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MO: Fachverband Molekülphysik

MO 1: Biomolecules

MO 1.5: Vortrag

Montag, 14. März 2011, 11:30–11:45, TOE 317

First-principles study of the conformational space of the NTA His-tag anchoring system for peptide force spectroscopy — •Franziska Schubert, Volker Blum, and Matthias Scheffler — Fritz-Haber-Institut der Max-Planck-Gesellschaft, D-14195 Berlin

For intramolecular force measurements with atomic force microscopy (AFM) a universal anchor system to grab and release the protein of interest is of high relevance [1]. The Ni-NTA His-tag has been proposed as a candidate for such an anchor. In recent years, there have been many experimental studies to analyze the stability and reversibility of the bond between Ni-NTA and Histidine tagged proteins [2]. In our theoretial analysis of the conformational space of the NTA His-tag, we performed prescreenings of the potential energy surface in the gasphase with the OPLS-AA force field potential in the Tinker package. On top of that we use density functional theory with a generalized-gradient functional (PBE) corrected for van der Waals interactions [3] as implemented in the all-electron code FHI-aims [4] to identify the energy hierarchy and lowest conformers. While in a vacuum environment binding to only one imidazole ring is preferred for unprotonated NTA-Ni, the second bond is closed when NTA is protonated or the molecule is solvated in water. To understand the screening mechanisms enhancing the stability of the Ni-imidazole bond, we also investigate the solvation of the molecule in chloroform for different protonation states of NTA. [1] L. Schmitt et al., Biophys. J. 78, 3275 (2000), [2] C. Verbelen et al., J. Mol. Recognit. 20, 490-494 (2007), [3] A. Tkatchenko et al., PRL 102, 7 (2009), [4] V. Blum et al., Comp. Phys. Comm. 180, 2175 (2009)