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. 1992 May 15;284(Pt 1):137–144. doi: 10.1042/bj2840137

Structural and computational investigations of the conformation of antigenic peptide fragments of human polymorphic epithelial mucin.

M J Scanlon 1, S D Morley 1, D E Jackson 1, M R Price 1, S J Tendler 1
PMCID: PMC1132708  PMID: 1376108

Abstract

Human polymorphic epithelial mucins (PEM) are complex glycoproteins that are associated with breast and ovarian carcinomas. The PEM core protein consists of variable numbers of a tandem repeat sequence which contains a short antigenic hydrophilic region (Pro1-Asp-Thr-Arg-Pro-Ala-Pro7). High-field n.m.r. studies undertaken on antigenic 20- and 11-amino acid fragments of the PEM core protein in dimethyl sulphoxide have identified a type-I beta-turn to be present in the region Pro1-Asp-Thr-Arg4. This region includes and overlaps the identified type-I (Asp2-Thr-Arg4) and type-II (Arg4-Pro-Ala6) epitopes of anti-PEM monoclonal antibodies. The studies indicate that the beta-turn is stabilized by the presence of a salt-bridge interaction between Asp-2 and Arg-4. In order to probe the conformations accessible to the PEM peptides a computational study was undertaken independently on the peptide Pro-Asp-Thr-Arg-Pro using a modified Metropolis Monte Carlo algorithm. This study identified the n.m.r.-observed salt-bridge type-I beta-turn as the major low-energy conformer. These results suggest that this structural motif may be involved in the immune recognition of PEM.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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