Polyphosphate exerts differential effects on blood clotting, depending on polymer size

Stephanie A. Smith, Sharon H. Choi, Rebecca Davis-Harrison, Jillian Huyck, John Boettcher, Chad M. Reinstra, James H. Morrissey

Research output: Contribution to journalArticlepeer-review


Polyphosphate, a linear polymer of inorganic phosphate, is secreted by activated platelets and accumulates in many infectious microorganisms. We recently showed that polyphosphate modulates the blood coagulation cascade at 3 steps: it triggers the contact pathway, it accelerates factor V activation, and it enhances fibrin polymerization. We now report that polyphosphate exerts differential effects on blood clotting, depending on polymer length. Very long polymers (≥ 500mers, such as those present in microorganisms) were required for optimal activation of the contact pathway, while shorter polymers (∼ 100mers, similar to the polymer lengths released by platelets) were sufficient to accelerate factor V activation and abrogate the anticoagulant function of the tissue factor pathway inhibitor. Optimal enhancement of fibrin clot turbidity by polyphosphate required ≥ 250mers. Pyrophosphate, which is also secreted by activated platelets, potently blocked polyphosphate-mediated enhancement of fibrin clot structure, suggesting that pyrophosphate is a novel regulator of fibrin function. In conclusion, polyphosphate of the size secreted by platelets is very efficient at accelerating blood clotting reactions but is less efficient at initiating them or at modulating clot structure. Microbial polyphosphate, which is highly procoagulant, may function in host responses to pathogens.

Original languageEnglish (US)
Pages (from-to)4353-4359
Number of pages7
Issue number20
StatePublished - Nov 18 2010

ASJC Scopus subject areas

  • Biochemistry
  • Immunology
  • Hematology
  • Cell Biology

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