Major proteins of yam bean tubers

Aldrin V Gomes, Grace Sirju-Charran, Junor A. Barnes

Research output: Contribution to journalArticle

15 Scopus citations


The tuberous roots of the Mexican yam bean, jicama, (Pachyrhizus erosus L, Urban) contained large quantities of two acidic glycoproteins which accounted for more than 70% of the total soluble proteins (about 3 g per 100 g of tuber on a dry weight basis). The two major proteins, tentatively named YBG1 and YBG2, had apparent M,s of 28 000 and 26 000, respectively, by SDS- PAGE. A third protein named YBP22 which accounted for 2-5% of the total soluble proteins had an M(r) of 22 000, YBG1 and YBG2 exhibited great similarity on the basis of their amino acid composition and had identical N- terminal amino acid sequences. The first 23 amino acids in the N-terminal region of YBG2 were DDLPDYVDWRDYGAVTRIKNQGQ which showed strong homology with the papain class of cysteine proteases. YBG1 and YBG2 were found to bind to a Concanavalin A-Sepharose column and were also stained positively by a sensitive glycoprotein stain. Both glycoproteins exhibited cysteine proteolytic activity. In contrast, YBP22 showed sequence homology with several known protease inhibitors, and a polyclonal antibody raised against this protein cross reacted with soybean trypsin inhibitor.

Original languageEnglish (US)
Pages (from-to)185-193
Number of pages9
Issue number2
StatePublished - Sep 1997
Externally publishedYes


  • Fabaceae
  • Mexican yam bean
  • Pachyrhizus erosus L. Urban
  • Protease inhibitor
  • Proteases
  • Storage proteins

ASJC Scopus subject areas

  • Plant Science
  • Biochemistry
  • Molecular Biology
  • Organic Chemistry
  • Drug Discovery

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  • Cite this

    Gomes, A. V., Sirju-Charran, G., & Barnes, J. A. (1997). Major proteins of yam bean tubers. Phytochemistry, 46(2), 185-193.