Purification and properties of heparin-releasable lipoprotein-associated coagulation inhibitor

W. F. Novotny, M. Palmier, T. C. Wun, G. J. Broze, J. P. Miletich

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130 Scopus citations


The lipoprotein-associated coagulation inhibitor (LACI) is present in vivo in at least three different pools: sequestered in platelets, associated with plasma lipoproteins, and released into plasma by intravenous heparin, possibly from vascular endothelium. In this study we have purified the heparin-releasable form of LACI from post-heparin plasma and show that it is structurally different from lipoprotein LACI. The purification scheme uses heparin-agarose chromatography, immunoaffinity chromatography, and size-exclusion chromatography and results in a 185,000-fold purification with a 33% yield. Heparin-releasable LACI (HRL), as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, under reducing conditions, appears as a major band at 40 Kd and a minor band at 36 Kd. Immunoblot analysis suggests that the 36-Kd band arises from carboxyl-terminus proteolysis that occurs during the purification. HRL has a specific activity similar to that of HepG2 or lipoprotein LACI. HRL and lipoprotein LACI combine with lipoproteins in vitro while purified HepG2 LACI does not. I125-labeled HRL, injected into a rabbit, is cleared more slowly than I125-labeled HepG2 LACI, which may be due to attachment to lipoproteins in vivo. Preliminary evidence suggests that HRL is associated with vascular endothelium, possibly by attachment to glycosaminoglycans.

Original languageEnglish
Pages (from-to)394-400
Number of pages7
Issue number2
StatePublished - Jan 1 1991

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    Novotny, W. F., Palmier, M., Wun, T. C., Broze, G. J., & Miletich, J. P. (1991). Purification and properties of heparin-releasable lipoprotein-associated coagulation inhibitor. Blood, 78(2), 394-400.