Cloning and expression of the elastase gene Bacillus subtilis and identification of the ability of preparation of soybean peptide

A elastase gene named TX1 was isolated from the genomic DNA of Bacillus subtilis by PCR amplification, and constructed into p EAZY E1 vector to generate a recombinant expression plasmid p EAZY E1-TX1. The recombinant plasmid was transformed into E.coli BL21. The expression was induced by IPTG and the fusion protein His-TX1 was purified by Ni-NTA. The ability of the purified expression of hydrolysis of Soybean Peptide was identified by p H-stat method. The sequence analysis suggested that TX1 gene was cloned with a length of 1143 bp, had 99.48% homology with the Elastase gene (JQ305692.1) published in the Gen Bank, and the mutants would not infected the sequence of the amimo acids encoded. The analysis of expression showed that the highest expression level was obtained with 0.3mmol·L-1IPTG at 28℃ for 4h. The SDS-PAGE and Western blotting analysis showed that fusion protein which was 39.4ku purified with nickel-nitrilotriacetic acid (Ni-NTA) metal-affinity chromatography matrices was the Elastase His-TX1. The highest hydrolysis activity of HIS-TX1 was detected at 50℃, p H7.4 for 4h, the hydrolysis reached 14.51%.