Effect of Peptide Glycosylation on the Conformation of the Peptide Backbone

Abstract

Supported by progress in the synthesis of glycopeptides and detailed analyses by NMR in the last decade, a better understanding has developed as to how glycosylation affects the peptide backbone conformation. In short, the attachment of carbohydrate moieties to a peptide affects the three-dimensional structure of the peptide backbone through interactions between the carbohydrate and the peptide portions. Although, superficially, the outcomes range from a real change in the local three-dimensional structure with specific contacts between the carbohydrate and the peptide atoms, which is easy to observe by analytical methods, to a subtle change in the conformational space caused by the excluded volume effect of carbohydrate without specific atomic contacts, which is difficult to observe by analytical methods, it is generally understood that glycosylation has a certain effect on the peptide backbone conformation. The apparent difference in conformational change depends on the structure of the glycosylated amino acid residue, the structure of the attached carbohydrate, and the glycosylation site or the amino acid sequence around it. Long range interactions between the carbohydrate and the peptide portions depend on the larger three-dimentional structure of the peptide or protein. In view of these general perspectives, our own results, obtained for glycosylated calcitonin derivatives, were revisited.