AVS 52nd International Symposium
    Biomaterial Interfaces Friday Sessions
       Session BI+SS-FrM

Paper BI+SS-FrM9
Understanding the Elasticity of Fibronectin Fibrils: A Single Molecule Force Spectroscopy Study

Friday, November 4, 2005, 11:00 am, Room 311

Session: Biomaterials Surface Characterization
Presenter: N.I. Abu-Lail, Duke University
Authors: N.I. Abu-Lail, Duke University
T. Ohashi, Duke University
R. Clark, Duke University
H. Erickson, Duke University
S. Zauscher, Duke University
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Although fibronectin (FN) is considered to be one of the most important components of the extracellular matrix, the detailed mechanism of the elasticity of FN fibrils is still unknown. To investigate the molecular origin of FN fibril elasticity we performed single molecule force spectroscopy (SMFS) measurements on a recombinant 1-8FN-III protein construct that contained two green fluorescent protein (GFP) domains spliced in-between the 3FN-III and 4FN-III domains. The relative strengths of both domains were investigated over a wide range of pulling rates (50 nm/s to 1745 nm/s). FN-III domains were distinguished from GFP domains based on their characteristic unfolding distance signature. We found that the mechanical stability of both domains was similar and that the unfolding forces of both domains were linearly related to the logarithm of the pulling rate. An extrapolation of the unfolding forces to small pulling rates showed that the force required to unfold the FN-III domains and GFP domains were undistinguishable and on the order of physiological forces (~10 pN). Our results, combined with earlier fluorescence resonance energy transfer (FRET) studies performed on the same recombinant proteins, suggests (1) that the FN-III domains are most likely bent and looped into a compact conformation in the cell culture and (2) stretching extends their conformation while the domains remain mostly folded.