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  • Universal method for protein immobilization on chemically functionalized germanium investigated by ATR-FTIR difference spectroscopy.

Universal method for protein immobilization on chemically functionalized germanium investigated by ATR-FTIR difference spectroscopy.

Journal of the American Chemical Society (2013-02-19)
Jonas Schartner, Jörn Güldenhaupt, Bastian Mei, Matthias Rögner, Martin Muhler, Klaus Gerwert, Carsten Kötting
摘要

Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy allows a detailed analysis of surface attached molecules, including their secondary structure, orientation, and interaction with small molecules in the case of proteins. Here, we present a universal immobilization technique on germanium for all oligo-histidine-tagged proteins. For this purpose, new triethoxysilane derivates were developed: we synthesized a linker-silane with a succinimidyl ester as amine-reactive headgroup and a matrix-silane with an unreactive ethylene glycol group. A new methodology for the attachment of triethoxysilanes on germanium was established, and the surface was characterized by ATR-FTIR and X-ray photoelectron spectroscopy. In the next step, the succinimidyl ester was reacted with aminonitrilotriacetic acid. Subsequently, Ni(2+) was coordinated to form Ni-nitrilotriacetic acid for His-tag binding. The capability of the functionalized surface was demonstrated by experiments using the small GTPase Ras and photosystem I (PS I). The native binding of the proteins was proven by difference spectroscopy, which probes protein function. The function of Ras as molecular switch was demonstrated by a beryllium trifluoride anion titration assay, which allows observation of the "on" and "off" switching of Ras at atomic resolution. Furthermore, the activity of immobilized PS I was proven by light-induced difference spectroscopy. Subsequent treatment with imidazole removes attached proteins, enabling repeated binding. This universal technique allows specific attachment of His-tagged proteins and a detailed study of their function at the atomic level using FTIR difference spectroscopy.

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Sigma-Aldrich
锗, powder, −100 mesh, ≥99.99% trace metals basis
Sigma-Aldrich
锗, chips, 99.999% trace metals basis