A comparative study of cyclization strategies applied to the synthesis of head-to-tail cyclic analogs of a viral epitope

J Pept Res. 1999 Jan;53(1):56-67. doi: 10.1111/j.1399-3011.1999.tb01617.x.

Abstract

A family of head-to-tail cyclic peptide models of the antigenic site A (G-H loop of viral protein 1) of foot-and-mouth disease virus has been designed on the basis of the three-dimensional structure adopted by the linear peptide YTASARGDLAHLTTT upon binding to neutralizing monoclonal antibodies. Three different methods of cyclization have been examined to access the peptides. Solution cyclization of a minimally protected linear precursor provided the expected products but required several purification steps that lowered the yields to approximately 10%. The two other approaches relied on side-chain anchoring of the peptide through the Asp residue and cyclization on the solid phase. A synthetic scheme combining Fmoc, tBu and OAI protections was practicable but inefficient when scaled-up. The combination of Boc, Bzl and OFm protections was more promising, but suffered from high epimerization during the initial esterification of Boc-Asp-OFm to benzyl alcohol-type resins. This problem was solved by performing the esterification via the cesium salt of Boc-Asp-OFm. With this improvement, the Boc/Bzl/OFm has become the method of choice for the preparation of cyclic head-to-tail peptides in satisfactory yields and with minimal purification.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Monoclonal / metabolism
  • Aphthovirus / immunology
  • Capsid / immunology
  • Capsid Proteins
  • Chromatography, High Pressure Liquid
  • Epitopes / chemistry*
  • Epitopes / immunology
  • Models, Molecular
  • Oligopeptides / chemical synthesis
  • Oligopeptides / immunology
  • Peptides, Cyclic / chemical synthesis*
  • Peptides, Cyclic / immunology

Substances

  • Antibodies, Monoclonal
  • Capsid Proteins
  • Epitopes
  • Oligopeptides
  • Peptides, Cyclic