Improved procedure for the isolation of human plasminogen.

Although plasminogen purification methods based on cellulose column chromatography have been described (l-4), the procedure based on acid extraction of Cohn’s plasma Fraction III (5) has continued to be widely used because of its simplicity, reproducibility and the absence of a limitation on the amount of Fraction III which can be processed. With the Fraction III available in 1953, plasminogen with a specific activity of 45 to 60 Remmert and Cohen (7) C.U.l per mg of N could be obtained by the acid method, but more recently, it has not been possible to obtain purities exceeding 40 C.U. per mg of N. In this paper are described a modification of the original method and the addition of two steps which permit the isolation of plasminogen with a specific activity of 110 to 173 CU. per mg of N. The over-all procedure can be applied to large quantities of material, requires no special apparatus or techniques, is reasonably reproducible, and yields a product which is homogeneous in the ultracentrifuge and in electrophoretic analyses.