title: Identification and characterization of α1 -antitrypsin in fibrin clots.
abstract: OBJECTIVE
  Preliminary studies indicated that α1 -antitrypsin (A1AT) is the most abundant protein that is non-covalently bound to fibrin clots prepared from plasma. The aim of this study was to identify and characterize fibrin(ogen)-bound A1AT.
  
  
  RESULTS
  Plasma clots were prepared and extensively washed with saline. Clot-bound A1AT could only be extracted using denaturing agents such as urea, thiourea or SDS, pointing to an apparently strong association. Purified fibrinogen, but still containing A1AT as a contaminant, was gel filtered, which showed that the A1AT was bound to fibrinogen. A specific ELISA detected the presence of A1AT-fibrinogen complexes in both purified fibrinogen and pooled normal plasma. Finally, fibrin(ogen)-Sepharose chromatography indicated that A1AT purified from plasma contained a small fraction of fibrin(ogen)-binding A1AT. To study the inhibitory activity of fibrin(ogen)-bound A1AT, both fibrinogen containing A1AT and washed plasma clots were incubated with increasing amounts of elastase. SDS-PAGE and Western blotting showed under both conditions the generation of the A1AT-elastase complex as well as cleaved A1AT. The inhibitory activity of fibrin(ogen)-bound A1AT was also demonstrated by measuring elastase-induced lysis of fibrin clots.
  
  
  CONCLUSIONS
  Fibrin clots contain strongly bound A1AT, which is functionally active as a serine protease inhibitor (serpin). This A1AT might play a role in the local regulation of proteases involved in coagulation or fibrinolysis and represent a novel link between the inflammatory and hemostatic systems.
authors: Department of Hematology, Erasmus University Medical Center, Rotterdam, the Netherlands.
authors: S
authors: S
authors: Talens
authors: J J M C
authors: JJ
authors: Malfliet
authors: P Th W
authors: PT
authors: van Hal
authors: F W G
authors: FW
authors: Leebeek
authors: D C
authors: DC
authors: Rijken
mesh_terms: D001777:Blood Coagulation; D015153:Blotting, Western; D016022:Case-Control Studies; D002847:Chromatography, Agarose; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005337:Fibrin / Q000737:chemistry / Q000378:metabolism*; D005340:Fibrinogen / Q000378:metabolism; D005342:Fibrinolysis; D006801:Humans; D010196:Pancreatic Elastase / Q000378:metabolism; D011485:Protein Binding; D011489:Protein Denaturation; D000515:alpha 1-Antitrypsin / Q000097:blood* / Q000737:chemistry; D019896:alpha 1-Antitrypsin Deficiency / Q000097:blood*
chemical_list: C043392:SERPINA1 protein, human; D000515:alpha 1-Antitrypsin; D005337:Fibrin; D005340:Fibrinogen; D010196:Pancreatic Elastase
keywords: alpha 1-antitrypsin; fibrin; fibrinogen; hemostasis; inflammation