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Elucidation of structural changes in soy protein isolate upon heating by Raman spectroscopy
Author(s) -
Herrero A. M.,
JiménezColmenero F.,
Carmona P.
Publication year - 2009
Publication title -
international journal of food science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.831
H-Index - 96
eISSN - 1365-2621
pISSN - 0950-5423
DOI - 10.1111/j.1365-2621.2008.01880.x
Subject(s) - protein tertiary structure , raman spectroscopy , protein secondary structure , chemistry , tryptophan , soy protein , solvent , hydrophobic effect , spectroscopy , tyrosine , crystallography , protein structure , organic chemistry , food science , biochemistry , amino acid , physics , quantum mechanics , optics
Summary Changes in protein secondary and tertiary structure of soy protein isolate (SPI) upon heating process were investigated by Raman spectroscopy. SPI refrigerated and heated at 70, 100 and 200 °C was analysed. Non‐significant differences in secondary structure (α‐helix, β‐sheet, unordered and turn) were observed in SPI upon heating at these temperatures. However, comparison of the Raman spectra of SPI refrigerated and heated at 70, 100 and 200 °C reveals changes in hydrophobic group environments. An intensity decreasing trend of the 1340 cm −1 band attributable to tryptophan vibrations was observed, which involves an increase in solvent exposure of tryptophan residues. The spectral results also showed intensity increasing trends for the 1450 and 2935 cm −1 bands of SPI upon heating, which can be ascribed to breaking of hydrophobic contacts and subsequent solvent exposure of the corresponding hydrophobic aliphatic groups. Finally, it was found tertiary structural transitions towards greater proportions of buried tyrosine residues upon heating of SPI.