illustrate
Heparin is a sulfated polysaccharide that has a high affinity for thrombin. When combined with heparin, antithrombin exhibits rapid and effective inhibitory activity against coagulation factors such as serine proteases IXa, Xa, and thrombin. Low-molecular-weight heparin (LMWH) and heparin analogues, such as dalteparin sodium, inhibit factor Xa activity more effectively than thrombin activity, while unfractionated heparin (UFH) effectively inhibits thrombin and other serine protease activity. Therefore, the Heparin Anti-Factor Assay Kit is the correct method to measure the antithrombin activity of large molecule heparin.
This heparin test is a two-step anti-dual activity test that is used to accurately and sensitively determine the concentration of heparin in plasma or purified solutions. The plasma of the test sample needs to be diluted before analysis.
The purified human thrombin used in the experiment is predominantly present in the α form (obtained by direct activation of prothrombin) and exhibits higher coagulation reactivity than the "degraded" β or γ form under the condition of an equivalent concentration of chromogenic substrate.
The assay uses antithrombin and thrombin reagents pre-diluted in specific buffers (not provided in this kit) and is compliant with the United States Pharmacopeia (USP) and European Pharmacopoeia (EP).

Reagent composition
R1: Reagent 1 : Antithrombin III (human)
Antithrombin III (human), lyophilized with approximately 1.25 IU of activity per vial, containing BSA.
2 bottles (10mL bottle size).
R2: Reagent 2 : Thrombin (human)
Purified human thrombin, mainly in the α form, contains about 120 IU of active lyophilized product per vial.
2 bottles (10mL bottle size).
R3: Reagent 3: Thrombin-specific chromogenic substrate S-2238
Thrombin-specific chromogenic substrate S-2238, lyophilized containing approximately 4 mg of chromogenic substrate per vial, containing mannitol.
2 bottles (10mL bottle size).