Beschreibung:
<jats:p>We have examined the antithrombin effects of various phosphate‐containing polyanions (including linear polyphosphates, polynucleotides and the phosphoserine glycoprotein, phosvitin) on the glycosaminoglycan‐binding plasma proteinase inhibitors, antithrombin III (ATIII) and heparin cofactor II (HCII). These phosphate‐containing polyanions accelerate the HCII‐thrombin reaction, as much as 1600‐fold in the case of phosvitin. The HCII‐thrombin reaction with both phosvitin and polynucleotides appears to follow the ternary complex mechanism. The HCII‐thrombin complex is rapidly formed in the presence of these phosphate polyanions (each at 10 μg/ml) when <jats:sup>125</jats:sup>I‐labeled thrombin is incubated with human plasma (ex vivo). None of these phosphate polyanions accelerate the ATIII‐thrombin reaction. Our results suggest that the antithrombotic effect of these phosphate‐containing polyanions is mediated by HCII activation and not by ATIII.</jats:p>