Using magnetic nanoparticles to probe protein damage in ferritin caused by freeze concentration
Using magnetic nanoparticles to probe protein damage in ferritin caused by freeze concentration
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DOI：
10.1063/1.4935261
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发表时间：
2015-11
期刊：
影响因子：
1.6
通讯作者：
E. Chagas;S. Carreira;W. Schwarzacher
中科院分区：
文献类型：
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作者：
E. Chagas;S. Carreira;W. Schwarzacher
我们展示了一种在甘油（一种低温保护剂）存在的情况下监测冻融过程中对蛋白质造成的损伤的方法。在这项工作中，我们合成了在蛋白质铁蛋白 (CMF) 内掺杂 2.5% 钴的磁铁矿纳米粒子，将它们溶解在不同浓度的甘油溶液中，并在高外加场 (5 T) 中冷冻后测量其磁化强度。随着温度升高，观察到样品磁化强度呈阶梯式下降，这对应于随着冷冻浓缩的甘油溶液的粘度下降而布朗弛豫的开始。台阶的位置揭示了蛋白质流体动力学半径的变化，我们将其归因于蛋白质展开，而其高度取决于冷冻浓缩过程中被冰捕获的蛋白质数量。蛋白质流体动力学半径的变化通过动态光散射 (DLS) 测量得到证实，但与 DLS 不同的是，磁性测量可以在溶液保持不变的情况下提供流体动力学数据。
We demonstrate a method for monitoring the damage caused to a protein during freeze-thawing in the presence of glycerol, a cryo-protectant. For this work we synthesized magnetite nanoparticles doped with 2.5% cobalt inside the protein ferritin (CMF), dissolved them in different concentration glycerol solutions and measured their magnetization after freezing in a high applied field (5 T). As the temperature was raised, a step-like decrease in the sample magnetization was observed, corresponding to the onset of Brownian relaxation as the viscosity of the freeze-concentrated glycerol solution decreased. The position of the step reveals changes to the protein hydrodynamic radius that we attribute to protein unfolding, while its height depends on how much protein is trapped by ice during freeze concentration. Changes to the protein hydrodynamic radius are confirmed by dynamic light scattering (DLS) measurements, but unlike DLS, the magnetic measurements can provide hydrodynamic data while the solution remains ...