MECHANISM OF CHROMIUM(VI) TOXICITY IN ESCHERICHIA-COLI - IS HYDROGEN-PEROXIDE ESSENTIAL IN CR(VI) TOXICITY
MECHANISM OF CHROMIUM(VI) TOXICITY IN ESCHERICHIA-COLI - IS HYDROGEN-PEROXIDE ESSENTIAL IN CR(VI) TOXICITY
复制标题
DOI：
10.1093/oxfordjournals.jbchem.a124776
复制
发表时间：
1995-04-01
影响因子：
2.7
通讯作者：
TAKAMIZAWA, K
中科院分区：
文献类型：
--
作者：
ITOH, M;NAKAMURA, M;TAKAMIZAWA, K
为了研究过氧化氢在Cr（VI）对细菌细胞的体内毒性中的作用，我们研究了Cr（VI），过氧化氢，叠氮化钠和甘露醇对大肠杆菌活力的影响。在Cr（VI）、过氧化氢、作为过氧化氢酶抑制剂的叠氮化钠和/或作为自由基清除剂的甘露醇的存在下振荡孵育细菌细胞1小时。检测细胞集落形成能力和双链DNA降解情况。活力测定表明，铬（VI）的毒性依赖于涉及过氧化氢和铬的反应中产生的羟基自由基。此外，大肠杆菌细胞与10 mM Cr（VI）和3 mM过氧化氢的孵育引起双链DNA在体内的降解，这是通过添加甘露醇抑制。这些结果表明，在孵育过程中产生的羟基自由基降解大肠杆菌细胞的DNA，导致细胞死亡。在不添加过氧化氢的情况下，E.大肠杆菌的表达量较低（低于1 μ M）。在不添加过氧化氢的情况下孵育的过氧化氢酶缺陷菌株在1小时后仍然完全存活，但在长时间孵育（4-8小时）后显示出活力降低。甘露醇的加入抑制了这种下降，这表明即使没有添加过氧化氢，羟基自由基也可能参与Cr（VI）毒性的表达。
To investigate the role of hydrogen peroxide in Cr(VI) toxicity in vivo toward bacterial cells, we examined the effect of Cr(VI), hydrogen peroxide, sodium azide, and mannitol on the viability of Escherichia coli. Bacterial cells were incubated for 1 h with shaking in the presence of Cr(VI), hydrogen peroxide, sodium azide as catalase inhibitor, and/or mannitol as radical scavenger. The colony-forming ability and double-strand DNA degradation were examined. The viability assays revealed that Cr(VI) toxicity depended on hydroxyl radicals generated in the reaction involving hydrogen peroxide and chromium. Moreover, incubation of E, coli cells with 10 mM Cr(VI) and 3 mM hydrogen peroxide caused the degradation of double-strand DNA in vivo, which was suppressed by the addition of mannitol. These results indicated that hydroxyl radicals generated in the incubation degraded DNA of E, coli cells, resulting in cell death. In the absence of added hydrogen peroxide, the intracellular concentration of hydrogen peroxide in E. coli was low (below 1 mu M). A catalase-defective strain incubated in the absence of added hydrogen peroxide remained fully viable after Ih but showed decreased viability after prolonged incubation (4-8 h). The addition of mannitol suppressed this decrease, suggesting that hydroxyl radicals may be involved in the expression of Cr(VI) toxicity even without added hydrogen peroxide.