ABSTRACT
Earthworm fibrinolytic enzyme (EFE) is a group of protease having fibrinolytic and plasminogen-activator activities isolated from earthworm. Molecular biology research showed that there were 21 EFE coding sequences, in which only one sequence, AY438624, whose translated protein had similar N-terminal amino-acid sequence to EfP-I purified from Eisenia fetida. To obtain coding sequence of EfP-I , we designed specific primers according to 5' and 3' sequences of AY438624. A new DNA sequence was obtained by RT-PCR, sequence analysis showed that the protein translated from the coding sequence had identical N-terminal amino-acid sequence with EfP-I purified from Eisenia fetida and Lumbricus rubellus. Analysis by using ScanProsite prediction programs proved that the sequence had high similarity to AY438624 and belonged to trypsin family of serine protease. But there was difference between two sequences, that was there was a domain of characteristic amino acids of N-glycosylation site Asn-Xaa-Ser/Thr(N-x-S/T)in the new sequence (DQ418454). Then the expressed vector pMAL-c2X-Efp-I was constructed by cloning the gene into the plasmid pMAL-c2X, and was transformed to E. coli TB1. After induction and expression of the recombinant, the product MBP-EfP-I was purified by MBP affinity chromatography. Western blotting analysis showed that the product reacted with both anti-MBP and anti-EfP-I -1 serum. Casein plate test and fibrin plate test showed that the protein expressed had fibrinolytic activity.
Subject(s)
Animals , Biocatalysis , Blotting, Western , Cloning, Molecular , Electrophoresis, Polyacrylamide Gel , Escherichia coli , Genetics , Fibrin , Metabolism , Fibrinolysis , Gene Expression Regulation, Enzymologic , Oligochaeta , Genetics , Recombinant Proteins , Metabolism , Reverse Transcriptase Polymerase Chain Reaction , Serine Proteases , Genetics , MetabolismABSTRACT
<p><b>AIM</b>To select higher thrombolytic and lower toxic single component of earthworm fibrinolytic enzymes (EFE).</p><p><b>METHODS</b>EFE containing total components were obtained by affinity chromatography from Eisenia fetida. Using ion-exchange chromatography to separate three main components EfP-0-2, EfP-I-1 and EfP-I-2 from EFE, their thrombolytic activity and toxicity were compared with EFE.</p><p><b>RESULTS</b>Among these components, EfP-I-1 had higher thrombolytic activity in vitro. When 4.5 mg x kg(-1) of these components were injected, the contents of fibrinogen in rat serum were not affected, but only EfP-I-1 exhibited distinct thrombolytic activity. When 6.0 mg x kg(-1) of them were injected intravenously, the bleeding time was not evidently delayed only by EfP-I-1. The acute toxicity test showed that the LD50 of EfP-I-1 was higher than EFE by 2. 17 times.</p><p><b>CONCLUSION</b>Because of distinct thrombolytic activity, lower toxicity in vivo, higher content in EFE and easy to purify, EfP-I-1 was adapted to be developed as a single component medicine for treating thrombus.</p>