Effect of dephosphorylation on calcium binding to αs1-casein-enriched protein

IF 3.1 3区农林科学 Q2 FOOD SCIENCE & TECHNOLOGY

International Dairy Journal Pub Date : 2024-07-02 DOI:10.1016/j.idairyj.2024.106030

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Abstract

The calcium binding to enriched α_s1-casein (71 % α_s1-casein on a protein basis) that was native or dephosphorylated to different extents was studied using a calcium ion selective electrode and at an ionic strength comparable to that found in milk. The calcium binding to α_s1-casein decreased as the level of dephosphorylation was increased. Langmuir adsorption modelling of the calcium binding gave the maximum calcium binding and calcium binding affinity for the native α_s1-casein and progressively dephosphorylated α_s1-casein. This evaluation indicated that the number of calcium binding sites on α_s1-casein decreased as dephosphorylation increased; however, the affinity for any remaining calcium binding sites was unchanged. Correlations were observed between calcium binding of native and dephosphorylated α_s1-casein with the calculated charge at pH 7.0, or the calculated or experimentally determined isoelectric pH of the α_s1-casein. Understanding the calcium binding to native and dephosphorylated α_s1-casein is important in understanding casein association in systems such as natural and artificial casein micelles.

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去磷酸化对αs1-酪蛋白富集蛋白钙结合的影响

使用钙离子选择性电极，在与牛奶中离子强度相当的条件下，研究了原生或不同程度去磷酸化的富集αs1-酪蛋白（αs1-酪蛋白的蛋白质含量为71%）与钙的结合情况。随着去磷酸化程度的增加，钙与αs1-酪蛋白的结合率下降。钙结合的朗缪尔吸附模型给出了原生αs1-酪蛋白和逐渐去磷酸化的αs1-酪蛋白的最大钙结合力和钙结合亲和力。这项评估表明，随着去磷酸化程度的增加，αs1-酪蛋白上钙结合位点的数量也在减少；但是，剩余的钙结合位点的亲和力却没有变化。原生αs1-酪蛋白和去磷酸化αs1-酪蛋白的钙结合与 pH 值 7.0 时的计算电荷或计算或实验测定的αs1-酪蛋白等电点 pH 值之间存在相关性。了解钙与原生αs1-酪蛋白和去磷酸化αs1-酪蛋白的结合对了解天然和人工酪蛋白胶束等系统中的酪蛋白关联非常重要。

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来源期刊

International Dairy Journal 工程技术-食品科技

CiteScore

6.50

自引率

9.70%

发文量

200

审稿时长

49 days

期刊介绍： The International Dairy Journal publishes significant advancements in dairy science and technology in the form of research articles and critical reviews that are of relevance to the broader international dairy community. Within this scope, research on the science and technology of milk and dairy products and the nutritional and health aspects of dairy foods are included; the journal pays particular attention to applied research and its interface with the dairy industry. The journal''s coverage includes the following, where directly applicable to dairy science and technology: • Chemistry and physico-chemical properties of milk constituents • Microbiology, food safety, enzymology, biotechnology • Processing and engineering • Emulsion science, food structure, and texture • Raw material quality and effect on relevant products • Flavour and off-flavour development • Technological functionality and applications of dairy ingredients • Sensory and consumer sciences • Nutrition and substantiation of human health implications of milk components or dairy products International Dairy Journal does not publish papers related to milk production, animal health and other aspects of on-farm milk production unless there is a clear relationship to dairy technology, human health or final product quality.