| Popis: |
A polypeptide with a molecular weight of approximately 20,000 daltons, produced at an early stage in the degradation of human fibrinogen by plasmin, has been isolated. Its amino acid composition is unique in that most of the residues are hydrophilie, with serine, glycine and proline making up more than 40% of the total. The polypeptide, which has tentatively been designated fragment H, has also been isolated from the Aα chain of fibrinogen and from fibrin. A radioimmunoassay for H, capable of measuring concentrations in vitro of less than 1 pmol/ml, has been developed for the purpose of obtaining a sensitive and quantitative measure of plasmin action on fibrinogen in clinical blood samples. This assay has been used to study the pattern of release of H from fibrinogen and fibrin and to confirm that it is cleaved from the Aα chain. Since fibrinogen cross reacts in the assay, it is necessary to remove it quantitatively from clinical samples. Preliminary studies show that normal serum levels are in the range of 50-200 pmols/inl, while elevated levels have been detected in patients with coagulation disorders associated with excessive proteolysis. |
