Expression, Purification, and Characterization of a Recombined Fibrinolytic Enzyme from Endophytic Paenibacillus polymyxa EJS-3 in Escherichia coli.

The gene encoding the fibrinolytic enzyme (PPFE-I) from Paenibacillus polymyxa EJS-3 was cloned and sequenced (Genbank No. KC176802). The 1773 bp gene encoded 590 amino acids and had low homology with other known fibrinolytic enzymes. PPFE-I was soluble and expressed in E. coli BL21 to enhance the activity. The recombinant enzyme (rPPFE-I) was purified to homogeneity, and enzymatic properties were characterized. The optimal temperature and pH for rPPFE-I were 37°C and 7.5, respectively. Observed activities of rPPFE-I were highest in the presence of Zn²⁺, Mg²⁺, and Fe²⁺ and the lowest in the presence of Ca²⁺ and Cu²⁺. The rPPFE-I activity was strongly inhibited by PMSF. The α-chain was affected by the rPPFE-I cleavage speed of fibrinogen, followed by the b and γ chains. The inhibitory effects of rPPFE-I against ADP-induced human platelet aggregation were dosedependent with an IC50 value of 1.54 μM. [ABSTRACT FROM AUTHOR]