Properties of Microsomal Activator of Profibrinolysin Found in Bovine and Porcine Heart Muscle

Summary

Mitochondrial, lysosomal, and microsomal fractions of pig and cow myocardial cells were screened for their ability to effect lysis of bovine fibrin plates prepared with Profibrinolysin-containing and profibrinolysin-free reagents. Little if any activity was observed on profibrinolysin-free fibrin plates. Maximum activity on Profibrinolysin-containing plates was found in association with the microsomes. Extraction of the microsome preparations with 0.15 M KCl and 2.0 M KCl dissolved activator molecules with different pH solubility and stability characteristics. The activator activity of the 2.0 M KCl extract was in general more stable to acid pH than that of the 0.15 M KCl extract.

The activator characteristic of the microsomal suspensions and of both types of microsome extracts was stable to acetone precipitation. However, the 2.0 M KCl extract lost its relatively greater stability to acid pH when precipitated with acetone. The significance of the chemical environment as a determining factor in final properties of purified enzyme molecules is discussed. The importance of using a relatively homogeneous cell population as starting material is also emphasized.

• References

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