Toward homogeneous erythropoietin: fine tuning of the C-terminal acyl donor in the chemical synthesis of the Cys29-Gly77 glycopeptide domain

J Am Chem Soc. 2009 Apr 22;131(15):5432-7. doi: 10.1021/ja808705v.

Abstract

Described herein is the chemical synthesis of the Cys(29)-Gly(77) glycopeptide domain (22) of erythropoietin. Our initial ligation strategy targeted a C --> N termini condensation between glycopeptide 3 and peptide 4. However, the reaction was hindered by the "unattainable" reactivity, mismatched polarity, and severe aggregation of the (glyco)peptide substrates. In contrast, by tuning the C-terminal acyl donor and using smaller peptide fragments, the Cys(29)-Gly(77) glycopeptide domain of erythropoietin was prepared through unconventional N --> C termini condensation reactions. The use of a p-cyanonitrophenyl ester and the development of a masked thiophenyl ester as acyl donors enabled us to promptly access glycopeptides bearing complex carbohydrates and offer potential synthetic applications beyond our current work.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acylation
  • Erythropoietin / chemical synthesis*
  • Glycopeptides / chemical synthesis*
  • Peptide Fragments / chemical synthesis*
  • Phenylacetates
  • Polysaccharides
  • Protein Structure, Tertiary

Substances

  • Glycopeptides
  • Peptide Fragments
  • Phenylacetates
  • Polysaccharides
  • Erythropoietin
  • thiophenyl acetate