title: Investigation of the heparin-thrombin interaction by dynamic force spectroscopy.
abstract: BACKGROUND
  The interaction between heparin and thrombin is a vital step in the blood (anti)coagulation process. Unraveling the molecular basis of the interactions is therefore extremely important in understanding the mechanisms of this complex biological process.
  
  
  METHODS
  In this study, we use a combination of an efficient thiolation chemistry of heparin, a self-assembled monolayer-based single molecule platform, and a dynamic force spectroscopy to provide new insights into the heparin-thrombin interaction from an energy viewpoint at the molecular scale.
  
  
  RESULTS
  Well-separated single molecules of heparin covalently attached to mixed self-assembled monolayers are demonstrated, whereby interaction forces with thrombin can be measured via atomic force microscopy-based spectroscopy. Further these interactions are studied at different loading rates and salt concentrations to directly obtain kinetic parameters.
  
  
  CONCLUSIONS
  An increase in the loading rate shows a higher interaction force between the heparin and thrombin, which can be directly linked to the kinetic dissociation rate constant (koff). The stability of the heparin/thrombin complex decreased with increasing NaCl concentration such that the off-rate was found to be driven primarily by non-ionic forces.
  
  
  CONCLUSIONS
  These results contribute to understanding the role of specific and nonspecific forces that drive heparin-thrombin interactions under applied force or flow conditions.
authors: Department of Chemical and Life Science Engineering, Virginia Commonwealth University, Richmond VA 23284, United States.
authors: Congzhou
authors: C
authors: Wang
authors: Department of Medicinal Chemistry, Institute for Structural Biology and Drug Discovery, Virginia Commonwealth University, Richmond, VA 23298, United States.
authors: Yingzi
authors: Y
authors: Jin
authors: Department of Medicinal Chemistry, Institute for Structural Biology and Drug Discovery, Virginia Commonwealth University, Richmond, VA 23298, United States.
authors: Umesh R
authors: UR
authors: Desai
authors: Department of Chemical and Life Science Engineering, Virginia Commonwealth University, Richmond VA 23284, United States. Electronic address: vyadavalli@vcu.edu.
authors: Vamsi K
authors: VK
authors: Yadavalli
mesh_terms: D000925:Anticoagulants / Q000138:chemical synthesis / Q000378:metabolism*; D001665:Binding Sites; D006493:Heparin / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D018625:Microscopy, Atomic Force; D008954:Models, Biological; D011485:Protein Binding; D012965:Sodium Chloride / Q000737:chemistry; D013057:Spectrum Analysis; D013438:Sulfhydryl Compounds / Q000138:chemical synthesis / Q000378:metabolism*; D013499:Surface Properties; D013917:Thrombin / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000925:Anticoagulants; D013438:Sulfhydryl Compounds; D012965:Sodium Chloride; D006493:Heparin; D013917:Thrombin
keywords: Atomic force microscopy; Force spectroscopy; Heparin; Self-assembled monolayers; Thrombin
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