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A dimeric 140 kDa [(Fib-2).sub.2] fragment containing both Fib-2 regions are prepared by limited proteolysis in order to clarify the role of another pair of fibrin-binding regions, Fib-2, located at the disulfide-linked COOH-terminal ends of fibronectin. Experiments revealed about 30% inhibition of the Fib-2 mediated binding by increasing concentrations of Fib-1 fragment.

Bleeding, the serious complication of thrombolytic therapy with tissue type plasminogen activator (t-PA), is a result from lysis of fibrin in hemostatic plugs and from the systemic lytic state caused by unopposed plasmin. It suggests that structural changes resulting from incorporation of fragment X into clots promote their lysis and the attenuation of thrombolytic therapy-induced fragment X formation might reduce the risk of bleeding.

Details of the crystal structure of human thrombin in complex with the central part of human fibrin are revealed and results are presented of the molecular modeling of the fibrinopeptides A and B (fpA- and fpB-) containing portions of the Aalpha and Bbeta chains, in both fibrinogen and protofibrils. Analysis provides a coherent rationale for the preferential removal of fpA from fibrinogen at the first stage of fibrin assembly and the accelerated cleavage of fpB from protofibrils at the second stage.

The binding of [[alpha].sub.2]-antiplasmin ([[alpha].sub.2]AP) to fibrin (ogen) and its fragments are analyzed by an enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance. The noncovalent interaction of [[alpha].sub.2]-AP with fibrin has contributed to regulation of the initial stage of fibrinolysis and has provided proper orientation of the cross-linking sites to facilitate covalent cross-linking of [[alpha]-2]-AP to the fibrin clot.

Several recombinant fragments containing individual extracellular domains of VE-cadherin and several fragments corresponding to various fibrin(ogen) regions are prepared to test the interactions involved in fibrin(ogen) region/domains and localize the complementary fibrin-binding site in VE-cadherin. The experimental results confirmed that the fibrin-binding properties of the VE-cadherin are not influenced by the calcius ions that are required to maintain proper conformation and adhesive properties of the VE-cadherin.

The crystal structure of fragment D from [gamma]D364A in the presence of the synthetic peptide GPRP and GHRP to was solved to examine the molecular nature of 'A:a' interactions in [gamma]364Asp variants. The results showed that negative charge in residue [gamma]364Asp plays a critical role in the electrostatic interactions that facilitate the important first step in fibrin polymerization and is not required for knob 'A' binding to hole 'a'.

A general strategy for bonding extracellular matrix gels such as collagens and fibrin into mechanically robust monolithic structures is used by using macromolecular hydrogels. The results revealed that the bonding occurs via reversible perturbation of the gels and the structures obtained can be used to generate spatially complex biological tissues for the study of physiological flows or multicellular biological processes.

EP-2104R is an MRI contrast agent that is designed to detect thrombus by binding to the protein fibrin, present in all thrombi. Strong fibrin binding, fibrin selectivity and high molecular relaxivity have enabled EP-2104R to detect blood clots in vivo.