Functional and sequence characterization of coagulation factor IX/factor X-binding protein from the venom of Echis carinatus leucogaster.

Y L Chen; I H Tsai

doi:10.1021/bi952520q

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Functional and sequence characterization of coagulation factor IX/factor X-binding protein from the venom of Echis carinatus leucogaster.

Y L Chen·I H Tsai

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Abstract

A new coagulation factor IX/factor X-binding protein (IX/X-bp) from Echis carinatus leucogaster venom has been purified and designated ECLV IX/X-bp. ECLV IX/X-bp binds factor IX and X in a Ca(2+)-dependent manner and is devoid of thrombin-inhibitory and platelet-aggregating activities. The apparent dissociation constants (Kd) for binding of ECLV IX/X-bp to factor IX and factor X are 6.6 and 125 nM, respectively. Upon the addition of Mg2+, the required Ca2+ concentration for optimal binding of ECLV IX/X-bp to factor IX and factor X was prominently reduced. Mg2+ also increases the affinity of factor X for the venom protein. Direct binding of IX/X-bp to factor IX and X could also be detected by far-Western blotting, and results of the experiment ruled out the lectin-like mechanism of ECLV IX/X-bp. The complete amino acid sequence and the disulfide pattern of ECLV IX/X-bp was deduced by enzymatic hydrolysis and automated sequencing of the S-pyridylethylated protein. The venom protein is a heterodimer with one subunit of 131 amino acid residues and another of 125 residues. Both subunits are homologous to each other and to other snake venom proteins of the C-type lectin superfamily.

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Amino Acid Sequence Animals Calcium Cattle Disulfides Factor IX Factor X Humans Lectins Lectins, C-Type Magnesium Models, Molecular Molecular Sequence Data Platelet Aggregation Protein Binding Thrombin Viper Venoms Journal Article Research Support, Non-U.S. Gov't

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Y L Chen, I H Tsai. 1996-04-23. Functional and sequence characterization of coagulation factor IX/factor X-binding protein from the venom of Echis carinatus leucogaster.. https://doi.org/10.1021/bi952520q

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