Purification and characterization of a novel anticoagulant and fibrinolytic enzyme produced by endophytic bacterium Paenibacillus polymyxa EJS-3

IntroductionEndophytes may become a new source of thrombolytic agents for thrombosis treatment.Materials and MethodsA novel fibrinolytic enzyme from Paenibacillus polymyxa EJS-3 (PPFE-I) was purified with ammonium sulfate precipitation, hydrophobic chromatography, ion exchange and gel filtration chromatography. The characterization of the enzyme was investigated by means of fibrinolysis plate, hydrolysis of fibrinogen and anticoagulant effect in vitro.ResultsThe fibrinolytic enzyme is purified to homogeneity with a purification of 14.5 fold and a recovery of 3.3%. The enzyme was shown to have a molecular mass of 63.3 kDa by matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The optimum temperature and pH value were 37 °C and 7.5, respectively. Results from the fibrinolysis pattern showed that the enzyme rapidly hydrolyzed the Aα-chain of fibrinogen, followed by the Bβ-chains. It also hydrolyzed the γ-chains, but more slowly. It was activated by metal ions such as Zn2+, Mg2+, and Fe2+, but inhibited by Ca2+ and Cu2+. Furthermore, PPFE-I activity was inhibited strongly by PMSF, and it was found to exhibit a higher specificity for the synthetic substrate N-succinyl-Ala-Ala-Pro-Phe-pNA for chymotrypsin, indicating that the enzyme is a chymotrypsin-like serine protease. Additionly, PPFE-I showed a significant anticoagulant effect in vitro.ConclusionThe fibrinolytic enzyme PPFE-I from endophytic bacterium Paenibacillu polymyxa EJS-3 exhibits a profound fibrinolytic activity.