Structural requirements of N-glycosylation of proteins. Studies with proline peptides as conformational probes

作者：Ernst Bause · 发表于：Biochemical Journal · 年份：1983 · DOI：10.1042/bj2090331 · 被引用次数：607 · 研究领域：Glycosylation and Glycoproteins Research、Carbohydrate Chemistry and Synthesis、Chemical Synthesis and Analysis

Conformational aspects of N-glycosylation have been investigated with a series of proline-containing peptides as molecular probes. The results demonstrate that, depending on the position of the imino acid in the peptide chain, dramatic alterations of glycosylation rates are produced, pointing to a critical contribution of the amino acids framing the 'marker sequence' triplet Asn-Xaa-Thr(Ser) on the formation of a potential sugar-attachment site. No glycosyl transfer at all was detectable to those peptides containing a proline residue either in position Xaa or in the next position beyond the threonine of the Asn-sequon on the C-terminal side, whereas the hexapeptide Pro-Asn-Gly-Thr-Ala-Val was glycosylated at a high rate. (Emboldened residues denote the 'marker sequence' that is identical in all the peptides; italicized residues distinguish the positions of proline in the various peptides.) Studies with space-filling models reveal that the lack of glycosyl-acceptor capabilities of Ala(Pro)-Asn-Gly-Thr-Pro-Val might be directly related to their inability to adopt and/or stabilize a turn or loop conformation which permits the catalytically essential interaction between the hydroxy amino acid and the asparagine residue within the 'marker sequence' [Bause & Legler (1981) Biochem. J. 195, 639-644]. This conclusion is supported by circular-dichroism spectroscopic data, which suggest structure-forming potentials in this type of non-acceptor peptides dominating over those that favour ...