Identification and analysis of a conserved immunoglobulin E-binding epitope in soybean G1a and G2a and peanut Ara h 3 glycinins

Ping Xiang, Tom A. Beardslee, Michael G. Zeece, John Markwell, Gautam Sarath

Research output: Contribution to journalArticle

49 Scopus citations


To identify conserved immunoglobulin E (IgE)-binding epitopes among legume glycinins, we utilized recombinant soybean G2a and G2a-derived polypeptide fragments. All of these fusion polypeptides bound IgE, and the C-terminal 94-residue fragment appeared to bind more IgE. Using synthetic peptides we identified S219-N233 (S219 GFAPEFLKEAFGVN233) as the dominant IgE-binding epitope. Alanine scanning of this epitope indicated that six amino acids (E224, F225, L226, F230, G231, and V232) contributed most to IgE binding. Among these amino acids, only G231 of soybean G2a is not conserved in soybean G1a (S234) and peanut Ara h 3 (Q256). Synthetic peptides corresponding to the equivalent regions in G1a and Ara h 3 bound IgE in the order Ara h 3 ≥ soybean G2a > soybean G1a. This sequence represents a new IgE-binding epitope that occurs in a highly conserved region present in legume glycinins. Such IgE-binding sites could provide a molecular explanation for the IgE cross-reactivity observed between soybean and peanut proteins.

Original languageEnglish (US)
Pages (from-to)51-57
Number of pages7
JournalArchives of Biochemistry and Biophysics
Issue number1
StatePublished - Dec 1 2002



  • Alanine scanning
  • Conserved epitope
  • Epitope mapping
  • IgE cross-reactivity
  • Peanut
  • Recombinant proteins
  • Soybean allergens

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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