Effect of enzymatic deamidation of soy protein by protein-glutaminase on the flavor-binding properties of the protein under aqueous conditions

Inthawoot Suppavorasatit, Keith R. Cadwallader

Research output: Contribution to journalArticle

Abstract

The effect of the enzymatic deamidation by protein-glutaminase (PG) on flavor-binding properties of soy protein isolate (SPI) under aqueous conditions was evaluated by a modified equilibrium dialysis (ultrafiltration) technique. Binding parameters, such as number of binding sites (n) and binding constants (K), were derived from Klotz plots. The partial deamidation of SPI by PG (43.7% degree of deamidation) decreased overall flavor-binding affinity (nK) at 25 °C for both vanillin and maltol by approximately 9- and 4-fold, respectively. The thermodynamic parameters of binding indicated that the flavor-protein interactions were spontaneous (negative ΔG°) and that the driving force of the interactions shifted from entropy to enthalpy driven as a result of deamidation. Deamidation of soy protein caused a change in the mechanism of binding from hydrophobic interactions or covalent bonding (Schiff base formation) to weaker van der Waals forces or hydrogen bonding.

Original languageEnglish (US)
Pages (from-to)7817-7823
Number of pages7
JournalJournal of Agricultural and Food Chemistry
Volume60
Issue number32
DOIs
StatePublished - Aug 15 2012

Keywords

  • flavor binding
  • maltol
  • protein deamidation
  • protein-glutaminase
  • soy protein
  • thermodynamics of binding
  • vanillin

ASJC Scopus subject areas

  • Chemistry(all)
  • Agricultural and Biological Sciences(all)

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