Rozenberg-Arska M, Van Asbeck B S, Martens T F, Verhoef J
J Gen Microbiol. 1985 Dec;131(12):3325-30. doi: 10.1099/00221287-131-12-3325.
Bacterial DNA was incubated with xanthine plus xanthine oxidase plus excess iron as an oxygen-species-generating system, and DNA injury was measured by agarose gel electrophoresis and by the ability of the DNA to transform competent bacteria. After 5 to 10 min incubation, the covalently closed circular form of plasmid DNA was converted into the open circular form, and after 30 min, to some extent into the linear form. Biological activity, measured as the number of transformed bacteria, decreased rapidly after 10 min incubation. Incubation of chromosomal DNA with the enzymic oxygen-species-generating system resulted in the degradation of DNA to small fragments within about 1 h. Excess iron was essential for the damaging effect of xanthine plus xanthine oxidase. Damage to DNA could be prevented by oxygen scavengers such as superoxide dismutase, catalase, mannitol and thiourea. Our results suggest that hydroxyl radical is the injurious oxidant for bacterial DNA, and that it can mediate physicochemical as well as biological alterations in DNA.
将细菌DNA与黄嘌呤、黄嘌呤氧化酶以及作为产氧体系的过量铁一起孵育，通过琼脂糖凝胶电泳以及DNA转化感受态细菌的能力来检测DNA损伤。孵育5至10分钟后，共价闭合环状形式的质粒DNA转变为开环形式，30分钟后在一定程度上转变为线性形式。以转化细菌数量衡量的生物活性在孵育10分钟后迅速下降。将染色体DNA与酶促产氧体系一起孵育会导致DNA在约1小时内降解为小片段。过量铁对于黄嘌呤加黄嘌呤氧化酶的损伤作用至关重要。超氧化物歧化酶、过氧化氢酶、甘露醇和硫脲等氧清除剂可防止DNA损伤。我们的结果表明，羟自由基是细菌DNA的损伤性氧化剂，并且它可介导DNA的物理化学以及生物学改变。
