Abstract：
This study investigated impact of high-density lipoprotein (HDL) on thermal aggregation and gelling behavior of myosin in relation to varied pHs. Results revealed that HDL modified myosin structure before and after heating, with distinct effects observed at varied pH. Under pH 5.0, both myosin and HDL-MS exhibited larger aggregates and altered microstructure; at pH 7.0 and 9.0, HDL inhibited myosin aggregation, resulting in enhanced solubility, reduced turbidity and particle size. Comparative analysis of surface hydrophobicity, free sulfhydryl groups and secondary structure highlighted distinct thermal aggregation behavior between MS and HDL-MS, with the latter showing inhibitory effects under neutral or alkaline conditions. Gelation behavior was enhanced at pH 7.0 with maximum strength, hardness, water-holding capacity and rheological properties. Under acidic pH, excessive protein aggregation resulted in increased whiteness and rough microstructure with granular aggregates. Under alkaline pH, gel network structure was weaker, possibly due to higher thermal stability of protein molecules. Scanning electron microscopy revealed expanded HDL protein particles at pH 7.0, accounting for decreased gel strength and altered rheological properties compared with myosin gel. Overall, the results indicated a positive role of HDL at varied pH in regulating thermal aggregation of myosin and further impacting heat-induced gel characteristics.
摘要：
这项研究调查了高密度脂蛋白（HDL）对肌球蛋白的热聚集和胶凝行为与不同pH值的影响。结果表明，HDL在加热前后修饰了肌球蛋白结构，在不同的pH下观察到不同的效果。在pH5.0下，肌球蛋白和HDL-MS均表现出较大的聚集体和改变的微观结构；在pH7.0和9.0下，HDL抑制肌球蛋白的聚集，导致溶解度增强，降低浊度和颗粒大小。表面疏水性的比较分析，游离巯基和二级结构突出了MS和HDL-MS之间明显的热聚集行为，后者在中性或碱性条件下表现出抑制作用。在pH7.0时，凝胶化行为得到增强，具有最大强度，硬度,持水性和流变特性。在酸性pH下，过度的蛋白质聚集导致颗粒聚集体的白度增加和粗糙的微观结构。在碱性pH下，凝胶网络结构较弱，可能是由于蛋白质分子的热稳定性较高。扫描电子显微镜显示，在pH7.0时HDL蛋白颗粒膨胀，与肌球蛋白凝胶相比，凝胶强度降低和流变特性改变。总的来说,结果表明HDL在不同pH值下在调节肌球蛋白的热聚集和进一步影响热诱导的凝胶特性方面具有积极作用。
