Otvos L, Urge L, Xiang Z Q, Krivulka G R, Nagy L, Szendrei G I, Ertl H C
Wistar Institute, Philadelphia, PA 19104.
Biochim Biophys Acta. 1994 Oct 20;1224(1):68-76. doi: 10.1016/0167-4889(94)90114-7.
The immunodominant T helper cell epitopes 31D and VF13N of rabies virus nucleoprotein and glycoprotein, respectively, correspond to peptide sequences AVYTRIMMNGGRLKR and VVEDEGCTNLSGF, and are expressed between amino acids 404-418 and 29-41, of the appropriate proteins. We investigated how internal or external glycosylation affects the biological activity and conformation of the peptides 31D and VF13N. Mid-chain incorporation of maltobiose or N-acetylglucosamine moieties into the asparagine residues greatly diminished the T-cell stimulatory activity in vitro (due to the diminished ability of the glycopeptides to bind to major histocompatibility complex determinants) and reduced the characteristic alpha-helicity of the peptides in aqueous trifluoroethanol solutions. In contrast, addition of maltobiose- or N-acetylglucosamine-coupled asparagines to the N-termini of peptides 31D and VF13N resulted in unchanged T-cell activity. Furthermore, N-terminal glycosylation of peptide 31D, as indicated by the functional assay, decreased the sensitivity of the peptide to degradation in human serum and did not affect the alpha-helical conformation. These data indicate that glycosylation of T-cell epitopes is not a preferable method for the preparation of antagonists, but incorporation of the sugars to appropriate positions may be advantageous in the design of T-cell agonists and peptide-based vaccines.
狂犬病病毒核蛋白和糖蛋白的免疫显性T辅助细胞表位31D和VF13N，分别对应肽序列AVYTRIMMNGGRLKR和VVEDEGCTNLSGF，且在相应蛋白质的氨基酸404 - 418位和29 - 41位之间表达。我们研究了内部或外部糖基化如何影响肽31D和VF13N的生物活性和构象。将麦芽糖或N - 乙酰葡糖胺部分掺入天冬酰胺残基的链中部，在体外极大地降低了T细胞刺激活性（由于糖肽与主要组织相容性复合体决定簇结合的能力降低），并降低了肽在三氟乙醇水溶液中的特征性α - 螺旋度。相比之下，将麦芽糖或N - 乙酰葡糖胺偶联的天冬酰胺添加到肽31D和VF13N的N末端，导致T细胞活性不变。此外，功能测定表明，肽31D的N末端糖基化降低了肽在人血清中的降解敏感性，且不影响α - 螺旋构象。这些数据表明，T细胞表位的糖基化不是制备拮抗剂的优选方法，但将糖掺入适当位置在T细胞激动剂和基于肽的疫苗设计中可能是有利的。
