A modular fibrinogen model that captures the stress-strain behavior of fibrin fibers.
We tested what to our knowledge is a new computational model for fibrin fiber mechanical behavior. The model is composed of three distinct elements: the folded fibrinogen core as seen in the crystal structure, the unstructured α-C connector, and the partially folded α-C domain. Previous studies have highlighted the importance of all three regions and how they may contribute to fibrin fiber stress-strain behavior. Yet no molecular model has been computationally tested that takes into account the individual contributions of all these regions. Constant velocity, steered molecular dynamics studies at 0.025 Å/ps were conducted on the folded fibrinogen core and the α-C domain to determine their force-displacement behavior. A wormlike chain model with a persistence length of 0.8 nm (Kuhn length = 1.6 nm) was used to model the mechanical behavior of the unfolded α-C connector. The three components were combined to calculate the total stress-strain response, which was then compared to experimental data. The results show that the three-component model successfully captures the experimentally determined stress-strain behavior of fibrin fibers. The model evinces the key contribution of the α-C domains to fibrin fiber stress-strain behavior. However, conversion of the α-helical coiled coils to β-strands, and partial unfolding of the protein, may also contribute.
Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, GA, USA.
Rodney D
RD
Averett
Bryant
B
Menn
Eric H
EH
Lee
Christine C
CC
Helms
Thomas
T
Barker
Martin
M
Guthold
D000818:Animals; D001696:Biomechanical Phenomena; D001777:Blood Coagulation; D002417:Cattle; D004548:Elasticity; D005337:Fibrin / Q000737:chemistry* / Q000378:metabolism*; D005340:Fibrinogen / Q000737:chemistry* / Q000378:metabolism*; D056004:Molecular Dynamics Simulation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D013314:Stress, Mechanical
D005337:Fibrin; D005340:Fibrinogen