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"Renaparin-Plasma-Test" is a set of reagents designed for quantitative determination of anti-Xa and anti-IIa activities of low molecular weight heparin (LMWH) in blood plasma using chromogenic substrates. This method is intended solely for scientific research purposes.

Method Principle: The method for determining LMWH activity is based on the ability of the antithrombin III-heparin complex (AT III-LMWH) to neutralize activated factors Xa and IIa.

The activity of LMWH in plasma is determined by adding excess antithrombin III and factor Xa or IIa. This leads to the inhibition of factors Xa or IIa by the AT III-LMWH complex, proportionally to the amount of LMWH in the plasma. The remaining amount of factor Xa or IIa catalyzes the cleavage of paranitroaniline (pNA) from synthetic chromogenic substrates. The absorption of free pNA, measured at 405 nm, is inversely proportional to the anti-Xa or anti-IIa activities of LMWH.

The process follows these schemes:

  1. For determining anti-Xa activity of LMWH: AT III (excess) + LMWH ⇒ AT III-LMWH. AT III-LMWH + Xa (excess) ⇒ AT III-LMWH-Xa + Xa (residual). Xa (residual) + Xa-Substrate-pNA ⇒ Peptide + pNA.

  2. For determining anti-IIa activity of LMWH: AT III (excess) + LMWH ⇒ AT III-LMWH. AT III-LMWH + IIa (excess) ⇒ AT III-LMWH-IIa + IIa (residual). IIa (residual) + IIa-Substrate-pNA ⇒ Peptide + pNA.


Composition of the set:

  1. Antithrombin III (~1 IU/vial), lyophilized – 4 vials.
  2. Factor Xa (~34 IU/vial), lyophilized – 1 vial.
  3. Thrombin (Factor IIa) (~20 IU/vial), lyophilized – 1 vial.
  4. Chromogenic substrate for Factor Xa, lyophilized – 2 vials.
  5. Chromogenic substrate for thrombin, lyophilized – 2 vials.
  6. Plasma calibrator, level 0 — 1 vial.
  7. Plasma calibrator, level 1 — 1 vial.
  8. Concentrated buffer solution (5 ml/vial) – 1 vial.
  9. Bovine serum albumin (1 g/vial) – 1 vial.

The set is intended for conducting 100 determinations of anti-Xa activity and 100 determinations of anti-IIa activity.