Binding sites and structure of peptides bound to SiO2 nanoparticles studied by solution NMR spectroscopy

• Published in: Polymer journal Vol. 50; no. 10; pp. 989 - 996
• Main Authors: Suzuki, Yu, Shindo, Heisaburo
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.10.2018; Nature Publishing Group
• Subjects: 140/131; 631/45; 639/301/357; 639/638/11; Binding sites; Biomaterials; Bioorganic Chemistry; Carboxyl group; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Inorganic materials; Nanoparticles; NMR spectroscopy; Original Article; Peptides; Polymer Sciences; Silicon dioxide; Spectrum analysis; Surfaces and Interfaces; Thin Films; Titanium; Titanium dioxide
• ISSN: 0032-3896; 1349-0540
• DOI: 10.1038/s41428-018-0084-0

Understanding the mechanism of the interaction between inorganic materials and peptides is important for the development of organic/inorganic hybrid materials. The titanium-binding peptide (TBP; Arg1-Lys2-Leu3-Pro4-Asp5-Ala6) has been reported to possess a high binding affinity to SiO 2 as well as TiO 2 surfaces. Here, we report the binding modes and mechanism of the TBP to SiO 2 nanoparticles. To accomplish this objective, we analyzed the binding sites of the TBP to a SiO 2 surface and the structure of the TBP bound to the SiO 2 using solution NMR spectroscopy. Saturation transfer difference (STD) NMR analysis was performed to identify the TBP sites that interact with the SiO 2 surface, and then Arg1 and Asp5 were identified to be in close contact with the SiO 2 surface. The structure of the TBP bound to SiO 2 was well defined, and the Arg1 and Asp5 side chains face in the same direction. The combination of these results validates that the guanidyl group of Arg1 and the carboxyl group of Asp5 interact electrostatically with the silanol groups SiO − and SiOH 2 + on the SiO 2 surface, respectively. The binding mode of TBP/SiO 2 was found to be different from that of the TBP/TiO 2 system, which has been previously reported. Saturation transfer difference (STD) NMR analysis was performed to identify the titanium-binding peptide (TBP) sites that interact with the SiO 2 nanoparticle surface, and then Arg1 and Asp5 were identified to be in close contact with the surface. The structure of the TBP bound to SiO 2 determined by the NOESY measurement was well defined, and the Arg1 and Asp5 side chains face in the same direction. These results validates that the NH 2 + of Arg1 and the COO − of Asp5 interact electrostatically with the SiO − and SiOH 2 + on the SiO 2 surface, respectively.