Regensburg 2004 – scientific programme

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SYLS: Life Sciences on the Nanometer Scale - Physics Meets Biology

SYLS 3: Symposium "Life Sciences on the Nanometer Scale - Physics Meets Biology"

SYLS 3.45: Poster

Wednesday, March 10, 2004, 16:00–18:30, B

Optical Tweezers: A Single Molecule Biosensor for molecular DNA manipulation and detection of individual receptors on cells — •A. Sischka¹, K. Toensing¹, A. Grabbe², K. Leffhalm¹, R. Eckel¹, S.D. Wilking³, N. Sewald³, J. Wienands², R. Ros¹, and D. Anselmetti¹ — ¹Experimental Biophysics and Applied Nanosciences, Faculty of Physics, Bielefeld University, Germany — ²Organic and Bioorganic Chemistry, Faculty of Chemistry, Bielefeld University, 33615 Bielefeld, Germany — ³Biochemistry, Faculty of Chemistry, Bielefeld University, 33615 Bielefeld, Germany

We used a compact, single beam optical tweezers system to investigate mechanical properties of double stranded DNA in the presence of different binding ligands. Individual binding modes could be distinguished by analyzing the mechanic response of a lambda-DNA molecule to an applied external force. We compared the effects of the minor groove binder distamycin-A, a major groove binding a-helical peptide, the intercalators ethidium bromide, YO-1 and daunomycin as well as the bisintercalator YOYO-1 on lambda-DNA.

Significant force hysteresis effects occurring during stretching/relaxation cycles with velocities in the range between 100 nm/s and 12,000 nm/s were found for daunomycin and YOYO-1. These time dependent mechanical properties were found to directly reflect the kinetics of the binding and unbinding behaviour.

Futhermore, specific interactions and rupture force properties of an antibody against a receptor on a living chicken-B-cell were successfully measured.