Fibrinogen sulfation

The answer is d. (Hardman, p 1346.) A slow intravenous infusion of protamine sulfate will quickly reverse the bleeding. Protamine binds to heparin to form a stable complex with no anticoagulant activity It may also have its own anticoagulant effect by binding with platelets and fibrinogen. 

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. ... 

A commonly employed first separation step is ammonium sulfate precipitation. This technique exploits the fact that the solubility of most proteins is lowered at high salt concentrations. As the salt concentration is increased, a point is reached where the protein comes out of solution and precipitates. The concentration of salt required for this salting out effect varies from protein to protein, and thus this procedure can be used to fractionate a mixture of proteins. For example, 0.8 M ammonium sulfate precipitates out the clotting protein fibrinogen from blood serum, whereas 2.4 M ammonium sulfate is required to precipitate albumin. Salting out is also sometimes used at later stages in a purification procedure to concentrate a dilute solution of the protein since the protein precipitates and can then be redissolved in a smaller volume of buffer. 

Spectral alterations of the tyrosyl spectrum resulting from the formation of an ether linkage with the phenolic oxygen may be quite small, as with 0-methyltyrosine (Wetlaufer et al. 1958), or substantial, as with the aromatic ether thyronine (Gemmill, 1955). The ester linkage is also of some interest in this connection, since tyrosine-O-sulfate has been shown by Bettelheim (1954) to occur in bovine fibrinogen. The spectrum of tyrosine sulfate .. . differs markedly from that of tyrosine, showing a much weaker absorption with a maximum near 2630 A. ... 

Fio. 2. Relation between log s and ionic strength of ammonium sulfate for several proteins. From Cohn and Edsall (1943). F = fibrinogen COHb = carboxyhemo-globin PG = pseudoglobulin SA = serum albumin COMb = carboxymyoglobin. 

Sulfation 3 -Phosphoadenosine-5 -phosphosulfate Fibrinogen Blood-clot formation... 

Activated sulfate. Fibrinogen contains tyrosine-G-sulfate. Propose an activated form of sulfate that could react in vivo with the aromatic hydroxyl group of a tyrosine residue in a protein to form tyrosine-G-sulfate. 

The matter deposited by normal plasma onto globulin films that had (Table IV, Exp. No. 1) or had not been pre-exposed to protamine sulfate (not listed) did not adsorb matter out of anti-human fibrinogen serum and therefore was probably not fibrinogen. 

Fig. 9. The effect of ammonium sulfate (1.2 M) on second antibody separation of the bound fraction in a radioimmunoassay for the fibrinogen degradation product, fragment E (FgE). In the presence of ammonium sulfate, complete precipitation of the bound fraction occurs at considerably reduced concentrations of second antibody despite a much shorter incubation period — , 30 min, 1.2 M (NHiljSOi O—O, 24 hr, no (NH4>jS04. From Martin and Landon. ...

Tyrosine-O-sulfate is present in many fibrinopeptides B (233). It is present in fish, frog, and a large number of mammalian fibrinogens but not in that of higher primates and the rat (242). 

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