IMUBIND® FSAP ELISA

INTENDED USE
The IMUBIND^® FSAP ELISA is intended for the measurement of factor seven activating protease in human plasma. The assay is intended for research use only.

EXPLANATION OF THE TEST
Factor Seven Activating Protease (FSAP, Factor VII activating protease, FVII activating protease) is a potent activator of factor VII independent of tissue factor and an activator of pro-urokinase. Present in human plasma at a concentration of 12 µg/mL (1 PEU/mL)¹, FSAP exists as a single-chain proenzyme with a molecular ratio of 64 kDa. The proenzyme can be activated by an autocatalytic mechanism or by urokinase generating an active two-chain form consisting of a 40 kDa heavy chain and a 30 kDa light chain which possesses the protease domain.  The autoactivation is enhanced in the presence of heparin. Conversely, calcium ions stabilize single-chain FSAP and retards the autoactivation.² FSAP playing a dual role, clot formation via factor VII activation and clot degradation via pro-urokinase activation, holds a key position in the delicate balance of the hemostatic system.

A mutant variant of FSAP with a single nucleotide polymorphism (SNP) has been identified, termed “Marburg I” (FSAP MI). The FSAP Marburg I variant shows a reduced ability to activate pro-urokinase, whereas its ability to activate Factor VII is normal.³ It seems likely that FSAP
Marburg I, due to the resulting haemostatic imbalance, may promote the development of thromboembolic diseases. The FSAP Marburg I variant was found to have an effect upon the risk for cardiovascular heart disease in those patients with elevated levels of cholesterol and triglyceride.⁴ In addition, the FSAP Marburg I variant was found to be a significant risk predictor for the evolution and progression of carotid stenosis⁵ and associated with idiopathic venous thromboembolism.⁶

PRINCIPLE OF THE METHOD
Diluted plasma samples are added to microwells coated with a monoclonal antibody directed against the light-chain of human FSAP.  During an incubation period, FSAP present in the sample will bind to the antibody coated to the wells. Following a washing step, a streptavidin-horseradish peroxidase (SA-HRP) conjugated monoclonal antibody directed against the Glu³⁶⁰ residue on the light-chain is added to the microwells and binds to FSAP captured on the plate. Following another washing step, the addition of a perborate-3,3’-5,5’-tetramethylbenzidine (TMB) substrate and its subsequent reaction with the HRP present creates a blue colored solution. The enzymatic reaction is stopped by adding citrate stop solution, which turns the solution color yellow. Measuring the solution absorbance at 450 nm and extrapolating the value with those of a standard curve determines the level of FSAP in the diluted plasma sample.

Category: Research use only

Type: ELISA

Product Availability: Worldwide

Manufacturer: ImmBioMed GmbH & Co KG, Germany

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