Studies on the purification of bovine plasminogen (profibrinolysin).

A crude bovine plasminogen product obtained from bovine serum by 30% ammonium sulphate precipitation has been purified 20-fold by means of isoelectric precipitation and calcium phosphate gel chromatography. A threefold purification was achieved by isoelectric precipitation. Plasminogen was precipitated in greatest yield and highest specific activity at 40-fold dilution in the pH range of 5.25–5.50. The conditions under which plasminogen is eluted from calcium phosphate gel columns have been investigated. Plasminogen fractions possessing specific activity seven times that of the isoelectric-precipitated materials have been obtained by elution with phosphate buffers over the range of 0.05 to 0.1 M, pH 6.8.