HYDROXYMETHYLURACIL DNA GLYCOSYLASE IN MAMMALIAN-CELLS
HYDROXYMETHYLURACIL DNA GLYCOSYLASE IN MAMMALIAN-CELLS
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DOI：
10.1073/pnas.81.13.4003
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发表时间：
1984-01-01
期刊：
影响因子：
--
通讯作者：
AMES, BN
中科院分区：
文献类型：
--
作者：
HOLLSTEIN, MC;BROOKS, P;AMES, BN
从小鼠浆细胞瘤细胞提取物中纯化350倍的活性物质，其形成5-羟甲基尿嘧啶（α-羟基胸腺嘧啶）和无嘧啶位点与噬菌体SPO 1 DNA，其中含有该碱基代替胸腺嘧啶。这种DNA糖基化酶的功能可能是消除羟甲基尿嘧啶，这是一种由电离辐射和氧化损伤产生的主要胸腺嘧啶衍生的DNA损伤。该酶不需要辅因子，在EDTA中有活性。既没有中间体的形成，也没有水解的羟甲基脱氧尿苷或羟甲基脱氧尿苷一磷酸检测。该酶不裂解DNA中的无嘧啶位点。它确实从噬菌体PBS 2的含尿嘧啶DNA中释放尿嘧啶，但这种活性小于细胞主要尿嘧啶DNA糖基化酶活性的2%，其通过磷酸纤维素色谱法分离。主要的尿嘧啶DNA糖基化酶不会从SPO 1 DNA中释放羟甲基尿嘧啶。羟甲基尿嘧啶糖基化酶也在磷酸纤维素色谱法上与胸腺嘧啶二醇DNA糖基化酶活性分离，所述胸腺嘧啶二醇DNA糖基化酶活性伴随无嘧啶核酸内切酶活性。
An activity was purified 350-fold from extracts of mouse plasmacytoma cells that forms 5-hydroxymethyluracil (.alpha.-hydroxythymine) and apyrimidinic sites with phage SPO1 DNA, which contains this base in place of thymine. This DNA glycosylase presumably functions to eliminate hydroxymethyluracil, a major thymine-derived DNA lesion produced by ionizing radiation and oxidative damage. The enzyme has no cofactor requirement and is active in EDTA. Neither intermediate formation nor hydrolysis of hydroxymethyldeoxyuridine or hydroxymethyldeoxyuridine monophosphate was detected. The enzyme does not cleave apyrimidinic sites in DNA. It does release uracil from the uracil-containing DNA of phage PBS2, but this activity is less than 2% of the predominant uracil DNA glycosylase activity of the cell, which is separated by phosphocellulose chromatography. The major uracil DNA glycosylase does not release hydroxymethyluracil from SPO1 DNA. The hydroxymethyluracil glycosylase is also separated upon phosphocellulose chromatography from a thymine glycol DNA glycosylase activity that is accompanied by an apyrimidinic endonuclease activity.