对损伤DNA具有特异性的人类酶的特性：从一种对烷基化DNA具有活性的明显N-糖苷酶中解析出辐照DNA的内切核酸酶。
Characterization of human enzymes specific for damaged DNA: resolution of endonuclease for irradiated DNA from an apparent N-glycosidase active on alkylated DNA.
作者信息
Brent T P
出版信息
Nucleic Acids Res. 1977 Jul;4(7):2445-54. doi: 10.1093/nar/4.7.2445.
An endonuclease partially purified from human lymphoblasts, and active against ultraviolet-irradiated DNA, was found to act additionally on DNA damaged by either x-radiation or methylmethanesulfonate. To determine if these activities were truly endonucleolytic, the reaction products were analyzed under conditions that prevented conversion of apurinic or apyrimidinic sites to single-strand breaks. With either ultraviolet- or x-irradiated DNA, strand breakage remained maximal, hence confirming the endonucleolytic character of the enzyme. By contrast, with DNA alkylated with methylmethanesulfonate, strand breakage was sharply reduced. Additional experiments indicated that the activity for alkylated DNA induces strand breaks only in concert with a purified endonuclease specific for apurinic sites, suggesting that it is an N-glycosidase that depurinates alkylated bases. This enzyme was separated from the endonuclease specific for irradiated DNA, by chromatography on DNA-agarose.
从人淋巴母细胞中部分纯化得到一种核酸内切酶，它对紫外线照射的DNA有活性，还发现它对受X射线或甲磺酸甲酯损伤的DNA也有作用。为了确定这些活性是否真的是核酸内切酶活性，在防止脱嘌呤或脱嘧啶位点转化为单链断裂的条件下分析反应产物。无论是紫外线还是X射线照射的DNA，链断裂都保持在最大值，从而证实了该酶的核酸内切酶特性。相比之下，对于用甲磺酸甲酯烷基化的DNA，链断裂明显减少。进一步的实验表明，烷基化DNA的活性仅与一种对脱嘌呤位点具有特异性的纯化核酸内切酶协同作用时才诱导链断裂，这表明它是一种使烷基化碱基脱嘌呤的N-糖苷酶。通过在DNA-琼脂糖上进行层析，将这种酶与对辐照DNA具有特异性的核酸内切酶分离。
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