Co-aggregation of ovalbumin and lysozyme
Co-aggregation of ovalbumin and lysozyme
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DOI：
10.1016/j.foodhyd.2017.01.014
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发表时间：
2017-06
影响因子：
10.7
通讯作者：
Kazuki Iwashita;A. Handa;K. Shiraki
中科院分区：
文献类型：
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作者：
Kazuki Iwashita;A. Handa;K. Shiraki
鸡蛋白色蛋白具有优异的热诱导凝胶特性。然而，由于鸡蛋白色蛋白的复杂组成，其聚集的分子机制尚未阐明。在这里，我们专注于热共聚集过程的主要成分，卵清蛋白（OVA），与充分研究溶菌酶（LYZ）的蛋白质组成，聚集速率，分子间的力量，和形态。通过在70 °C下热处理的OVA-LYZ混合物的尺寸排阻色谱分析表明，在等摩尔OVA存在下，LYZ的聚集速率常数增加64倍。与此相反，卵清蛋白的聚集率不依赖于存在的LYZ。酶法和SDS-PAGE分析表明，LYZ与未折叠的OVA通过可逆的非共价相互作用和不可逆的二硫键形成沉淀。OVA的解折叠通过暴露聚集倾向区域触发共聚集，随后在OVA和LYZ之间进行二硫键交换。LYZ通过二硫键共价连接到小的OVA聚集体，导致具有较大网络的OVA-LYZ聚集体的分层生长。这些结果提供了关于鸡蛋白色中蛋白质的热共聚集的信息。
Hen egg white has excellent heat-induced gelation properties. However, the molecular mechanisms underlying the aggregation of egg white proteins have not been elucidated due to their complex composition. Here, we focused on the thermal co-aggregation process of the main component, ovalbumin (OVA), with well-studied lysozyme (LYZ) in terms of protein composition, aggregation rate, intermolecular forces, and morphology. Size exclusion chromatographic analysis of OVA–LYZ mixture by heat treatment at 70 °C indicated that the aggregation-rate constant of LYZ increased 64-fold in the presence of equimolar OVA. In contrast, the aggregation rate of OVA was not dependent on the presence of LYZ. Enzyme assay and SDS-PAGE analysis showed that LYZ forms precipitates with unfolded OVA via reversible non-covalent interactions and irreversible disulfide bonds. The unfolding of OVA triggers co-aggregation by exposure of the aggregation-prone region, followed by disulfide bond exchange between OVA and LYZ. LYZ links covalently to small OVA aggregates through disulfide bonds, leading to the hierarchical growth of OVA–LYZ aggregates with larger networks. These results provide information regarding the thermal co-aggregation of proteins in hen egg white.