title: A new factor Xa inhibitor (lefaxin) from the Haementeria depressa leech.
abstract: 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.
authors.affiliation: Laboratorio de Fisiopatologia, Instituto Butantan, São-Paulo, Brasil.
authors.forename: F
authors.initials: F
authors.lastname: Faria
authors.forename: E M
authors.initials: EM
authors.lastname: Kelen
authors.forename: C A
authors.initials: CA
authors.lastname: Sampaio
authors.forename: C
authors.initials: C
authors.lastname: Bon
authors.forename: N
authors.initials: N
authors.lastname: Duval
authors.forename: A M
authors.initials: AM
authors.lastname: Chudzinski-Tavassi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000925:Anticoagulants / Q000494:pharmacology*; D001777:Blood Coagulation / Q000187:drug effects*; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D002863:Chromogenic Compounds / Q000378:metabolism; D065427:Factor Xa Inhibitors; D015801:Helminth Proteins / Q000302:isolation & purification* / Q000494:pharmacology; D006420:Hemeproteins / Q000737:chemistry / Q000494:pharmacology; D006422:Hemerythrin / Q000031:analogs & derivatives / Q000737:chemistry; D006801:Humans; D007865:Leeches / Q000737:chemistry*; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000378:metabolism; D012463:Saliva / Q000737:chemistry*; D012471:Salivary Proteins and Peptides / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015842:Serine Proteinase Inhibitors / Q000302:isolation & purification* / Q000494:pharmacology; D013045:Species Specificity; D013379:Substrate Specificity; D013925:Thromboplastin / Q000037:antagonists & inhibitors
chemical_list: D000925:Anticoagulants; D002863:Chromogenic Compounds; D065427:Factor Xa Inhibitors; D015801:Helminth Proteins; D006420:Hemeproteins; D006422:Hemerythrin; D009842:Oligopeptides; D012471:Salivary Proteins and Peptides; D015842:Serine Proteinase Inhibitors; C403770:lefaxin; C008571:myohemerythrin; C090560:nitrophorin; C015608:benzoyl-Ile-Glu-Gly-Arg-p-nitroanilide; D013925:Thromboplastin