【摘要】 从产ε-聚赖氨酸菌株白色链霉菌ZC7中纯化了ε-聚赖氨酸降解酶,并对其性质进行了研究。结果表明,该酶的酶活力在pH=6.0～8.0间稳定,最适宜pH=7.0;酶的最适温度为35℃,在20～40℃水浴30min酶活力未见明显下降。研究了不同金属离子对酶活力的影响,结果表明,Zn2+和Cu2+可分别提高酶活力34%和21%;但Co2+、Mn2+、Fe3+对酶活力有强烈的抑制作用,Mg2+、Ca2+对酶活力没有影响。以ε-聚赖氨酸为底物时,该酶的Km和Vmax值分别为0.226mmol/L和0.402×10-3mmol/(L.S)。ε-聚赖氨酸降解酶很可能与ε-聚赖氨酸合成酶是相互依存的关系,而且ε-聚赖氨酸生产菌表现出强烈的ε-聚赖氨酸降解酶活性,应该与其自身保护作用有关。更多还原

【Abstract】 An ε-poly-L-lysine-degrading enzyme of an ε-poly-L-lysine-producing strain of Streptomyces albulus ZC7 was purified and characterized.The enzyme was stable between pH 6.0 and 8.0 with a maxinum at pH=7.0.The optimum temperature was 35℃,and no significant activity loss was observed when the enzyme was incubated at 20～40℃ for 30min.The effect of different metal ions on the activity of the enzyme were also investigated,some metal ions,including Zn2+ and Cu2+,increased the enzyme activities by 34% and 21%,respectively;while some other metal ions,including Co2+,Mn2+and Fe3+,strongly inhibited the enzyme activity.The enzyme activity was not affected by Mg2+ and Ca2+.Experiment results also showed that EDTA strongly inhibited the enzyme activity.The Km and Vmax values of ε-poly-L-lysine-degrading enzyme for ε-poly-L-lysine were 0.226mmol/L and 0.402×10-3 mmol/(L·S),respectively.ε-Poly-L-lysine-degrading activity was found in the membrane fraction of some other Streptomyces strains as well as that of Streptomyces albulus,which exhibited high ε-poly-L-lysine-degrading activity.Both strains could produce ε-poly-L-lysine which indicating a correlation between the distribution of membrane-bound ε-poly-L-lysine-degrading enzyme and ε-poly-L-lysine-producing activity.更多还原