ABSTRACT
Objective The stability and other characteristics of the active recombinant human anionic trypsin(hT 2) with site-mutation R 122 L(mhT 2) were investigated. Methods An active human anionic trypsin and its R 122 L mutate were produced with E.coli BL 21(DE 3) and purified with ion-exchange chromatography. The properties of mutant were studied and compared with the wild type. Results The optimal pH for mhT 2 was 7~11. mhT 2 was active over a broad temperature range (4℃~80℃) and owned a little better thermal stability than the wild type. The inhibition of typical metal chelating agent(EDTA), Fe 3+, denaturant, reducer(β-ME) on activity of mhT 2 was the same as the wild type. Michaelis constant Km of mhT 2 was 0.010 mmol/L with BAEE as a substrate, a little lower than wild type. Conclusion Compared with the wild type, the R 122 L site mutate significantly enhanced tolerance to acidic pH、denaturants、reductions and autolysis.