Details

Autor(en) / Beteiligte

• Mishra, Narendra Kumar
• Østergaard, Mads
• Midtgaard, Søren Roi
• Strindberg, Sophie S
• Winkler, Stefan
• Wu, Shunliang
• Sørensen, Thomas Just
• Hassenkam, Tue
• Poulsen, Jens-Christian N
• Lo Leggio, Leila
• Nielsen, Hanne Mørck
• Arleth, Lise
• Christensen, Niels Johan
• Thulstrup, Peter W
• Jensen, Knud J

Titel

Controlling the fractal dimension in self-assembly of terpyridine modified insulin by Fe and Eu to direct effects

Ist Teil von

• Nanoscale, 2021-05, Vol.13 (18), p.8467-8473

Erscheinungsjahr

2021

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Metal ion-induced self-assembly (SA) of proteins into higher-order structures can provide new, dynamic nano-assemblies. Here, the synthesis and characterization of a human insulin (HI) analog modified at Lys B29 with the tridentate chelator 2,2′:6′,2′′-terpyridine (Tpy) is described. SA of this new insulin analog (Lys B29 Tpy-HI) in the presence of the metal ions Fe 2+ and Eu 3+ at different concentrations was studied in solution by fluorescence luminescence and CD spectroscopy, dynamic light scattering, and small-angle X-ray scattering, while surface assembly was probed by AFM. Unique oligomerization was observed in solution, as Fe 2+ yielded small magenta-colored discrete non-native assemblies, while Eu 3+ caused the formation of large fractal assemblies. Binding of both metal ions to Tpy was demonstrated spectroscopically, and emission lifetime experiments revealed a distinct Eu 3+ coordination geometry that included two water molecules. SAXS suggested that Lys B29 Tpy-HI with Fe 2+ oligomerized to a discrete, roughly octameric species, while Lys B29 Tpy-HI with Eu 3+ gave very large assemblies that could be modelled as fractals. The fractal dimensionality increased with the Eu 3+ concentration. We propose that this is a consequence of Eu 3+ binding to both Tpy and to free carboxylic acid groups on the insulin surface. Lys B29 Tpy-HI maintained insulin receptor affinity, and showed extended blood glucose lowering and plasma concentration after subcutaneous injection in rats. The combination of metal ion directed SA and native SA provides control of nano-scale fractal dimensionality and points towards use in therapeutics. The fractal dimensionality in the self-assembly of insulin-terpyridine conjugates was directed by complexation with metal ions, Fe 2+ vs . Eu 3+ .