Berlin 2001 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 8: Biological Systems

CPP 8.2: Talk

Wednesday, April 4, 2001, 16:05–16:25, 111

Dynamic Force Spectroscopy of the Coordination Bond between a Histidine Tag and Ni - Nitriloacetate — •Matthias Hofmann, Susanne Witt, and Reinhard Guckenberger — Max-Planck-Institute for Biochemistry, Am Klopferspitz 18a, D-82152 Martinsried, Germany

The N - nitrilo-triacetic acid (NTA)/Histag system is a powerful tool in the biosciences for the one-step isolation and purification of gene products. The tetradental ligand NTA forms a hexagonal complex with divalent metal ions (Me²⁺) such as Ni²⁺ occupying four of the six binding sites in the complex. The remaining two binding sites are accessible to electron donor groups. In the case of proteins, these electron donors are the side groups of amino acids such as histidine.
Theoretical studies considering simple models of the underlying energy landscape of binding have suggested that direct experimental access to force profiles should be possible through loading rate dependent force probe experiments (”dynamic force spectroscopy”).
We performed dynamic force spectroscopy experiments at the His tag system with the atomic force microscope (AFM) using the cantilever as a soft spring. The tip was functionalized with a polypeptide containing the histidine stretch, the NTA - groups were chemically attached to the surface. We measured the rupture forces of the coordination bond at varying loading rate.
First results will be presented.