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Preparation and characterization of NH2-terminal fibrinogen B beta fragments from N-DSK of human fibrinogen.

In order to investigate the early release of NH2-terminal plasmic fragments from the B beta chain of fibrinogen, substantial quantities of B beta 1-42 and B beta 1-21 are required as immunogens, as radioimmunoassay standards and for infusion into human volunteers to determine the half-lives of these peptides. Towards this end methods that employ selective proteolytic cleavage of these fragments from fibrinogen have been developed. Both the N-DSK fragment, produced by CNBr cleavage of fibrinogen, and B beta 1-118 were employed as substrates for plasmin with the finding of higher yields from N-DSK. B beta 1-42 and B beta 1-21 were purified by gel filtration and ion-exchange chromatography on SP-Sephadex using volatile buffers. When the purified preparation of B beta 1-42 was chromatographed on reverse-phase high performance liquid chromatography, two peaks of identical amino acid composition were separated, presumably due either to pyroglutamate or to amide differences.