Colloidal Stability & Conformational Changes in β-Lactoglobulin: Unfolding to Self-Assembly.
Colloidal Stability & Conformational Changes in β-Lactoglobulin: Unfolding to Self-Assembly.
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DOI：
10.3390/ijms160817719
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发表时间：
2015-08-03
影响因子：
5.6
通讯作者：
Lewis EN
中科院分区：
文献类型：
--
作者：
Blake S;Amin S;Qi W;Majumdar M;Lewis EN
本研究通过动态光散射（DLS）、光学显微流变学、拉曼光谱和差示扫描量热法（DSC）对β-乳球蛋白在不同pH值下的解折叠、聚集和相关流变学变化的机制进行了详细的了解。扩散相互作用参数kD出现作为一个准确的预测胶体稳定性与观察到的聚集趋势和流变学的这种蛋白质。在pH 5.5下观察到剧烈的聚集和凝胶化。在此条件下，蛋白质的二级和三级结构同时发生变化。在较高的pH值（7.0和8.5），低聚没有凝胶形成发生。对于这些溶液，三级结构和二级结构的转变是连续的。低频拉曼数据，这是一个很好的指示剂的氢键和结构在水中，已被证明表现出很强的相关性与流变学随温度的演变。这项研究首次表明，这种低频拉曼数据，结合DSC吸热，可以用来去卷积蛋白质展开和聚集/凝胶化。这些发现可能对基于蛋白质的生物治疗药物的开发具有重要意义，其中制剂粘度，聚集和稳定性强烈影响功效，或者在蛋白质结构对功能和感官性能至关重要的食品中。
A detailed understanding of the mechanism of unfolding, aggregation, and associated rheological changes is developed in this study for β-Lactoglobulin at different pH values through concomitant measurements utilizing dynamic light scattering (DLS), optical microrheology, Raman spectroscopy, and differential scanning calorimetry (DSC). The diffusion interaction parameter kD emerges as an accurate predictor of colloidal stability for this protein consistent with observed aggregation trends and rheology. Drastic aggregation and gelation were observed at pH 5.5. Under this condition, the protein’s secondary and tertiary structures changed simultaneously. At higher pH (7.0 and 8.5), oligomerizaton with no gel formation occurred. For these solutions, tertiary structure and secondary structure transitions were sequential. The low frequency Raman data, which is a good indicator of hydrogen bonding and structuring in water, has been shown to exhibit a strong correlation with the rheological evolution with temperature. This study has, for the first time, demonstrated that this low frequency Raman data, in conjunction with the DSC endotherm, can be been utilized to deconvolve protein unfolding and aggregation/gelation. These findings can have important implications for the development of protein-based biotherapeutics, where the formulation viscosity, aggregation, and stability strongly affects efficacy or in foods where protein structuring is critical for functional and sensory performance.