Chromogenix Factor Xa. 71 nkat, is for the determination of Heparin in plasma. Factor X is purified from a barium cytrate elution of bovine plasma and it is activated to FXa by a Russell’s Viper Venom matrix.

For laboratory use only.

Packaging, Storage and Stability

  • Factor Xa: 71±10 nkat S-2222™
  • Bovine Albumin: 20 mg
  • Polyethyleneglycol 8000: 10 mg
  • Sodium Chloride: 10 mg
  • Tris (hydroxymethyl) aminomethane: 6.4 mg
  • Tris (hydroxymethyl) aminomethane HCI: 69 mg

The lyophilized powder is stable at 2-8°C until the expiry date printed on the label. The reconstituted Factor Xa is stable for 1 month at 2-8°C or 6 months at -20°C when used for the determination of Heparin, according to the test conditions of the Chromogenix® Coatest® Heparin kit, catalog # K255539 (25553963). Reconstitute with 10 ml sterile water to obtain an activity of 7 nkat/ml (reaction buffer: 0.05 mol/l Tris buffer pH 8.4).

Chromogenix Factor Xa can be used for anti-FXa chromogenic assays.

The activity of FXa can be measured using the following chromogenic substrates:

  • Chromogenix® S-2222™, 25 mg vial, catalog # S820316 (82031639)
  • Chromogenix® S-2765™, 25 mg vial, catalog # S821413 (82141339)
The Chromogenix Factor Xa reagent says it is 71 nkat, but I need to know what that is in g/ml and mol/ml.
One katal (kat) is the amount of enzyme that converts one mole of substrate per second. Activated enzymes from Chromogenix such as FXa and thrombin are measured in nkat. 1 nkat = 1 x 10-9 mol of product released per second. The conversion is as follows:

FXa has a MW approximately 44,000.

The specific activity for FXa is 1.9 nkat/mg, as determined with chromogenic substrate S-2222™.

This gives that 71 nkat corresponds to 37.4 mg FXa (=37.4 x10-6 g FXa)

This corresponds to 8.5 x 10-10 mol = 0.85nmol.

The concentration in mol/l and g/l will depend on the dilution volume you choose.

Note: 1 IU corresponds to 20 nkats, which means 71 nkatS-2222 = 3.55 IU.