Fibrinogen properties

Table 2 shows that if fibrinogen oxidation occurs in the absence of KN-14-CD or dihydroquercetin, then fibrinogen completely loses its functional activity. Whereas if fibrinogen oxidation occurs in the presence of KN-14-CD or dihydroquercetin, then fibrinogen retains its functional properties. These results (DHQ activity) are almost coincident with results of our previous work [18]. There was a less time of clot formation of unoxidized fibrinogen. The fact of different time of an unoxidized fibrin clot formation (as other differences) takes place due to moderate difference in fibrinogen properties. 

Thrombin, the two-chain derivative of the prothrombin molecule, has a molecular weight of approximately 37,000 daltons. Its proteolytic properties induce the conversion of fibrinogen to fibrin to produce the initial visible manifestation of coagulation, the soluble fibrin clot. In addition, thrombin influences the activity of Factors V, VIII, and XIII and plasmin. Thrombin affects platelet function by inducing viscous metamorphosis and the release reaction with subsequent aggregation. 

Alpha helices are sufficiently versatile to produce many very different classes of structures. In membrane-bound proteins, the regions inside the membranes are frequently a helices whose surfaces are covered by hydrophobic side chains suitable for the hydrophobic environment inside the membranes. Membrane-bound proteins are described in Chapter 12. Alpha helices are also frequently used to produce structural and motile proteins with various different properties and functions. These can be typical fibrous proteins such as keratin, which is present in skin, hair, and feathers, or parts of the cellular machinery such as fibrinogen or the muscle proteins myosin and dystrophin. These a-helical proteins will be discussed in Chapter 14. 

Fibrinolytic agents have prothrombotic properties as well. The plasmin generated by thrombolysis leads to the production of thrombin, which is a potent platelet activator and converts fibrinogen to fibrin. Indeed, studies have shown early reocclusion in as many as 17% of the patients treated with lAT and 34% of the patients treated with IV rt-PA. Therefore, a strong rationale exists for the adjuvant use of antithrombotic agents. 

Tegoulia VA, Rao W, Kalambur AT, Rabolt JF, Cooper SL (2001) Surface properties, fibrinogen adsorption, and cellular interactions of a novel phosphorylcholine-containing self-assembled monolayer on gold. Langmuir 17 4396-4404... 

Tyrosine (Tyr or Y) (4-hydroxyphenylalanine ((5)-2-amino-3-(4-hydroxyphenyl)-propanoic acid)) is a polar, neutral, aromatic amino acid with the formula H00CCH(NH2)CH2C6H50H and is the precursor of thyroxin, dopamine, norepinephrine (noradrenaline), epinephrine (adrenaline), and the pigment melanin. Being the precursor amino acid for the thyroid gland hormone thyroxin, a defect in this may result in hypothyroidism. Tyr is extremely soluble in water, a property that has proven useful in isolating this amino acid from protein hydrolysates. The occurrence of tyrosine- 0-sulfate as a constituent of human urine and fibrinogen has been reported. ... 

Brash, J.L. and Uniyal, S., Dependence of albumin-fibrinogen simple and competitive adsorption on surface properties of biomaterials, J. Polymer Sci., C66, 377-389 1979. 

Studies of plasma clots made under a variety of conditions suggest that the network is established early as a result of the activation process (Blomback et al., 1994) and that the thrombin activation pathway modulates clot structure (Torbet, 1995). Light scattering studies, combined with other physical chemical techniques, have substantiated this conclusion for purified fibrinogen and provided more information about the structure and properties of the assembling clot (Bernocco et al., 2000 Ferri et al., 2001, 2002 Profumo et al., 2003). 

Note In fibrinolysis, plasmin, an endopeptidase that is converted from plasminogen by an activator, hydrolyzes fibrin, fibrinogen, factor V, and factor VIII to their inactive products. Hageman factor (factor XII) converts a proactivator to the active activator. Agents such as thrombin, streptokinase, and urokinase therefore enhance the formation of plasmin and hence have fibrin lytic properties. Epsilon-aminocaproic acid inhibits the activator-mediated formation of plasmin and hence may be used as an antidote to streptokinase-urokinase, or in a defibrination syndrome when bleeding from a mucous membrane occurs. 

Cheresh DA, Spiro RC. Biosynthetic and functional properties of an Arg-Gly-Asp directed receptor involved in human melanoma cell attachment to vitronectin, fibrinogen, and von Willebrand factor. J Biol Chem 1987 262(36) 17,703-17,71 I. 

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