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Pressure–Temperature Stability, Ca2+ Binding, and Pressure–Temperature Phase Diagram of Cod Parvalbumin: Gad m 1
- Source :
- Biochemistry. 51:5903-5911
- Publication Year :
- 2012
- Publisher :
- American Chemical Society (ACS), 2012.
-
Abstract
- Fish allergy is associated with IgE-mediated hypersensitivity reactions to parvalbumins, which are small calcium-binding muscle proteins and represent the major and sole allergens for 95% of fish-allergic patients. We performed Fourier transform infrared and tryptophan fluorescence spectroscopy to explore the pressure-temperature (p-T) phase diagram of cod parvalbumin (Gad m 1) and to elucidate possible new ways of pressure-temperature inactivation of this food allergen. Besides the secondary structure of the protein, the Ca(2+) binding to aspartic and glutamic acid residues was detected. The phase diagram was found to be quite complex, containing partially unfolded and molten globule states. The Ca(2+) ions were essential for the formation of the native structure. A molten globule conformation appears at 50 °C and atmospheric pressure, which converts into an unordered aggregated state at 75 °C. At200 MPa, only heat unfolding, but no aggregation, was observed. A pressure of 500 MPa leads to a partially unfolded state at 27 °C. The complete pressure unfolding could only be reached at an elevated temperature (40 °C) and pressure (1.14 GPa). A strong correlation was found between Ca(2+) binding and the protein conformation. The partially unfolded state was reversibly refolded. The completely unfolded molecule, however, from which Ca(2+) was released, could not refold. The heat-unfolded protein was trapped either in the aggregated state or in the molten globule state without aggregation at elevated pressures. The heat-treated and the combined heat- and pressure-treated protein samples were tested with sera of allergic patients, but no change in allergenicity was found.
- Subjects :
- Fish Proteins
Protein Folding
Atmospheric pressure
biology
Protein Stability
Chemistry
Parvalbumins
Temperature
Glutamic acid
Biochemistry
Molten globule
Crystallography
Gadus morhua
Spectroscopy, Fourier Transform Infrared
Pressure
biology.protein
Animals
Humans
Calcium
Spectroscopy
Protein secondary structure
Parvalbumin
Protein Binding
Phase diagram
Subjects
Details
- ISSN :
- 15204995 and 00062960
- Volume :
- 51
- Database :
- OpenAIRE
- Journal :
- Biochemistry
- Accession number :
- edsair.doi.dedup.....da65018b59cd450f95709b19bd0aa249