Purification，characterization and application of ε-poly-Llysine-degrading enzyme from Streptomyces sp．M-Z18

Abstract:

Abstract:［Objective］The ε-poly-L-lysine-degrading enzyme (Pld) derived from Streptomyces sp．M-Z18 was purified and characterized． Furthermore，Pld was used to produce the low polymerization of ε-poly-L-lysine (ε-PL)．［Methods］ Pld was purified to electrophoretical homogeneity through HiTrapTM Butyl HP hydrophobic chromatography after pretreated by ultrasonic and NaSCN dissolving． Subsequently，enzymatic characteristics，kinetic parameters and the time profile of ε-PL degradation by the purified Pld were studied． Meanwhile，we examined the effect of ε-PL with different degrees of polymerization on the minimal inhibitory concentration of bacteria and fungi．［Results］Pld was purified to homogeneity with a final fold of 80.4 and an overall yield of 59.3%. The optimal temperature and pH for the purified Pld were 37°C and 7.0，respectively．Moreover，the Km with L-lysyl-p-nitroanilide as substrate was calculated to be 0. 621 mmol/L，and the Vmax was 701.16 nmol /min·mg．Pld was stable in the range of pH 7.0－10.0，and temperature up to 50°C，respectively． Time profile of ε-PL degradation by the purified Pld indicated that Pld catalyzed endo-type degradation of ε-PL. The experiments of minimal inhibitory showed that ε-PL with high degree of polymerization (30－35) had a superior antibacterial effect on bacteria and the low degree of polymerization ε-PL (8－20) had a better antibacterial effect on yeasts．However，ε-PL with various degrees of polymerization had a poor antibacterial effect on mould． ［Conclusion］The present result showed that an endo-type Pld from ε-PL-producing strain was purified． Meanwhile，it is proved that ε-PL with different degrees of polymerization have exhibited significant different antibacterial effects on microorganism.