Cleavage of fibrinogen by the human neutrophil neutral peptide-generating protease.

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Abstract
The human neutrophil neutral peptide-generating protease, which generates a low MW vasoactive peptide from a plasma protein substrate, is directly fibrinolytic and cleaves human fibrinogen in a manner distinct from plasmin. Fibrinogen was reduced from 340,000 Mr [molecular ratio] to derivatives of 270,000-325,000 Mr during interaction with the protease at enzyme-to-substrate ratios of 0.3 or 1.0 .mu.g/1.0 mg. The 310,000-325,000 Mr cleavage fragments exhibited prolonged thrombin-induced clotting activity but were able to be coagulated, whereas the 270,000-290,000 Mr fragments were not able to be coagulated. Anticoagulants were not generated at either enzyme dose. As analyzed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis in 4-30% gradient gels and 10% gels stained for protein and carbohydrate, the diminution to 310,000-325,000 Mr and the prolongation of thrombin-induced clotting time resulted from cleavage of the fibrinogen A.alpha. chain. The further decrease in size to 270,000-290,000 Mr was associated with B.beta.-chain and .gamma.-chain cleavage and an inability to form .gamma.-.gamma. dimers. The neutral peptide-generating protease, a distinct human neutrophil neutral protease with fibrinolytic and fibrinogenolytic activities comparable to those of plasmin on a weight basis, cleaves fibrinogen in a manner that is distinct from the action of plasmin, leukocyte elastase and leukocyte granule extracts. The concerted action of this neutrophil protease to generate a vasoactive peptide and to digest fibrinogen and fibrin may facilitate neutrophil movement through vascular and extravascular sites.