Kang S K, Jung Y J, Kim C H, Song C Y
Department of Biology, Chung-Ang University, Dongjak-ku, Seoul 156-756, Korea.
Clin Diagn Lab Immunol. 1998 Nov;5(6):784-9. doi: 10.1128/CDLI.5.6.784-789.1998.
Two forms of iron superoxide dismutase (SOD) were purified from cell extract (CE) and culture filtrate (CF) of Mycobacterium bovis BCG, respectively. The molecular weight of both enzymes was estimated to be approximately 84,000 by gel filtration, whereas that of their subunits was 21,500, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, indicating that each of purified enzymes is composed of four identical subunits. The specific activities of CE SOD and CF SOD were 3,850 and 4,040, respectively. The purified enzymes were not joined by disulfide bonds and were, to some extent, resistant to sodium dodecyl sulfate. Their activities were lost by H2O2, but not by azide and cyanide, indicating iron SODs. Enzyme activities were detectable over a broad range of pHs, from 5.0 to 9.0, and were stable for 6 months at -20 degreesC. Each value of pI was 4.5. In Western blots, both enzymes reacted with sera of tuberculosis patients, but not with normal sera. The N-terminal amino acid sequences of CE SOD and CF SOD were the same, suggesting that there is no N-terminal signal sequence.
分别从卡介苗（Mycobacterium bovis BCG）的细胞提取物（CE）和培养滤液（CF）中纯化出两种形式的铁超氧化物歧化酶（SOD）。通过凝胶过滤法估计这两种酶的分子量约为84,000，而通过十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳测定其亚基的分子量为21,500，这表明每种纯化的酶均由四个相同的亚基组成。CE SOD和CF SOD的比活性分别为3,850和4,040。纯化的酶不是通过二硫键连接的，并且在一定程度上对十二烷基硫酸钠具有抗性。它们的活性被过氧化氢（H2O2）灭活，但不被叠氮化物和氰化物灭活，表明是铁SOD。在5.0至9.0的广泛pH范围内可检测到酶活性，并且在-20℃下可稳定保存6个月。每个pI值均为4.5。在蛋白质免疫印迹中，两种酶均与结核病患者的血清发生反应，但与正常血清不发生反应。CE SOD和CF SOD的N端氨基酸序列相同，表明不存在N端信号序列。
