Dresden 2020 – scientific programme

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BP: Fachverband Biologische Physik

BP 22: Single Molecule Biophysics (joint session BP/CPP)

BP 22.2: Talk

Wednesday, March 18, 2020, 09:45–10:00, SCH A251

Magnetic Tweezers Protein Force Spectroscopy — •Jan Lipfert¹, Achim Löf¹, Philipp Walker¹, Steffen Sedlak¹, Sophia Gruber¹, Tobias Obser², Maria Brehm², and Martin Benoit¹ — ¹Department of Physics, LMU Munich — ²Department of Pediatric Hematology and Oncology, University Medical Center Hamburg Eppendorf

The physiological function of proteins is often critically regulated by mechanical forces acting on them. Single-molecule manipulation techniques such as atomic force microscopy or optical tweezers have enabled unprecedented insights into the molecular mechanisms underlying such force regulation. However, these techniques have limited throughput and lack resolution at low forces. We have developed a versatile and modular approach for force measurements on proteins in magnetic tweezers [Löf et al. PNAS 2019] that enables ultra-stable (> days) and parallel measurements (> 50) of single molecules in a wide force range including very low forces (<1 pN). Leveraging our new assay, we directly probe regulatory low-force transitions within von Willebrand factor, a vascular protein that is activated for its critical role in hemostasis by hydrodynamic forces in the bloodstream. Or results reveal fast (~250 ms) opening and closing transitions in the dimeric VWF stem at a critical force of 1 pN, which like constitute the first steps in VWF mechano-activation.