Human Fibrinogen Heterogeneities

High solubilityhuman fibrinogens isolated from plasma (Fractions I-8 and I-9) or from plasmin digests of fibrinogen in vitro (Fractions I-SD and I-9D) were found to have substantially reduced cross-linking capacity.Under conditions in which Fraction I-4 formed 6 moles of e-(y-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 crosslinking of the y chains was complete, it was concluded that the Aa: chains of high solubility fibrinogens lack an average of two to three cross-linking sites.This finding, plus the fact that the Acr chains of the high solubility fibrinogens have undergone COOH-terminal degradation, permitted the conclusion that the ACY chain of fibrinogen contains cross-linking sites in its COOH-terminal region.Studies involving identification of monomeric cx chain remnants in the electrophoretie patterns of fibrin from high solubility fibrinogens suggested that the NHZ-terminal half of the Acu chain may also contain a cross-linking site (or sites), utilization of which depends on sites in the COOH-terminal region of Aoc chains of neighboring molecules.