Control and isotopic quantification of affinity of antithrombin III for heparin-like surfaces.

Heparin-like materials, characterized by a defined superficial density of functional groups which activate antithrombin III (AT III), when in contact with blood specifically inhibit thrombin as soon as it appears. This paper describes an isotopic method to estimate this density and to visualize the distribution of the affinity sites concerned, both directly with AT III labelled with 125Iodine and indirectly with an anti AT III monoclonal antibody labelled with 111Indium.

Conditions for radioiodination of antithrombin III retaining its biological properties.

In order to obtain a radioiodinated antithrombin III (AT III) with a good labelling yield and optimal biological properties towards heparin, thrombin and its anti-AT III monoclonal antibodies, we compared the classical labelling methods and found them wanting. Thus, we perfected a new labelling procedure which fulfils the above requirements.