Plasminogen activator in bronchoalveolar fluid.

Area of Science:

• Biochemistry
• Pulmonary Medicine
• Enzymology

Background:

• Bronchoalveolar lavage fluid contains various enzymes.
• Plasminogen activators play crucial roles in fibrinolysis and tissue remodeling.
• Characterization of novel enzymes from lung lavage is important for understanding respiratory physiology.

Purpose of the Study:

• To purify and characterize a plasminogen activator from bronchoalveolar lavage fluid.
• To determine its biological and immunological properties.
• To compare its characteristics with known plasminogen activators like urokinase.

Main Methods:

• Purification of plasminogen activator from bronchoalveolar lavage fluid.
• Electrophoretic enzymography for molecular weight determination.
• Enzyme activity assays using specific substrates (S-2288, S-2444) and inhibitors (DFP).
• Immunological assays using anti-urokinase and anti-tissue-type plasminogen activator antibodies.

Main Results:

• A single band with a molecular weight of 53,000 was observed.
• Enzyme activity was inhibited by DFP, indicating serine protease activity.
• The activator lacked fibrin affinity.
• Immunologically, it reacted with anti-urokinase antibodies but not anti-tissue-type plasminogen activator antibodies.
• It showed preferential cleavage of S-2288 over S-2444, differing from urokinase.

Conclusions:

• A distinct plasminogen activator was identified in bronchoalveolar lavage fluid.
• This activator possesses unique biochemical and immunological characteristics.
• Its properties differ from urokinase and tissue-type plasminogen activator, suggesting a novel enzyme with potential roles in lung physiology.