A new factor Xa inhibitor (lefaxin) from the Haementeria depressa leech

The salivary complex of the leech Haementeria depressa produces potent anticoagulant components. Among them, a protein named lefaxin inhibits factor Xa (FXa). Lefaxin was purified to homogeneity from dissected salivary complexes by gel filtration in Sephadex G-150 followed by two ion exchange chromatography steps in Mono-Q. Inhibition of FXa by lefaxin was demonstrated by the inhibition of its amidolytic activity, measured with chromogenic substrate S-2765 (apparent K(I) of 4 nM), and of its ability to inhibit thrombin generation in the prothrombinase complex (EC50 of 40 nM). Lefaxin has a molecular weight of 30 kDa and an isoelectric point of 5.7. It is made of a polypeptide chain whose N-terminal sequence shows no similarity with that of other FXa inhibitors (antistasin and ghilianten) isolated from leech saliva. On the other hand, the N-terminal sequence of lefaxin presents significant sequence similarity with nitric oxide carrier proteins myohemerythrin from the annelid Nereis diversicolor and prolixin S from the triatoma Rhodnius prolixus. Interestingly, prolixin S also proved to be an anticoagulant protein acting on FXa.

Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.

Isolates lefaxin, a 30-kDa Factor Xa inhibitor from Haementeria depressa — characterizes inhibition kinetics and anticoagulant activity.

Leech-derived molecules this paper discusses, each with a full profile in the ASH compound registry:

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