title: Interactions mediated by the N-terminus of fibrinogen's Bbeta chain.
abstract: Specific molecular interactions mediated by the N-terminus of fibrinogen's Bbeta chain were revealed using laser tweezers-based force spectroscopy. We examined interactions between fibrinogen fragments representing the center of the molecule, NDSK, desA-NDSK, and desAB-NDSK, and two recombinant fibrinogens, gammaD364H and gammaD364A, which have nonfunctional gamma-chain polymerization sites to prevent the dominant knob-hole binding. Interactions between desA-NDSK, where the N-terminus of the Bbeta chain is present, and the fibrinogen variants showed a complex spectrum of rupture forces which disappeared with desAB-NDSK, lacking both FpA and FpB. The interactions between desA-NDSK and gammaD364H or gammaD364A were inhibited by addition of soluble FpB, but not FpA or the polymerization inhibitor peptides GPRP and GHRP. When gammaD364H fibrinogen was replaced with its X-fragment lacking alphaC- domains or with fragment D, the strongest component of the rupture force spectrum disappeared, suggesting interactions between the uncleaved FpB and the alphaC-domain. Electron microscopy confirmed the binding of desA-NDSK to either D or E regions of fibrinogen as well as to alphaC-domains. The data demonstrate the existence of weak transient interactions within and between fibrin molecules mediated by the N-terminus of the fibrinogen Bbeta chain.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7525, USA. ovg@med.unc.edu
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Gorkun
authors.forename: Rustem I
authors.initials: RI
authors.lastname: Litvinov
authors.forename: Yuri I
authors.initials: YI
authors.lastname: Veklich
authors.forename: John W
authors.initials: JW
authors.lastname: Weisel
mesh_terms: D005340:Fibrinogen / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D021122:Protein Subunits / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D017384:Sequence Deletion
chemical_list: D010446:Peptide Fragments; D021122:Protein Subunits; D011994:Recombinant Proteins; D005340:Fibrinogen