Human fibrinogen heterogeneities. II. Cross-linking capacity of high solubility catabolic intermediates.

Abstract High solubility human fibrinogens isolated from plasma (Fractions I-8 and I-9) or from plasmin digests of fibrinogen in vitro (Fractions I-8D and I-9D) were found to have substantially reduced cross-linking capacity. Under conditions in which Fraction I-4 formed 6 moles of e-(γ-glutamyl)lysine cross-link per mole of fibrin, the high solubility fibrinogens formed approximately three. Since polyacrylamide gel electrophoresis in sodium dodecyl sulfate showed that cross-linking of the γ chains was complete, it was concluded that the Aα chains of high solubility fibrinogens lack an average of two to three cross-linking sites. This finding, plus the fact that the Aα chains of the high solubility fibrinogens have undergone COOH-terminal degradation, permitted the conclusion that the Aα chain of fibrinogen contains cross-linking sites in its COOH-terminal region. Studies involving identification of monomeric α chain remnants in the electrophoretic patterns of fibrin from high solubility fibrinogens suggested that the NH2-terminal half of the Aα chain may also contain a cross-linking site (or sites), utilization of which depends on sites in the COOH-terminal region of Aα chains of neighboring molecules.