期刊
JOURNAL OF NANOPARTICLE RESEARCH
卷 15, 期 9, 页码 -出版社
SPRINGER
DOI: 10.1007/s11051-013-1914-9
关键词
Quantum dots; SpeA; Dimeric protein; Co-assembly; Capillary electrophoresis
资金
- Research Grants Council of Hong Kong (GRF) [CUHK 403711, 404812]
- National Natural Science Foundation of China [81201085, 31100530]
- Science & Technology Support Program of Changzhou (Society Development) [CE20125052]
- Priority Academic Program Development of Jiangsu Higher Education Institutions
How protein-protein interaction affects protein-nanoparticle self-assembly is the key to the understanding of biomolecular coating of nanoparticle in biological fluids. However, the relationship between protein shape and its interaction with nanoparticles is still under-exploited because of lack of a well-conceived binding system and a method to detect the subtle change in the protein-nanoparticle assemblies. Noticing this unresolved need, we cloned and expressed a His-tagged SpeA protein that adopts a bridge-shaped dimer structure, and utilized a high-resolution capillary electrophoresis method to monitor assembly formation between the protein and quantum dots (QDs, 5 nm in diameter). We observed that the bridge-shaped structure rendered a low SpeA:QD stoichiometry at saturation. Also, close monitoring of imidazole (Im) displacement of surface-bound protein revealed a unique two-step process. High-concentration Im could displace surface-bound SpeA protein and form a transient QD-protein intermediate, through a kinetically controlled displacement process. An affinity-driven equilibrium step then followed, resulting in re-assembling of the QD-protein complex in about 1 h. Through a temporarily formed intermediate, Im causes a rearrangement of His-tagged proteins on the surface. Thus, our work showcases that the synergistic interplay between QD-His-tag interaction and protein-protein interaction can result in unique properties of protein-nanoparticle assembly for the first time.
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