Thrombin converts singlet oxygen (1O2)-oxidized fibrinogen into a soluble t-PA cofactor. A new method for preparing a stimulator for functional t-PA assays.
Activated phagocytes, particularly polymorphonuclear leukocytes (neutrophils), by means of oxidative photonic burst, i.e., the combined activation of NADPH-oxidase and myeloperoxidase, generate large amounts of oxidants of the hypochlorite/chloramine type that are an important physiologic source for the nonradical, photon-emitting oxidant singlet oxygen (1O2), which (in the dark blood stream) is both a signal and an agent of defense against bacteria or fibrin. 1O2-oxidized fibrinogen or oxidized fibrin monomer has previously been shown to be unpolymerizable, and methionine to methionine sulfoxide-oxidized fibrinogen occurs in circulating blood. The present study demonstrates that thrombin converts oxidized fibrinogen into a soluble stimulator of tissue-type plasminogen activator (t-PA). After addition of 0.1 IU thrombin to 25 microl oxidized normal human plasma and an incubation time of 10 min (room temperature), t-PA activity increases about 20-fold when compared with oxidized plasma without the addition of thrombin. Thus, since oxidized fibrin monomer is a t-PA cofactor, thrombin-degraded oxidized fibrinogen can be used as a stimulator in functional t-PA assays.
Stief
T W
TW
Institute of Clinical Chemistry and Molecular Diagnostics, Philipps University, Marburg, Germany. thstief@post.med.uni-marburg.de
Kretschmer
V
V
Kosche
B
B
Doss
M O
MO
Renz
H
H
D004591:Electrophoresis, Polyacrylamide Gel; D005340:Fibrinogen / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism*; D010586:Phagocytes / Q000378:metabolism; D026082:Singlet Oxygen; D012995:Solubility; D013917:Thrombin / Q000378:metabolism* / Q000494:pharmacology; D010959:Tissue Plasminogen Activator / Q000378:metabolism*
D026082:Singlet Oxygen; D005340:Fibrinogen; D013917:Thrombin; D010959:Tissue Plasminogen Activator; D010100:Oxygen