbohydrate side-chains characterized.(Brief Article)

2003 FEB 5 - (NewsRx.com & NewsRx.net) -- According to a study from the United States, "To answer the question whether or not T cells to immunodominant protein fragments recognize glycosylated antigens, we synthesized a series of glycopeptides corresponding to peptide 31D a major T-helper cell epitope of the rabies virus nucleoprotein. Thr4 of the epitope is known to allow mono- or disaccharide side-chain substitutions in either alpha- or beta-anomeric configuration without interfering with MHC-binding. To model naturally occurring glycoprotein fragments that carry extended sugar chains, we prepared Fmoc-Ser/Thr-OPfp building blocks containing alpha- and beta-linked linear tri- and heptasaccharides."

"Peptide 31D was synthesized with the complex carbohydrates attached to Thr4, and the T-helper cell activity of the glycopeptides was determined," reported Mare Cudic and colleagues at The Wistar Institute in Philadelphia. "Addition of alpha-linked carbohydrates, that mimic most of the natural O-linked glycoproteins, resulted in a major drop in the T-cell stimulatory ability in a sugar length-dependent manner.

"In contrast," the investigators added, "the cytosolic glycoprotein mimicking beta-linked glycopeptides retained their T-cell stimulatory activity, with the trisaccharide-containing analogue being almost as potent as the unglycosylated peptide. When the peptides were preincubated with diluted human serum, all peptides lost their ability to stimulate the 9C5.D8-H hybridoma."

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