Print Email Facebook Twitter Soy glycinin Influence of pH and ionic strength on solubility and molecular structure at ambient temperatures Title Soy glycinin Influence of pH and ionic strength on solubility and molecular structure at ambient temperatures Author TNO Voeding Lakemond, C.M.M. de Jongh, H.H.J. Hessing, M. Gruppen, H. Voragen, A.G.J. Publication year 2000 Abstract This study describes the relationship between the solubility of glycinin, a major soy protein, and its structural properties at a quaternary, tertiary, and secondary folding level under conditions representative for food products. When the ionic strength is lowered from 0.5 to 0.2 or 0.03, the basic polypeptides shift more to the exterior of the glycinin complex, as determined at pH 7.6 by labeling solvent-exposed lysines, supported by the study of the proteolytic action of clostripain on glycinin. This structural reorganization caused the pH of minimal solubility to shift to higher values. Ultracentrifugational analysis shows that at pH 7.6 and an ionic strength of 0.5 glycinin forms hexameric complexes (11S), whereas at pH 3.8 and at anionic strength of 0.03 glycinin exists as trimers (7S). Intermediate situations are obtained by modulation of pH and ionic strength. The observed quaternary dissociation correlates with an increased amount of nonstructured protein at a secondary level and with changes in tertiary folding as determined using circular dichroism. Tryptophan fluorescence shows no significant structural changes for different ionic strengths but demonstrates a more tightly packed fluorophore environment when the pH is lowered from 7.6 to 3.8. Chemicals / CAS glycinin, 9007-93-6; soybean protein, 9010-10-0; Globulins; Plant Proteins; Soybean Proteins; glycinin, 9007-93-6. Subject GlycininIonic strengthPHSoysoybean proteinvegetable proteinchemistrycircular dichroismfood processingnonhumanosmolarityprotein denaturationprotein quaternary structurestructure analysisGlobulinsHydrogen-Ion ConcentrationOsmolar ConcentrationPlant ProteinsProtein FoldingProtein Structure, QuaternaryProtein Structure, SecondaryProtein Structure, TertiarySolubilitySoybean ProteinsSoybeansThermodynamics To reference this document use: http://resolver.tudelft.nl/uuid:f2547e5a-8e00-45ad-9816-83b13a29f7d1 DOI https://doi.org/10.1021/jf9908695 TNO identifier 953482 ISSN 0021-8561 Source Journal of Agricultural and Food Chemistry, 48 (48), 1985-1990 Document type article Files To receive the publication files, please send an e-mail request to TNO Library.