title: Analysis using fluorescence labeling and mass spectrometry of disulfide-mediated interactions of soy protein when heated.
abstract: It is well-known that disulfide-mediated interactions are important when soy protein is heated, in which soy proteins are dissociated and rearranged to some new forms. In this study, the disulfide bond (SS) linked polymer, which was composed of the acidic (A) polypeptides of glycinin, basic (B) polypeptides of glycinin, and a small amount of α' and α of β-conglycinin, was formed as the major product, accompanied by the formation of SS-linked dimer of B and monomer of A as minor products. The role of sulfhydryl (SH) of different subunits/polypeptides for forming intermolecular SS was investigated. The SH of B in glycinin (Cys298 of G1, Cys289 of G2, Cys440 of G4) was transformed into SS in polymer identified by mass spectrometry analysis. The SH content of polymer was lower than that of glycinin and β-conglycinin subunits when heated. The SH content of B in polymer was lower than that in glycinin subunit, and both of them were decreased by heating. The SH content of A in polymer was increased and higher than that of B in polymer and A in glycinin subunit when heated. These results indicated that the SH of B in glycinin subunit was subjected to not only SH oxidation but also SH-SS exchange (with SS of A) for forming intermolecular SS of polymer. The SH oxidation and SH-SS exchange were proven by the change of SH content for the first time. The SH of B was suggested to be reactive for forming intermolecular SS of polymer.
authors.affiliation: State Key Laboratory of Food Science and Technology and School of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, Jiangsu Province, People's Republic of China.
authors.forename: Qijun
authors.initials: Q
authors.lastname: Ruan
authors.affiliation: State Key Laboratory of Food Science and Technology and School of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, Jiangsu Province, People's Republic of China.
authors.forename: Yeming
authors.initials: Y
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Food Science and Technology and School of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, Jiangsu Province, People's Republic of China.
authors.forename: Xiangzhen
authors.initials: X
authors.lastname: Kong
authors.affiliation: State Key Laboratory of Food Science and Technology and School of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, Jiangsu Province, People's Republic of China.
authors.forename: Yufei
authors.initials: Y
authors.lastname: Hua
mesh_terms: D052179:Antigens, Plant / Q000737:chemistry; D001643:Bridged Bicyclo Compounds; D003545:Cysteine / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D005456:Fluorescent Dyes; D005916:Globulins / Q000737:chemistry; D006358:Hot Temperature; D013058:Mass Spectrometry / Q000379:methods*; D055503:Protein Multimerization; D055314:Seed Storage Proteins / Q000737:chemistry; D030262:Soybean Proteins / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D052179:Antigens, Plant; D001643:Bridged Bicyclo Compounds; D004220:Disulfides; D005456:Fluorescent Dyes; D005916:Globulins; D055314:Seed Storage Proteins; D030262:Soybean Proteins; C013894:beta-conglycinin protein, Glycine max; C011474:glycinin; D003545:Cysteine; C028381:monobromobimane
keywords: cysteine status; sulfhydryl oxidation; sulfhydryl−disulfide exchange