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Phosphorylation Does Not Improve the Solubility of Rice Protein
Author(s) -
Chen LiYu,
Liu SiChen,
Wang YingZhi,
Ye CaiQing,
Sheu Fuu
Publication year - 2017
Publication title -
cereal chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.558
H-Index - 100
eISSN - 1943-3638
pISSN - 0009-0352
DOI - 10.1094/cchem-02-17-0039-r
Subject(s) - solubility , chemistry , chaotropic agent , phosphorylation , disulfide bond , thiourea , urea , biochemistry , organic chemistry
The present study tried to phosphorylate rice protein (RP), a known insoluble food ingredient, and determine the improvement of its solubility. RP was allowed to react with sodium trimetaphosphate (STMP) at pH 11.5 and 35°C, and the results indicated that 20.6% of the RP seryl residues were phosphorylated. Interestingly, the solubility of phosphorylated RP (2.6%) was not improved compared with that of RP (2.5%) at pH 7. The involvement of hydrophobic interactions and disulfide bonds in phosphorylated RP solubility was further evaluated. The phosphorylation of RP in the presence of urea as a chaotropic agent for weakening the hydrophobic effect resulted in 22.0% phosphoseryl residues but still did not increase RP solubility. The reduction of RP disulfide bonds prior to phosphorylation resulted in 31.3% phosphoseryl residues and increased RP solubility to 8.3% at pH 7, indicating that disulfide bonds within RP could be responsible for the failure to increase its solubility after phosphorylation.