Fibrinolytic activities of euglobulins precipitated at pH 6.4, 6.0, and 5.3

Abstract

As a result of problems encountered with euglobulin preparation at pH 5.3, a study was undertaken to determine the pH level that provided the best recovery of fibrinolytic material. The euglobulin lysis test was used to measure the difference in activity at each pH level. Euglobulins were prepared from rabbit plasma at pH 6.4, 6.0, and 5.3, subjected to a variety of treatments, and separated on a DEAE cellulose column. Samples were assayed for plasminogen, plasmin, fibrinogen, prothrombin, and antithrombin levels. Results indicated the presence of plasminogen and plasmin at all three pH levels, with the greatest specific activity in the pH 6.0 and 5.3 euglobulins precipitated from defibrinated, urokinase-activated plasma. Maximum total activity was found in the pH 6.0 euglobulins. Approximately 25% of the plasma fibrinogen was precipitated at the pH 5.3 level. Trace amounts of prothrombin were found at all three pH levels. No measurable antithrombin was found in any of the samples. It was concluded that, of the three pH levels studied and with a two-stage euglobulin lysis test, the pH 6.0 precipitation provided the best measure of change in the fibrinolytic system.