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Thrombin as a C5 Convertase
Author(s) -
Zetoune Firas S,
Sarma J Vidya,
Rittirsch Daniel,
Lambris John D,
McGuire Stephanie R,
Ward Peter A
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a641-c
Subject(s) - thrombin , chemistry , bronchoalveolar lavage , complement system , fibrin , blot , microbiology and biotechnology , immune system , biochemistry , immunology , platelet , lung , medicine , biology , gene
Incubation of human C5 with purified plasma human thrombin at pH 7.4 resulted in the appearance of C5a as determined by ELISA. The fragment of C5 in Western blots after SDS‐PAGE positioned near the 10 kDa and 15 kDa reference markers. The production of this C5 fragmentation product was dependent on the amount of thrombin employed and the dose of C5. When the C5 fragmentation product was isolated and deglycosylated with PNGase F, MALDI‐TOF analysis revealed a mass of 8269 Da, which is the theoretical mass of deglycosylated human C5a. C3−/− mice developing acute lung injury after distal airway deposition of IgG immune complexes showed the same intensity of inflammatory injury as C3+/+ mice. In C3−/− mice, it appears that the generation of C5a present in bronchoalveolar lavage fluids can be linked to thrombin whereas C5a generated in C3+/+ lung is the traditional C3‐dependent C5 convertase. These data suggest a linkage between the complement and the clotting systems. This work is supported by NIH grants GM‐029507 and HL‐31963.