title: Fibrinogen is a heme-associated, carbon monoxide sensing molecule: a preliminary report.
abstract: The objective of this study was to determine how carbon monoxide directly modifies fibrinogen utilizing liquid chromatography-mass spectrometry (LC-MS/MS) by examining fibrinogen exposed to carbon monoxide releasing molecule-2 [tricarbonyldichlororuthenium (II) dimer; CORM-2]. Purified fibrinogen was exposed to 0, 25, 50 or 100 μmol/l CORM-2 for 5 min at 37°C and then stored at -80°C before analyses with LC-MS/MS. In a second series of experiments, normal plasma was exposed to 0 or 100 μmol/l CORM-2 in the absence or presence of the nitric oxide donor sodium nitroprusside and hydroquinone (an organic reductant) to compete with carbon monoxide binding to a putative heme group found on fibrinogen. Coagulation was activated with tissue factor (n=8 per condition). Thrombus growth was monitored with thrombelastography for 15 min. LC-MS/MS did not detect any direct modifications of amino acids in fibrinogen, but detection of small regions of both the alpha and gamma chains was lost following exposure to CORM-2 and endoproteinase digestion with trypsin and Glu-C. An ion with the same m/z and expected retention time as heme was found in the purified fibrinogen. Exposure of plasma to nitric oxide/hydroquinone significantly decreased CORM-2-mediated enhancement of coagulation without affecting the coagulation kinetics of plasma not exposed to CORM-2. Carbon monoxide derived from CORM-2 likely modifies fibrinogen via modulation of a fibrinogen-associated heme group(s). Whereas the precise molecular location of heme attachment and three-dimensional conformational change secondary to carbon monoxide exposure remain to be determined, fibrinogen appears to be a carbon monoxide sensing molecule.
authors: Department of Anesthesiology bDepartment of Biochemistry, Drexel University College of Medicine, Broad & Vine Streets, Philadelphia, PA 19102, USA. vance.nielsen@drexelmed.edu
authors: Vance G
authors: VG
authors: Nielsen
authors: Jack B
authors: JB
authors: Cohen
authors: S Nini
authors: SN
authors: Malayaman
authors: Mathew
authors: M
authors: Nowak
authors: Keith
authors: K
authors: Vosseller
mesh_terms: D001777:Blood Coagulation; D002248:Carbon Monoxide / Q000378:metabolism*; D005340:Fibrinogen / Q000378:metabolism*; D006418:Heme / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D009942:Organometallic Compounds / Q000494:pharmacology; D010949:Plasma; D053719:Tandem Mass Spectrometry; D013916:Thrombelastography; D013927:Thrombosis
chemical_list: D009942:Organometallic Compounds; C447082:tricarbonyldichlororuthenium (II) dimer; D006418:Heme; D002248:Carbon Monoxide; D005340:Fibrinogen