Title
Heat denaturation of soy glycinin: Influence of pH and ionic strength on molecular structure
Author
Lakemond, C.M.M.
de Jongh, H.H.J.
Hessing, M.
Gruppen, H.
Voragen, A.G.J.
Publication year
2000
Abstract
The 7S/11S glycinin equilibrium as found in Lakemond et al. (J. Agric. Food Chem. 2000, 48, xxxxxxxx) at ambient temperatures influences heat denaturation. It is found that the 7S form of glycinin denatures at a lower temperature than the 11S form, as demonstrated by a combination of calorimetric (DSC) and circular dichroism (CD) experiments. At pH 7.6, at which glycinin is mainly present in the 11S form, the disulfide bridge linking the acidic and the basic polypeptides is broken during heat denaturation. At pH 3.8, at which glycinin has dissociated partly into the 7S form, and at pH 5.2 this disruption does not take place, as demonstrated by solubility and gel electrophoretic experiments. A larger exposure of the acidic polypeptides (Lakemond et al., 2000) possibly correlates with a higher endothermic transition temperature and with the appearance of an exothermic transition as observed with DSC. Denaturation/aggregation (studied by DSC) and changes in secondary structure (studied by far-UV CD) take place simultaneously. Generally, changes in tertiary structure (studied by near-UV CD) occur at lower temperatures than changes in secondary structure. Chemicals/CAS: Globulins; glycinin, 9007-93-6; Plant Proteins; Soybean Proteins
Subject
Glycinin
Heat denaturation
Ionic strength
PH
Protein structure
Soy
polypeptide
vegetable protein
chemistry
circular dichroism
food processing
heat treatment
ionic strength
nonhuman
osmolarity
protein conformation
protein denaturation
protein folding
protein quaternary structure
protein secondary structure
protein tertiary structure
Circular Dichroism
Globulins
Heat
Hydrogen-Ion Concentration
Osmolar Concentration
Plant Proteins
Protein Conformation
Protein Denaturation
Solubility
Soybean Proteins
Soybeans
Thermodynamics
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DOI
https://doi.org/10.1021/jf9908704
TNO identifier
235585
ISSN
0021-8561
Source
Journal of Agricultural and Food Chemistry, 48 (48), 1991-1995
Document type
article