Major proteins of yam bean tubers

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

Research output: Contribution to journalArticlepeer-review

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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