Thromb Haemost 1984; 52(02): 117-120
DOI: 10.1055/s-0038-1661152
Original Article
Schattauer GmbH Stuttgart

Role of Endogenous Proteinase Inhibitors in the Regulation of the Blood Clotting System of the Horseshoe Crab, Limulus Polyphemus

Peter B Armstrong
1   The Marine Biological Laboratory, Woods Hole, MA, U.S.A.
2   The Department of Zoology, University of California, Davis, CA, U.S.A.
,
Jack Levin
1   The Marine Biological Laboratory, Woods Hole, MA, U.S.A.
3   The Departments of Laboratory Medicine and Medicine, University of California School of Medicine, San Francisco, CA, U.S.A.
,
James P Quigley
1   The Marine Biological Laboratory, Woods Hole, MA, U.S.A.
4   The Department of Microbiology and Immunology, Downstate Medical Center, State University of New York, Brooklyn, NY, U.S.A.
› Author Affiliations
Further Information

Publication History

Received 14 February 1984

Accepted 14 June 1984

Publication Date:
19 July 2018 (online)

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Summary

Blood clotting in Limulus is dependent on the activity of a proteinase which converts the zymogen, coagulogen, into a form that undergoes polymerization to form the clot. The abilities of a series of recently discovered endogenous proteinase inhibitors to inhibit this enzyme and thereby serve as potential regulators of its activity were explored. The blood plasma of Limulus contains a single inhibitor that is functionally and structurally homologous to vertebrate α2 macroglobulin. During exocytosis, the blood cells (amebocytes) release a series of inhibitors, including small quantities of the α2 macroglobulin homologue; a low molecular weight, acid-and heat-stable inhibitor; and an acid-labile activity. Of the three inhibitory activities, only the cell-released, acidlabile inhibitor is capable of inhibiting the clotting enzyme.