Colloidal Properties of Recombinant Spider Silk Protein Particles
Colloidal Properties of Recombinant Spider Silk Protein Particles
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DOI：
10.1021/acs.jpcc.6b03957
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发表时间：
2016-08-18
影响因子：
3.7
通讯作者：
Papastavrou, Georg
中科院分区：
文献类型：
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作者：
Helfricht, Nicolas;Doblhofer, Elena;Papastavrou, Georg
以聚阴离子和聚阳离子重组蜘蛛丝蛋白为原料制备了胶体颗粒。这些蜘蛛丝蛋白的氨基酸序列是相同的，除了16个残基含有阳离子或阴离子可电离基团。电泳滴定表明，酸性和碱性氨基酸的质子化对蛋白质颗粒的凝胶迁移率有显著的影响，特别是对它们的零迁移率(PZM)。实验测定的PZM与根据相关氨基酸序列评价的理论值符合得很好。充分应用软粒子的电动理论，全面描述了重组蜘蛛丝蛋白粒子的电动性质与pH和溶液离子强度的关系。在这种形式主义的框架内，蜘蛛丝蛋白颗粒被视为可穿透离子的多孔胶体，并进行了表征。电渗流的有限穿透长度。粒子的差动电动力学性质表明：仅受其外周层的电流体特性控制，外周层的厚度约为10-20 nm。这一发现进一步得到了实验的证实，证明了含有由相反电荷的蜘蛛丝蛋白组成的额外外层的颗粒的电动力学完全因此被支配。通过使用胶体探针原子力显微镜(AFM)技术直接测量所产生的空间力，证实了存在延伸了十分之几纳米网的模糊的、离子可渗透的粒子界面。
Colloidal particles have been prepared from polyanionic and polycationic recombinant spider silk protein. The amino acid sequences of these spider silk proteins are identical except for 16 residues bearing either a cationic or an anionic ionizable group. Electrophoretic titration showed that protonation of the acidic and basic amino acids had significant impact on the electrophoretic mobility of the protein particles and, in particular, on their point of zero mobility (PZM). The experimentally determined PZMs are in good agreement with the themetical values evaluated on the basis of the relevant amino acid sequences. A comprehensive description of the electrokinetic properties of the recombinant spider silk protein particles as a function of pH and solution ionic strength was provided from adequate application of electrokinetic theory for soft particles. Within the framework of this formalism, spider silk protein particles are viewed as porous colloids penetrable for ions and characterized. by a finite penetration length for the eleetroosmotic flow. The differentiated electrokinetic properties of the particles were shown to be :solely governed by the electrohydrodynamic features of their poorly charged outer peripheral layer with a thickness of about 10-20 nm. This finding was further corroborated experimentally by demonstrating that electrokinetics of particles bearing an additional outer layer consisting of oppositely charged spider silk proteins is entirely dominated thereby. The presence of a fuzzy, ion-permeable particle interface with an extension of several tenths of a nanorneter was confirmed by direct Measurement of the resulting steric forces using the colloidal probe atomic force microscopy (AFM) technique.