Abstract: The present invention relates to a process for separating and purifying proteases and antiproteases. This process is characterized in that there are placed in contact an insoluble cross-linked polymer including in its chain the group --SO.sub.3 R.sub.1 -- and/or the group --SO.sub.2 R.sub.2 -- in which R.sub.1 denotes a hydrogen atom or metal and R.sub.2 denotes the remainder of an amino acid linked to the --SO.sub.2 -- bridge through its amine --NH--, function, with the solution containing proteases and antiproteases or their complex; separating the polymer which has absorbed the desired protein, washing it carefully with the buffer, desorbing the absorbed protein by a solution of a polycationic compound in the case of T or by an albumin solution in the case of AT or of the complex T-AT, and isolating the protein, if desired, by known means, such as, especially, freeze drying. The invention is useful for studying the mechanism of blood coagulation.

Abstract: A megakarytocyte stimulatory factor (MSF), purified to homogeneity, is an acidic protein (pI=5.1) with an Mr=15,000 which stimulates PF4-like protein synthesis in rat promegakaryoblast cells by as much as 7-fold, and exhibits half-maximal activity at a concentration of 0.8 pM. MSF exhibits no biologic activity corresponding to other known hemopoietic growth factors, and appears to be specific for the megakaryocyte lineage.In the given examples, MSF was purified to homogeneity (as judged by SDS-PAGE and isoelectric focusing in the presence of 9.2 M urea) from serum-free conditioned medium obtained from cultured human embryonic kidney (HEK) cells, and to near homogeneity from thrombocytopenic plasma.

Abstract: A highly discriminating technique utilizing Concanavalin A, immobilized on a solid substrate, e.g. sepharose 4B, for the fractionation of heparin is disclosed. The heparin to be fractionated is incubated with antithrombin whereby a fraction complete with the antithrombin and the whole is then either passed through a column of the immobilized Concanavalin A or slurried with same. In both modes that fraction of the heparin complexed with the antithrombin is selectively absorbed by the immobilized Concanavalin A and constitutes the anticoagulant active fraction. That heparin which complexes with the antithrombin can be further fractionated to yield yet more highly active fractions by complexing the heparin in stages, adding an increment of a molar amount of antithrombin in each stage.

Abstract: A heparin preparation which exhibits elevated anticoagulant activity and a process for producing the preparation. Conventional heparin exhibiting characteristic anticoagulant activity and molecular heterogeneity is incubated with antithrombin-heparin cofactor extracted from plasma. A portion of the heparin forms a complex with the cofactor. The uncomplexed heparin fraction is then separated from the complexed fraction, and the complexed fraction is broken down to produce cofactor and an active form of heparin.