WFU Physics Colloquium

TITLE: Mechanism of forced elongation of fibrin

SPEAKER: Professor Valeri Barsegov,

TIME: Wednesday April 18, 2012 at 4:00 PM

PLACE: Room 101 Olin Physical Laboratory

Fibrinogen provides the building blocks for fibrin polymer, the scaffold of blood clots and thrombi. We determined mechanisms of the forced elongation of fibrin(ogen) monomers and oligomers using atomic force microscopy and biomolecular simulations on Graphics Processing Units (GPUs). The 200-fold computational speedup enabled us to follow the unfolding dynamics in the experimental (centisecond) timescale using experimental conditions of force application. Mechanical unraveling of fibrin(ogen) is determined by stepwise unfolding of the C-terminal gamma chain nodules coupled to reversible extension-contraction of the alpha-helical coiled-coil connectors. We found that under the influence of an applied force, the coiled-coils, undergo phase transition to form extended parallel beta-sheets. These results provide important qualitative and quantitative characteristics for fibrin(ogen) nanomechanics at the single-molecule level, and offer new insight into rich dynamic mechanical behavior of fibrin monomers and oligomers and the molecular origin of fibrin viscoelasticity.