Stability of the allergenic soybean Kunitz trypsin inhibitor

Robin Roychaudhuri, Gautam Sarath, Michael Zeece, John Markwell

Research output: Contribution to journalArticlepeer-review

57 Scopus citations


The soybean Kunitz trypsin inhibitor (SKTI) is a 21.5 kDa allergenic protein that belongs to the family of all antiparallel β-sheet proteins that are highly resistant to thermal and chemical denaturation. Spectroscopic and biochemical techniques such as circular dichroism (CD), ANS fluorescence and proteolysis were used to study its molecular structure under denaturing conditions such as acid and heat to which these allergens are commonly exposed during food processing. Reduction of native SKTI leads to its complete and rapid proteolysis by pepsin in simulated gastric fluid (SGF). Limited proteolysis with chymotrypsin during renaturation after heating showed that the native structure reforms at around 60°C reversing the denaturation. CD spectra revealed that under acid denaturing conditions, SKTI shows major changes in conformation, indicating the possibility of a molten structure. The existence of this intermediate was established by ANS fluorescence studies at different concentrations of HCl. The remarkable stability of SKTI to both thermal and acid denaturation may be important for its role as a food allergen.

Original languageEnglish (US)
Pages (from-to)207-212
Number of pages6
JournalBiochimica et Biophysica Acta - Proteins and Proteomics
Issue number1-2
StatePublished - Jun 1 2004
Externally publishedYes


  • 8-anilino-1-napthalene sulfonate
  • ANS
  • Acid denaturation
  • CD spectra
  • Food allergen
  • SGF
  • SKTI
  • Simulated gastric fluid
  • Thermal renaturation
  • simulated gastric fluid
  • soybean Kunitz trypsin inhibitor

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biophysics
  • Biochemistry
  • Molecular Biology


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