Berlin 2015 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 11: Biomaterials and Biopolymers I (joint BP/CPP)
MM 11.2: Talk
Monday, March 16, 2015, 14:45–15:00, EB 202
Mechanical rupture of mono- and bivalent coordination compounds — •Manuel Gensler1, Christian Eidamshaus2, Arthur Galstyan2, Ernst-Walter Knapp2, Hans-Ulrich Reißig2, and Jürgen P. Rabe1 — 1Department of Physics, Humboldt-Universität zu Berlin — 2Institute of Chemistry and Biochemistry, Freie Universität Berlin
Biomolecular systems are commonly exposed to a manifold of forces, often acting between multivalent ligands. To understand these forces we studied a monovalent and three bivalent pyridine Cu(II) coordination complexes with varying backbone structures. We performed SFM based single-molecule force spectroscopy in aqueous environment and compared results with ab-initio DFT calculations. According to the Kramers-Bell-Evans theory, all interactions show remarkably long rupture lengths of more than 3 Å. We explain this observation by dissociation mechanisms involving hydrogen-bound intermediate states. Additionally we show that most probable rupture forces of the bivalent systems can be larger, but also smaller than those of the monovalent counterpart. In contrast, when our results are extrapolated to forceless conditions, all bivalent systems show lower thermal off-rates. The mechanical stability is not solely determined by binding energy, but also by rupture lengths. Thus both parameters should be considered in the rational design of biomolecular ligands.