Phosphorylation of egg white proteins by dry-heating in the presence of phosphate
Phosphorylation of egg white proteins by dry-heating in the presence of phosphate
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DOI：
10.1021/jf030043
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发表时间：
2003-11-05
影响因子：
6.1
通讯作者：
Aoki, T
中科院分区：
文献类型：
--
作者：
Li, CP;Salvador, AS;Aoki, T
在有磷酸盐存在的干燥状态下加热，可使食物蛋白磷酸化。将酪蛋白、乳清分离蛋白（WPI）和蛋清蛋白（EWP）在磷酸盐缓冲液中冻干后，在不同温度和pH水平下干热1-5天，EWP的磷酸化程度高于酪蛋白和WPI。当孵育温度从55℃提高到100℃时，pH从7.0降低到3.0，促进EWP的磷酸化。在pH 3.0、85℃条件下，在磷酸盐存在下干加热5 d， EWP的磷含量由0.08%提高到0.64%。EWP的电泳迁移率随磷酸化水平的增加而增加。干热法制备EWP的热诱导聚合不受磷酸盐存在的影响。在pH 3.0 ~ 5.5的干燥加热条件下，虽然EWP的溶解度降低，但在低pH条件下，磷酸化抑制了EWP的不溶性。磷酸化EWP （P-EWP）的磷酸键在pH 2.0 ~ 10.0的范围内是稳定的，并且比蛋核黄素结合蛋白（RfBP）的磷酸酯具有更强的酸稳定性和碱稳定性。P-31核磁共振谱数据表明，P-EWP中除了磷酸酯外，还引入了磷酸二酯和多磷酸键。通过磷酸化提高了EWP的热稳定性，增强了EWP对磷酸钙的增溶能力。
Food proteins were phosphorylated by heating in a dry state in the presence of phosphate. When casein, whey protein isolate (WPI), and egg white proteins (EWP), which were lyophilized from their solutions in a phosphate buffer, were dry-heated at various temperatures and pH levels for 1-5 days, EWP was more highly phosphorylated than casein and WPI. Phosphorylation of EWP was promoted with a decrease of pH from 7.0 to 3.0 when the incubation temperature was raised from 55 to 100 degreesC. The phosphorus content of EWP increased from 0.08 to 0.64% by dry-heating at pH 3.0 and 85 degreesC for 5 days in the presence of phosphate. The electrophoretic mobility of EWP increased with an increase in the phosphorylation level. The heat-induced polymerization of EWP by dry-heating was not affected by the presence of phosphate. Although the solubility of EWP decreased by dry-heating at pH 3.0-5.5, the phosphorylation depressed the insolubilization at low pH. The phosphate bonds in phosphorylated EWP (P-EWP) were stable at pH 2.0-10.0 and were more acid-labile and base-stable than phosphoesters of egg riboflavin-binding protein (RfBP). P-31 NMR spectral data suggested that besides phosphoesters, phosphodiester and polyphosphate bonds were introduced in P-EWP. Heat stability of EWP was improved, and calcium phosphate-solubilizing ability of EWP was enhanced by phosphorylation.