Casein precipitation equilibria in the presence of calcium ions and phosphates
Casein precipitation equilibria in the presence of calcium ions and phosphates
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DOI：
10.1016/s0927-7765(03)00018-3
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发表时间：
2003-06-15
影响因子：
5.8
通讯作者：
Velev, OD
中科院分区：
文献类型：
--
作者：
Guo, C;Campbell, BE;Velev, OD
在 pH 5.5 和 7.5 存在或不存在单磷酸盐和多磷酸盐的情况下，研究了钙离子诱导的 β-酪蛋白聚集和沉淀平衡。我们通过假设离子以明确的化学计量比结合来分析数据，导致蛋白质电荷中和并形成微溶复合物。降水曲线与模型非常吻合，显示出预期的较大诱导区和较低 pH 值下较陡的斜率。添加磷酸盐可以更好地沉淀蛋白质，这可以通过涉及磷酸钙微晶形成的机制来解释。这些晶体为蛋白质吸附提供底物，随后酪蛋白胶束交叉结合并形成共沉淀磷酸钙和酪蛋白的坚固聚集体。微晶的形成导致商业级联产物的有效分离，而单独使用 Ca2+ 是不可能实现的。 (C) 2003 Elsevier Science B.V. 保留所有权利。
Calcium ion induced aggregation and precipitation equilibria of beta-casein were studied in the presence or absence of mono- and polyphosphates at pH 5.5 and 7.5. We analyze the data by assuming ion binding at a well-defined stoichiometric ratio, leading to protein charge neutralization and formation of slightly soluble complexes. The precipitation curves are in good agreement with the model, showing the expected larger induction region and steeper slope at the lower pH. The addition of phosphates leads to better precipitation of the protein, which can be explained by a mechanism involving the formation of calcium phosphate microcrystals. These crystals provide a substrate for protein adsorption, with subsequent cross-binding of the casein micelles and formation of sturdy aggregates of co-precipitated calcium phosphate and casein. The crystallite formation leads to effective separations in commercial cascinates, which would be impossible with Ca2+ alone. (C) 2003 Elsevier Science B.V. All rights reserved.