MODELING CATION-DRIVEN (PROTO)FIBRIN COAGULATION

The coagulation mechanism of thrombin‐ and reptilase‐activated fibrinogen is the focus of this report. Three types of gels were evaluated for their sensitivity to physiologic levels of Ca(II) and Zn(II): Fibrin gel formed directly by adding thrombin or reptilase to fibrinogen, protofibrin gel generated by adding Ca(II) and Zn(II) to soluble fibrin oligomers (protofibrills), and gels induced by sudden pH increase of fibrin monomer (pH 4.9–7.4). The turbidity and viscoelasticity of reptilase‐ and thrombin‐activated fibrin are similarly sensitive to Ca(II) and Zn(II) scanning electron micrographs (SEM) of fibrin gels from pH jump experiments show that their constituent fibers are relatively homogeneous and only mildly affected by divalent cations. This contrasts with the cation sensitivity of normally formed fibrin and protofibrin gels. Based on these and previously published experiments, a graphic shorthand is developed to describe the directionality of linear and lateral polymerization modes that result in cation‐driven (proto)fibrin gelation. Copyright © 1990 John Wiley & Sons, Inc.