Purification and characterization of a novel extracellular esterase from pathogenic Streptomyces scabies that is inducible by zinc
Purification and characterization of a novel extracellular esterase from pathogenic Streptomyces scabies that is inducible by zinc
复制标题
锌诱导的致病性疥疮链霉菌新型胞外酯酶的纯化和表征
作者：
D A McQueen;J. Schottel
天然聚丙烯酰胺凝胶的胞外蛋白产生的几个链霉菌菌株生长与木栓林酯酶活性原位测定。来自不同地理区域的两个致病性疥疮链霉菌菌株被发现产生类似的酯酶活性，而非致病性菌株不产生。EDTA处理后，木栓质不再诱导酯酶的产生。当EDTA处理的木栓蛋白补充锌时，表达恢复。酯酶产生所需的最佳锌浓度为2 μ M。这种酯酶纯化的致病菌株之一，其特征在于。用Sephadex G-100凝胶过滤法测得酶的分子量为38，000道尔顿，用变性聚丙烯酰胺凝胶电泳法测得酶的分子量为36，000道尔顿。该酯酶在pH 8.0以上的磷酸钠缓冲液中显示出最大活性，在高达60 ℃的温度下稳定，并且具有125 μ M的表观Km。
Native polyacrylamide gels of extracellular proteins produced by several Streptomyces isolates grown with suberin were assayed in situ for esterase activity. Two pathogenic isolates of Streptomyces scabies from different geographical regions were found to produce a similar esterase activity that was not produced by nonpathogenic strains. After treatment with EDTA, suberin no longer induced esterase production. Expression was restored when EDTA-treated suberin was supplemented with zinc. The optimal concentration of zinc required for esterase production was 2 microM. This esterase was purified from one of the pathogenic isolates and characterized. The enzyme was 38,000 daltons when determined by gel filtration on Sephadex G-100 and 36,000 daltons when determined by denaturing polyacrylamide gel electrophoresis. The esterase showed maximal activity in sodium phosphate buffer above pH 8.0, was stable to temperatures of up to 60 degrees C, and had an apparent Km of 125 microM p-nitrophenyl butyrate.