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Fasxiator, a novel factor XIa inhibitor from snake venom, and its site-specific mutagenesis to improve potency and selectivity

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dc.contributor.authorChen, W.
dc.contributor.authorCarvalho, L.P.D.
dc.contributor.authorChan, M.Y.
dc.contributor.authorKini, R.M.
dc.contributor.authorKang, T.S.
dc.date.issued2015
dc.descriptionData source: Supporting information, http://onlinelibrary.wiley.com/doi/10.1111/jth.12797/suppinfo
dc.description.abstractBackground: Bleeding remains a major limitation of standard anticoagulant drugs that target the extrinsic and common coagulation pathways. Recently, intrinsic coagulation factors are increasingly being investigated as alternative targets for developing anticoagulant drugs with lower bleeding risk.Objectives: Goals were to (i) identify novel anticoagulants selectively targeting intrinsic coagulation pathway and (ii) characterize and further improve the properties of the identified anticoagulants. Methods and Results: We have isolated and sequenced a specific factor XIa (FXIa) inhibitor, henceforth named Fasxiator, from the venom of the banded krait snake, Bungarus fasciatus. It is a Kunitz-type protease inhibitor that prolonged activated partial thromboplastin time without significant effects on prothrombin time. Fasxiator was recombinantly expressed (rFasxiator), purified, and characterized to be a slow-type inhibitor of FXIa that exerts its anticoagulant activities (doubled activated partial thromboplastin time at ~ 3 μmol L–1) by selectively inhibiting human FXIa in in vitro assays. A series of mutants were subsequently generated to improve the potency and selectivity of recombinant rFasxiator. rFasxiatorN17R,L19E showed the best balance between potency (IC50 ~ 1 nmol L–1) and selectivity (> 100 times). rFasxiatorN17R,L19E is a competitive slow-type inhibitor of FXIa (Ki = 0.86 nmol L–1), possesses anticoagulant activity that is ~ 10 times stronger in human plasma than in murine plasma, and prolonged the occlusion time of mice carotid artery in FeCl3-induced thrombosis models. Conclusion: We have isolated an exogenous FXIa specific inhibitor, engineered it to improve its potency by ~ 1000 times and demonstrated its in vitro and in vivo efficacy. These proof-of-principle data supported the further development of Fasxiator as a novel anticoagulant candidate.
dc.identifier.citationJournal of Thrombosis and Haemostasis, 2015; 13(2):248-261
dc.identifier.doi10.1111/jth.12797
dc.identifier.issn1538-7933
dc.identifier.issn1538-7836
dc.identifier.urihttps://hdl.handle.net/11541.2/118867
dc.language.isoen
dc.publisherWiley-Blackwell
dc.relation.fundingDepartment of Pharmacy, National University of Singapore
dc.rightsCopyright 2014 International Society on Thrombosis and Haemostatsis
dc.source.urihttps://doi.org/10.1111/jth.12797
dc.subjectAnticoagulants
dc.subjectCarotid artery thrombosis
dc.subjectFactor XIa
dc.subjectProtease inhibitors
dc.subjectSnake venom
dc.titleFasxiator, a novel factor XIa inhibitor from snake venom, and its site-specific mutagenesis to improve potency and selectivity
dc.typeJournal article
pubs.publication-statusPublished
ror.mmsid9915989761601831

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