Early Events in the Polymerization of Fibrin

• Published in: Annals of the New York Academy of Sciences Vol. 936; no. 1; pp. 167 - 184
• Main Authors: ROCCO, MATTIA, BERNOCCO, SIMONETTA, TURCI, MARCO, PROFUMO, ALDO, CUNIBERTI, CARLA, FERRI, FABIO
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.01.2001
• Subjects: Biopolymers - metabolism; Calcium Chloride; Edetic Acid; Fibrin - metabolism; Fibrin polymerization; Kinetics; Light scattering; Mean square radius of gyration; Polymer distribution; Thrombin - metabolism; Thrombin induced
• ISSN: 0077-8923; 1749-6632
• DOI: 10.1111/j.1749-6632.2001.tb03504.x

: The early events in the thrombin‐induced formation of fibrin have been studied by the use of stopped‐flow multiangle laser light scattering (SF‐MALLS). This technological advancement has allowed the recovering, as a function of time with a resolution of about 0.5 sec, of the mean square radius of gyration and of the molecular weight Mw, and to place an upper bound to the values of the mass/unit length ML. The ionic strength, pH and salt type conditions investigated were all close to physiological, starting with a 50 mM Tris, 104 mM NaCl, pH 7.4 buffer (TBS), to which either 1 mM EDTA‐Na2 or 2.5 mM CaCl2 were also added. Fibrinogen was 0.2–0.3 mg/ml and rate‐limiting concentrations of thrombin were used (0.05–0.25 NIH units/mg fibrinogen). By plotting and ML versus Mw on log‐log scales, runs proceeding at different velocities and under different solvent conditions could be compared and confronted with model curves. It was found that: (1) within this thrombin range, the mechanism of association does not depend on its concentration, nor on the buffers employed; (2) the versus Mw curves could all be reasonably fitted with a bifunctional polycondensation scheme involving semiflexible worm‐like, double‐stranded, half‐staggered polymers with persistence length between 200–600 nm, provided that a ratio Q= 16 between the rate of release of the two fibrinopeptides A was employed; (3) the ML versus Mw data seemed more compatible with lower Q values (4 < Q < 8), but their uncertainty prevented a better assessment of this issue; the formation of fibrinogen‐fibrin monomer complexes may also play a role in the polymer distributions; (4) in the very early stages (e.g., when Mw < 7 × 105), the versus Mw data were fitted well only in TBS and at the lowest thrombin concentration, suggesting that a transient, either sequential or concurrent fast second mechanism, involving longer and thinner polymers, may be at work.