The interaction between heparin and antithrombin III: a comparison of two different heparin-dye conjugates.
The interactions of antithrombin III with two heparin-dye conjugates have been compared using their fluorescence anisotropy. The first, heparin labelled with 5-isothiocyanatofluorescein, where the dye was mostly bound to unsulphated glucosamine residues, exhibited binding which was characteristic of heparin with a low affinity for antithrombin III. The second, heparin labelled with a reactive naphthalene dye (DENMT), showed similar binding character. However, when the heparin was treated with an amino group blocking agent prior to labelling with DENMT, the resultant heparin-dye conjugate showed binding behaviour, the strength of which was consistent with heparin molecules having both high and low affinity for antithrombin III. Heparin molecules with a high affinity for antithrombin III did not possess free amino groups. The implications of these findings are discussed with regard to the reliability of the data obtained using heparin-fluorescein conjugates.
D000990:Antithrombin III / Q000378:metabolism*; D003979:Diazonium Compounds / Q000378:metabolism; D016650:Fluorescein-5-isothiocyanate; D005452:Fluoresceins / Q000378:metabolism; D005454:Fluorescence Polarization; D006493:Heparin / Q000378:metabolism*; D008970:Molecular Weight; D013861:Thiocyanates / Q000378:metabolism; D014227:Triazines / Q000378:metabolism
D003979:Diazonium Compounds; D005452:Fluoresceins; D013861:Thiocyanates; D014227:Triazines; C053180:2-(1,4-diazobicyclo-2,2,2-octyl)-4-(1-ethoxy-4'-naphthyl)-6-(morpholinyl)-1,3,5-triazine; D000990:Antithrombin III; D006493:Heparin; D016650:Fluorescein-5-isothiocyanate