Cloning, expression, purification and bioactivity evaluation of a thrombin-like enzyme from Deinagkistrodon acutus...

To identify a new member of serine proteases from Deinagkistrodon acutus via phage display technique and appraise its biocatalytic activities.

A novel thrombin-like enzyme gene was cloned by screening the phage display library of D. acutus venom gland. The gene has a 783 bp ORF encoding 260 amino acids. A recombinant enzyme expression vector was constructed and the fused protein was expressed in Escherichia coli. The protein was purified showing a single band of approx. 49.4 kDa after SDS-PAGE. The recombinant enzyme was capable of congealing normal human plasma in vitro with the minimum coagulant dose of 6 µg in 57 s. It exhibited fibrinogenolytic activity by hydrolyzing the Aα-chain of human fibrinogen. It was most active at pH 7.5-8.0 and 35-40 °C with the highest clotting activity of 120 NIH units/mg. It was completely inhibited by PMSF but not by EDTA. Multiple sequence alignments demonstrate that this protein shares high identity with other thrombin-like enzymes from snake venoms.

A novel thrombin-like protein from D. acutus venom was identified, expressed and biologically characterized in vitro. Its fibrinogenolytic properties make the enzyme applicable for biochemical research and drug development on thrombolytic therapy.