title: Nanoscale probing reveals that reduced stiffness of clots from fibrinogen lacking 42 N-terminal Bbeta-chain residues is due to the formation of abnormal oligomers.
abstract: Removal of Bbetal-42 from fibrinogen by Crotalus atrox venom results in a molecule lacking fibrinopeptide B and part of a thrombin binding site. We investigated the mechanism of polymerization of desBbeta1-42 fibrin. Fibrinogen trinodular structure was clearly observed using high resolution noncontact atomic force microscopy. E-regions were smaller in desBbeta1-42 than normal fibrinogen (1.2 nm +/- 0.3 vs. 1.5 nm +/- 0.2), whereas there were no differences between the D-regions (1.7 nm +/- 0.4 vs. 1.7 nm +/- 0.3). Polymerization rate for desBbeta1-42 was slower than normal, resulting in clots with thinner fibers. Differences in oligomers were found, with predominantly lateral associations for desBbeta1-42 and longitudinal associations for normal fibrin. Clot elasticity as measured by magnetic tweezers showed a G' of approximately 1 Pa for desBbeta1-42 compared with approximately 8 Pa for normal fibrin. Spring constants of early stage desBbeta1-42 single fibers determined by atomic force microscopy were approximately 3 times less than normal fibers of comparable dimensions and development. We conclude that Bbeta1-42 plays an important role in fibrin oligomer formation. Absence of Bbeta1-42 influences oligomer structure, affects the structure and properties of the final clot, and markedly reduces stiffness of the whole clot as well as individual fibrin fibers.
authors.affiliation: Molecular and Nanoscale Physics Group, Department of Physics and Astronomy, University of Leeds, Leeds, United Kingdom.
authors.forename: Radwa H
authors.initials: RH
authors.lastname: Abou-Saleh
authors.forename: Simon D
authors.initials: SD
authors.lastname: Connell
authors.forename: Robert
authors.initials: R
authors.lastname: Harrand
authors.forename: Ramzi A
authors.initials: RA
authors.lastname: Ajjan
authors.forename: Michael W
authors.initials: MW
authors.lastname: Mosesson
authors.forename: D Alastair M
authors.initials: DA
authors.lastname: Smith
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Grant
authors.forename: Robert A S
authors.initials: RA
authors.lastname: Ariëns
mesh_terms: D001665:Binding Sites; D004548:Elasticity; D004591:Electrophoresis, Polyacrylamide Gel; D005340:Fibrinogen / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D018625:Microscopy, Atomic Force; D055503:Protein Multimerization; D013057:Spectrum Analysis; D013917:Thrombin / Q000378:metabolism
chemical_list: D005340:Fibrinogen; D013917:Thrombin