GLYCOPEPTIDES FROM FIBRINOGEN AND FIBRIN

Four major glycopeptides fractions were isolated from bovine fibrinogen and from fibrin. Two of them are characterized by the presence of lysine and the other t wo by the presence of arginine, glutamic acid, glycine, and valine. One of the lysine-containing glycopeptides present in both fibrinogen and fibrin contained 1.4-2.0 moles of sialic acid. This glycopeptide has not been reported previously. (When this manuscript was in preparation, we read the report of Mester et al. (Mester, L., Moczar, E., and Szabados, L. (1967), Compt. Rend. Acad. Sei. Paris 265. 877) who have now obtained as many as seven glycopeptides by high-voltage electrophoresis, one of which has lysine and 24% sialic acid.) These data and the facts that in the glycopeptide mixtures arginine and lysine are equal on a molar basis, and that glutamic acid is present to the extent of only 3 moles/mole of fibrinogen indicate the chains of fibrinogen are not all paired with respect to their glycopeptides. Degradation of one of the glycopeptides with sialidase followed by crude β-glucosidase indicated the sequence from the nonreducing end of sialic acid, galactose, N-acetylglucosamine, and mannose. In each glycopeptide, both N-acetyl- and N-glycolylsialic acids were present and could be removed by purified Clostridium perfringens sialidase. The glycopeptides from cross-bonded fibrin contained 1 mole less of aspartic acid than those from fibrinogen. Also, one of the glycopeptides from fibrin was held more strongly on Dowex 1 (formate column) than was its counterpart from fibrinogen. © 1968, American Chemical Society. All rights reserved.