Browsing by Author "Wijeratne, Sitara"

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    Force Activation of a Multimeric Adhesive Protein through Domain Conformational Change
    (2013-07-24) Wijeratne, Sitara; Kiang, Ching-Hwa; Tao, Yizhi Jane; Kono, Junichiro
    The force-induced activation of adhesive proteins such as von Willebrand Factor (VWF), which experience high hydrodynamic forces, is essential in initiating platelet adhesion. The importance of the mechanical force induced functional change is manifested in the multimeric VWF’s crucial role in blood coagulation, when high fluid shear stress activates pVWF multimers to bind platelets. Here we showed that a pathological level of high shear flow exposure of pVWF multimers results in domain conformational changes, and the subsequent shifts in the unfolding force allow us to use force as a marker to track the dynamic states of multimeric VWF. We found that shear-activated pVWF multimers (spVWF) are more resistant to mechanical unfolding than non-sheared pVWF multimers, as indicated in the higher peak unfolding force. These results provide insight into the mechanism of shear-induced activation of pVWF multimers.
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    Understanding the physics of DNA using nanoscale single-molecule manipulation
    (Springer, 2012) Frey, Eric W.; Gooding, Ashton A.; Wijeratne, Sitara; Kiang, Ching-Hwa
    Processes for decoding the genetic information in cells, including transcription, replication, recombination and repair, involve the deformation of DNA from its equilibrium structures such as bending, stretching, twisting, and unzipping of the double helix. Single-molecule manipulation techniques have made it possible to control DNA conformation and simultaneously detect the induced changes, revealing a rich variety of mechanically-induced conformational changes and thermodynamic states. These single-molecule techniques helped us to reveal the physics of DNA and the processes involved in the passing on of the genetic code.